1 Scope
NOTE This standard governs chilled water (CHW) and condenser water (CW) distribution piping for central-plant HVAC systems, including plant headers, secondary and tertiary distribution mains, risers, and the isolation, balancing, metering, and air-management specialties installed on those mains. (1.1)
NOTE The defining condition is central-plant scale: large-diameter steel piping (typically 4 in. and larger) tying water-cooled chillers to cooling towers on the open condenser circuit and to air-handling and terminal equipment on the closed chilled water circuit. This is the depth a chiller-plant engineer needs beyond the generic hydronic standard. (1.2)
NOTE Applicable project types include new central chiller plants, plant expansions, campus chilled water loop additions and extensions, data center cooling distribution, and hospital and other critical-cooling infrastructure. (1.3)
NOTE This standard is the central-plant / large-distribution specialization of closed- and open-loop water piping; the generic and smaller-diameter case is covered separately. (1.4)
NOTE For closed-loop heating hot water (HHW), small-diameter CHW runouts to individual terminal units, and general hydronic distribution, use
Hydronic Piping. Refer to
Chillers for the refrigeration machine, evaporator, and condenser barrel; to
Cooling Towers for the tower, cold-water basin, and tower distribution; and to
Hvac Pumps for pump selection and base-mounted pump arrangements.
(1.5) NOTE The following are outside this scope and are governed by the referenced companion standards or codes. (1.6)
- Chillers, including the evaporator/condenser heat exchanger and refrigerant circuit — Chillers.
- Cooling towers, cold-water basin, tower hot-water distribution, fill, and drift eliminators — Cooling Towers.
- CHW and CW circulating pumps and pump sets — Hvac Pumps.
- Chemical water treatment, biocide and inhibitor dosing, and Legionella risk-management programs for the circulating water — Hvac Water Treatment.
- Pump and fan variable frequency drives — Hvac Variable Frequency Drives.
- Refrigerant piping between chiller and remote condenser or evaporator — ASME B31.5.
- High-temperature hot water above 250°F or above 160 psig — ASME B31.1.
- Fire protection piping — Fire Protection Piping.
- Domestic (potable) cold and hot water piping — outside this scope.
- HVAC condensate drainage piping — Condensate Drainage Piping.
- Building automation system controls integration and programming — a separate BAS/controls standard.
- Testing, adjusting, and balancing of connected water-system flows — a separate TAB standard.
- Evaporative coolers serving the airstream rather than a condenser-water loop — Evaporative Coolers.
- Pressure and temperature instrumentation and transmitters beyond the piping specialties named here — Pressure Instrumentation and Temperature Instrumentation.
1.7The piping system shall be designed and installed within the pressure and temperature limits of ASME B31.9 for building services piping: 150 psig maximum and below 200°F.
NOTE Chilled and condenser water service falls well inside these limits. Systems that exceed them are not building services piping and must be designed to a higher-tier code (ASME B31.1), which is outside this standard. (1.8)
2 Referenced Standards
2.1Equipment, materials, fabrication, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
| Standard |
Title |
| ASME B31.9 |
Building Services Piping |
| ASTM A53/A53M |
Black and Hot-Dipped Galvanized Welded and Seamless Steel Pipe |
| ASTM A106/A106M |
Seamless Carbon Steel Pipe for High-Temperature Service |
| ASTM A234/A234M |
Wrought Carbon and Alloy Steel Piping Fittings for Moderate and High Temperature Service |
| ASME B16.9 |
Factory-Made Wrought Buttwelding Fittings |
| ASME B16.5 |
Pipe Flanges and Flanged Fittings, NPS 1/2 through NPS 24 |
| ASME B16.47 |
Large Diameter Steel Flanges, NPS 26 through NPS 60 |
| ASME B16.34 |
Valves — Flanged, Threaded, and Welding End |
| ASME BPVC Section IX |
Welding and Brazing Qualifications |
| ASTM C534/C534M |
Preformed Flexible Elastomeric Cellular Thermal Insulation |
| ASTM C547 |
Mineral Fiber Pipe Insulation |
| ASTM C553 |
Mineral Fiber Blanket Thermal Insulation for Commercial and Industrial Applications |
| ASTM C585 |
Inner and Outer Diameters of Rigid Thermal Insulation for Nominal Pipe and Tubing Sizes |
| ASTM C1290 |
