+---
+title: Mechanical Insulation
+category: Mechanical / Piping & Pumps
+toc_depth: 3
+description: >
+ When to use: Field-applied thermal insulation for mechanical piping, ductwork, and equipment in commercial, institutional, and light-industrial buildings. Covers insulation of heating hot water, steam, steam condensate, and other hot service piping; chilled water, dual-temperature, and other below-ambient service piping that requires a continuous vapor barrier; HVAC supply, return, outside-air, and exhaust ductwork (concealed and exposed, indoor and outdoor); and mechanical equipment such as tanks, breechings, pumps, and heat exchangers. Includes selection of insulation material by service (mineral or glass fiber, closed-cell elastomeric, rigid cellular phenolic, cellular glass, and calcium silicate for high temperature), insulation thickness by the adopted edition of ASHRAE 90.1, jacketing and vapor retarders (all-service jacket indoors, PVC fitting covers, metal jacket outdoors and in mechanical rooms), insulated pipe supports and protection shields, penetration coordination, and the condensation-control provisions that govern cold-service work.
+ Not intended for: Refrigerant line-set insulation, which is part of the refrigerant piping work (see [[sync/refrigerant-piping]]); domestic water and other plumbing pipe insulation (see [[sync/plumbing-insulation]]); firestopping of insulated penetrations (see [[sync/firestopping]]); interior acoustical duct lining where specified separately as part of the ductwork work (see [[sync/hvac-ductwork]]); below-grade and buried pre-insulated piping systems; and the boilers, chillers, and packaged equipment whose factory insulation is provided by the equipment manufacturer (see [[sync/boilers]]).
+---
+
+# Scope
+
+This specification covers the materials, application, jacketing, and finishing of field-applied thermal insulation for mechanical piping, ductwork, and equipment. The work includes insulation of hot-service piping, below-ambient (cold and dual-temperature) piping with continuous vapor seal, supply and return and outside-air and exhaust ductwork, and mechanical equipment, together with the jackets, vapor retarders, fitting covers, insulated supports, and weatherproofing required to make each system complete. All work shall comply with the adopted edition of ASHRAE 90.1 for minimum insulation thickness, the International Mechanical Code (IMC) and International Energy Conservation Code (IECC) as adopted, NFPA 90A for the fire performance of insulation in air-distribution systems, and the workmanship requirements of the MICA National Commercial & Industrial Insulation Standards.
+
+Mechanical insulation does two jobs that are easy to confuse but governed by different physics. On hot service it conserves energy and protects personnel by keeping the outer surface below a safe touch temperature. On cold service it does those things too, but its controlling job is to stop water vapor in the surrounding air from reaching a surface that is below the dew point and condensing there. These are not symmetric problems. A hot pipe drives heat and moisture outward, away from itself; a small gap in hot insulation wastes a little energy but does no lasting harm. A cold pipe pulls moisture inward, toward itself; a small gap in cold insulation, or a single unsealed seam in its vapor retarder, lets humid air reach the cold surface, condense, wet the insulation, and begin a cycle of corrosion under insulation and progressive thermal failure that does not stop until the system is torn out and redone. For this reason the governing design principle of this standard is the continuous, unbroken vapor barrier on every below-ambient system, and most of the installation requirements that follow exist to protect that barrier.
+
+The boundary of work under this standard is the insulation system applied in the field over piping, ductwork, and equipment furnished and erected under the mechanical work. The piping and ductwork themselves, their supports, and their pressure testing are not part of this standard; insulation shall not be applied until the system it covers has been tested and accepted. Factory-applied insulation furnished as part of packaged equipment is not duplicated in the field. Where a service is excluded above — refrigerant line sets, plumbing pipe insulation, buried pre-insulated systems — that service is insulated under its own standard and not here.
+
+# Referenced Standards
+
+Materials, fabrication, and installation shall comply with the latest adopted editions of the following standards and codes. Where the contract documents, the adopted energy or mechanical code, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing. ASHRAE 90.1 and the adopted energy code establish minimum thicknesses; the contract documents may require more but shall not specify less.
