Hydronic Piping
Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
Showing changes from Rev 7
to Rev 8
in Hydronic Piping.
−---
−title: Hydronic Piping
−category: Mechanical / Piping & Pumps
−toc_depth: 3
−description: >
− When to use: Closed-loop hydronic piping systems for heating hot water (HHW), chilled water (CHW), and condenser water (CW) in commercial, institutional, and industrial buildings. Covers pipe materials and joining by service and size, isolation and balancing valves, control valves, fittings, pipe insulation, hangers and supports, pipe anchors and guides, expansion compensation, air separation, expansion tanks, pressure testing, and system cleaning, flushing, and chemical treatment. Intended for systems operating within the pressure and temperature limits of ASME B31.9 — up to 160 psig and 250°F for hot water, and 150 psig for chilled and condenser water.
− Not intended for: Domestic (potable) cold and hot water supply (see [[sync/domestic-water-piping]]); sanitary waste and vent piping (see [[sync/sanitary-waste-and-vent-piping]]); fire protection piping (see [[sync/wet-pipe-fire-sprinkler-systems]]); steam distribution or steam condensate return piping; refrigerant piping (governed by ASME B31.5); high-temperature hot water systems above 250°F or above 160 psig (governed by ASME B31.1); or air-side equipment (see [[sync/air-handling-units]] and [[sync/hvac-ductwork]]). Pumps, water treatment systems, and variable frequency drives for pump motors are addressed in companion standards [[sync/hvac-pumps]], [[sync/hvac-water-treatment]], and [[sync/hvac-variable-frequency-drives]].
−---
−
−# Scope {toc}
−
−## This specification covers the materials, fabrication, installation, testing, and commissioning of closed-loop hydronic piping systems within commercial, institutional, and industrial buildings. {note}
−## The systems addressed include heating hot water (HHW), chilled water (CHW), and condenser water (CW) distribution, including the supply and return mains, risers, runouts, terminal unit connections, and all associated components — valves, strainers, expansion devices, air separators, expansion tanks, flexible connectors, and insulation. {note}
−
−## Hydronic piping is the circulatory system of the building's HVAC plant. {note}
−## It moves thermal energy between central equipment — boilers, chillers, cooling towers, heat exchangers — and the terminal equipment that conditions occupied spaces. {note}
−## Because the system is entirely closed and recirculating, the quality, cleanliness, and chemistry of the system water profoundly affects the long-term integrity of all piping, valves, and equipment surfaces. {note}
−## This standard addresses not only the structural installation of the piping system but the entire commissioning sequence — flushing, chemical treatment, and testing — that determines whether the system will operate reliably over its service life. {note}
−
−## The work shall comply with ASME B31.9, Building Services Piping, the adopted edition of the International Mechanical Code (IMC) Chapter 12, and all applicable provisions of the local Authority Having Jurisdiction.
−
−## The boundary of work under this standard is the piping and piping specialties from the flanged or mechanical-joint connections at central plant equipment through all distribution piping to the flanged or union connections at terminal heating and cooling coils, fan-coil units, heat exchangers, and induction units.
−
−## Terminal unit equipment itself is not covered; coordinate equipment requirements with [[sync/air-handling-units]] and relevant equipment standards. {note}
−
−## Pumps and pump sets are covered in [[sync/hvac-pumps]], variable frequency drives on pump motors in [[sync/hvac-variable-frequency-drives]], and water treatment chemical programs in [[sync/hvac-water-treatment]]; this standard covers the physical flushing, fill, and initial treatment that places the system in condition to receive the chemical treatment program. {note}
−
−# Referenced Standards {toc}
−
−## Equipment, materials, and installation shall comply with the latest adopted editions of the following standards.
−
−| Standard | Title |
−|----------|-------|
−| ASME B31.9 | Building Services Piping |
−| ASME B16.9 | Factory-Made Wrought Buttwelding Fittings |
−| ASME B16.11 | Forged Fittings, Socket-Welding and Threaded |
−| ASME B16.21 | Nonmetallic Flat Gaskets for Pipe Flanges |
−| ASME B16.22 | Wrought Copper and Copper Alloy Solder-Joint Pressure Fittings |
−| ASME B16.24 | Cast Copper Alloy Pipe Flanges, Flanged Fittings, and Valves |
−| ASME B16.25 | Buttwelding Ends |
−| ASME B16.34 | Valves — Flanged, Threaded, and Welding End |
−| ASME Sec. IX | Boiler and Pressure Vessel Code — Welding and Brazing Qualifications |
−| ASTM A53 | Seamless and Welded Steel Pipe |
−| ASTM A106 | Seamless Carbon Steel Pipe for High-Temperature Service |
−| ASTM A234 | Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service |
−| ASTM B88 | Seamless Copper Water Tube |
−| ASTM B88M | Seamless Copper Water Tube (Metric) |
−| ASTM C534 | Preformed Flexible Elastomeric Cellular Thermal Insulation in Sheet and Tubular Form |
−| ASTM C553 | Mineral Fiber Blanket Thermal Insulation for Commercial and Industrial Applications |
−| ASTM C585 | Inner and Outer Diameters of Rigid Thermal Insulation for Nominal Sizes of Pipe and Tubing |
−| ASTM C1290 | Flexible Fibrous Glass Pipe Insulation |
−| AWS A5.8 | Specification for Filler Metals for Brazing and Braze Welding |
−| ANSI/ASHRAE/IES 90.1 | Energy Standard for Buildings Except Low-Rise Residential Buildings |
−| IMC | International Mechanical Code, Chapter 12 (Hydronic Piping) |
−| MSS SP-58 | Pipe Hangers and Supports — Materials, Design, Manufacture, Selection, Application, and Installation |
−| SMACNA | HVAC Systems — Duct Design (for system coordination) |
−| NFPA 13 | Standard for the Installation of Sprinkler Systems (for system separation) |
−
−## Where the contract documents, the adopted building code, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
−
−# Submittals {toc}
−
−## Action Submittals {toc}
−
−### The action submittals required for the Engineer's review and return before procurement and installation are the product data, drawings, qualification records, and plans listed below. {note}
−
−- Product data sheets for all pipe materials, including manufacturer, standard designation, wall schedule or type, pressure rating, and service temperature range, for each service (HHW, CHW, CW) and each pipe size range covered
−- Product data sheets for all fitting types, showing material, applicable ASME standard, pressure class, and compatible pipe schedule
−- Product data sheets and dimensional drawings for all valves — isolation, balancing, control, check, pressure relief, pressure-reducing, and butterfly — with pressure and temperature ratings, Cv values for control valves, and end connection details
−- Product data sheets for grooved mechanical couplings and fittings where used, including the gasket material and pressure rating by service
−- Product data sheets for flexible pipe connectors (pump connections and equipment connections), with pressure rating and movement capability
−- Product data sheets for air separators, combination air separator/dirt separator units, and automatic air vents, with ratings and connection sizes
−- Product data sheets for expansion tanks, with pre-charge pressure, acceptance volume, total volume, and design working pressure
−- Product data sheets for dielectric unions and dielectric fittings where used
−- Pipe hanger and support catalog cuts, with hanger types per MSS SP-58 designation, rod and beam clamp ratings, and thermal insulation shield details for insulated lines
−- Pipe insulation product data, showing thermal conductivity (k-factor) at the specified mean temperature, moisture vapor permeability, facing description, and applicable ASTM standards
−- A hydronic piping coordination drawing set showing routing, pipe sizes, support locations, anchor and guide locations, expansion loop or expansion joint locations, valve locations, and equipment connection details. Coordination drawings shall be at a scale sufficient to resolve conflicts with structural members, conduit, duct, and other mechanical piping before rough-in. Coordinate with [[sync/hvac-ductwork]] and [[sync/raceways-and-conduit]] spatial envelopes
−- Welding and brazing procedure specifications (WPS) and procedure qualification records (PQR) per ASME Section IX for all butt-weld and brazed joints, where required by ASME B31.9
−- Welder and brazer qualification records for all personnel who will perform work on this project
−- A written pressure test plan describing the test boundaries, test medium, test pressure, test duration, pressure gauges to be used, method of isolation, and the sequence of testing that allows progressive testing before systems are insulated
−- A written flushing and cleaning plan describing the sequence, temporary piping or bypass arrangements, flush velocity requirements, flush duration, sample collection method, and acceptance criteria
−- Chemical treatment start-up plan coordinated with [[sync/hvac-water-treatment]]
−
−```datasheet
−label: Action Submittals Required
−type: checkbox
−options:
− - "Pipe material product data by service and size"
− - "Fitting product data by type and pressure class"
− - "Valve product data (isolation, balancing, control, check, PRV)"
− - "Grooved coupling product data (where used)"
− - "Flexible connector product data"
− - "Air separator and automatic air vent product data"
− - "Expansion tank product data"
− - "Pipe hanger and support product data"
− - "Pipe insulation product data"
− - "Hydronic piping coordination drawings"
− - "Welding/brazing procedure and qualification records"
− - "Pressure test plan"
− - "Flushing and cleaning plan"
− - "Chemical treatment start-up plan"
−default: "Pipe material product data by service and size"
−```
−
−### The Contractor shall submit the action submittals listed above for the Engineer's review and return before procurement and installation.
−
−### Work on each system shall not proceed until the corresponding submittals are returned.
−
−### Submittals shall be complete and coordinated across all system components before any item is submitted; piecemeal submittals that require multiple resubmissions due to internal inconsistency will not be accepted.
−
−## Closeout Submittals {toc}
−
−### The closeout submittals required at substantial completion before the hydronic systems are accepted are the reports, drawings, schedules, and records listed below. {note}
−
−- Signed and dated pressure test reports for all systems, with measured pressure, test duration, observed pressure drop, and pass/fail determination
−- Signed and dated flushing reports documenting the flush velocity achieved, flush duration, water clarity before and after flushing, and particle count or turbidity measurement if specified
−- Initial chemical treatment reports documenting the water treatment chemical added, dosage, initial chemistry results (pH, inhibitor concentration, conductivity), and the baseline reading established for the ongoing treatment program
−- As-built piping drawings reflecting the actual installed routing, all valve numbers, hanger locations, anchor and guide locations, and expansion device locations
−- Valve tag schedule correlating each valve tag number to its system, service, size, type, normal position (open/closed), and location description
−- Operation and maintenance manuals for all specialty items — expansion tanks, air separators, strainers, balancing valves, pressure-reducing valves, and pressure relief valves — including scheduled maintenance intervals and procedures
−- Record of all welding and brazing, including the joint number, welder/brazer identification, procedure used, and inspection result
−
−```datasheet
−label: Closeout Submittals Required
−type: checkbox
−options:
− - "Signed and dated pressure test reports for all systems"
− - "Signed and dated flushing reports"
− - "Initial chemical treatment reports with baseline chemistry"
− - "As-built piping drawings"
− - "Valve tag schedule"
− - "Operation and maintenance manuals for all specialty items"
− - "Record of all welding and brazing"
−default: "Signed and dated pressure test reports for all systems"
−```
−
−### At substantial completion, the Contractor shall provide the closeout submittals listed above before the hydronic systems are accepted.
−
−# Quality Assurance {toc}
−
−## Code Compliance {toc}
−
−### All piping work shall comply with ASME B31.9, Building Services Piping, including its requirements for design, materials selection, fabrication, installation, examination, and testing.
−
−### Where ASME B31.9 defers to other codes (for example, ASME Section IX for welder qualification), those referenced codes shall be followed.
−
−### The Contractor shall maintain a copy of ASME B31.9 at the project site throughout installation and shall make it available for inspection.
−
−## Welder and Brazer Qualifications {toc}
−
−### Personnel performing welded or brazed pipe joints shall be qualified under ASME Section IX for the procedure, position, and pipe schedule being welded or brazed.
−
−### Welder and brazer qualification records shall be available at the site.
−
−### Where a welder or brazer has not performed qualified work within six months, requalification shall be required before that person performs production work on this project.
−
−### The Contractor shall not allow unqualified personnel to make production joints under any circumstances; rework of joints made by unqualified personnel is at the Contractor's expense.
−
−## Examination of Welds {toc}
−
−### Welded joints in steel piping shall be visually examined in accordance with ASME B31.9 after each joint is completed and before the joint is buried, covered by insulation, or otherwise made inaccessible.
−
−### Visual examination shall confirm that the weld is full profile, free of cracks, undercut, overlap, and surface porosity, and that the weld smoothly transitions to the base metal on each side.
−
−### Random radiographic or ultrasonic examination shall be performed where called for by ASME B31.9 based on the system operating conditions, or as specified by the Engineer of Record.
−
−### Unacceptable welds shall be repaired or cut out and re-welded, and repair welds shall be re-examined.
−
−## Brazed Joint Quality {toc}
−
−### Brazed joints shall be made by qualified brazers using the approved brazing procedure.
−
−### On completion, each brazed joint shall show a uniform fillet of brazing filler metal around the entire circumference of the socket joint, with the filler metal visible at the socket mouth.
−
−### Joints that show voiding, incomplete fill, or incomplete flow of filler metal shall be re-made.
−
−## Installer Qualifications {toc}
−
−### The Contractor performing hydronic piping work shall have a minimum of five years of documented experience installing commercial HVAC hydronic piping systems of similar scope and complexity.
−
−### The Contractor's supervision shall include at least one individual who has completed a recognized mechanical contractor apprenticeship program or holds a current journeyman license in the applicable jurisdiction.
−
−## Single-Source Responsibility for Grooved Systems {toc}
−
−### Where mechanical grooved coupling systems are used, all grooved couplings, fittings, gaskets, and grooving tools for a given pipe size and service shall be products of a single manufacturer to ensure geometric compatibility and consistent gasket compression.
−
−### Mixing grooved coupling components from different manufacturers is not permitted.
−
−# Environmental and Service Conditions {toc}
−
−## System Design Parameters {toc}
−
−### The design operating conditions governing material selection, pressure class, and hanger spacing shall be as indicated on the contract drawings for each system.
−### The datasheet fields below record the project-specific operating parameters; they shall be completed by the Engineer of Record before the standard is issued for construction.
−
−```datasheet
−label: Heating Hot Water (HHW) — Design Supply Temperature
−type: range
−unit: °F
−options:
− min: 120
− max: 250
− setpoints: [120, 140, 160, 180, 200, 210, 250]
−default: 180
−```
−
−```datasheet
−label: Heating Hot Water (HHW) — Design System Operating Pressure
−type: range
−unit: psig
−options:
− min: 30
− max: 160
− setpoints: [30, 50, 75, 100, 125, 150, 160]
−default: 125
−```
−
−```datasheet
−label: Chilled Water (CHW) — Design Supply Temperature
−type: range
−unit: °F
−options:
− min: 36
− max: 55
− setpoints: [40, 42, 44, 45, 48, 50, 55]
−default: 44
−```
−
−```datasheet
−label: Chilled Water (CHW) — Design System Operating Pressure
−type: range
−unit: psig
−options:
− min: 30
− max: 150
− setpoints: [30, 50, 75, 100, 125, 150]
−default: 100
−```
−
−```datasheet
−label: Condenser Water (CW) — Design Supply Temperature
−type: range
−unit: °F
−options:
− min: 65
− max: 100
− setpoints: [65, 75, 85, 90, 95, 100]
−default: 85
−```
−
−```datasheet
−label: Condenser Water (CW) — Design System Operating Pressure
−type: range
−unit: psig
−options:
− min: 30
− max: 150
− setpoints: [30, 50, 75, 100, 125, 150]
−default: 75
−```
−
−### The maximum allowable operating pressure (MAOP) established on the drawings governs; the Contractor shall not select pipe schedule, valve pressure class, or fitting pressure class for a lower MAOP than shown.
−
−## Freeze Protection {toc}
−
−### The freeze protection method shall be selected and confirmed on the contract drawings, recorded in the datasheets below.
−
−```datasheet
−label: Freeze Protection Method
−type: radio
−options:
− - "Glycol solution — concentration per design"
− - "Self-regulating electric heat trace with insulation"
− - "System drained seasonally (no freeze protection piping required)"
− - "Not required — system entirely within conditioned or heated spaces"
−default: "Not required — system entirely within conditioned or heated spaces"
−```
−
−```datasheet
−label: Glycol Type (where glycol protection is used)
−type: radio
−options:
− - "Propylene glycol (food-grade compatible, recommended for most systems)"
− - "Ethylene glycol (higher heat-transfer efficiency, restricted from potable contact)"
−default: "Propylene glycol (food-grade compatible, recommended for most systems)"
−```
−
−```datasheet
−label: Glycol Concentration (percent by volume, where glycol is used)
−type: range
−unit: '% (by volume)'
−options:
− min: 20
− max: 50
− setpoints: [20, 25, 30, 35, 40, 50]
−default: 30
−```
−
−### Where any portion of hydronic piping is installed in unheated spaces, parking structures, exterior tunnels, or locations exposed to ambient temperatures below 35°F, freeze protection shall be provided.
−
−### Glycol addition shall be the primary freeze protection method for most applications; heat trace with insulation is acceptable for short runs or where glycol is incompatible with the connected equipment.
−
−### CHW and condenser water systems that are drained seasonally or that have sections exposed to freezing conditions shall be evaluated and the protection method confirmed on the drawings.
−
−### Freeze protection for HHW systems typically does not require glycol because the boilers maintain system temperature. {note}
−
−### The Engineer shall confirm the design glycol concentration based on the local design freeze temperature with at least a 10°F safety margin, and the actual required freeze protection shall govern over the default.
−
−### A glycol concentration of 30% propylene glycol provides freeze protection to approximately 0°F and is appropriate for most conditioned-building applications; higher concentrations reduce heat-transfer efficiency and increase pump energy. {note}
−
−# Piping Materials by Service {toc}
−
−## General Material Selection Principles {toc}
−
−### The choice between steel and copper for a given service and size range is driven by pressure-temperature requirements, installation labor practices, the local contractor market, and the available fittings and joining equipment. {note}
−### Steel butt-welded systems are standard for large-diameter work (generally 2½ in. and above) because welded joints are strong, fully restrained, and free-draining. {note}
−### Copper is standard for small-diameter work (generally 2 in. and below) in commercial buildings because brazed and solder-joint copper systems are leak-resistant and require no hot-work permits in many jurisdictions. {note}
−### Grooved mechanical coupling systems offer a no-hot-work alternative for steel pipe at medium-to-large diameters and are widely used on projects where open flame is restricted. {note}
−
−### Pipe material shall be selected by service, operating pressure, temperature, and size in accordance with ASME B31.9 and as further specified in this section.