Flexible Fibrous Glass Pipe Insulation |
| ANSI/ASHRAE/IES 90.1 |
Energy Standard for Buildings Except Low-Rise Residential Buildings |
| AWWA C504 |
Rubber-Seated Butterfly Valves, 3 in. through 72 in. |
| AWWA C516 |
Large-Diameter Rubber-Seated Butterfly Valves, 78 in. and Larger |
| MSS SP-58 |
Pipe Hangers and Supports — Materials, Design, Manufacture, Selection, Application, and Installation |
| MSS SP-89 |
Pipe Hangers and Supports — Fabrication and Installation Practices |
| ASHRAE Handbook |
HVAC Systems and Equipment (district cooling, chiller plant, and pipe sizing chapters) |
| ANSI/ASHRAE 188 |
Legionellosis: Risk Management for Building Water Systems |
| ASSE 1010 |
Performance Requirements for Water Hammer Arresters |
| ASTM F714 |
Polyethylene (PE) Plastic Pipe (DR-PR) Based on Outside Diameter |
| ASCE 7 |
Minimum Design Loads and Associated Criteria for Buildings and Other Structures |
3 Submittals
3.1The Contractor shall submit the following Action Submittals for review and approval before fabrication or procurement:
- Pipe and fitting product data showing material grade, schedule/wall, and manufacturing standard for each service and size range.
- Valve schedule listing each isolation, balancing, and check valve by service, size, type, end connection, pressure class, and actuation.
- Joining-method schedule by pipe size identifying threaded, grooved, butt-weld, and flanged joints.
- Insulation product data and a condensation-control calculation for chilled water piping at the worst-case ambient dew point.
- Pipe support, hanger, guide, anchor, and seismic-bracing layout with MSS SP-58 type designations and spacing.
- Expansion-compensation design (loops, offsets, or joints) with anchor and guide forces and movement calculations.
- Welding procedure specifications (WPS), procedure qualification records (PQR), and welder performance qualifications per ASME Section IX.
- Pre-insulated buried piping system data, field-joint kit details, and installer certification where buried systems are used.
- Flow meter and differential-pressure transmitter data with required upstream/downstream straight-pipe runs.
☑ Pipe and fitting product data
☑ Valve schedule
☑ Joining-method schedule by size
☑ Insulation product data + condensation calc
☑ Support, hanger, guide, anchor, and seismic layout
☐ Expansion-compensation design and force calcs
☑ Welding WPS / PQR / welder qualifications
☐ Pre-insulated buried system data + installer cert
☐ Flow meter and DP transmitter data
3.2The Contractor shall submit the following Informational Submittals:
- Hydrostatic test plan and signed test records for each tested segment.
- System flushing plan, flushing velocity calculations, and cleaning-agent data.
- Temporary startup strainer details and a cleaning/removal record.
- Welder continuity and weld examination records.
☑ Hydrostatic test plan and records
☑ Flushing plan and velocity calcs
☑ Temporary startup strainer details + cleaning record
☑ Weld examination records
3.3The Contractor shall submit the following Closeout Submittals:
- Record drawings showing as-built routing, valve tags, anchor and guide locations, and meter stations.
- Valve tag schedule and operation/maintenance data for valves, strainers, meters, and specialties.
- Commissioning records including flow verification at each chiller evaporator and condenser connection.
☑ Record drawings
☑ Valve tag schedule + O&M data
☑ Commissioning / flow verification records
4 Quality Assurance
4.1All butt-weld joints on steel piping shall be made by welders and procedures qualified in accordance with ASME Section IX.
4.2Welding procedures and welder qualifications shall be current and on file before any production welding begins.
4.3Buried pre-insulated piping field joints shall be made only by installers certified by the pre-insulated system manufacturer.
NOTE Factory-applied jacket and insulation are reliably installed; the recurring failure point is the field joint. Heat-shrink sleeves and foam-injection kits applied by untrained crews admit moisture, saturate the insulation, and corrode the carrier pipe. Manufacturer-trained installers and documented joint procedures are the practical defense. (4.4)
4.5Grooved mechanical coupling installation shall follow the coupling manufacturer's published procedures, including groove dimension verification and key engagement before fastener torquing.