−
−### Where a range of sizes spans more than one material option, the break point in sizes shall be as noted.
−
−### All pipe shall be new, free of rust, scale, excessive mill scale, pits, and cracks, and shall bear the required standard marking; reconditioned, used, or salvaged pipe is not permitted.
−
−## Steel Pipe — Heating Hot Water {toc}
−
−```datasheet
−label: Steel Pipe — HHW — ASTM Standard
−type: radio
−options:
− - "ASTM A53 Grade B, seamless or ERW"
− - "ASTM A106 Grade B, seamless"
−default: "ASTM A53 Grade B, seamless or ERW"
−```
−
−```datasheet
−label: Steel Pipe — HHW — Wall Schedule
−type: select
−options:
− - "Schedule 40 (all sizes)"
− - "Schedule 40 through 2 in.; Schedule 40 or standard weight above 2 in."
− - "Schedule 80 (high-pressure applications above 125 psig)"
−drawing_ref: true
−default: "Schedule 40 (all sizes)"
−```
−
−### Black carbon steel pipe shall be used for heating hot water service in sizes 2½ in. and above, and is permitted in sizes 2 in. and below where the Contractor elects to use steel throughout for coordination or preference.
−
−### ASTM A53 Grade B and ASTM A106 Grade B are both suitable for heating hot water service within ASME B31.9 pressure and temperature limits. {note}
−
−### ASTM A106 Grade B seamless shall be used for service temperatures above 400°F or where a seamless product is required by the designer for all sizes; ASTM A53 Grade B ERW is suitable for the temperature ranges typical of commercial HHW systems (up to 250°F).
−
−### Schedule 40 is the standard wall for most commercial HHW applications. {note}
−
−### Schedule 80 shall be used where the design operating pressure exceeds 125 psig and the Engineer of Record specifies heavier wall, or where the contract drawings call for it.
−
−### Galvanized steel pipe shall not be used for HHW, CHW, or CW closed-loop services and is not permitted in any closed-loop system under this standard.
−
−### Galvanizing releases zinc into the system water, which at elevated temperatures can flake and plate out on heat-transfer surfaces, degrades corrosion inhibitor programs, and is incompatible with aluminum alloy components. {note}
−
−## Steel Pipe — Chilled Water and Condenser Water {toc}
−
−```datasheet
−label: Steel Pipe — CHW/CW — ASTM Standard
−type: radio
−options:
− - "ASTM A53 Grade B, seamless or ERW"
− - "ASTM A106 Grade B, seamless"
−default: "ASTM A53 Grade B, seamless or ERW"
−```
−
−```datasheet
−label: Steel Pipe — CHW/CW — Wall Schedule
−type: radio
−options:
− - "Schedule 40"
− - "Schedule 80 (high-pressure applications)"
−drawing_ref: true
−default: "Schedule 40"
−```
−
−### Black carbon steel pipe shall be used for chilled water and condenser water service in sizes 2½ in. and above.
−
−### For chilled water and condenser water, the system operating temperatures are moderate (40°F to 100°F) and ASTM A53 Grade B is fully adequate for the thermal conditions. {note}
−
−### All CHW steel piping shall be insulated with vapor retarder facing; any joint, fitting, valve, or hanger that creates a thermal bridge or a gap in the vapor retarder is a condensation risk and shall be addressed during installation.
−
−### The primary concern for chilled water steel pipe is external condensation if insulation is breached and the surface temperature drops below the dew point, which accelerates external corrosion. {note}
−
−## Copper Tube — All Services, Small Diameter {toc}
−
−```datasheet
−label: Copper Tube — Type
−type: radio
−options:
− - "Type L (medium wall) — standard for all hydronic services"
− - "Type K (heavy wall) — where exposed to mechanical damage, underground, or per design"
− - "Type M (light wall) — not permitted for hydronic services under this standard"
−default: "Type L (medium wall) — standard for all hydronic services"
−```
−
−### Drawn-temper copper tube shall be used for all hydronic services — HHW, CHW, and CW — in sizes 2 in. and below, and is permitted in sizes up to and including 4 in. where the Engineer elects to use copper throughout a building's above-ceiling distribution.
−
−### Copper tube shall conform to ASTM B88, and Type L shall be the standard for all hydronic applications.
−
−### Type M light-wall copper shall not be used for hydronic heating, chilled water, or condenser water service and is not permitted under this standard, because its reduced wall thickness provides inadequate corrosion margin in closed systems.
−
−### Type K shall be used where the contract drawings specify it, for any buried or embedded segments, or where the pipe is exposed to physical damage.
−
−### Hard-drawn (drawn-temper) tube shall be used throughout; soft-temper (annealed) tube shall not be used for in-wall or in-ceiling runs.
−
−## Pipe Size Selection {toc}
−
−```datasheet
−label: Minimum Pipe Size — New Runout to Terminal Units
−type: select
−unit: in. nominal
−options:
− - "3/4 in."
− - "1 in."
− - "1-1/4 in."
− - "1-1/2 in."
−drawing_ref: true
−default: "3/4 in."
−```
−
−### Pipe sizes for all services shall be [[drawing: as indicated on the mechanical piping drawings]].
−
−### The Contractor shall not substitute smaller pipe sizes for those shown, regardless of velocity or pressure drop calculations, without written approval of the Engineer of Record.
−
−### Pipe sizing is a system design decision that accounts for pump selection, balancing, future expansion, and noise criteria; field substitution of smaller pipe sizes is a common source of system under-performance and noise complaints and shall not occur.
−
−# Joining Methods {toc}
−
−## General {toc}
−
−### Joining method shall be selected based on pipe material, pipe size, service, and the availability of open flame or hot-work permits in the project area.
−
−### All joining methods shall be qualified under the applicable ASME standard.
−
−### Mixing of incompatible joining methods — for example, using mechanical press-fit fittings on a butt-weld main — shall be performed only at rated transitions and with appropriate adapters.
−
−## Butt Welding — Steel Pipe, 2½ in. and Larger {toc}
−
−```datasheet
−label: Steel Pipe Butt Weld — Root Pass Method
−type: radio
−options:
− - "SMAW (shielded metal arc welding)"
− - "GTAW (gas tungsten arc welding)"
− - "GMAW (gas metal arc welding)"
− - "Per qualified WPS — method per Contractor's qualification"
−default: "Per qualified WPS — method per Contractor's qualification"
−```
−
−### Steel pipe in sizes 2½ in. and larger shall be joined by butt welding in accordance with ASME B31.9 and qualified under ASME Section IX.
−
−### Butt-welded joints shall use beveled ends prepared per ASME B16.25.
−
−### Tack welding shall be done by qualified welders using the same procedure as the production weld.
−
−### Root passes shall be fully penetrating, and full-penetration welds shall be verified during visual examination.
−
−### Steel pipe flanges, when used for equipment connections and for valves requiring access, shall conform to ASME B16.5 or ASME B16.47 at the appropriate pressure class.
−
−## Socket Welding and Threaded — Steel Pipe, 2 in. and Below {toc}
−
−```datasheet
−label: Steel Pipe Joining — 2 in. and Below
−type: radio
−options:
− - "Socket welded throughout"
− - "Threaded throughout"
− - "Socket welded mains; threaded runouts at terminal units"
− - "Grooved mechanical coupling (no-flame alternative)"
−default: "Socket welded throughout"
−```
−
−### Steel pipe in sizes 2 in. and below may be joined by socket welding using ASME B16.11 socket-weld fittings and couplings.
−
−### Socket-weld joints shall be spaced with the pipe end set back approximately 1/16 in. from the bottom of the socket to allow for thermal expansion during the weld and to avoid cracking during service thermal cycling.
−
−### Threaded joints in steel piping shall use ASME B16.11 threaded fittings and shall be sealed with PTFE tape or anaerobic thread sealant listed for hydronic service; threading compound containing red or white lead is not permitted.
−
−## Grooved Mechanical Coupling — Steel Pipe {toc}
−
−```datasheet
−label: Grooved Coupling — Gasket Material by Service
−type: select
−options:
− - "EPDM — heating hot water up to 230°F and chilled water"
− - "Nitrile (Buna-N) — condenser water and low-temperature HHW"
− - "Silicone — heating hot water above 230°F"
−default: "EPDM — heating hot water up to 230°F and chilled water"
−```
−
−### Grooved mechanical couplings are an approved joining method for steel pipe in all sizes where the pipe material and wall thickness are compatible with roll-grooving.
−
−### Grooved joints shall use standard rigid couplings on straight runs to maintain pipe alignment, and flexible (deflection-capable) couplings only where the manufacturer's installation instructions allow their use and where the Engineer of Record has specifically located them for vibration isolation, seismic flexibility, or expansion accommodation.
−
−### The use of flexible couplings on long horizontal runs as an economical substitute for expansion compensation is not permitted, because flexible couplings at high density without proper guides allow random pipe movement that eventually fatigues the coupling gaskets.
−
−### Where the system contains glycol, the gasket manufacturer shall confirm compatibility with the glycol type and concentration selected.
−
−### Gasket material selection is critical because the gasket is the pressure boundary of the joint; EPDM is the most common choice for HHW and CHW, Nitrile is used for condenser water for its superior resistance to oil contamination, and EPDM is compatible with propylene and ethylene glycol solutions at normal hydronic concentrations. {note}
−
−## Brazing — Copper Tube {toc}
−
−```datasheet
−label: Copper Tube Brazing Filler Metal Type
−type: radio
−options:
− - "BCuP series (phosphorus-copper) — copper-to-copper joints, no flux required"
− - "BAg series (silver alloy) — copper-to-brass and all dissimilar metal joints, flux required"
−default: "BCuP series (phosphorus-copper) — copper-to-copper joints, no flux required"
−```
−
−```datasheet
−label: Nitrogen Purge During Brazing
−type: radio
−options:
− - "Required on all copper brazed joints"
− - "Required on HHW and CHW; not required on CW open-circuit segments"
−default: "Required on all copper brazed joints"
−```
−
−### Copper tube joints shall be brazed using the socket-type wrought copper fittings of ASME B16.22 or cast copper alloy fittings.
−
−### Brazing filler metal shall conform to AWS A5.8 and shall be a silver-bearing alloy of the BCuP or BAg series appropriate to the joint configuration and the service temperature.
−
−### Cadmium-bearing brazing filler metals shall not be used.
−
−### Phosphorus-bearing filler metals (BCuP series) may be used on copper-to-copper joints without flux; flux shall be used for all copper-to-brass joints and for all silver alloy (BAg series) filler metals.
−
−### Flux residue shall be completely removed after brazing by washing with hot water, because flux is hygroscopic and mildly corrosive and, if left in place, will attack the joint over time.
−
−### During brazing, the inside of the tube shall be purged with dry nitrogen flowing at a low rate to prevent the formation of copper oxide scale (cuprite) on the interior surface.
−
−### Nitrogen purge during brazing is mandatory for this standard; a nitrogen purge fitting shall be inserted at the upstream end of each active brazing section and maintained until each joint cools below 300°F.
−
−### Interior oxide scale is a contaminant that flakes off under system flow and carries through the system to foul strainers, coil passages, and control valve seats. {note}
−
−## Solder Joints — Not Permitted for Hydronic Services Under This Standard {toc}
−
−### Solder (soft solder) joints using tin-lead or lead-free tin-based alloys are not permitted for any hydronic service under this standard.
−
−### All small-diameter copper joints shall be brazed.
−
−### Solder joints have significantly lower temperature and pressure ratings than brazed joints, and the solder alloy is susceptible to attack by aggressive water chemistry. {note}
−
−## Dielectric Isolation {toc}
−
−```datasheet
−label: Dielectric Isolation — Required Between Copper and Steel
−type: radio
−options:
− - "Yes — provide dielectric unions or flanges at every dissimilar metal connection"
− - "No — system is all-steel or all-copper (no dissimilar metal joints)"
−default: "Yes — provide dielectric unions or flanges at every dissimilar metal connection"
−```
−
−### Where copper piping connects to steel piping or to equipment with steel or cast-iron bodies, dielectric isolation fittings shall be installed to prevent galvanic corrosion.
−
−### Dielectric unions shall be used in sizes 2 in. and below; dielectric flanges shall be used in sizes 2½ in. and above.
−
−### Dielectric fittings shall be rated for the system operating pressure and temperature.
−
−### The internal barrier of the dielectric fitting shall be verified to be intact and undamaged at installation; dielectric fittings with cracked or damaged barriers shall be rejected.
−
−# Fittings {toc}
−
−## Steel Fittings — Butt Weld {toc}
−
−```datasheet
−label: Steel Butt-Weld Fitting Standard
−type: radio
−options:
− - "ASME B16.9, ASTM A234 WPB"
−drawing_ref: true
−default: "ASME B16.9, ASTM A234 WPB"
−```
−
−### Butt-weld fittings for steel pipe in sizes 2½ in. and larger shall conform to ASME B16.9 (factory-made wrought fittings) and shall be of the same or higher pipe schedule as the connecting pipe.
−
−### Fitting material shall be ASTM A234 WPB or equivalent.
−
−### Reducing fittings shall be eccentric reducers on horizontal runs carrying liquid (flat on top to avoid air pockets in supply piping) and concentric reducers on vertical runs.
−
−### Miter elbows cut from straight pipe are not permitted.
−
−## Steel Fittings — Socket Weld and Threaded {toc}
−
−### Socket-weld and threaded fittings for steel pipe in sizes 2 in. and below shall conform to ASME B16.11 and shall be forged steel Class 3000 for socket-weld connections and Class 2000 for threaded connections, unless the system design pressure requires Class 6000, which shall be specified on the drawings.
−
−### Cast iron threaded fittings shall not be used on hydronic systems.
−
−## Copper Fittings {toc}
−
−### Wrought copper solder-joint fittings shall conform to ASME B16.22, and cast copper alloy fittings for solder-joint use shall conform to ASME B16.18.
−
−### All copper fittings shall be rated for the system operating pressure.
−
−### Rolled or drawn elbows cut from copper tube are not permitted; fittings shall be the formed, socket-type fittings meeting the applicable ASME standard.
−
−## Branch Connections {toc}
−
−### Branch connections in steel pipe shall be made using full-size tee fittings per ASME B16.9, reducing-outlet tee fittings, or listed welding-outlet fittings (weld-o-lets, branch-o-lets) for openings in the run pipe where a tee fitting is not available in the size combination required.
−
−### Fabricated branch connections formed by cutting a hole in the run pipe and welding a straight-pipe nipple without a listed outlet fitting are not permitted.
−
−### In copper tube, branch connections shall be made using wrought tee fittings; mechanical tee fittings (press-in-seat type) are acceptable only where rated for the system service and listed for the pipe OD.
−
−# Valves {toc}
−
−## Isolation Valves — General {toc}
−
−```datasheet
−label: Isolation Valve Type — 2 in. and Below
−type: radio
−options:
− - "Full-port ball valve, bronze body, threaded or solder-joint ends"
− - "Full-port ball valve, stainless steel trim, threaded or solder-joint ends"
− - "Gate valve, bronze, threaded (not recommended for frequent operation)"
−default: "Full-port ball valve, bronze body, threaded or solder-joint ends"
−```
−
−```datasheet
−label: Isolation Valve Type — 2½ in. and Above
−type: select
−options:
− - "Butterfly valve, grooved or lugged, EPDM seat, ductile iron or cast iron body"
− - "Butterfly valve, wafer pattern, for flanged connections"
− - "Gate valve, flanged, cast iron or ductile iron body"
− - "Ball valve, full-port, flanged, cast iron body"
−default: "Butterfly valve, grooved or lugged, EPDM seat, ductile iron or cast iron body"
−```
−
−```datasheet
−label: Isolation Valve Stem and Seat — HHW Service Temperature
−type: radio
−options:
− - "Bronze stem, EPDM seat (up to 230°F)"
− - "Stainless steel stem, high-temperature EPDM or PTFE seat (up to 250°F)"
−default: "Bronze stem, EPDM seat (up to 230°F)"
−```
−
−### Isolation valves shall be provided at all locations shown on the contract drawings and at any additional locations required to permit isolation of each major equipment item, each riser, each branch serving more than two terminal units, each side of each piece of central plant equipment, and each terminal unit or coil.
−
−### Isolation valves shall have bubble-tight shutoff at full system operating pressure.
−
−### Valve body material, end connections, and pressure rating shall match the system pipe material, size, and design pressure.
−
−### Ball valves are preferred for isolation service in sizes 2 in. and below because they are quarter-turn, provide positive visual indication of open/closed position, and maintain reliable bubble-tight shutoff through many operating cycles; butterfly valves are the standard isolation valve for sizes 2½ in. and above in commercial hydronic work. {note}
−
−## Balancing Valves {toc}
−
−```datasheet
−label: Balancing Valve Type
−type: radio
−options:
− - "Manual circuit setter with calibrated Cv ports (standard commercial application)"
− - "Automatic flow-limiting valve (pressure-independent, where specified)"
− - "Combination balancing and shutoff valve"
−default: "Manual circuit setter with calibrated Cv ports (standard commercial application)"
−```
−
−### A manual balancing valve with integral readout ports shall be provided at each terminal unit return connection and at each branch return as indicated on the contract drawings.
−
−### Balancing valves shall allow setting and locking a calibrated flow position and shall provide differential pressure readout ports compatible with the balancing instrument used by the Test, Adjust, and Balance (TAB) contractor.
−
−### The TAB contractor shall read actual flow using the valve's factory-certified Cv-versus-position curve and a differential pressure meter.
−
−### Balancing valves shall have a memory stop feature so they can be fully closed for service and returned to the precisely set balance position without recalibration.
−
−### Pressure-independent control valves (PICVs) that combine flow-limiting, balancing, and two-way control valve functions in a single body are acceptable where specified on the contract drawings.
−
−### Where PICVs are used, separate manual balancing valves are not required at those terminal unit locations, but isolation valves on both supply and return are still required for equipment service, and PICV specifications shall be coordinated with the control system contractor.
−
−## Check Valves {toc}
−
−```datasheet
−label: Check Valve Type
−type: radio
−options:
− - "Silent (spring-loaded) check valve, bronze or cast iron body"
− - "Swing check valve, flanged, cast iron body (horizontal runs only)"
− - "Dual-plate wafer check valve (space-saving, high-flow applications)"
−default: "Silent (spring-loaded) check valve, bronze or cast iron body"
−```
−
−### Check valves shall be installed where shown on the contract drawings and at all pump discharges, equipment outlets, and any other locations where reverse flow could damage equipment or create a bypass condition.