4.6Pressure testing, flushing, and chiller-connection flow verification shall be witnessed by the Engineer of Record or the commissioning authority.
NOTE These are one-time, concealable events; debris fouling and undersized flow are expensive to discover after the plant is energized. Witnessed acceptance closes the loop before insulation and concealment. (4.7)
5 Environmental and Service Conditions
5.1Design temperatures and pressures shall be coordinated with the chiller, tower, and pump selections; the piping shall be designed for the most severe combination of pressure and temperature it will experience.
NOTE Chilled water leaves the plant cold and returns warmer; condenser water leaves warm and returns warmer still. The piping, insulation, and gasket selections all follow from these service points, so they are fixed here before material selection. (5.2)
5.3 Design Service Temperatures
5.3.1Chilled water supply temperature shall be as scheduled; the design setpoint is the most common comfort-cooling value unless process or low-temperature service is shown.
NOTE A 44°F supply with a 56°F return (12°F delta-T) is the dominant comfort-cooling design point. Lower supply temperatures raise compressor lift and energy use; higher delta-T reduces flow and pump energy but demands disciplined coil and control selection. (5.3.2)
5.3.3Condenser water supply temperature (tower to chiller) shall be as scheduled; the design value reflects the project climate and tower selection.
NOTE 85°F entering condenser water at design load is the 80% case across most US climates, with a 10°F rise to 95°F leaving the chiller. The lower limit matters as much as the design point: most chillers require a minimum entering condenser water temperature to maintain refrigerant pressure differential. (5.3.4)
5.3.5The minimum entering condenser water temperature required by the chiller shall be specified, and a head-pressure control method (tower bypass valve, tower fan staging, or both) shall be provided to maintain it.
NOTE The minimum entering condenser water temperature is a chiller-imposed limit, typically in the 55°F to 65°F range; allowing condenser water to fall below it in spring and fall will trip chiller safeties. (5.3.6)
5.4 Design Pressure
5.4.1The system design pressure for pipe, valve, and specialty selection shall be the greater of the static fill pressure plus pump head or the project-specified design pressure, and shall not exceed the ASME B31.9 limit of 150 psig.
NOTE Closed CHW loops typically operate at 30 psig to 80 psig static plus pump head; open CW loops at 20 psig to 60 psig. A 125 psig design pressure is the common selection basis for commercial central plants. (5.4.2)
6 Pipe Materials and Joining
6.1Pipe material shall be selected by service, pressure, and size; black steel is the default for closed CHW and most CW mains, with corrosion-resistant alternatives reserved for the open condenser circuit.
NOTE Closed chilled water has low dissolved oxygen once deaerated and treated, so standard black steel performs well. The open condenser circuit continuously absorbs oxygen at the tower and concentrates dissolved solids, which drives the material decision toward lined, galvanized, or non-metallic options for high-cycle or high-makeup systems. (6.2)
6.3 Chilled Water and Closed-Loop Pipe Material
6.3.1Black steel pipe 2½ in. and larger shall be ASTM A53 Grade B (ERW or seamless) or ASTM A106 Grade B (seamless), Schedule 40 unless a heavier wall is required by pressure or seismic design.
6.3.2Seamless ASTM A106 Grade B should be specified for systems above 100 psig or where seamless pipe is required by the project.
6.3.3Copper tube may be used only for runouts and connections 2 in. and smaller; central-plant mains shall be steel.
● ASTM A53 Grade B ERW black steel, Sch 40
○ ASTM A53 Grade B seamless black steel, Sch 40
○ ASTM A106 Grade B seamless black steel, Sch 40
○ ASTM A106 Grade B seamless black steel, Sch 80
6.3.4Butt-welding fittings shall conform to ASTM A234/A234M Grade WPB and ASME B16.9 dimensions.
6.4 Condenser Water (Open-Circuit) Pipe Material
6.4.1Condenser water pipe material shall account for internal corrosion from dissolved oxygen, chlorides, and microbiological activity inherent to open cooling-tower circuits.