−
−### Check valves shall be silent (spring-loaded, non-slam) type wherever possible to prevent water hammer.
−
−### Swing check valves shall be used only on horizontal runs and shall be oriented per the manufacturer's requirements; they shall not be installed in vertical downward flow orientation.
−
−## Pressure Relief Valves {toc}
−
−```datasheet
−label: Pressure Relief Valve Setting
−type: range
−unit: psig
−drawing_ref: true
−options:
− min: 30
− max: 160
− setpoints: [30, 50, 75, 100, 125, 150, 160]
−default: 125
−```
−
−### Pressure relief valves shall be provided on every closed hydronic circuit at the highest pressure point of the circuit, set to open before the system pressure exceeds the design maximum operating pressure, in accordance with IMC Chapter 12 and ASME B31.9.
−
−### Relief valve discharge piping shall be full-size, directed to an appropriate drain point or floor drain, and shall not be reduced in size or valved off at any time.
−
−### The relief valve shall never be used as a pressure control device; if a system's operating pressure is consistently approaching the relief valve set point, the expansion tank pre-charge pressure, sizing, or fill pressure is incorrect and shall be corrected.
−
−## Pressure-Reducing Valves {toc}
−
−```datasheet
−label: Pressure-Reducing Valve — System Fill Pressure Set Point
−type: range
−unit: psig
−drawing_ref: true
−options:
− min: 12
− max: 80
− setpoints: [12, 15, 20, 25, 30, 40, 50]
−default: 20
−```
−
−### Where the building domestic water or city water supply is used for system make-up and the make-up supply pressure exceeds the hydronic system design fill pressure, a pressure-reducing valve (PRV) shall be installed on the make-up water line.
−
−### The PRV shall be set to maintain system static fill pressure as indicated on the drawings; setting the PRV too high results in over-pressurization and chronic relief valve discharge.
−
−## Strainers {toc}
−
−```datasheet
−label: Strainer Screen Mesh — Pump Suction
−type: select
−options:
− - "1/16 in. perforated screen"
− - "1/32 in. perforated screen"
− - "20-mesh stainless steel wire"
−default: "1/16 in. perforated screen"
−```
−
−### Full-bore Y-strainers shall be installed on the suction side of all pumps, on the entering-water side of all control valves in sizes 2 in. and below, and at any locations indicated on the contract drawings.
−
−### Strainer body shall be the same material as the connecting pipe.
−
−### The strainer screen shall be stainless steel with mesh size as recommended by the pump or control valve manufacturer for the pipe size and flow velocity.
−
−### Y-strainer blowdown valves shall be piped to a floor drain or provided with a hose bib.
−
−# Piping Specialties {toc}
−
−## Air Separators {toc}
−
−```datasheet
−label: Air Separator Type
−type: radio
−options:
− - "In-line air separator with integral automatic vent"
− - "Combination air/dirt separator (removes both air and sediment)"
− - "Air scoop (low-velocity chamber type, older design, acceptable for retrofit)"
−default: "Combination air/dirt separator (removes both air and sediment)"
−```
−
−### An air separator shall be installed on the outlet of each boiler or chiller and on the return main adjacent to the expansion tank connection, as indicated on the contract drawings.
−
−### Air separators shall be designed for the full system flow rate and shall provide a low-velocity chamber, coalescing media, or both to cause entrained air to collect and be automatically vented.
−
−### Air separators shall incorporate an integral automatic air vent on the top connection; the automatic vent shall be float-operated and shall close when liquid is present to prevent water discharge.
−
−### In glycol systems, the air vent shall be rated for the glycol solution and shall not discharge glycol to the atmosphere without collection provisions.
−
−### The pump shall be arranged to "pump away" from the air separator and expansion tank connection, which together define the point of no pressure change, so that the pump discharge is on the side of the air separator/expansion tank tee that sees increased pressure.
−
−### Incorrect placement of the air separator relative to the expansion tank connection results in system pressures that fluctuate with pump operation, causing nuisance relief valve discharge or air ingestion. {note}
−
−### Combination air and dirt separators are the preferred product for new construction because they remove both entrained air and suspended particulate in a single device, reducing system dirt loading on coils and control valves. {note}
−
−## Automatic Air Vents {toc}
−
−```datasheet
−label: Automatic Air Vent Type
−type: radio
−options:
− - "Coin-top float vent (standard for accessible locations)"
− - "Float vent with lock feature (for glycol systems, prevents inadvertent discharge)"
− - "Manual petcock vent (acceptable only where accessible and regularly serviced)"
−default: "Coin-top float vent (standard for accessible locations)"
−```
−
−### Automatic air vents shall be installed at all high points in the piping system that cannot be reached by the air separator's venting action.
−
−### Every high point, including those created by pipe offsets, riser tops, and coil headers that pitch upward, shall have an automatic vent sized for the pipe diameter.
−
−### In glycol systems, automatic vents shall be of a type that closes against liquid so glycol solution is not discharged in normal operation.
−
−### Where a vent location is in a finished ceiling or inaccessible space, the vent shall be piped to an accessible location with a drain cup.
−
−## Expansion Tanks {toc}
−
−```datasheet
−label: Expansion Tank Type
−type: radio
−options:
− - "Diaphragm type with butyl rubber diaphragm (standard)"
− - "Bladder type with replaceable internal bladder"
−default: "Diaphragm type with butyl rubber diaphragm (standard)"
−```
−
−```datasheet
−label: Expansion Tank Pre-Charge Pressure
−type: range
−unit: psig
−drawing_ref: true
−options:
− min: 10
− max: 80
− setpoints: [10, 12, 15, 18, 20, 25, 30]
−default: 12
−```
−
−```datasheet
−label: Expansion Tank Total Volume
−type: range
−unit: gallons
−drawing_ref: true
−options:
− min: 2
− max: 500
− setpoints: [2, 4, 6, 8, 10, 15, 20, 30, 40, 50, 80, 100, 150, 200, 300, 500]
−default: 15
−```
−
−### A diaphragm-type (bladder or diaphragm) expansion tank shall be provided on each closed hydronic circuit to absorb the volumetric expansion of system water as it is heated, maintaining system pressure within the design operating range.
−
−### Open expansion tanks and plain (non-diaphragm) air-cushion tanks shall not be used on new construction.
−
−### Diaphragm tanks eliminate continuous air-water contact that leads to oxygen corrosion and are the current industry standard for all commercial closed-loop systems. {note}
−
−### The expansion tank pre-charge pressure shall be set at the factory to equal the static pressure at the tank connection point with the system cold-filled, which is the fill pressure at the expansion tank location.
−
−### The Contractor shall verify the pre-charge pressure against the system static pressure calculation before installation and shall not install a tank with a pre-charge pressure that does not match the system design.
−
−### Tank pre-charge verification shall be documented in the commissioning records.
−
−### If the pre-charge pressure is set too high, water will not enter the tank during cold fill and the system will be over-pressurized when the water heats; if set too low, the tank accepts water during cold fill and has insufficient acceptance volume for the thermal expansion. {note}
−
−### The expansion tank total volume shall be [[drawing: as indicated on the mechanical drawings or equipment schedule]], calculated by the Engineer of Record based on total system volume, maximum operating temperature, minimum system pressure, and maximum allowable pressure.
−
−### Undersized expansion tanks result in chronic high-pressure relief valve discharge, one of the most common hydronic system problems in the field, almost always caused by either an undersized tank or incorrect pre-charge pressure. {note}
−
−## Flexible Pipe Connectors {toc}
−
−```datasheet
−label: Flexible Connector Type — Pump Connections
−type: radio
−options:
− - "Braided stainless steel flexible hose with ends to match pipe system (standard)"
− - "Rubber expansion joint, spool type (where greater movement is required)"
− - "Grooved flexible coupling (where grooved pipe system is used throughout)"
−default: "Braided stainless steel flexible hose with ends to match pipe system (standard)"
−```
−
−### Flexible pipe connectors (flexible hose or expansion fittings) shall be provided at all pump suction and discharge connections and at all connections to rooftop, pad-mounted, and suspended equipment subject to vibration.
−
−### Flexible connectors shall be rated for the system service, operating pressure, temperature, and glycol concentration where applicable.
−
−### Flexible connectors used in vibration isolation service shall be installed with pipe guides within two pipe diameters of each end to prevent lateral movement that would reduce the isolator effectiveness and impose side loads on the pump flanges.
−
−# Hangers, Supports, and Pipe Guides {toc}
−
−## Hanger Standards {toc}
−
−```datasheet
−label: Hanger Type — Uninsulated Steel Pipe
−type: select
−options:
− - "MSS SP-58 Type 1 — adjustable clevis hanger (standard for horizontal steel pipe)"
− - "MSS SP-58 Type 7 — beam clamp with clevis hanger"
− - "MSS SP-58 Type 9 — adjustable swivel split ring"
−default: "MSS SP-58 Type 1 — adjustable clevis hanger (standard for horizontal steel pipe)"
−```
−
−```datasheet
−label: Hanger Type — Insulated Pipe (all materials)
−type: select
−options:
− - "MSS SP-58 Type 40 — insulated clevis hanger with insulation shield"
− - "Insulation protection saddle (pipe cradle with pre-insulated insert)"
− - "Pre-insulated pipe support assembly"
−default: "MSS SP-58 Type 40 — insulated clevis hanger with insulation shield"
−```
−
−### Pipe hangers and supports shall conform to MSS SP-58, the consolidated standard for materials, design, manufacture, selection, application, and installation of pipe hangers and supports.
−
−### All hangers shall be new and free of defects, and the Contractor shall not reuse hangers from other projects or from demolition work.
−
−### Hangers shall be selected for the pipe material, size, insulation outside diameter, and operating temperature in accordance with MSS SP-58 type designations.
−
−### Insulated pipe shall never be supported by a hanger that compresses, punctures, or bridges the insulation.
−
−### Insulation shields (load-bearing inserts) shall be provided at every hanger on insulated pipe, and the shield length shall be sufficient to distribute the pipe load without compressing the insulation below the specified minimum thickness.
−
−### Thermal insulation that is compressed at support points creates cold bridges on chilled water piping (resulting in condensation drips) and thermal losses on hot water piping. {note}
−
−## Hanger Spacing — Steel Pipe {toc}
−
−```datasheet
−label: Maximum Hanger Spacing — Steel Pipe
−type: select
−unit: ft (nominal pipe size)
−options:
− - "3/4 in. through 1 in. — 7 ft; 1-1/4 in. through 1-1/2 in. — 9 ft; 2 in. — 10 ft; 2-1/2 in. through 3 in. — 12 ft; 4 in. — 14 ft; 6 in. — 17 ft; 8 in. — 19 ft; 10 in. — 22 ft; 12 in. — 23 ft"
−drawing_ref: true
−default: "3/4 in. through 1 in. — 7 ft; 1-1/4 in. through 1-1/2 in. — 9 ft; 2 in. — 10 ft; 2-1/2 in. through 3 in. — 12 ft; 4 in. — 14 ft; 6 in. — 17 ft; 8 in. — 19 ft; 10 in. — 22 ft; 12 in. — 23 ft"
−```
−
−### Maximum hanger spacing for steel pipe shall not exceed the values in the datasheet above, measured center-to-center of supports on horizontal runs.
−
−### Vertical runs shall have a riser clamp at each floor penetration or at intervals not exceeding the equivalent of the horizontal spacing, whichever is less.
−
−### The Contractor shall add supplemental supports at equipment connections, at changes in direction, and where the distributed load from valves, flanges, or specialty items requires an intermediate support.
−
−## Hanger Spacing — Copper Tube {toc}
−
−```datasheet
−label: Maximum Hanger Spacing — Copper Tube
−type: select
−unit: ft (nominal tube size)
−options:
− - "1/2 in. through 1 in. — 5 ft; 1-1/4 in. through 2 in. — 6 ft; 2-1/2 in. through 3 in. — 8 ft; 4 in. — 10 ft"
−drawing_ref: true
−default: "1/2 in. through 1 in. — 5 ft; 1-1/4 in. through 2 in. — 6 ft; 2-1/2 in. through 3 in. — 8 ft; 4 in. — 10 ft"
−```
−
−### Maximum hanger spacing for copper tube on horizontal runs shall not exceed the values in the datasheet above.
−
−### Copper tube must be supported more frequently than steel pipe of equivalent nominal size because copper is significantly less stiff; inadequate hanger spacing on copper results in sag that traps air at high points and concentrates bending stress at fittings. {note}
−
−## Pipe Anchors {toc}
−
−```datasheet
−label: Pipe Anchor Type
−type: radio
−options:
− - "Welded anchor assembly per structural drawings"
− - "Fabricated clamp-and-bracket anchor per Contractor's shop drawing, Engineer-approved"
− - "Pre-engineered pipe anchor assembly per manufacturer's load ratings"
−default: "Pre-engineered pipe anchor assembly per manufacturer's load ratings"
−```
−
−### Pipe anchors shall be provided at all locations shown on the contract drawings to fix the pipe position and absorb the reaction forces of expansion loops, expansion joints, and branch connections.
−
−### Anchors shall be designed by the Engineer of Record to resist the actual axial forces developed by thermal expansion, fluid pressure thrust, and any seismic or wind loads applicable to the system.
−
−### The Contractor shall not substitute anchor locations or omit anchors shown on the drawings; the entire expansion compensation design is predicated on the force path defined by the anchor-guide-loop system, and any change to anchor locations requires re-evaluation of all expansion compensation between those anchors.
−
−## Pipe Guides {toc}
−
−```datasheet
−label: Pipe Guide Maximum Spacing — After Expansion Device
−type: select
−unit: pipe diameters
−options:
− - "First guide: 4 pipe diameters; second guide: 14 pipe diameters; subsequent: 40 pipe diameters"
− - "Per expansion device manufacturer's published guide spacing chart"
−default: "Per expansion device manufacturer's published guide spacing chart"
−```
−
−### Pipe guides shall be provided to constrain pipe movement to the axial direction only, preventing lateral buckling and side movement at expansion loops and between anchors.
−
−### Guides shall be close-clearance (not tight) to allow axial movement and shall not bind the pipe.
−
−### The first guide on each side of an expansion loop or expansion joint shall be within two pipe diameters of the expansion device; subsequent guides shall be spaced per the expansion device manufacturer's installation instructions, typically at intervals not exceeding 40 to 50 pipe diameters.
−
−### Spacing guides too far apart is one of the leading causes of lateral buckling (snaking) in piping with expansion devices, which eventually fatigues both the expansion device and adjacent joints. {note}
−
−# Thermal Expansion Compensation {toc}
−
−## General {toc}
−
−### The thermal expansion of carbon steel is approximately 0.0073 in./ft/100°F temperature rise. {note}
−### A 200 ft straight run of HHW piping operating at 180°F installed at 70°F will expand approximately 0.0073 × 200 × (180 − 70) ≈ 1.6 in., which must be absorbed without imposing excessive stress.
−### Copper has a higher coefficient of linear thermal expansion than steel (approximately 0.0095 in./ft/100°F), so copper pipe on long runs requires even more careful expansion analysis. {note}
−
−```datasheet
−label: Primary Expansion Compensation Method
−type: radio
−options:
− - "Natural flexibility — direction changes designed as expansion offsets"
− - "Expansion loops — fabricated from straight pipe and elbows"
− - "Axial expansion joints (bellows type)"
− - "Combined — natural flexibility supplemented by loops or joints where required"
−default: "Combined — natural flexibility supplemented by loops or joints where required"
−```
−
−### All steel hydronic piping shall be analyzed for thermal expansion and designed with adequate compensation to prevent overstress of piping, fittings, equipment connections, and supports.
−
−### Expansion compensation shall be provided by one or more of the following methods: natural flexibility of changes in direction (L-bends, Z-offsets), expansion loops, or expansion joints.
−
−### Expansion joints (bellows, ball joints, or flexible hose) shall be used only where natural flexibility and expansion loops cannot accommodate the required movement within the available space.
−
−### Natural flexibility is preferred because it requires no maintenance and cannot fail; expansion loops are the second choice. {note}
−
−## Expansion Loops {toc}
−
−```datasheet
−label: Expansion Loop Configuration
−type: radio
−options:
− - "U-loop (single-plane offset, standard)"
− - "L-offset (change-of-direction flexibility)"
− - "Z-offset (double-plane, for congested routing)"
−drawing_ref: true
−default: "U-loop (single-plane offset, standard)"
−```
−
−### Expansion loops shall be fabricated from the same pipe and fittings as the main run, using long-radius elbows (1.5D minimum radius).
−
−### The loop dimensions shall be calculated to maintain piping stresses within ASME B31.9 allowables with the calculated expansion and shall be indicated on the contract drawings.
−
−### The Contractor shall not field-size expansion loops; sizing shall be done by the Engineer of Record or by the Contractor's licensed mechanical engineer and submitted for review.
−
−### Anchors at both ends of the loop run and guides between the anchor and the loop are essential; loops installed without proper anchors and guides will move laterally rather than expanding the loop, which defeats their purpose.
−
−## Expansion Joints {toc}
−
−```datasheet
−label: Expansion Joint Type (where expansion joints are used)
−type: radio
−options:
− - "Axial bellows — single-plane axial movement only"
− - "Hinged — angular rotation, installed in pairs for lateral offset"
− - "Gimbal — multi-plane angular rotation"
− - "Rubber expansion joint — vibration isolation and small movement"
−drawing_ref: true
−default: "Axial bellows — single-plane axial movement only"
−```
−
−### Expansion joints (axial bellows, gimbal, or universal joints) shall be used only where shown on the contract drawings.
−
−### The Contractor shall install expansion joints in strict accordance with the manufacturer's installation instructions, including the correct pre-compression or pre-extension adjustment and the required number and location of anchors and guides.
−
−### Bellows-type expansion joints installed without control rods on a straight run between anchors shall be positively guided to prevent pressure-thrust buckling.
−
−### Expansion joints shall not be installed in buried locations unless specifically designed and rated for buried service.
−
−# Pipe Insulation {toc}
−
−## General Insulation Requirements {toc}
−
−```datasheet
−label: Insulation Standard for Minimum Thickness
−type: radio
−options:
− - "ANSI/ASHRAE/IES 90.1, current adopted edition"
− - "International Energy Conservation Code (IECC), current adopted edition"
− - "More stringent of 90.1 and local energy code (default)"
−default: "More stringent of 90.1 and local energy code (default)"
−```
−
−### All hydronic piping shall be insulated to the thicknesses required by ANSI/ASHRAE/IES 90.1 for the applicable fluid temperature and pipe size.