NOTE Specifying bare black steel for the open condenser circuit without addressing oxygen-driven corrosion produces early wall loss; inhibitor treatment alone is insufficient for high-cycle or high-makeup systems. (6.4.2)
NOTE The open circuit is the most common premature-failure mode in central plants. Match the material to the water chemistry and cycles of concentration rather than defaulting to the chilled-water material. (6.4.3)
● ASTM A53 Grade B black steel, Sch 40 (treated, low-cycle service)
○ ASTM A53 hot-dipped galvanized steel, Sch 40
○ Cement-mortar or epoxy-lined steel
○ Fiberglass-reinforced plastic (FRP), filament-wound
6.4.4Where FRP is selected for the open condenser circuit, pipe shall be filament-wound to the applicable ASTM D2310/D2996 classification with manufacturer-rated pressure and temperature for the service.
6.5 Joining Methods by Size
6.5.1Joining methods shall be selected by pipe size: threaded for 2 in. and smaller, grooved mechanical couplings for 2 in. through 12 in., butt-welding for 4 in. and larger mains, and flanged at equipment and at valves 4 in. and larger.
NOTE Welded mains give the most leak-resistant, lowest-maintenance distribution; grooved couplings speed field assembly and provide controlled flexibility; flanges allow equipment and valve removal. Most plants mix all four, assigned by size and location. (6.5.2)
● Butt-weld (ASME Section IX, B16.9 fittings)
○ Grooved mechanical coupling (roll- or cut-groove)
○ Flanged (at equipment and valves)
6.5.3Grooved coupling gaskets shall be selected for the full service-temperature range of the circuit; standard EPDM gaskets shall be verified against the design temperature excursions in heat-recovery or geothermal applications.
NOTE A gasket rated only for nominal CHW/CW temperatures can fail in systems that see wider temperature swings, such as heat-recovery condenser water. (6.5.4)
EPDM (standard CHW/CW service)
Nitrile (oil-resistant / specific service)
EPDM, high-temperature grade (heat recovery / geothermal)
6.5.5Flanges shall conform to ASME B16.5 through NPS 24 and ASME B16.47 for NPS 26 and larger, with pressure class matched to the system design pressure.
7 Pipe Sizing and Hydraulic Architecture
7.1Distribution piping shall be sized to satisfy both the friction-loss and velocity criteria below and the ASHRAE 90.1 maximum pipe-size limits, whichever governs the smaller pipe energy outcome.
NOTE Three constraints act at once: friction loss sets pump head, velocity bounds erosion and noise, and ASHRAE 90.1 Table 6.5.4.5 caps pipe size for energy compliance by flow and annual operating hours. Sizing for velocity alone routinely produces oversized pipe that fails energy-code review. (7.2)
7.3 Velocity and Friction Criteria
7.3.1Pipe velocity shall be not less than 2 fps to ensure air transport and not more than 10 fps in steel mains to limit erosion and noise; the typical design range is 3 fps to 8 fps.
7.3.2Distribution mains shall be sized to a friction-loss target in the range of 1 ft to 4 ft per 100 ft; plant headers should be sized at the low end (1 ft to 1.5 ft per 100 ft) to minimize pump head.
7.3.3Pipe sizing shall not violate ASHRAE 90.1 maximum pipe sizes for the system's flow rate and annual operating hours; any exceedance shall be documented through an energy trade-off.
NOTE ASHRAE 90.1 Table 6.5.4.5 caps maximum pipe diameter by flow and operating hours; ignoring it is a common cause of energy-review failure on oversized distribution. (7.3.4)
7.4 Hydraulic Distribution Architecture
7.4.1The hydraulic architecture shall be coordinated with the pump and chiller selections, because it determines header sizing, bypass requirements, and pump arrangement.
NOTE Constant-primary, primary/secondary, primary/secondary/tertiary, and variable-primary each impose different piping. Primary/secondary requires a decoupling bypass bridge; variable-primary requires a minimum-flow bypass and well-placed differential-pressure control. The piping cannot be sized until the architecture is fixed. (7.4.2)
○ Constant-primary
○ Primary / secondary (decoupled bypass bridge)
○ Primary / secondary / tertiary
● Variable-primary (minimum-flow bypass)
7.4.3Where a decoupled or variable-primary architecture is used, a bypass shall be provided and sized for the chiller minimum-flow requirement.
7.4.4Differential-pressure transmitters shall be located to control the distribution against the most remote critical load, and the number and location of sensing points shall be coordinated with the pump control sequence.
NOTE Locating the DP sensor at the plant header rather than at the end of the loop over-pressurizes the distribution and contributes to low-delta-T operation; end-of-loop sensing with setpoint reset is preferred for variable-flow systems. (7.4.5)
● End of loop (most remote critical load)
○ Multiple distributed sensing points
○ Plant header
7.5 Low-Delta-T Avoidance
7.5.1Pipe and control selections shall avoid low-delta-T syndrome, in which excessive distribution pressure drop forces the plant to minimum flow before the design delta-T is reached.
NOTE Undersized pipe that drives up pressure drop, combined with end-of-loop pressure-bias control, makes the plant over-pump and the chillers run inefficiently at part-load. Enforcing the ASHRAE 90.1 maximum sizes and end-of-loop DP control directly counters it. (7.5.2)
8 Valves and Piping Specialties
8.1.1Isolation valves shall be provided at each chiller, each pump, each cooling tower connection, and at each branch takeoff from the plant headers to permit sectional isolation without draining the system.
NOTE Sectional isolation is what allows a single chiller or pump to be serviced while the plant stays online. The valve type follows from size and pressure class. (8.1.2)
● Lug-type butterfly, AWWA C504, gear-operated
○ Wafer butterfly, AWWA C504, gear-operated
○ Resilient-wedge gate, flanged
○ OS&Y gate, ASME 125/250
8.1.3Butterfly valves on condenser and chilled water mains 6 in. and larger shall conform to AWWA C504; valves 78 in. and larger shall conform to AWWA C516.
8.1.4Lug-type butterfly valves shall be used where downstream piping must be removed with the valve holding system pressure (dead-end service).
8.1.5Isolation valves at flanged chiller and pump connections may be flanged OS&Y gate valves to ASME 125/250 where a full-bore, low-pressure-drop shutoff is required.
8.2 Motor-Actuated Valve Closure Speed
8.2.1Motor-actuated isolation valves 6 in. and larger on condenser and chilled water mains shall have a minimum 15 second to 30 second close time to limit water-hammer transients.
NOTE Rapidly closing a large butterfly valve on a main flowing at 6 fps generates pressure transients that can exceed design pressure; slow-close actuation is the control. (8.2.2)
NOTE Water hammer at large valve closures and pump trips is a real overpressure source on central-plant mains. Slow-close actuators, and water-hammer arresters to ASSE 1010 where transients remain, protect the piping and joints. (8.2.3)
8.3 Balancing and Check Valves
8.3.1Balancing valves with readout ports shall be provided at each chiller and at each balanced branch to allow flow verification and adjustment during commissioning.
8.3.2Balancing valves shall be accessible for readout and adjustment after insulation is applied.
8.3.3Check valves shall be provided at each pump discharge to prevent reverse flow on pump shutdown.
8.3.4The check valve type shall be selected to minimize closing transients; silent or spring-assisted check valves are preferred on large mains.
8.4 Strainers
8.4.1A basket or Y-strainer shall be provided upstream of each chiller, pump, control valve, and flow meter that requires protection from debris.
8.4.2Strainer screen mesh shall be selected for the protected device, and strainers shall have blowdown connections for cleaning without disassembly.
8.5 Air Management
8.5.1Manual air vents shall be provided at all high points of chilled water and closed-loop piping, and drain valves at all low points.
NOTE Air collecting at high points blocks flow and accelerates corrosion; high-point venting and low-point draining are required for fill, flushing, and service. (8.5.2)
9 Flow and Pressure Measurement
9.1 Flow Metering
9.1.1A flow-measurement device shall be provided at each chiller evaporator and condenser connection to prove water flow before and during operation.
9.1.2The flow-metering method shall be selected for accuracy, installed straight-pipe availability, and maintenance access.
NOTE Inline magnetic meters are accurate and unobstructed but require flanged insertion and straight-run length; ultrasonic clamp-on meters avoid penetration but depend on pipe condition; orifice plates are simple but lossy. The choice is constrained by available straight pipe upstream and downstream. (9.1.3)
● Inline magnetic flow meter (flanged)
○ Ultrasonic clamp-on flow meter
○ Orifice plate with DP transmitter
9.1.4Flow meters shall be installed with the manufacturer's required upstream and downstream straight-pipe runs; insufficient straight run shall be corrected before acceptance.