−
−### Where the local energy code adopts a different standard, the more stringent of 90.1 and the local energy code shall apply.
−
−### Insulation shall be applied after pressure testing is complete and the pipe surface is clean, dry, and free of rust and scale.
−
−### Pipe insulation applied over damp or corroded pipe is a common quality deficiency that accelerates pipe corrosion and degrades insulation performance. {note}
−
−## Heating Hot Water Insulation {toc}
−
−```datasheet
−label: HHW Pipe Insulation — Material Type
−type: radio
−options:
− - "Fiberglass (glass fiber) pipe insulation, ASTM C553 or C1290, with ASJ facing"
− - "Mineral wool (rock wool) pipe insulation with vapor-barrier jacket"
− - "Pre-insulated pipe assembly (for underground or tunneled distribution)"
−default: "Fiberglass (glass fiber) pipe insulation, ASTM C553 or C1290, with ASJ facing"
−```
−
−```datasheet
−label: HHW Pipe Insulation — Nominal Thickness (pipes 1 in. and below, 140-200°F fluid)
−type: select
−unit: in.
−options:
− - "1.0"
− - "1.5"
− - "2.0"
− - "Per ASHRAE 90.1 Table 6.8.3-1"
−default: "1.5"
−```
−
−```datasheet
−label: HHW Pipe Insulation — Nominal Thickness (pipes above 1 in., 140-200°F fluid)
−type: select
−unit: in.
−options:
− - "1.5"
− - "2.0"
− - "2.5"
− - "Per ASHRAE 90.1 Table 6.8.3-1"
−default: "2.0"
−```
−
−### Insulation for HHW supply and return piping shall be fiberglass pipe insulation with an all-service jacket (ASJ) facing conforming to ASTM C553 or ASTM C1290.
−
−### The HHW insulation shall be rated for the maximum system operating temperature.
−
−### Minimum HHW insulation thickness shall comply with ASHRAE 90.1 Table 6.8.3-1 for heating hot water service at the design supply temperature.
−
−## Chilled Water Insulation {toc}
−
−```datasheet
−label: CHW Pipe Insulation — Material Type
−type: radio
−options:
− - "Flexible closed-cell elastomeric, ASTM C534 (preferred — inherent vapor barrier)"
− - "Fiberglass pipe insulation with factory vapor-barrier jacket"
−default: "Flexible closed-cell elastomeric, ASTM C534 (preferred — inherent vapor barrier)"
−```
−
−```datasheet
−label: CHW Pipe Insulation — Nominal Thickness (pipes 1 in. and below, 40-55°F fluid)
−type: select
−unit: in.
−options:
− - "0.75"
− - "1.0"
− - "1.5"
− - "Per ASHRAE 90.1 Table 6.8.3-2"
−default: "1.0"
−```
−
−```datasheet
−label: CHW Pipe Insulation — Nominal Thickness (pipes above 1 in., 40-55°F fluid)
−type: select
−unit: in.
−options:
− - "1.0"
− - "1.5"
− - "2.0"
− - "Per ASHRAE 90.1 Table 6.8.3-2"
−default: "1.5"
−```
−
−### Insulation for CHW supply and return piping shall be flexible closed-cell elastomeric cellular insulation conforming to ASTM C534, or fiberglass pipe insulation with a factory-applied vapor barrier jacket.
−
−### The insulation system for CHW piping shall provide an effective vapor retarder to prevent condensation on the cold pipe surface.
−
−### The vapor retarder shall be continuous, including at fittings, valves, and flanges, which shall be insulated with mitered sections, blanket insulation, or pre-molded fitting covers with a vapor-barrier seam.
−
−### Elastomeric foam insulation shall not be used on HHW piping above its rated temperature.
−
−### Adhesive closures on elastomeric insulation shall be the manufacturer's specified adhesive applied to both surfaces before joining; mechanical staples and tape alone are not acceptable for sealing the longitudinal seam.
−
−### Any breach in the CHW vapor retarder allows moisture to diffuse into the insulation and reach the cold pipe, where it condenses and promotes external corrosion. {note}
−
−### Elastomeric foam insulation is preferred for CHW piping because the closed-cell structure provides a built-in vapor retarder and the flexible material is easily applied around fittings and valves without complex mitered sections, but it has a lower service temperature limit than fiberglass. {note}
−
−## Condenser Water Insulation {toc}
−
−```datasheet
−label: Condenser Water Piping — Insulation Required
−type: radio
−options:
− - "Yes — insulate per drawings (spaces where pipe sweating is a concern)"
− - "No — condenser water piping uninsulated (standard for fully indoor routing)"
−default: "No — condenser water piping uninsulated (standard for fully indoor routing)"
−```
−
−### Where condenser water piping passes through spaces where surface temperatures could cause discomfort, sweating, or where energy conservation analysis indicates a benefit, insulation shall be applied as indicated on the contract drawings.
−
−### Condenser water piping serving cooling towers is open-circuit, and insulation is typically not required for energy conservation or condensation prevention on condenser water systems. {note}
−
−## Insulation Application and Accessories {toc}
−
−```datasheet
−label: Insulation Jacket Type — HHW and Above-Ceiling Piping
−type: radio
−options:
− - "All-service jacket (ASJ) — white kraft paper/foil laminate with self-sealing lap"
− - "PVC jacketed (for exposed/mechanical room locations)"
− - "Canvas jacket with lagging adhesive (for decorative or museum applications)"
−default: "All-service jacket (ASJ) — white kraft paper/foil laminate with self-sealing lap"
−```
−
−```datasheet
−label: Insulation Finish — Exposed in Mechanical Rooms
−type: radio
−options:
− - "PVC jacket over existing insulation"
− - "Aluminum jacket (for outdoor or high-traffic mechanical room piping)"
− - "ASJ facing with no additional jacket (acceptable in clean mechanical rooms)"
−default: "PVC jacket over existing insulation"
−```
−
−### Pipe insulation shall be applied in full-length sections with longitudinal seams on the side of the pipe, not on the top or bottom, to minimize the effect of any seam opening on the vapor barrier.
−
−### Sections shall be staggered so that circumferential joints do not align on adjacent layers where double-layer insulation is specified.
−
−### All joints, seams, and the overlap at fittings shall be sealed with the insulation manufacturer's specified adhesive; vapor-retarder tape may be used for the outer jacket seam on CHW insulation but shall not be the only sealing method on the vapor barrier.
−
−# Installation {toc}
−
−## General Installation Requirements {toc}
−
−### Piping shall be installed in accordance with ASME B31.9, the contract drawings, the approved coordination drawings, and the requirements of this standard.
−
−### The Contractor shall thoroughly examine all piping materials upon delivery and shall reject any pipe, fitting, valve, or specialty item that is dented, kinked, cracked, improperly threaded, or otherwise defective.
−
−### Defective material shall be removed from the site immediately and replaced.
−
−### Pipe shall be installed so that it is plumb, level, and aligned with the adjacent piping, structural grid, and building geometry.
−
−### All horizontal supply and return mains shall pitch a minimum of 1/8 in. per foot toward the low point designated for drain connections.
−
−### Where the system geometry does not permit continuous pitch, local low points shall be provided with drain valves and local high points shall be provided with automatic air vents.
−
−### Racking, sagging, and misaligned pipe is visually unacceptable and causes uneven stress distribution at joints and supports. {note}
−
−## Pipe Penetrations {toc}
−
−### Where piping passes through walls, floors, and ceilings, sleeves shall be provided that are two pipe sizes larger than the outside diameter of the insulated pipe.
−
−### Sleeves shall be set flush with the finished wall surface on each side.
−
−### Pipe shall be centered in the sleeve, and the annular space shall be packed with a listed firestopping material where the penetration is through a fire-rated assembly, in accordance with the IBC and the contract drawings.
−
−### Pipe shall not bear on the sleeve; the sleeve is a clearance sleeve, not a support, and the pipe shall be independently supported on each side of the penetration.
−
−### Escutcheon plates shall be provided at all exposed penetrations through finished surfaces.
−
−## Drains and Drain Valves {toc}
−
−### Drain valves shall be provided at all low points in the piping system, at the base of all risers, at all equipment isolation valve pairs, and at any other location where the system cannot be drained without disassembly.
−
−### Drain valves shall be ball-type with hose bib end connection, minimum 3/4 in. size.
−
−### Plugged nipples are not acceptable as drain provisions; all drain points shall have a valve.
−
−### Ball-type drain valves are preferred over hose bibs for system drain service because they provide positive full-bore shutoff. {note}
−
−## Equipment Connections {toc}
−
−### Piping connections to all equipment — chillers, boilers, heat exchangers, coils, pumps, and cooling towers — shall include isolation valves on both supply and return, a drain valve between the isolation valves on each side, and a union or flanged connection to allow equipment removal without disturbing the distribution piping.
−
−### All equipment connections shall be flexible connector, union, or flanged to allow equipment service without cutting piping.
−
−### Grouted-in or welded equipment connections that prevent removal of the equipment without cutting pipe are not acceptable.
−
−## Valve Accessibility {toc}
−
−### All isolation valves, balancing valves, check valves, pressure relief valves, pressure-reducing valves, and automatic air vents shall be located so they are accessible for operation and maintenance without the need for cutting finishes, removing permanent construction, or using unusual tools.
−
−### Where system layout results in valves above a hard ceiling, access panels shall be provided at every such valve location.
−
−### The Contractor shall coordinate access panel locations with the ceiling Contractor and shall identify all above-ceiling valve locations on the record drawings.
−
−## Labeling and Identification {toc}
−
−```datasheet
−label: Piping Label Color Coding — Heating Hot Water
−type: radio
−options:
− - "ASME A13.1 — yellow label with black text (dangerous contents)"
− - "Green label with white text (per ANSI/ASME A13.1 optional scheme)"
−drawing_ref: true
−default: "ASME A13.1 — yellow label with black text (dangerous contents)"
−```
−
−```datasheet
−label: Piping Label Color Coding — Chilled Water
−type: radio
−options:
− - "ASME A13.1 — green label with white text (safe/low hazard)"
− - "Blue label (common industry practice for CHW)"
−drawing_ref: true
−default: "ASME A13.1 — green label with white text (safe/low hazard)"
−```
−
−### All supply and return piping shall be labeled with the system name (HHW, CHW, CW), flow direction, and pipe size at intervals not exceeding 25 ft on each straight run, at each side of every wall, floor, and ceiling penetration, and adjacent to every valve.
−
−### Labels shall be color-coded per ASME A13.1 or per the Owner's building-wide color-coding standard if one is established.
−
−### Valve tags shall be brass or aluminum, permanently engraved or stamped with the valve number per the valve schedule.
−
−### Cable ties or wire shall be used to attach valve tags; adhesive tags are not acceptable because they fall off in mechanical rooms.
−
−# Cleaning, Flushing, and Chemical Treatment {toc}
−
−## Sequence Overview {toc}
−
−### System cleaning, flushing, and initial chemical treatment shall be completed in the following sequence before pressure testing is witnessed by the Engineer: (1) pre-flush mechanical cleaning to remove gross construction debris; (2) high-velocity dynamic flushing to remove fine debris, scale, and pipe compound; (3) water sample collection and evaluation; (4) drain and rinse; (5) initial fill with treated water and chemical inhibitor; and (6) baseline chemistry analysis.
−
−### Where the contract documents require witnessing of the pressure test before insulation, flushing shall be completed before the witnessed test, and insulation shall not begin until after the test is completed and documented.
−
−### Pressure testing on cleaned, chemically treated water is performed after flushing is complete so that the test water matches the operating chemistry and does not introduce contamination. {note}
−
−## Pre-Flush Cleaning {toc}
−
−```datasheet
−label: Temporary Bypass Configuration for Flushing
−type: radio
−options:
− - "Full-bore bypass valves across each terminal unit coil (required)"
− - "Modular flushing cart with temporary connections at equipment headers"
−drawing_ref: "flushing plan"
−default: "Full-bore bypass valves across each terminal unit coil (required)"
−```
−
−### Before flushing, the Contractor shall remove and clean or replace all Y-strainer screens, shall verify that all control valves and automatic control devices are protected or bypassed, and shall install temporary bypasses across all coils and terminal unit heat exchangers so that the full flush velocity is achieved in the mains.
−
−### Temporary bypasses shall be full-bore and shall be clearly tagged for removal before system commissioning.
−
−### Equipment manufacturers' coil and heat exchanger passages are too small to flush at the required velocity; flushing through coils at inadequate velocity leaves debris in the equipment and can pack fine debris into the coil fins and core passages where it is difficult to remove. {note}
−
−## Flushing Velocity {toc}
−
−```datasheet
−label: Minimum Flushing Velocity
−type: range
−unit: ft/s
−options:
− min: 2.5
− max: 5.0
− setpoints: [2.5, 3.0, 3.5, 4.0, 5.0]
−default: 3.0
−```
−
−### Flushing shall be performed with clean potable water at a flow velocity of not less than 3 ft/s (0.9 m/s) in every section of main and branch piping.
−
−### The Contractor shall calculate the flow rate required to achieve 3 ft/s in each pipe segment and shall use portable pumping equipment capable of delivering that flow rate.
−
−### The flushing plan shall demonstrate that 3 ft/s is achieved in every segment, including the largest mains.
−
−### The minimum flush velocity is the most critical parameter; at lower velocities, particulate is not fully suspended and is not carried out of the system, and flushing through the building's permanent circulation pumps at normal system flow rates is generally not sufficient in large-diameter distribution mains. {note}
−
−## Flushing Duration and Acceptance {toc}
−
−```datasheet
−label: Flushing Acceptance Criterion
−type: radio
−options:
− - "Visual clarity — discharge water matches clarity of city water supply"
− - "Turbidity ≤ 5 NTU on two consecutive 30-minute samples"
− - "Per laboratory analysis protocol specified by water treatment consultant"
−default: "Turbidity ≤ 5 NTU on two consecutive 30-minute samples"
−```
−
−### Flushing shall continue until the discharge water is visually clear.
−
−### Samples shall be collected from the flush discharge every 30 minutes after initial clarity is achieved and evaluated for turbidity and particulate.
−
−### Flushing shall be deemed complete when two consecutive 30-minute samples both show turbidity below 5 NTU (Nephelometric Turbidity Units) or visual clarity equivalent to clear tap water, whichever criterion is used per the accepted flushing plan.
−
−### Flushing reports shall document the start time, end time, total volume flushed, and the turbidity readings.
−
−## System Fill Water Quality {toc}
−
−### After flushing and draining, the system shall be filled with water meeting the requirements of the water treatment program specified in [[sync/hvac-water-treatment]].
−
−### Fill water shall be either potable city water or treated water with hardness, pH, and dissolved oxygen as specified by the water treatment consultant.
−
−### Systems that will be operated with a glycol solution shall be filled with the glycol pre-mix or by adding inhibited glycol concentrate to the fill water connection during fill, in accordance with the glycol supplier's instructions.
−
−## Initial Chemical Treatment {toc}
−
−```datasheet
−label: Initial Chemical Treatment Program — Inhibitor Type
−type: radio
−options:
− - "Molybdate-based inhibitor (HHW and CHW, no aluminum components)"
− - "Nitrite-based inhibitor (HHW only, compatible with steel and iron)"
− - "Phosphate-based inhibitor (CHW systems with mixed metallurgy)"
− - "Per water treatment consultant's specification"
−default: "Per water treatment consultant's specification"
−```
−
−```datasheet
−label: Initial Chemical Treatment — Baseline pH Target
−type: range
−unit: (unitless pH)
−options:
− min: 7.5
− max: 9.5
− setpoints: [7.5, 8.0, 8.5, 9.0, 9.5]
−default: 8.5
−```
−
−### After system fill, an initial charge of corrosion inhibitor, scale inhibitor, and, if applicable, biocide shall be added in the concentrations recommended by the water treatment consultant for the initial passivation of the system.
−
−### The Contractor shall circulate the treated water for a minimum of 72 hours before collecting the baseline water chemistry sample.
−
−### Baseline chemistry results shall be submitted to both the Engineer of Record and the Owner's water treatment service provider to establish the starting reference for the ongoing chemical treatment program.
−
−### The actual baseline pH target shall be confirmed by the water treatment consultant for the specific system metallurgy and inhibitor program selected.
−
−### A pH of 8.5 provides a mildly alkaline environment that passivates carbon steel surfaces and minimizes corrosion rates while being compatible with copper tube and brass fittings; pH below 7.5 is corrosive to steel and pH above 9.5 attacks copper. {note}
−
−## Strainer Screen Cleaning After Initial Operation {toc}
−
−### Y-strainer screens and dirt separator bowls shall be removed and cleaned after the first 24 hours and again after the first 72 hours of system operation after commissioning.
−
−### The initial strainer-cleaning protocol shall be documented in the O&M manual.
−
−### Strainer screens not cleaned during this initial period will blind and cause pump cavitation or inadequate flow to terminal units, generating service calls and potentially damaging control valves or coil circuits, because initial operation invariably dislodges scale, weld spatter, brazing flux residue, and other debris that was not captured during flushing. {note}
−
−# Pressure Testing {toc}
−
−## General {toc}
−
−### All hydronic piping shall be pressure tested before insulation is applied and before connection to equipment that is not rated for the test pressure.
−
−### The test shall demonstrate that all joints, welds, brazes, and fittings are leak-free and that the as-installed system can withstand the test pressure without permanent deformation or distress.
−
−## Hydrostatic Test {toc}
−
−```datasheet
−label: Hydrostatic Test Pressure
−type: range
−unit: psig
−drawing_ref: true
−options:
− min: 100
− max: 250
− setpoints: [100, 125, 150, 175, 200, 225, 250]
−default: 150
−```
−
−### Hydronic piping shall be subjected to a hydrostatic test pressure of not less than 1.5 times the design maximum operating pressure, but not less than 100 psig, in accordance with ASME B31.9 and IMC Chapter 12.
−
−### Where the calculated 1.5× value exceeds the pressure rating of any installed component (expansion tank, equipment, pressure relief valve set point), the test boundary shall be established to exclude that component and it shall be separately pressure tested at its rated pressure.
−
−### The test medium shall be clean potable water.
−
−### Air or nitrogen shall not be used as the primary test medium for hydronic piping, because the elastic energy stored in a compressed gas creates an explosion hazard if a joint fails during the test.
−
−### The test pressure shall be applied using a hand pump or small power pump and gauged at the test point.