9.2 Pressure and Differential-Pressure Taps
9.2.1Pressure gauge taps shall be provided across each pump, chiller, strainer, and control valve to allow pressure-drop verification.
9.2.2Differential-pressure transmitters used for distribution control shall be provided at the locations established by the hydraulic architecture above.
10 Insulation
10.1Chilled water piping shall be insulated to control both heat gain and surface condensation; condenser water piping insulation shall be provided only where required by energy code or freeze protection.
NOTE On chilled water the controlling criterion is usually condensation, not heat gain. Insulation sized to ASHRAE 90.1 energy-compliance thickness alone is frequently too thin to keep the jacket above the ambient dew point in a humid mechanical room, and the result is dripping insulation and mold. (10.2)
10.3 Insulation Thickness and Condensation Control
10.3.1Chilled water insulation thickness shall be the greater of the ASHRAE 90.1 minimum and the thickness required by condensation analysis at the worst-case ambient dew point.
NOTE Insulation sized only for energy compliance is often insufficient to prevent condensation in humid spaces; a condensation calculation at the design dew point is required, not just an energy-thickness lookup. (10.3.2)
10.3.3Insulation thickness shall be increased for piping in unconditioned or high-humidity spaces relative to conditioned-space requirements.
○ Elastomeric foam, ASTM C534 (pipe 3 in. and smaller)
● Mineral fiber / fiberglass, ASTM C547 with ASJ (pipe larger than 3 in.)
○ Flexible fibrous glass, ASTM C1290
● Greater of ASHRAE 90.1 minimum and condensation analysis
○ ASHRAE 90.1 minimum only
10.4 Vapor Retarder
10.4.1Chilled water insulation shall have a continuous vapor retarder.
10.4.2The vapor seal shall be maintained unbroken at fittings, valves, flanges, hangers, and supports.
NOTE A single break in the vapor barrier admits moisture that migrates through the insulation and condenses on the cold pipe, causing corrosion under insulation and mold; continuity is the entire point. (10.4.3)
● All-service jacket (ASJ), interior dry spaces
○ PVC jacket, exterior and mechanical rooms
○ Aluminum jacket, exposed / high-abuse locations
10.4.4Insulated chilled water piping shall have a thermal-protection shield and a load-bearing insert at each hanger to carry pipe loads without crushing the insulation or breaking the vapor seal.
11 Expansion, Supports, and Anchoring
11.1 Thermal Expansion and Contraction
11.1.1Expansion compensation shall be sized for the full installation-to-operating temperature differential of each service, including the contraction of chilled water piping installed warm and operated cold.
NOTE Chilled water at 44°F installed at a 70°F ambient contracts measurably; designing only for heating-side expansion ignores it. Expansion loops, offsets, or joints, with anchors sized for the resulting forces, must accommodate the movement of both circuits. (11.1.2)
● Natural offsets and expansion loops
○ Grooved flexible couplings
○ Bellows / packed expansion joints
11.1.3Anchors shall be designed to resist the thrust and expansion forces developed by the selected compensation method.
11.1.4Guides shall be located to direct movement into loops, offsets, or joints.
11.2 Supports and Hangers
11.2.1Pipe hangers and supports shall conform to MSS SP-58 and MSS SP-89, with spacing per ASME B31.9 for the pipe size, schedule, and contents.
11.2.2Hanger spacing shall not exceed the code maximum for the pipe size; representative maxima are 10 ft for 3 in., 14 ft for 6 in., and 23 ft for 12 in. pipe.
11.2.3Hangers and supports for chilled water piping shall not penetrate or compress the vapor barrier; supports shall bear on a protection shield and insulation insert sized for the load.
11.3 Seismic Bracing
11.3.1Where required by the building code, piping shall be seismically braced in accordance with ASCE 7 and the locally adopted IBC provisions.
NOTE Seismic bracing is governed by the building code's seismic design category and is not optional where triggered; coordinate brace locations with expansion guides and anchors. (11.3.2)
12 Buried and Tunnel Installation
12.1Buried and tunnel chilled water distribution shall use a pre-insulated piping system or a field-insulated system with protective casing appropriate to the soil and groundwater conditions.
NOTE Campus loop extensions and tunnel runs are where most long-term insulation and corrosion failures originate. The carrier-pipe, insulation, and jacket are selected as a system, and the field joints determine whether the system survives. (12.2)
● Pre-insulated steel carrier, polyurethane foam, HDPE jacket (ASTM F714)
○ Pre-insulated steel carrier, polyurethane foam, steel outer casing
○ Field-insulated steel with protective casing
12.3Buried steel piping in corrosive soils shall be provided with cathodic protection appropriate to the soil resistivity.
12.4Buried piping shall be installed at a depth that protects against freezing and surface loading for the project location.
12.5Field joints on pre-insulated buried piping shall be made with the manufacturer's field-joint kit by a certified installer and tested for jacket integrity before backfill.
13 Open Condenser Circuit Provisions
13.1The open condenser water circuit shall include makeup water, overflow, blowdown, and sump-strainer provisions consistent with the tower and water-treatment design.
NOTE The condenser circuit is open to atmosphere at the tower, so it continuously loses water to evaporation and drift and gains dissolved solids. The piping must accept makeup, reject overflow and blowdown, and protect downstream equipment with adequate strainer area. Coordinate the Legionella risk-management requirements with
Hvac Water Treatment and ANSI/ASHRAE 188.
(13.2) 13.3A makeup water connection sized for design evaporation, drift, and blowdown losses shall be provided to the tower basin or the condenser circuit.
13.4Sump and circuit strainers shall be sized for the open-circuit debris load, with adequate screen area to avoid premature fouling.
13.5Blowdown piping shall be provided and sized to maintain the cycles of concentration established by the water-treatment program.
14 Testing
14.1 Hydrostatic Test
14.1.1Each piping segment shall be hydrostatically tested at 1.5 times the system design pressure for a minimum 4 hour hold with no visible leakage and no pressure drop exceeding 5 percent, in accordance with ASME B31.9.
14.1.2Hydrostatic testing shall be completed before insulation is applied and before any portion of the piping is concealed.
● 1.5 x system design pressure (ASME B31.9)
14.2 System Flushing
14.2.1The system shall be flushed at a minimum velocity of 3 fps through each pipe segment until strainer baskets retain no particles larger than 1/32 in.
14.2.2Temporary fine-mesh startup strainers shall be installed at each chiller evaporator and condenser connection during flushing, then cleaned and either removed or replaced with the permanent screen before chiller startup.
NOTE Construction debris, weld slag, and mill scale released during flushing will foul the chiller tube sheet within the first operating season if temporary strainers are omitted; they are mandatory, not optional. (14.2.3)
14.2.4Initial corrosion inhibitor shall be dosed in accordance with the water-treatment program before the chillers are placed in service.
14.3 Chiller-Connection Flow Verification
14.3.1Water flow through each chiller evaporator and condenser shall be verified to be within the chiller manufacturer's minimum and maximum limits before chiller startup.
NOTE Chillers impose minimum and maximum evaporator and condenser flow rates; verifying them at the piping connections, with balancing valves accessible, is a precondition to startup. (14.3.2)
15 Delivery, Storage, and Handling
15.1Pipe, fittings, valves, and insulation shall be delivered with manufacturer labeling intact and stored to protect them from weather, soil, and physical damage.
15.2Pipe ends shall be capped during storage to keep out dirt, debris, and moisture.
15.3Pre-insulated pipe and insulation materials shall be stored under cover and kept dry; insulation that has been wetted shall not be installed.
15.4Grooved-end and flanged-end pipe shall be handled to protect the sealing surfaces and groove dimensions from damage.
16 Warranty
16.1The Contractor shall warrant the installed piping system against defects in materials and workmanship for the warranty period below from the date of substantial completion.
16.2Manufacturer warranties on pipe, valves, meters, and pre-insulated systems shall be assigned to the Owner.
● 1 year
○ 2 years
○ 3 years
17 Spare Parts
17.1The Contractor shall furnish the spare parts and special tools below for Owner stock.
NOTE Spare gaskets, strainer screens, and the special tools for grooved and flanged joints keep the plant serviceable without procurement delay during the first operating season. (17.2)
☑ Spare grooved-coupling gaskets (each size)
☐ Spare flange gaskets (each size/class)
☑ Spare strainer screens / baskets (each size)
☐ Valve gland packing and seat kits
☐ Grooving and coupling special tools