−
−### The hydrostatic (water pressure) test is the standard test method for hydronic piping; water is incompressible and a test joint failure releases water rather than explosive energy. {note}
−
−## Test Procedure {toc}
−
−```datasheet
−label: Minimum Pressure Test Hold Duration
−type: select
−unit: hours
−options:
− - "1 hour"
− - "2 hours"
− - "4 hours"
− - "8 hours"
−default: "2 hours"
−```
−
−### The Contractor shall fill the system from the lowest point, venting air from all high points as the system fills, until all air is expelled and the system is full of water.
−
−### The test pressure shall then be applied and held for a minimum of two hours.
−
−### During the test, the Contractor and the Engineer's inspector shall walk all accessible piping and visually inspect every joint, fitting, weld, braze, and valve body for leaks, wet marks, seepage, or sweating.
−
−### No visible leaks of any magnitude shall be acceptable; a leak at any joint requires the test to be stopped, the joint repaired, the system refilled, and the test repeated from the beginning.
−
−## Pressure Gauge Requirements {toc}
−
−```datasheet
−label: Test Pressure Gauge Range
−type: select
−unit: psig
−options:
− - "0-160 psig (for tests up to 100 psig)"
− - "0-200 psig (for tests up to 150 psig)"
− - "0-300 psig (for tests up to 200 psig)"
− - "Calibrated instrument with range approximately 1.5-2× test pressure"
−default: "Calibrated instrument with range approximately 1.5-2× test pressure"
−```
−
−### Test pressure gauges shall be calibrated, with a range of approximately 1.5 to 2 times the test pressure, and shall have graduations that allow pressure changes of 5 psi or less to be read.
−
−### Uncalibrated or unranged gauges shall not be used for acceptance testing.
−
−### The pressure gauge shall be located at the low point of the test boundary for hydrostatic tests; readings at the pump or at a high point do not represent the maximum pressure in the system and shall not be used as the sole gauge for test acceptance.
−
−## Pneumatic Test (Alternative) {toc}
−
−```datasheet
−label: Pressure Test Medium
−type: radio
−options:
− - "Hydrostatic (water) — standard and required unless Engineer approves otherwise"
− - "Pneumatic (clean dry nitrogen) — alternative with Engineer's written approval only"
−default: "Hydrostatic (water) — standard and required unless Engineer approves otherwise"
−```
−
−### Where it is not practicable to perform a hydrostatic test — for example, on pre-insulated piping systems that cannot be wet-tested before insulation is applied, or on systems in completed spaces where water damage from a joint failure would be catastrophic — a pneumatic test using clean dry nitrogen is acceptable, subject to the approval of the Engineer of Record.
−
−### Pneumatic tests shall be conducted at a maximum pressure not exceeding the smaller of 150% of design pressure or the lowest pressure rating of any component in the test boundary.
−
−### A pneumatic test shall use a preliminary air test at 25 psig to check for gross leaks by sound before proceeding to full test pressure.
−
−### Personnel and equipment not essential to the test shall be excluded from the immediate area during pressurization.
−
−## Test Documentation {toc}
−
−### A signed and dated pressure test report shall be prepared for each test, including the date of test; the test boundaries (pipe systems and locations included); the test medium; the test pressure; the test duration; the name and signature of the Contractor's representative performing the test; and the name and signature of the Engineer's inspector witnessing the test.
−
−### The report shall record "pass" only if no pressure drop was observed during the hold period and no leaks were found by visual inspection.
−
−### A "pass with repairs" notation is not acceptable; each repaired joint requires a new complete test record.
−
−# Commissioning and Balancing {toc}
−
−## System Commissioning {toc}
−
−### After pressure testing, initial flushing, chemical treatment, and insulation, the hydronic systems shall be commissioned in accordance with the commissioning plan.
−
−### Commissioning shall include start-up of all pumps, verification of flow direction in every circuit, calibration of differential pressure sensors, verification of expansion tank pre-charge, verification of pressure relief valve set points, and verification that all automatic air vents and air separators are functioning.
−
−### All deficiencies identified during commissioning shall be corrected before the TAB contractor is called to balance the system.
−
−## Testing, Adjusting, and Balancing (TAB) {toc}
−
−### The TAB contractor shall balance each hydronic system so that design flow is achieved at each terminal unit within ±10% of the design flow rate shown on the contract drawings, using the calibrated circuit setter balancing valves installed by the Contractor.
−
−### The Contractor shall provide the TAB contractor with the valve schedule identifying each valve number and design flow rate.
−
−### Any circuit that cannot be balanced within tolerance because the installed pipe size is smaller than design, a strainer is blocked, or a valve is defective shall be immediately reported to the Engineer of Record, and the Contractor shall correct the physical deficiency.
−
−### TAB reports shall include each valve identification, design flow, measured flow, and percent of design for every terminal unit and branch.
−
−### Hydronic TAB shall be coordinated with the air-side TAB required by [[sync/testing-adjusting-and-balancing]] so that both air and water sides of each coil are balanced in the same commissioning sequence.
−
−# Warranty {toc}
−
−## Contractor Warranty {toc}
−
−```datasheet
−label: Contractor Installation Warranty Period
−type: select
−options:
− - "1 year from substantial completion"
− - "2 years from substantial completion"
− - "Per contract General Conditions"
−default: "1 year from substantial completion"
−```
−
−### The Contractor shall warrant all hydronic piping work — including materials, joints, welds, brazes, valve packings, insulation, and chemical treatment services — against defects in workmanship and materials for a period of not less than one year from the date of substantial completion, or the project warranty period specified in the General Conditions, whichever is longer.
−
−### Any leak, deterioration of insulation, valve packing failure, or corrosion attributable to improper installation discovered during the warranty period shall be repaired by the Contractor at no additional cost to the Owner.
−
−## Equipment Warranties {toc}
−
−```datasheet
−label: Expansion Tank Manufacturer Warranty Period
−type: select
−options:
− - "1 year"
− - "2 years"
− - "5 years (diaphragm/bladder type — typical for listed expansion tanks)"
−default: "5 years (diaphragm/bladder type — typical for listed expansion tanks)"
−```
−
−### Specialty items — expansion tanks, air separators, balancing valves, pressure relief valves, pressure-reducing valves, and flexible connectors — shall carry the manufacturer's standard warranty against defects in materials and workmanship.
−
−### The Contractor shall record and transmit to the Owner the start date, end date, and warranty terms for each warranted item.
−
−### The warranty period for any item that requires service during the project warranty period shall be documented; warranty periods do not toll for items that are repaired or replaced during the original warranty term unless the manufacturer provides a new warranty on the replacement.
−
−## Common Deficiencies and RFI Generators {toc}
−
−### The following conditions are the most frequent sources of field RFIs, warranty calls, and commissioning failures on hydronic piping projects. {note}
−
−### The Contractor shall specifically review each common deficiency item before final inspection.
−
−### The expansion tank pre-charge shall be field-verified against the static fill pressure before tank installation, because incorrect pre-charge pressure is the leading cause of chronic pressure relief valve discharge and system pressure instability.
−
−### Every true high point, including those created by pipe offsets, shall have an air vent, because automatic air vents installed at anything other than the true high point in the piping will not vent.
−
−### The initial strainer-cleaning protocol shall be included in the O&M documentation and performed as specified, because strainer screens that are not cleaned after the initial system operation quickly block flow, causing poor performance and pump trips.
−
−### Every expansion loop installation shall be visually verified against the guide and anchor plan before insulation, because loops installed without proper anchors and guides allow the pipe to snake sideways instead of expanding within the loop, eventually fatiguing the loop elbows.
−
−### All balancing valves shall be on the return piping of each terminal unit, because balancing valves installed on the supply side rather than the return side cannot be balanced accurately.
−
−### Every CHW fitting, flange, and valve shall be insulated with fitting covers or mitered sections sealed with manufacturer's vapor-retarder adhesive before final inspection, because chilled water insulation vapor retarder breaches at supports, valve bodies, and fitting insulation seams cause condensation drips on ceilings and floors.
+---
+title: Hydronic Piping
+category: Mechanical / Piping & Pumps
+description: >
+ When to use: Closed-loop hydronic distribution piping for heating hot water (HHW), chilled water (CHW), dual-temperature water (DTW), and condenser water (CW) in commercial, institutional, and industrial buildings, within the ASME B31.9 building-services envelope (up to 160 psig and 250°F). Covers pipe material and wall selection by service and size band, joining methods, fittings and flanges, dissimilar-metal isolation, delivery and storage, piping installation and routing discipline, the interfaces to supports, expansion compensation, valves, specialties, insulation, identification, and system cleaning, and the structural pressure test that proves the installed system.
+ Not intended for: central-plant, large-diameter chilled and condenser water distribution (see [[sync/chilled-and-condenser-water-piping]]); general-duty valves (see [[sync/hvac-piping-valves]]); balancing valves, strainers, and in-line specialties (see [[sync/hydronic-specialties]]); expansion tanks, air separators, and automatic air vents (see [[sync/expansion-tanks-and-air-separators]]); expansion joints, loops, anchors, and guides (see [[sync/expansion-fittings-and-loops]]); hangers, supports, and seismic bracing (see [[sync/hangers-and-supports]]); pipe insulation (see [[sync/mechanical-insulation]]); system cleaning, flushing, and passivation (see [[sync/hydronic-cleaning-and-flushing]]); the ongoing water treatment program (see [[sync/hvac-water-treatment]]); pumps (see [[sync/hvac-pumps]]); domestic water piping (see [[sync/domestic-water-piping]]); steam and condensate piping (see [[sync/steam-and-condensate-piping]]); refrigerant piping under ASME B31.5 (see [[sync/refrigerant-piping]]); HVAC condensate drainage (see [[sync/condensate-drainage-piping]]); fire protection piping (see [[sync/fire-protection-piping]]); and high-temperature water systems above 250°F or above 160 psig, which are governed by ASME B31.1.
+---
+
+# Scope {toc}
+
+## This standard covers the pipe, fittings, joints, and installation of closed-loop hydronic distribution piping carrying heating hot water, chilled water, dual-temperature water, and condenser water between central plant equipment and the terminal equipment that conditions occupied spaces. {note}
+
+## The boundary of the work is the pipe itself and the joints that make it continuous: material and wall selection, joining method, fittings and flanges, dissimilar-metal isolation, routing and support interfaces, and the structural pressure test that proves the assembly before it is concealed. {note}
+
+## Hydronic piping is the one part of an HVAC system that is installed once, buried in ceilings and shafts, and expected to hold pressure for the life of the building without inspection. A joint that leaks after the ceiling closes costs many times what it cost to make, and the water it releases damages work by other trades. That asymmetry is why this standard is prescriptive about qualification, examination, and testing, and permissive about the choices a designer legitimately owns. {note}
+
+## The systems in scope operate within the ASME B31.9 building-services envelope. Above 250°F or above 160 psig the design falls under ASME B31.1 and this standard does not apply. {note}
+
+## Piping and joining shall comply with ASME B31.9, the adopted edition of the International Mechanical Code Chapter 12, and the requirements of the Authority Having Jurisdiction.
+
+## Where a hydronic system carries a glycol solution, every requirement of this standard for water service applies equally to the glycol solution, and the additional gasket, seal, and venting provisions of this standard apply.
+
+## The following are outside this scope and are governed by the companion standards named. {note}
+- General-duty isolation, shutoff, and throttling valves - [[sync/hvac-piping-valves]].
+- Balancing valves, pressure-independent control valves, strainers, flexible connectors, gauges, and thermometers - [[sync/hydronic-specialties]].
+- Expansion tanks, air separators, dirt separators, and automatic air vents - [[sync/expansion-tanks-and-air-separators]].
+- Expansion joints, fabricated expansion loops, and the anchors and guides that make them work - [[sync/expansion-fittings-and-loops]].
+- Hangers, supports, structural attachments, and seismic bracing - [[sync/hangers-and-supports]].
+- Field-applied pipe insulation, jacketing, and vapor retarders - [[sync/mechanical-insulation]].
+- Pipe markers, valve tags, and equipment identification - [[sync/mechanical-identification]].
+- Cleaning, flushing, passivation, and the inhibitor start charge - [[sync/hydronic-cleaning-and-flushing]] and [[sync/hvac-water-treatment]].
+- Pumps, pump sets, and pump motor drives - [[sync/hvac-pumps]] and [[sync/hvac-variable-frequency-drives]].
+- Central-plant, large-diameter chilled and condenser water distribution - [[sync/chilled-and-condenser-water-piping]].
+- Air and water balancing of the completed systems - [[sync/testing-adjusting-and-balancing]].
+
+# Referenced Standards {toc}
+
+## Materials, fabrication, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
+
+## Where the contract documents, the adopted building code, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+| Standard | Title |
+|----------|-------|
+| ANSI/ASHRAE/IES 90.1 | Energy Standard for Buildings Except Low-Rise Residential Buildings |
+| ASME A13.1 | Scheme for the Identification of Piping Systems |
+| ASME B1.20.1 | Pipe Threads, General Purpose (Inch) |
+| ASME B16.3 | Malleable Iron Threaded Fittings, Classes 150 and 300 |
+| ASME B16.5 | Pipe Flanges and Flanged Fittings, NPS 1/2 through NPS 24 |
+| ASME B16.9 | Factory-Made Wrought Buttwelding Fittings |
+| ASME B16.11 | Forged Fittings, Socket-Welding and Threaded |
+| ASME B16.18 | Cast Copper Alloy Solder Joint Pressure Fittings |
+| ASME B16.21 | Nonmetallic Flat Gaskets for Pipe Flanges |
+| ASME B16.22 | Wrought Copper and Copper Alloy Solder Joint Pressure Fittings |
+| ASME B16.24 | Cast Copper Alloy Pipe Flanges, Flanged Fittings, and Valves |
+| ASME B16.25 | Buttwelding Ends |
+| ASME B16.50 | Wrought Copper and Copper Alloy Braze-Joint Pressure Fittings |
+| ASME B31.9 | Building Services Piping |
+| ASME B36.10M | Welded and Seamless Wrought Steel Pipe |
+| ASME BPVC Section IX | Boiler and Pressure Vessel Code — Welding, Brazing, and Fusing Qualifications |
+| ASTM A53 / A53M | Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless |
+| ASTM A105 / A105M | Carbon Steel Forgings for Piping Applications |
+| ASTM A106 / A106M | Seamless Carbon Steel Pipe for High-Temperature Service |
+| ASTM A234 / A234M | Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service |
+| ASTM A312 / A312M | Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes |
+| ASTM A536 | Ductile Iron Castings |
+| ASTM B32 | Solder Metal |
+| ASTM B88 | Seamless Copper Water Tube |
+| ASTM B813 | Liquid and Paste Fluxes for Soldering of Copper and Copper Alloy Tube and Fittings |
+| ASTM B828 | Making Capillary Joints by Soldering of Copper and Copper Alloy Tube and Fittings |
+| ASTM F441 / F441M | Chlorinated Poly(Vinyl Chloride) (CPVC) Plastic Pipe, Schedules 40 and 80 |
+| ASTM F876 | Crosslinked Polyethylene (PEX) Tubing |
+| ASTM F2389 | Pressure-Rated Polypropylene (PP) Piping Systems |
+| AWS A5.8 / A5.8M | Filler Metals for Brazing and Braze Welding |
+| AWWA C606 | Grooved and Shouldered Joints |
+| IMC | International Mechanical Code, Chapter 12 (Hydronic Piping) |
+| MSS SP-25 | Standard Marking System for Valves, Fittings, Flanges, and Unions |
+| MSS SP-58 | Pipe Hangers and Supports — Materials, Design, Manufacture, Selection, Application, and Installation |
+
+# Submittals {toc}
+
+## Action Submittals {toc}
+
+### The Contractor shall submit the following for the Engineer of Record's review and return before any hydronic pipe, fitting, or joining component is procured:
+
+- Pipe product data for each service and size band, identifying the material standard, grade, wall schedule or tube type, marking, pressure rating, and service temperature limit
+- Fitting product data for each joining method, identifying the governing ASME or ASTM standard, material, and pressure class, with the compatible pipe wall schedule stated
+- Flange, bolting, and gasket product data, identifying the pressure class, facing, gasket material, and temperature limit
+- Grooved coupling system product data covering couplings, fittings, gaskets, and the grooving method, with the gasket compound and its service temperature range stated for each service
+- Press-connect system product data, including the listing, the sealing element compound, the jaw and tool set required, and the size range covered by the listing
+- Polymer piping system product data, including the pipe standard, the listed joining system, the oxygen diffusion barrier where required, and the pressure-temperature derating curve
+- Dissimilar-metal isolation fitting product data for each size band, showing the pressure and temperature rating and the construction of the insulating barrier
+- Welding and brazing procedure specifications and supporting procedure qualification records under ASME BPVC Section IX for every joint configuration to be used
+- Qualification records for each welder, welding operator, and brazer who will perform work on this project, with the qualification date and continuity record
+- A pressure test plan identifying test boundaries, staging, medium, pressure, hold duration, isolation method, gauge selection, and the sequence that allows concealed work to be tested before it is covered
+- Piping coordination drawings at a scale sufficient to resolve conflicts, showing routing, sizes, joint types, support and anchor points, and equipment connection details
+
+```datasheet
+label: Action Submittals Required
+type: checkbox
+options:
+ - "Pipe product data by service and size band"
+ - "Fitting product data by joining method"
+ - "Flange, bolting, and gasket product data"
+ - "Grooved coupling system product data"
+ - "Press-connect system product data"
+ - "Polymer piping system product data"
+ - "Dissimilar-metal isolation fitting product data"
+ - "Welding and brazing procedure specifications and qualification records"
+ - "Welder, operator, and brazer qualification records"
+ - "Pressure test plan"
+ - "Piping coordination drawings"
+default:
+ - "Pipe product data by service and size band"
+ - "Fitting product data by joining method"
+ - "Flange, bolting, and gasket product data"
+ - "Welding and brazing procedure specifications and qualification records"
+ - "Welder, operator, and brazer qualification records"
+ - "Pressure test plan"
+ - "Piping coordination drawings"
+```
+
+### Work on a system shall not proceed until the submittals covering that system have been returned by the Engineer of Record.
+
+### Each submittal shall be internally consistent across pipe, fittings, joints, and flanges before it is transmitted, and the Contractor shall bear the cost of resubmission caused by internal inconsistency in its own submittal.
+
+## Closeout Submittals {toc}
+
+### The Contractor shall submit the following at substantial completion, before the hydronic piping work is accepted:
+
+- Signed and dated pressure test reports for every test boundary, recording the medium, pressure, hold duration, observed pressure loss, and the pass determination
+- A weld and braze record listing each joint by location or joint number, the welder or brazer identification, the procedure used, and the examination result
+- Nondestructive examination reports for every joint examined beyond visual, with the examiner's certification level
+- As-built piping drawings recording the installed routing, sizes, joint types, anchor and guide locations, and the locations of concealed joints
+- A concealed-joint schedule identifying every joint that is not accessible after completion, with its access route
+- Material certifications and mill test reports for pipe and fittings where required by the accepted action submittals
+
+```datasheet
+label: Closeout Submittals Required
+type: checkbox
+options:
+ - "Signed pressure test reports for every test boundary"
+ - "Weld and braze record"
+ - "Nondestructive examination reports"
+ - "As-built piping drawings"
+ - "Concealed-joint schedule"
+ - "Material certifications and mill test reports"
+default:
+ - "Signed pressure test reports for every test boundary"
+ - "Weld and braze record"
+ - "As-built piping drawings"
+ - "Concealed-joint schedule"
+```
+
+# Quality Assurance {toc}
+
+## Installer and Welder Qualification {toc}
+
+### The mechanical contractor performing hydronic piping work shall have completed at least three commercial or institutional hydronic piping installations comparable to this project in scope and complexity within the preceding five years, and shall submit those project references on request.
+
+### Where the parties disagree whether a submitted reference project is comparable in scope and complexity, the Engineer of Record shall make the initial determination.
+
+### Personnel making welded or brazed joints shall hold current qualification under ASME BPVC Section IX for the process, position, material, and wall thickness of the joint being made.
+
+### Qualification and continuity records for every welder, welding operator, and brazer on site shall be available at the site for inspection throughout installation.
+
+### A welder or brazer whose Section IX continuity record has lapsed shall requalify before making any production joint on this project.
+
+### Joints made by personnel who were not qualified at the time the joint was made shall be cut out and remade, and the Contractor shall bear the cost of the removal, the replacement material, the remake, the re-examination, and the repair of any other trade's work disturbed by that removal.
+
+### Personnel making press-connect joints shall have completed the pipe system manufacturer's training for the tool set and size range in use.
+
+### The Contractor shall keep a current copy of ASME B31.9 at the site throughout installation.
+
+## Examination of Welded Joints {toc}
+
+### Every welded joint in carbon steel or stainless steel piping shall be visually examined after completion and before the joint is insulated, buried, enclosed, or otherwise made inaccessible.
+
+### Visual examination shall confirm full weld profile, complete fusion to the base metal on both sides, and freedom from cracks, undercut, overlap, and surface porosity.
+
+### Nondestructive examination beyond visual shall be performed by the method indicated in the datasheet.
+
+```datasheet
+label: Nondestructive Examination Method for Welded Joints
+type: select
+options:
+ - "Visual examination only"
+ - "Visual examination and random radiographic examination"
+ - "Visual examination and random ultrasonic examination"
+default: "Visual examination only"
+```
+
+### Where a random examination method is selected, the proportion of welded joints examined shall be as indicated in the datasheet, distributed across welders and across each day's production rather than concentrated in one run.
+
+```datasheet
+label: Random Examination Rate for Welded Joints
+type: range
+unit: '%'
+options:
+ min: 0
+ max: 100
+ setpoints: [0, 2, 5, 10, 20, 100]
+```
+
+### ASME B31.9 requires visual examination as the baseline for building services piping, so a project that specifies radiographic or ultrasonic examination is buying confidence beyond the code minimum. Where the piping is concealed behind permanent construction, runs above occupied space that cannot be shut down, or serves a facility where an outage carries an operational penalty, the added examination buys back the cost of a failure that could not otherwise be found until the system is filled. {note}
+
+### A joint that fails examination shall be repaired or cut out and remade, and the repaired or remade joint shall be re-examined by the same method.
+
+### The Contractor shall bear the cost of examining, repairing, and re-examining a joint that fails examination.
+
+### Where the proportion of examined joints that fail exceeds ten percent for any welder, all joints made by that welder since the last passing examination shall be examined at the Contractor's expense.
+
+## Brazed and Soldered Joint Acceptance {toc}
+
+### Each completed brazed joint shall show a continuous fillet of filler metal around the full circumference at the mouth of the socket.
+
+### Each completed soldered joint shall show a continuous solder bead around the full circumference at the mouth of the socket, with no gap and no evidence of unmelted solder.
+
+### A joint showing voids, incomplete fill, or interrupted flow of filler metal shall be cut out and remade rather than reheated and refilled.
+
+### Reheating a joint that did not fill on the first attempt rarely draws filler the rest of the way into the capillary gap, because the flux is already spent and the oxide film that blocked the flow has grown. The remake is a repair the system can be tested against; the reheat is a joint that passes the test and fails in service. {note}
+
+### Flux residue shall be washed from the exterior of every fluxed joint with hot water after the joint cools.
+
+## Grooved Coupling System Single-Source Responsibility {toc}
+
+### Where grooved mechanical joints are used, the couplings, grooved fittings, gaskets, and grooving tooling for a given pipe size and service shall be the products of a single manufacturer.
+
+### Grooved coupling components from different manufacturers shall not be combined in one joint.
+
+### The groove geometry, the housing casting, and the gasket cross-section of a grooved joint are a matched set whose sealing depends on the gasket being compressed a specific amount by a specific housing against a specific groove depth. Components that individually meet AWWA C606 can still combine into a joint that never reaches its designed compression. {note}
+
+# System Design Conditions {toc}
+
+## Design Temperatures and Pressures {toc}
+
+### The design operating temperature and pressure of each hydronic system govern pipe wall selection, fitting and flange pressure class, gasket compound, polymer derating, and the pressure test target, and shall be as indicated in the datasheets below.
+
+```datasheet
+label: Heating Hot Water Design Supply Temperature
+type: range
+unit: °F
+drawing_ref: "the mechanical equipment schedule"
+options:
+ min: 100
+ max: 250
+ setpoints: [100, 120, 140, 160, 180, 200, 220, 250]
+default: deferred
+```
+
+```datasheet
+label: Chilled Water Design Supply Temperature
+type: range
+unit: °F
+drawing_ref: "the mechanical equipment schedule"
+options:
+ min: 34
+ max: 60
+ setpoints: [34, 38, 40, 42, 44, 46, 50, 55, 60]
+default: deferred
+```
+
+```datasheet
+label: Condenser Water Design Supply Temperature
+type: range
+unit: °F
+drawing_ref: "the mechanical equipment schedule"
+options:
+ min: 55
+ max: 110
+ setpoints: [55, 65, 75, 85, 90, 95, 100, 110]
+default: deferred
+```
+
+```datasheet
+label: Heating Hot Water Maximum Design Pressure
+type: range
+unit: psig
+drawing_ref: "the mechanical equipment schedule"
+options:
+ min: 30
+ max: 160
+ setpoints: [30, 50, 75, 100, 125, 150, 160]
+default: deferred
+```
+
+```datasheet
+label: Chilled Water Maximum Design Pressure
+type: range
+unit: psig
+drawing_ref: "the mechanical equipment schedule"
+options:
+ min: 30
+ max: 150
+ setpoints: [30, 50, 75, 100, 125, 150]
+default: deferred
+```
+
+```datasheet
+label: Condenser Water Maximum Design Pressure
+type: range
+unit: psig
+drawing_ref: "the mechanical equipment schedule"
+options:
+ min: 30
+ max: 150
+ setpoints: [30, 50, 75, 100, 125, 150]
+default: deferred
+```
+
+### Design temperature and pressure are outputs of the system design, not properties of the pipe, which is why they are deferred to the equipment schedule rather than defaulted here. A standard that asserts a supply temperature has decided the plant. {note}
+
+### The Contractor shall not select a pipe wall, fitting class, flange class, or gasket compound rated below the design pressure at the design temperature of the system in which it is installed.
+
+### Where a component's pressure rating derates with temperature, the rating at the design temperature shall govern, not the rating at ambient.
+
+## Freeze Protection {toc}
+
+### The freeze protection method for the hydronic systems shall be as indicated in the datasheet.
+
+```datasheet
+label: Freeze Protection Method
+type: radio
+options:
+ - "None required"
+ - "Glycol solution"
+ - "Electric heat tracing"
+ - "Seasonal drainage of exposed sections"
+```
+
+### No freeze protection method is the norm across projects, because the answer follows the climate and the routing rather than the piping system. Where piping is entirely within conditioned space, no protection is required; where a run crosses an unconditioned garage in a cold climate, glycol or tracing is unavoidable. {note}
+
+### Where any portion of a hydronic system is routed through a space that can fall below 35°F, the freeze protection method selected in the datasheet shall be applied to that portion.
+
+### Where the Contractor identifies a routing that exposes piping to freezing conditions and is not covered by the selected freeze protection method, the Contractor shall notify the Engineer of Record in writing before installing that portion.
+
+### Where glycol is used, the glycol type shall be as indicated in the datasheet.
+
+```datasheet
+label: Glycol Type
+type: radio
+options:
+ - "Inhibited propylene glycol"
+ - "Inhibited ethylene glycol"
+ - "Not applicable - no glycol in the system"
+default: "Inhibited propylene glycol"
+```
+
+### Where glycol is used, the concentration by volume shall be as indicated in the datasheet.
+
+```datasheet
+label: Glycol Concentration by Volume
+type: range
+unit: '% by volume'
+drawing_ref: "the mechanical equipment schedule"
+options:
+ min: 20
+ max: 60
+ setpoints: [20, 25, 30, 35, 40, 45, 50, 60]
+default: deferred
+```
+
+### Glycol concentration follows the local design freeze temperature with a margin, so it belongs to the project rather than to the standard. Both glycols carry a heat-transfer and pumping-power penalty that rises with concentration, and both require an inhibitor package that uninhibited automotive glycol does not have. Where a system serves a space subject to potable or food contact, propylene glycol is selected because ethylene glycol is toxic if ingested. {note}
+
+### Glycol solutions shall be inhibited formulations intended for closed hydronic service, and uninhibited or automotive glycol shall not be used.
+
+### Where glycol is used, every gasket, sealing element, and packing in the system shall be confirmed compatible with the glycol type and concentration selected.
+
+### Where glycol is used, the Contractor shall verify the delivered concentration by refractometer at fill and shall record the reading.
+
+# Pipe Materials by Service and Size {toc}
+
+## Material Selection by Service Class {toc}
+
+### The pipe material for each service class and size band shall be as indicated in the datasheets below.
+
+```datasheet
+label: Pipe Material - Heating Hot Water and Dual-Temperature, NPS 2 and Smaller
+type: select
+options:
+ - "Copper water tube"
+ - "Carbon steel"
+ - "Stainless steel"
+ - "Crosslinked polyethylene (PEX)"
+ - "Polypropylene-random (PP-R)"
+default: "Copper water tube"
+```
+
+```datasheet
+label: Pipe Material - Heating Hot Water and Dual-Temperature, NPS 2½ and Larger
+type: select
+options:
+ - "Carbon steel"
+ - "Copper water tube"
+ - "Stainless steel"
+ - "Polypropylene-random (PP-R)"
+default: "Carbon steel"
+```
+
+```datasheet
+label: Pipe Material - Chilled Water and Condenser Water, NPS 2 and Smaller
+type: select
+options:
+ - "Copper water tube"
+ - "Carbon steel"
+ - "Stainless steel"
+ - "Chlorinated polyvinyl chloride (CPVC)"
+ - "Polypropylene-random (PP-R)"
+default: "Copper water tube"
+```
+
+```datasheet
+label: Pipe Material - Chilled Water and Condenser Water, NPS 2½ and Larger
+type: select
+options:
+ - "Carbon steel"
+ - "Copper water tube"
+ - "Stainless steel"
+ - "Polypropylene-random (PP-R)"
+default: "Carbon steel"
+```
+
+### The size band split at NPS 2 is where the economics of the joint change. Below it, a copper tube joint is made by one worker with a torch or a press tool in a few minutes and no hot-work permit is needed for a press joint; above it, the wall thickness and the handling weight favor a welded or grooved steel joint that a crew makes on a rack. That is why the same building routinely uses one material for its mains and another for its runouts, and why the two decisions are recorded separately here. {note}
+
+### Heating and chilled service are separated because the failure modes differ. Hot service drives the temperature limit of polymers and elastomers and puts the joint through repeated thermal cycles; cold service puts the outside of the pipe below the dew point, so the controlling risk moves from the joint to the continuity of the vapor barrier over it. {note}
+
+### Where the datasheet selects the same material for both size bands of a service, the size-band break shall not be used as a reason to change material mid-run, and any material transition shall occur at a fitting or flange indicated on the coordination drawings.
+
+### All pipe and tube shall be new, shall bear the marking required by its material standard, and shall be free of rust scale, pitting, dents, kinks, and cracks.
+
+### Reconditioned, previously installed, or salvaged pipe shall not be used.
+
+### Galvanized steel pipe shall not be used in any closed hydronic system under this standard.
+
+### Zinc from a galvanized surface dissolves into closed-loop water, plates out on heat-transfer surfaces, and consumes the corrosion inhibitor package the water treatment program depends on. In a closed loop the zinc has nowhere to go, so the effect accumulates rather than flushing away. This is a chemistry constraint, not a preference, which is why the datasheet does not offer galvanized steel as a material. {note}
+
+## Carbon Steel Pipe {toc}
+
+### Carbon steel pipe shall conform to ASTM A53 / A53M Grade B, seamless or electric-resistance-welded, or to ASTM A106 / A106M Grade B, seamless.
+
+### Carbon steel pipe dimensions and wall schedules shall conform to ASME B36.10M.
+
+### The carbon steel wall schedule for each size band shall be as indicated in the datasheets below.
+
+```datasheet
+label: Carbon Steel Wall Schedule - NPS 2 and Smaller
+type: select
+options:
+ - "Schedule 40"
+ - "Schedule 80"
+ - "Not applicable - no carbon steel in this size band"
+default: "Schedule 40"
+```
+
+```datasheet
+label: Carbon Steel Wall Schedule - NPS 2½ and Larger
+type: select
+options:
+ - "Schedule 40"
+ - "Standard weight"
+ - "Schedule 80"
+ - "Not applicable - no carbon steel in this size band"
+default: "Schedule 40"
+```
+
+### Schedule 40 and standard weight are identical through NPS 10 and diverge above it, which is why the two appear as separate selections only in the larger size band. Where a run is threaded, the wall selection also has to survive the thread depth, so a heavier wall is chosen for threaded work at a given pressure than for welded work at the same pressure. {note}
+
+### Where carbon steel pipe is threaded, the remaining wall at the root of the thread shall satisfy the ASME B31.9 pressure design requirement at the system design pressure and temperature.
+
+### Carbon steel pipe shall be stored and handled so that mill scale is not driven into the bore and so that the ends are not deformed out of round.
+
+## Copper Tube {toc}
+
+### Copper water tube shall conform to ASTM B88.
+
+### The copper tube wall type shall be as indicated in the datasheet.
+
+```datasheet
+label: Copper Tube Wall Type
+type: select
+options:
+ - "Type K"
+ - "Type L"
+ - "Type M"
+default: "Type L"
+```
+
+### The copper tube temper shall be as indicated in the datasheet.
+
+```datasheet
+label: Copper Tube Temper
+type: radio
+options:
+ - "Drawn temper"
+ - "Annealed temper"
+default: "Drawn temper"
+```
+
+### Type L is the wall that commercial hydronic work has settled on, and Type K is selected where the tube is buried, embedded, or exposed to impact, because the extra wall is corrosion and damage margin rather than pressure margin. Type M is thinner than either and carries correspondingly less of that margin. {note}
+
+### Unless the datasheet selects otherwise, copper tube in concealed, buried, or embedded locations shall be Type K.
+
+### Drawn-temper tube holds a straight line between supports and resists the ovalling that a press or grooved joint depends on to seal, so it is selected wherever the tube is supported on hangers. Annealed tube is selected where the run must be bent continuously rather than fitted, as in a coil buried in a slab. {note}
+
+### Unless the datasheet selects otherwise, copper tube installed in walls, above ceilings, and in shafts shall be drawn temper.
+
+### Annealed-temper copper tube shall not be joined by press-connect or grooved methods unless the joining system is listed for annealed tube.
+
+### Copper tube shall be cut square with a wheel cutter or a fine-tooth saw, and the burr shall be removed from the bore before the joint is made.
+
+## Stainless Steel Pipe {toc}
+
+### Stainless steel pipe shall conform to ASTM A312 / A312M, Type 304L or Type 316L.
+
+### Stainless steel pipe shall be handled with tooling that has not been used on carbon steel, and shall be stored so that it does not contact carbon steel racking, banding, or fasteners.
+
+### Free iron transferred to a stainless surface by a carbon steel wire brush, grinding wheel, or storage rack rusts in place and initiates pitting under the rust bloom. The contamination happens in the laydown yard, not in the system, and it is not visible until the pipe is wet. {note}
+
+### Where stainless steel piping is welded, the root of the weld shall be purged with inert gas.
+
+## Polymer Piping {toc}
+
+### Crosslinked polyethylene tubing shall conform to ASTM F876 and shall incorporate an oxygen diffusion barrier where the system contains ferrous components.
+
+### Chlorinated polyvinyl chloride pipe shall conform to ASTM F441 / F441M.
+
+### Pressure-rated polypropylene piping shall conform to ASTM F2389.
+
+### Polymer piping shall be selected using the manufacturer's published pressure-temperature derating curve at the system design temperature, and the derated rating shall be not less than the system design pressure.
+
+### Oxygen that diffuses through a bare polymer wall dissolves into the loop water and corrodes every ferrous surface it reaches, which on a hydronic system means the boiler, the pump volutes, and any steel piping downstream. A barrier layer is what makes polymer tubing compatible with a mixed-metal closed loop; without one the loop has a continuous oxygen source it cannot vent. {note}
+
+### Polymer piping shall be supported at the spacing published for that material and temperature rather than at the spacing used for metal pipe of the same nominal size.
+
+### Polymer piping shall not be installed where it is exposed to direct sunlight after installation unless the product is listed for ultraviolet exposure.
+
+### Polymer piping shall be protected from open flame, hot work, and welding spatter during and after installation.
+
+# Joining Methods {toc}
+
+## Joining Method Selection {toc}
+
+### The joining method for carbon steel in each size band shall be as indicated in the datasheets below.
+
+```datasheet
+label: Carbon Steel Joining Method - NPS 2 and Smaller
+type: select
+options:
+ - "Threaded"
+ - "Socket welded"
+ - "Grooved mechanical coupling"
+ - "Press-connect"
+ - "Not applicable - no carbon steel in this size band"
+```
+
+```datasheet
+label: Carbon Steel Joining Method - NPS 2½ and Larger
+type: select
+options:
+ - "Butt welded"
+ - "Grooved mechanical coupling"
+ - "Flanged"
+ - "Press-connect"
+ - "Not applicable - no carbon steel in this size band"
+```
+
+### Neither steel size band has a joining method that most projects would choose without discussion, so neither field carries a default. Welded joints are the strongest and the most restrained but need a hot-work permit and a qualified welder; grooved joints need neither and go together fast but introduce an elastomer into the pressure boundary at every joint; press-connect joints are the fastest of the three within their listed size range and depend entirely on the tool being calibrated and the pipe being fully inserted. Where open flame is restricted by the facility or by an occupied-building phasing plan, the two flameless methods are the ones that remain available. {note}
+
+### The joining method for copper tube shall be as indicated in the datasheet.
+
+```datasheet
+label: Copper Tube Joining Method
+type: select
+options:
+ - "Brazed"
+ - "Soldered"
+ - "Press-connect"
+ - "Grooved mechanical coupling"
+default: "Brazed"
+```
+
+### Brazed copper joints carry a higher temperature and pressure rating than soldered joints of the same geometry, which is why brazing is the baseline for a standard that has to cover heating service up to 250°F in the same document as chilled service. Where a system operates well below the solder alloy's derating point and the specifier accepts the lower margin, soldered joints remain a code-legal and widely used selection. {note}
+
+### Joining methods shall not be mixed within a continuous run except at a fitting, flange, adapter, or transition coupling listed for both methods.
+
+### Every transition between two joining methods shall be made with a component rated for the system design pressure at the system design temperature.
+
+## Welded Joints in Carbon Steel {toc}
+
+### Butt-welded joints shall have ends prepared in accordance with ASME B16.25.
+
+### Butt-welded joints shall be full-penetration welds.
+
+### Socket-welded joints shall be assembled with the pipe end withdrawn approximately 1/16 in. from the bottom of the socket before welding.
+
+### The gap at the bottom of a socket weld exists so the pipe can grow into the socket when the fillet is laid down and when the system cycles thermally. Bottomed-out pipe puts the expansion into the fillet itself, and the fillet cracks at the root where nothing can be seen. {note}
+
+### Tack welds shall be made by qualified welders using the qualified procedure for the production weld, and shall be fused into or removed before the production weld.
+
+### Welding shall not be performed when the surface to be welded is wet, when the base metal is below the preheat temperature required by the qualified procedure, or in weather that prevents the shielding gas or flux from protecting the arc.
+
+### The Contractor shall provide fire watch, shielding, and permits for all hot work, and shall bear the cost of repairing any damage caused by welding spatter, slag, or heat.
+
+## Threaded Joints in Carbon Steel {toc}
+
+### Pipe threads shall conform to ASME B1.20.1.
+
+### Threads shall be cut clean and full, and shall be reamed to remove the burr from the bore before assembly.
+
+### Thread sealant shall be polytetrafluoroethylene tape or an anaerobic thread sealant listed for hydronic service at the system design temperature.
+
+### Thread compounds containing lead shall not be used.
+
+### Sealant shall be applied to the male thread only, and shall be kept back from the first thread so that it is not extruded into the bore.
+
+### Sealant extruded into the bore travels to the nearest strainer, control valve seat, or coil circuit and lodges there. A threaded system assembled with sealant applied generously to both halves of every joint delivers a measurable amount of that sealant to the equipment it was installed to protect. {note}
+
+### Threaded joints shall not be back-turned to align a fitting after the joint is made up.
+
+## Grooved Mechanical Joints {toc}
+
+### Grooved joints shall conform to AWWA C606, and grooved fittings of cast construction shall conform to ASTM A536.
+
+### Grooves shall be roll-formed or cut to the coupling manufacturer's published dimensions for the pipe material and wall, and shall be verified with the manufacturer's groove gauge.
+
+### Cut grooving removes wall, so it is limited to the pipe walls for which the coupling manufacturer publishes a cut-groove rating; roll grooving displaces wall instead of removing it and is the method available on thinner walls. The groove dimension, not the coupling, is what sets the joint's pressure rating. {note}
+
+### The grooved coupling gasket compound shall be as indicated in the datasheet.
+
+```datasheet
+label: Grooved Coupling Gasket Compound
+type: select
+options:
+ - "EPDM"
+ - "Nitrile"
+ - "Silicone"
+ - "Fluoroelastomer"
+ - "Not applicable - no grooved joints"
+default: "EPDM"
+```
+
+### The gasket is the pressure boundary of a grooved joint, so its compound has to match both the temperature and the chemistry of the service. EPDM holds up in hot and chilled water and is compatible with propylene and ethylene glycol at hydronic concentrations, and it is attacked by petroleum oils. Nitrile is selected where petroleum oil contamination is expected, and it has a lower upper temperature limit than EPDM. Silicone extends the upper temperature limit beyond EPDM. Fluoroelastomer is selected where a chemistry is present that attacks the other three. {note}
+
+### The gasket compound selected shall be rated by its manufacturer for the system design temperature and for the glycol type and concentration where glycol is used.
+
+### The gasket shall be lubricated with the coupling manufacturer's lubricant only, and petroleum-based lubricant shall not be used on an EPDM gasket.
+
+### The grooved coupling type on straight runs shall be as indicated in the datasheet.
+
+```datasheet
+label: Grooved Coupling Type on Straight Runs
+type: select
+options:
+ - "Rigid"
+ - "Flexible"
+default: "Rigid"
+```
+
+### A flexible grooved coupling permits angular and axial movement at every joint. Used deliberately at a defined location it accommodates vibration, seismic drift, or a designed movement; used as the default coupling along a long run it turns the whole run into a chain of small hinges that wanders under thermal load and works the gaskets. Where flexible couplings are used to accommodate movement, they are located and guided as part of the expansion design rather than distributed along the run. {note}
+
+### Unless the datasheet selects flexible couplings, flexible couplings shall be used only at locations designated on [[drawing: the piping coordination drawings]] for vibration, seismic, or expansion accommodation.
+
+### Flexible grooved couplings shall not be substituted for the expansion compensation required by [[sync/expansion-fittings-and-loops]].
+
+## Brazed and Soldered Copper Joints {toc}
+
+### Brazed joints shall use wrought copper braze-joint fittings conforming to ASME B16.50 or wrought copper solder-joint fittings conforming to ASME B16.22.
+
+### Brazing filler metal shall conform to AWS A5.8 / A5.8M.
+
+### Filler metal of the BCuP series may be used without flux on copper-to-copper joints, and flux shall be used on all joints between copper and a copper alloy and with all filler metal of the BAg series.
+
+### Cadmium-bearing brazing filler metal shall not be used.
+
+### Soldered joints shall use solder conforming to ASTM B32, flux conforming to ASTM B813, and the joint-making practice of ASTM B828.
+
+### Solder and flux containing lead shall not be used.
+
+### The nitrogen purge requirement during brazing shall be as indicated in the datasheet.
+
+```datasheet
+label: Nitrogen Purge During Brazing
+type: radio
+options:
+ - "Required at all brazed joints"
+ - "Not required"
+default: "Required at all brazed joints"
+```
+
+### Brazing temperature is high enough to grow a black copper oxide scale on the inside of the tube, and that scale flakes off under flow and travels. Where it lands it blinds strainers, packs coil passages, and holds control valve seats off their stops. A low-flow dry nitrogen purge displaces the oxygen from the bore while the joint is hot and prevents the scale from forming, which is why most hydronic specifications require it and why it is the default here. {note}
+
+### Where the datasheet requires a nitrogen purge, a low-flow dry nitrogen purge shall be established through the section being brazed before heat is applied and shall be maintained until the joint cools below 300°F.
+
+### The purge flow shall be low enough that it does not blow the molten filler metal out of the capillary gap.
+
+### Joints shall be brazed or soldered with the tube fully inserted to the bottom of the socket and supported so that it does not move while the filler metal solidifies.
+
+## Press-Connect Joints {toc}
+
+### Press-connect fittings shall be listed for the pipe material, wall, and size in which they are installed, and for the system design pressure at the system design temperature.
+
+### The sealing element of a press-connect fitting shall be rated for the service temperature and for the glycol type and concentration where glycol is used.
+
+### Press-connect joints shall be made with the tool set and jaws specified by the fitting manufacturer for that fitting, and the tool shall be within its published calibration interval.
+
+### The pipe shall be marked at the manufacturer's published insertion depth before assembly, and the mark shall be verified at the fitting face before the joint is pressed.
+
+### A press joint that is not fully inserted still presses, still looks finished, and still holds a short hydrostatic test, because the sealing element can seat on the pipe without the pipe reaching the stop. It fails later under thermal cycling, when the shortened engagement lets the pipe walk out of the fitting. The insertion mark is the only field evidence that the joint was made correctly. {note}
+
+### Each pressed joint shall be marked by the installer to distinguish pressed from unpressed fittings during installation.
+
+### An unpressed fitting discovered after the system is filled shall be cut out and replaced rather than pressed in place.
+
+## Polymer Pipe Joints {toc}
+
+### Polymer piping shall be joined only by a joining system listed by the pipe manufacturer for that pipe.
+
+### Socket-fusion and butt-fusion joints in polypropylene piping shall be made with the fusion tooling, temperature, and dwell time published for the pipe and fitting being joined.
+
+### Solvent-cemented joints in chlorinated polyvinyl chloride piping shall use the primer and cement listed by the pipe manufacturer, and the joint shall not be pressurized until the cure time published for the ambient temperature and pipe size has elapsed.
+
+### Crosslinked polyethylene joints shall be made with a cold-expansion, crimp-ring, or press-sleeve system listed for the tubing, using the tool specified for that system.
+
+### Metallic transition fittings at polymer piping shall be supported so that the weight and the thermal movement of the metal piping are not carried by the polymer.
+
+# Fittings and Flanges {toc}
+
+## Carbon Steel Fittings {toc}
+
+### Butt-weld fittings shall conform to ASME B16.9 and shall be of ASTM A234 / A234M Grade WPB material, with a wall matching or exceeding the connecting pipe.
+
+### Socket-weld and threaded forged fittings shall conform to ASME B16.11, of ASTM A105 / A105M material.
+
+### The socket-weld forged fitting pressure class shall be as indicated in the datasheet.
+
+```datasheet
+label: Socket-Weld Forged Fitting Pressure Class
+type: range
+options:
+ min: 3000
+ max: 9000
+ setpoints: [3000, 6000, 9000]
+default: 3000
+```
+
+### The threaded fitting material shall be as indicated in the datasheet.
+
+```datasheet
+label: Threaded Fitting Material
+type: select
+options:
+ - "Malleable iron"
+ - "Forged carbon steel"
+ - "Cast bronze"
+ - "Not applicable - no threaded joints"
+default: "Malleable iron"
+```
+
+### Malleable iron threaded fittings shall conform to ASME B16.3, Class 150 minimum, and shall be Class 300 where the system design pressure exceeds the Class 150 rating at the system design temperature.
+
+### Gray cast iron threaded fittings shall not be used in hydronic piping.
+
+### Reducers on horizontal runs shall be eccentric and installed flat side up, and reducers on vertical runs shall be concentric.
+
+### A concentric reducer on a horizontal run leaves a pocket at the top of the larger pipe where air collects and cannot be carried away by flow. The eccentric reducer installed flat side up keeps the top of the bore continuous so the air keeps moving toward a vent. {note}
+
+### Miter elbows fabricated from straight pipe shall not be used.
+
+## Copper Fittings {toc}
+
+### Wrought copper solder-joint fittings shall conform to ASME B16.22, and cast copper alloy solder-joint fittings shall conform to ASME B16.18.
+
+### Cast copper alloy flanges and flanged fittings shall conform to ASME B16.24.
+
+### Every copper fitting shall be rated for the system design pressure at the system design temperature.
+
+### Elbows and tees formed by bending or notching copper tube shall not be used in place of fittings.
+
+## Flanged Connections {toc}
+
+### Steel flanges shall conform to ASME B16.5, of ASTM A105 / A105M material.
+
+### The steel flange pressure class shall be as indicated in the datasheet.
+
+```datasheet
+label: Steel Flange Pressure Class
+type: range
+options:
+ min: 150
+ max: 600
+ setpoints: [150, 300, 400, 600]
+default: 150
+```
+
+### The steel flange facing shall be as indicated in the datasheet.
+
+```datasheet
+label: Steel Flange Facing
+type: select
+options:
+ - "Raised face"
+ - "Flat face"
+default: "Raised face"
+```
+
+### The flange gasket material shall be as indicated in the datasheet.
+
+```datasheet
+label: Flange Gasket Material
+type: select
+options:
+ - "Non-asbestos compressed fiber"
+ - "EPDM rubber"
+ - "Flexible graphite"
+ - "Polytetrafluoroethylene"
+default: "Non-asbestos compressed fiber"
+```
+
+### Flange gaskets shall conform to ASME B16.21 and shall be rated for the system design temperature and for the glycol type and concentration where glycol is used.
+
+### Where a steel flange mates to a cast iron flange, the joint shall use a flat-face flange and a full-face gasket on the steel side.
+
+### A raised-face steel flange bolted to a flat-faced cast iron flange bends the cast iron over the edge of the raised face as the bolts are drawn up, and cast iron has almost no ductility to absorb that bending. The crack usually appears at the pump or the strainer body rather than at the flange the installer was watching. {note}
+
+### Flange bolts shall be tightened in a crossing pattern in at least three passes to the torque published for the gasket.
+
+### Flange joints shall be aligned before bolting, and bolts shall not be used to pull misaligned flanges together.
+
+## Branch Connections {toc}
+
+### The branch connection method in carbon steel piping shall be as indicated in the datasheet.
+
+```datasheet
+label: Branch Connection Method in Carbon Steel Piping
+type: select
+options:
+ - "Tee fittings"
+ - "Integrally reinforced branch outlet fittings"
+ - "Grooved mechanical branch outlet fittings"
+ - "Not applicable - no carbon steel piping"
+default: "Tee fittings"
+```
+
+### Branch connections made by cutting an opening in the run pipe and welding an unreinforced nipple or coupling over it shall not be used.
+
+### An unreinforced fabricated branch removes metal from the run pipe at exactly the point where the branch load is introduced, and nothing replaces the removed area. The listed outlet fitting exists because it carries that reinforcement in its own body, which is what lets ASME B31.9 accept it without a separate area-replacement calculation. {note}
+
+### Branch connections in copper tube shall be made with wrought tee fittings or with mechanically extracted outlets listed for the tube size and wall.
+
+### Branch outlets shall be taken from the top or the side of a horizontal main, and shall not be taken from the bottom.
+
+# Dissimilar-Metal Isolation {toc}
+
+## Where copper or copper alloy piping connects to carbon steel piping, to a cast iron body, or to a steel-bodied item of equipment, a dissimilar-metal isolation fitting shall be installed at the connection.
+
+## The dissimilar-metal isolation method for each size band shall be as indicated in the datasheets below.
+
+```datasheet
+label: Dissimilar-Metal Isolation Method - NPS 2 and Smaller
+type: select
+options:
+ - "Dielectric union"
+ - "Dielectric nipple"
+ - "Brass or bronze adapter"
+ - "Not applicable - piping and equipment are a single metal"
+default: "Dielectric union"
+```
+
+```datasheet
+label: Dissimilar-Metal Isolation Method - NPS 2½ and Larger
+type: select
+options:
+ - "Insulating flange kit"
+ - "Dielectric waterway flange"
+ - "Not applicable - piping and equipment are a single metal"
+default: "Insulating flange kit"
+```
+
+## An insulating flange kit shall comprise a full-face insulating gasket, insulating sleeves on every bolt, and insulating washers under every nut and bolt head on one side of the joint.
+
+## An insulating flange kit that omits the bolt sleeves leaves every bolt as a metallic bridge across the gasket, so the joint is electrically continuous and the isolation the kit was bought for does not exist. The failure is invisible after assembly and is the reason the sleeve count belongs in the specification rather than in the installer's judgment. {note}
+
+## Dissimilar-metal isolation fittings shall be rated for the system design pressure at the system design temperature.
+
+## The insulating barrier of each isolation fitting shall be inspected before installation, and a fitting with a cracked, chipped, or deformed barrier shall be rejected.
+
+## Isolation fittings shall be installed so that they remain accessible for inspection and replacement.
+
+# Delivery, Storage, and Handling {toc}
+
+## Pipe, tube, and fittings shall be delivered with the manufacturer's markings intact and legible.
+
+## Pipe and tube ends shall be capped or plugged at the mill or at the point of fabrication and shall remain closed until the moment the joint is made.
+
+## Pipe and tube shall be stored off the ground on continuous supports, in a manner that prevents standing water inside the bore and prevents permanent bending between supports.
+
+## Gaskets, sealing elements, and solvent cements shall be stored within the temperature range published by their manufacturer and shall not be used after their marked expiration date.
+
+## Copper tube and stainless steel pipe shall be stored so that they do not contact carbon steel racking, banding, or fasteners.
+
+## Open piping at the end of each work period shall be capped, plugged, or taped closed.
+
+## An uncapped riser is a drain for everything that falls in a mechanical shaft, and the debris that enters it is not discovered until it reaches a strainer or a control valve after the system is filled. The cost of finding it then is far greater than the cost of the cap. {note}
+
+## The Contractor shall bear the cost of cleaning or replacing material that was damaged or contaminated by improper storage or handling.
+
+# Piping Installation {toc}
+
+## Routing, Pitch, and Alignment {toc}
+
+### Piping shall be installed along the routing shown on [[drawing: the mechanical piping plans]] and on the accepted coordination drawings.
+
+### Pipe sizes shall be as shown on [[drawing: the mechanical piping plans]].
+
+### The Contractor shall not install a pipe smaller than the size shown without the written approval of the Engineer of Record.
+
+### Pipe size is set by the system design against pump head, balancing authority, velocity noise limits, and whatever future load the designer reserved for. A substitution justified on the pressure drop of a single circuit does not see the rest of that reasoning, and the consequences show up as an unbalanceable branch or a velocity noise complaint after occupancy. {note}
+
+### The minimum runout size to a terminal unit shall be as indicated in the datasheet, regardless of any smaller size that a velocity or pressure drop calculation would permit.
+
+```datasheet
+label: Minimum Terminal Unit Runout Size
+type: range
+unit: in. NPS
+options:
+ min: 0.5
+ max: 2
+ setpoints: [0.5, 0.75, 1, 1.25, 1.5, 2]
+default: 0.75
+```
+
+### Piping shall be installed plumb, level, and parallel to the building structure, and runs shall be aligned with adjacent piping in the same rack.
+
+### Horizontal mains and branches shall pitch continuously toward the low point serving them at not less than the slope indicated in the datasheet.
+
+```datasheet
+label: Minimum Horizontal Pitch
+type: range
+unit: in. per ft
+options:
+ min: 0
+ max: 0.25
+ setpoints: [0, 0.0625, 0.125, 0.25]
+default: 0.125
+```
+
+### Continuous pitch is what lets a hydronic system move its own air to a vent and its own water to a drain without help. Where the structure or a coordination conflict makes continuous pitch impossible, the run stops being self-clearing and every local high and low point it creates has to be given a vent or a drain of its own. {note}
+
+### Where continuous pitch cannot be achieved, every local high point created shall be provided with a vent connection and every local low point with a drain connection.
+
+### Piping shall not be sprung, forced, or pulled into position to meet an equipment connection or a hanger.
+
+## Penetrations and Sleeves {toc}
+
+### Piping passing through a wall, floor, or ceiling shall pass through a sleeve sized at least two nominal pipe sizes larger than the outside diameter of the pipe including its insulation.
+
+### Sleeves shall be set flush with the finished surface on each side, except where a sleeve is extended above a floor to resist water entry.
+
+### Pipe shall be centered in the sleeve and shall not bear on it, and the pipe shall be independently supported on both sides of the penetration.
+
+### The annular space at a penetration through a fire-rated or smoke-rated assembly shall be closed with a firestop system listed for that assembly, that pipe material, and that annular dimension.
+
+### Escutcheons shall be installed at penetrations exposed to view in finished spaces.
+
+## Drain and Vent Provisions {toc}
+
+### A drain connection with a valve shall be provided at every low point in the piping, at the base of every riser, and between every pair of equipment isolation valves.
+
+### The minimum drain valve size shall be as indicated in the datasheet.
+
+```datasheet
+label: Minimum Drain Valve Size
+type: range
+unit: in. NPS
+options:
+ min: 0.5
+ max: 2
+ setpoints: [0.5, 0.75, 1, 1.25, 1.5, 2]
+default: 0.75
+```
+
+### A plugged nipple, a capped tee, or a valveless tapping shall not be used in place of a drain valve.
+
+### A vent connection shall be provided at every high point in the piping, including high points created by an offset around a structural member or a duct.
+
+### The vent connection at a high point that is concealed above a finished ceiling or otherwise inaccessible shall be extended by tubing to an accessible location.
+
+### A vent installed near a high point rather than at it vents the pipe down to the vent and leaves the air above it, which is why an offset over a beam that was never drawn as a high point is one of the more common sources of an air-bound circuit. The vent has to be at the actual apex of the installed run, not the apex of the drawn run. {note}
+
+### The vent and drain devices themselves are furnished under [[sync/expansion-tanks-and-air-separators]] and [[sync/hydronic-specialties]]; this standard requires the connections and their locations.
+
+## Equipment Connections {toc}
+
+### Every connection to an item of equipment shall include a removable joint that permits the equipment to be disconnected and removed without cutting pipe.
+
+### The removable joint type at equipment connections shall be as indicated in the datasheets below.
+
+```datasheet
+label: Removable Joint at Equipment Connections - NPS 2 and Smaller
+type: select
+options:
+ - "Union"
+ - "Flanged"
+ - "Grooved coupling"
+default: "Union"
+```
+
+```datasheet
+label: Removable Joint at Equipment Connections - NPS 2½ and Larger
+type: select
+options:
+ - "Flanged"
+ - "Grooved coupling"
+default: "Flanged"
+```
+
+### Piping at an equipment connection shall be supported independently of the equipment so that no piping weight or thermal load is carried by the equipment nozzle.
+
+### Piping shall be aligned to the equipment nozzle before the connection is made, and the connection shall not be used to draw the piping into alignment.
+
+### A pump volute, a coil header, and a heat exchanger nozzle are cast or brazed connections with a published allowable load, and a misaligned pipe applies a moment to that connection every hour the system operates. The leak that follows is usually blamed on the equipment. {note}
+
+### Connections to equipment shall be made in the sequence and with the isolation arrangement shown on [[drawing: the mechanical piping plans]].
+
+## Component Accessibility {toc}
+
+### Valves, isolation fittings, vents, drains, unions, and flanged joints shall be located so that they can be reached and operated without removing permanent construction.
+
+### Where a component is located above a hard ceiling or behind a permanent wall finish, an access panel sized for the service operation shall be provided.
+
+### The Contractor shall coordinate access panel locations with the trade installing the finish, and shall record every concealed valve, joint, and vent location on the as-built drawings.
+
+### Where the parties disagree whether a component is reachable for the operation it requires, the Engineer of Record shall make the initial determination.
+
+# Support, Anchor, and Expansion Interfaces {toc}
+
+## Hanger and Support Interface {toc}
+
+### Hangers, supports, structural attachments, and seismic bracing for hydronic piping shall be furnished and installed in accordance with [[sync/hangers-and-supports]] and MSS SP-58.
+
+### The Contractor shall establish support locations before piping is installed, and shall not use an installed pipe to locate a support.
+
+### Support spacing for each pipe material and size shall follow [[sync/hangers-and-supports]], and shall be reduced where a valve, flange, strainer, or specialty item concentrates weight between supports.
+
+### Copper tube requires closer support spacing than steel pipe of the same nominal size because it is markedly less stiff. Sag between supports traps air at the low side of each bay and concentrates bending stress at the fittings, both of which are hidden once the insulation is on. {note}
+
+### Insulated piping shall be supported on insulation shields or insulated supports sized for the insulation outside diameter, and no hanger shall bear directly on insulation.
+
+### Where the parties disagree whether a support arrangement is adequate for a concentrated load, the Engineer of Record shall make the initial determination.
+
+## Thermal Expansion Interface {toc}
+
+### The Contractor shall install the expansion compensation, anchors, and guides shown on [[drawing: the mechanical piping plans]] in accordance with [[sync/expansion-fittings-and-loops]].
+
+### Anchor and guide locations shall not be relocated or omitted without the written approval of the Engineer of Record.
+
+### Carbon steel expands about 0.0075 in. per foot per 100°F of temperature rise, so a 200 ft heating main installed at 70°F and operated at 180°F grows roughly 1.6 in. over its length. Copper grows about 0.011 in. per foot per 100°F, so the same run in copper grows roughly half again as much. Those numbers are why a heating distribution main cannot simply be clamped at both ends. {note}
+
+### The expansion design is a force path between anchors, and a relocated anchor changes the movement every guide and every loop between it and the next anchor was sized for. Moving one anchor to clear a conflict invalidates the compensation on both sides of it, which is why the relocation is an engineering decision rather than a field one. {note}
+
+### Where a conflict prevents installing an anchor or a guide at the location shown, the Contractor shall report the conflict to the Engineer of Record before proceeding with that run.
+
+# Valve, Specialty, and Air-Management Interfaces {toc}
+
+## General-duty isolation, shutoff, and throttling valves shall be furnished and installed in accordance with [[sync/hvac-piping-valves]].
+
+## Balancing valves, pressure-independent control valves, strainers, flexible connectors, gauges, and thermometers shall be furnished and installed in accordance with [[sync/hydronic-specialties]].
+
+## Expansion tanks, air separators, dirt separators, and automatic air vents shall be furnished and installed in accordance with [[sync/expansion-tanks-and-air-separators]].
+
+## The piping shall provide an isolation valve connection on each side of every item of equipment, at the base and top of every riser, on every branch serving more than two terminal units, and at every terminal unit connection.
+
+## The piping shall provide the connection, orientation, and clearance each specialty item requires, including the straight run of pipe upstream and downstream that the item's manufacturer publishes.
+
+## A balancing device is a flow-measuring instrument as well as a throttle, and its published accuracy assumes a developed velocity profile at its inlet. Installing it directly downstream of an elbow or a tee gives it a swirling profile it cannot read correctly, so the balance is set against a measurement that is wrong by an amount nobody can see. {note}
+
+## Balancing devices shall be installed on the return side of each terminal unit.
+
+## Where an item of equipment or a specialty is set before the piping is complete, the Contractor shall protect its connections from construction debris until the connection is made.
+
+## Terminal unit and central plant equipment themselves are outside this standard; the piping connections to them are within it. {note}
+
+# Insulation and Identification Interfaces {toc}
+
+## Insulation Interface {toc}
+
+### Pipe, fitting, valve, and equipment insulation shall be furnished and installed in accordance with [[sync/mechanical-insulation]] and shall meet the minimum thickness required by the adopted edition of ANSI/ASHRAE/IES 90.1.
+
+### Insulation shall not be applied to any portion of the piping until that portion has passed its pressure test and the test has been documented.
+
+### The pipe surface shall be clean, dry, and free of loose rust and scale when insulation is applied.
+
+### Insulation applied over a wet or corroding surface seals the moisture against the pipe and removes the only condition under which the corrosion would have stopped. On chilled water the same detail also saturates the insulation, so the thermal performance the project paid for is gone before the building opens. {note}
+
+### The Contractor shall complete all joints, connections, and repairs on a run before the insulation contractor is released to that run.
+
+### Where a joint must be opened after insulation is applied, the Contractor shall bear the cost of removing and reinstating the insulation and the vapor retarder.
+
+### The continuity of the vapor retarder over fittings, valves, flanges, and supports on below-ambient piping is required by [[sync/mechanical-insulation]]; this standard requires that the piping be presented in a condition that allows that continuity to be achieved.
+
+## Identification Interface {toc}
+
+### Pipe markers, flow direction indicators, and valve tags shall be furnished and installed in accordance with [[sync/mechanical-identification]] and ASME A13.1.
+
+### Piping shall be identified after insulation is complete and before the ceiling or shaft enclosure is closed.
+
+### Valves, fittings, flanges, and unions shall bear the manufacturer's markings required by MSS SP-25, and those markings shall remain legible and visible after installation where the component is accessible.
+
+# Cleaning, Flushing, and Water Treatment Interface {toc}
+
+## Cleaning, flushing, passivation, and the corrosion inhibitor start charge shall be performed in accordance with [[sync/hydronic-cleaning-and-flushing]], and the ongoing treatment program shall be established in accordance with [[sync/hvac-water-treatment]].
+
+## The Contractor shall keep the interior of the piping clean during installation and shall not rely on flushing to remove construction debris that could have been kept out.
+
+## Strainer screens, control valves, and coils shall be protected or bypassed before flushing, in the arrangement required by [[sync/hydronic-cleaning-and-flushing]].
+
+## The piping shall be complete, pressure tested, and accepted before the cleaning and flushing sequence begins.
+
+## The sequence matters in one direction only: the pressure test proves the assembly, the cleaning and flushing prepare the water, and the insulation closes the work. Running the test after the system has been chemically treated means a leak discharges treated water and the boundary has to be re-established; running the insulation before the test means finding a leak through a jacket. {note}
+
+## Where a leak repair is made after cleaning and flushing are complete, the Contractor shall re-flush the affected section and shall bear the cost of the re-flush and of any treatment chemical lost.
+
+## The Contractor shall provide the fill, drain, and temporary connection points that the cleaning and flushing procedure requires, at the locations shown on [[drawing: the mechanical piping plans]].
+
+# Pressure Testing {toc}
+
+## Test Medium and Boundaries {toc}
+
+### Every portion of the hydronic piping shall be pressure tested before it is insulated, concealed, buried, or enclosed.
+
+### The pressure test medium shall be as indicated in the datasheet.
+
+```datasheet
+label: Pressure Test Medium
+type: radio
+options:
+ - "Hydrostatic, using clean water"
+ - "Pneumatic, using clean dry air or nitrogen"
+default: "Hydrostatic, using clean water"
+```
+
+### Water is nearly incompressible, so a hydrostatic test stores almost no energy and a joint that lets go releases water at the rate the pump can supply. A gas at the same pressure stores enough elastic energy that the same failure becomes a projectile hazard, which is why the hydrostatic test is the baseline and the pneumatic test is reserved for situations where water cannot be used, such as a pre-insulated system that cannot be wet-tested or piping over finished work where a discharge would be more damaging than the test is useful. {note}
+
+### The test pressure shall be 1.5 times the maximum system design pressure and not less than 100 psig, in accordance with ASME B31.9 and the International Mechanical Code Chapter 12.
+
+### Where the calculated test pressure exceeds the rating of a component within the intended boundary, that component shall be isolated or removed from the boundary and shall be tested separately at its own rated pressure.
+
+### The pressure test staging shall be as indicated in the datasheet.
+
+```datasheet
+label: Pressure Test Staging
+type: select
+options:
+ - "Sectional test of each portion as it is completed"
+ - "Single test of the completed system"
+ - "Sectional tests followed by a final test of the completed system"
+default: "Sectional test of each portion as it is completed"
+```
+
+### Sectional testing is what allows concealed work to close on schedule, because a section can be tested and released as soon as it is complete rather than waiting for the whole system. Where the system is small enough to complete in one sequence, or where every joint stays accessible until the end, a single test of the whole system is simpler and proves the same thing. {note}
+
+### Every test boundary shall be recorded on the pressure test plan before the test is performed.
+
+### A pneumatic test shall be preceded by a preliminary test at 25 psig to find gross leaks by sound, and shall not exceed the lowest pressure rating of any component within the boundary.
+
+### Personnel not essential to a pneumatic test shall be excluded from the test area while the system is pressurized.
+
+## Test Procedure and Acceptance {toc}
+
+### The system shall be filled from its lowest point with air vented continuously from every high point until the boundary is full of the test medium.
+
+### The test pressure shall be applied and held for not less than the duration indicated in the datasheet.
+
+```datasheet
+label: Minimum Test Hold Duration
+type: range
+unit: hours
+options:
+ min: 1
+ max: 24
+ setpoints: [1, 2, 4, 8, 12, 24]
+default: 2
+```
+
+### The pressure loss over the hold period shall not exceed the value indicated in the datasheet.
+
+```datasheet
+label: Maximum Permitted Pressure Loss During the Hold
+type: range
+unit: psi
+options:
+ min: 0
+ max: 10
+ setpoints: [0, 2, 5, 10]
+default: 0
+```
+
+### A zero-loss criterion is achievable on a hydrostatic test of a stable system and is the reason hydrostatic testing is trusted. On a long hold, on a pneumatic test, or where the boundary spans a large temperature swing between day and night, thermal effects on the medium can produce a reading that is not a leak, and an allowance keeps the criterion honest. Where an allowance is used, a temperature reading at the start and end of the hold is what separates a thermal change from a leak. {note}
+
+### Where a pressure loss allowance greater than zero is selected, the temperature of the test medium shall be recorded at the start and at the end of the hold period.
+
+### Every joint, fitting, weld, braze, flange, and valve body within the boundary shall be visually inspected during the hold period.
+
+### Visible leakage at any joint shall fail the test regardless of the measured pressure loss.
+
+### A failed test shall be followed by repair of the cause, restoration of the boundary, and a complete repeat of the test from the beginning.
+
+### The Contractor shall bear the cost of the repair, the retest, the test medium, and the repair of any other trade's work damaged by the failure or by the water released.
+
+### Test gauges shall be calibrated within the preceding twelve months, shall have a full-scale range between 1.5 and 2 times the test pressure, and shall be graduated finely enough to resolve a change of 5 psi.
+
+### A gauge reading in the bottom fifth of its scale cannot resolve the change the test is looking for, and a gauge reading near full scale has no margin. Ranging the gauge at 1.5 to 2 times the test pressure puts the reading in the part of the dial where the instrument is accurate. {note}
+
+### The test gauge shall be located at the low point of the test boundary, and a reading taken at the pump or at a high point shall not be used as the sole basis for acceptance.
+
+## Test Documentation {toc}
+
+### The pressure test shall be witnessed by the party indicated in the datasheet.
+
+```datasheet
+label: Pressure Test Witness
+type: select
+options:
+ - "Engineer of Record or the Engineer's representative"
+ - "Owner's commissioning authority"
+ - "Authority Having Jurisdiction inspector"
+ - "Contractor's quality control representative"
+default: "Engineer of Record or the Engineer's representative"
+```
+
+### The Contractor shall give the witnessing party not less than five business days notice of a scheduled test.
+
+### A signed and dated test report shall be prepared for every test boundary, recording the date, the boundary, the medium, the test pressure, the hold duration, the starting and ending pressure, the temperature readings where required, the name and signature of the Contractor's representative, and the name and signature of the witness.
+
+### A test report shall record a pass only where the pressure loss was within the permitted value and no leakage was found by visual inspection.
+
+### A test report shall not record a conditional or qualified pass, and a boundary in which a repair was made shall be recorded on a new report covering the complete repeat test.
+
+# Warranty {toc}
+
+## The Contractor shall warrant the hydronic piping work, including pipe, fittings, joints, welds, brazes, soldered joints, pressed joints, flanged joints, and isolation fittings, against defects in materials and workmanship for the period indicated in the datasheet, measured from the date of substantial completion.
+
+```datasheet
+label: Contractor Installation Warranty Period
+type: range
+unit: years
+options:
+ min: 1
+ max: 5
+ setpoints: [1, 2, 3, 5]
+default: 1
+```
+
+## Where the contract General Conditions specify a longer warranty period than the datasheet, the longer period shall govern.
+
+## Any leak, joint failure, or corrosion attributable to the installation discovered within the warranty period shall be repaired by the Contractor at no cost to the Owner.
+
+## The Contractor shall bear the cost of removing and reinstating insulation, ceiling, and finish work required to reach a warranted repair, and the cost of repairing damage caused by the failure or by the repair itself.
+
+## The unassigned cost in a piping warranty is almost never the joint. It is the ceiling that has to come down to reach it, the insulation that has to be rebuilt over it, and the finishes below that the leak reached first. Naming those costs here is what makes the warranty enforceable without an argument. {note}
+
+## A repaired or replaced portion of the piping shall carry a warranty running for a full new term from the date the repair is accepted, or for the remainder of the original term, whichever ends later.
+
+## The Contractor shall pressure test any repaired portion in accordance with this standard before the repair is accepted.