+
+| Standard | Title |
+|----------|-------|
+| ASTM C547 | Mineral Fiber Pipe Insulation |
+| ASTM C553 | Mineral Fiber Blanket Thermal Insulation for Commercial and Industrial Applications |
+| ASTM C612 | Mineral Fiber Block and Board Thermal Insulation |
+| ASTM C534 | Preformed Flexible Elastomeric Cellular Thermal Insulation in Sheet and Tubular Form |
+| ASTM C552 | Cellular Glass Thermal Insulation |
+| ASTM C1126 | Faced or Unfaced Rigid Cellular Phenolic Thermal Insulation |
+| ASTM C533 | Calcium Silicate Block and Pipe Thermal Insulation |
+| ASTM C1136 | Flexible, Low Permeance Vapor Retarders for Thermal Insulation |
+| ASTM C921 | Determining the Properties of Jacketing Materials for Thermal Insulation |
+| ASTM C795 | Thermal Insulation for Use in Contact with Austenitic Stainless Steel |
+| ASTM C692 | Evaluating the Influence of Thermal Insulations on External Stress Corrosion Cracking Tendency of Austenitic Stainless Steel |
+| ASTM C871 | Chemical Analysis of Thermal Insulation Materials for Leachable Chloride, Fluoride, Silicate, and Sodium Ions |
+| ASTM C411 | Hot-Surface Performance of High-Temperature Thermal Insulation |
+| ASTM C1338 | Determining Fungi Resistance of Insulation Materials and Facings |
+| ASTM E84 | Surface Burning Characteristics of Building Materials (flame spread / smoke developed) |
+| ASHRAE 90.1 | Energy Standard for Buildings Except Low-Rise Residential Buildings |
+| IMC | International Mechanical Code |
+| IECC | International Energy Conservation Code |
+| NFPA 90A | Installation of Air-Conditioning and Ventilating Systems |
+| UL 181 | Factory-Made Air Ducts and Air Connectors |
+| MSS SP-58 | Pipe Hangers and Supports — Materials, Design, Manufacture, Selection, Application, and Installation |
+| MICA | National Commercial & Industrial Insulation Standards (Midwest Insulation Contractors Association) |
+
+# Submittals
+
+## Action Submittals
+
+The Contractor shall submit the following for the Engineer's review and return before procurement and installation. Submittals shall be coordinated so that the proposed material, jacket, and thickness for each service are presented together, not piecemeal.
+
+- Product data for each insulation material proposed, showing the governing ASTM specification and type/grade, the thermal conductivity at the applicable mean temperature, the water-vapor permeability (for below-ambient materials), the maximum service temperature, the density, and the ASTM E84 flame-spread and smoke-developed indices
+- Product data for each jacket and vapor-retarder material, showing the ASTM C1136 classification (for vapor-retarder jackets), the water-vapor permeance, the puncture and tensile properties, and the ASTM E84 indices
+- Product data for accessories: fitting covers, adhesives, sealants, mastics, vapor-retarder coatings, tapes, banding, insulation protection shields, and rigid insulation inserts at supports
+- A complete insulation thickness schedule listing every insulated service, the material selected, and the thickness for each pipe-size band, demonstrating compliance with the adopted edition of ASHRAE 90.1
+- Manufacturer's certification that insulation, mastics, adhesives, and jackets used in contact with austenitic stainless steel meet ASTM C795 (verified by ASTM C692 and ASTM C871) for leachable-chloride limits
+- Manufacturer's installation instructions for elastomeric, phenolic, and cellular-glass systems, including seam-sealing and vapor-seal procedures
+- Where mockups are required, the proposed location and the systems and details to be represented
+
+```datasheet
+label: Action Submittals Required
+type: checkbox
+options:
+ - "Insulation material product data (ASTM spec, k-value, permeability, E84 indices)"
+ - "Jacket and vapor-retarder product data (ASTM C1136, permeance)"
+ - "Accessory product data (fitting covers, mastics, sealants, shields, inserts)"
+ - "Insulation thickness schedule (ASHRAE 90.1 compliance)"
+ - "Stainless-steel compatibility certification (ASTM C795 / C692 / C871)"
+ - "Manufacturer installation instructions (vapor-seal procedures)"
+ - "Mockup location and scope"
+default: "Insulation thickness schedule (ASHRAE 90.1 compliance)"
+```
+
+## Closeout Submittals
+
+At substantial completion the Contractor shall provide manufacturer maintenance data for jacketed and weatherproofed systems, including recommended inspection intervals for outdoor metal jacket and field-applied mastics, and as-installed documentation of any system where the installed thickness or material differs from the schedule by approved substitution.
+
+# Quality Assurance
+
+## Workmanship Standard
+
+All insulation work shall be performed to the applicable details and tolerances of the MICA National Commercial & Industrial Insulation Standards. The MICA plates are the reference for how a given detail — a pipe fitting, a valve, a flange, a duct corner, a pipe support, a vapor stop — is to be insulated and finished. Where this standard, the drawings, and MICA are silent on a detail, the manufacturer's published detail governs.
+
+## Installer Qualifications
+
+The Contractor performing insulation work shall be regularly engaged in commercial and industrial mechanical insulation and shall employ applicators experienced in vapor-sealed below-ambient systems. Below-ambient vapor-seal work is the part of this trade where inexperience is most costly, because a defect is invisible until condensation and corrosion have already done their damage.
+
+## Mockups
+
+Where required by the contract documents, the Contractor shall provide a field mockup of representative insulated assemblies — at minimum one cold-pipe run with a fitting, a valve, and an insulated support showing the continuous vapor seal, and one section of jacketed outdoor pipe — for the Engineer's review before production work proceeds. The accepted mockup establishes the standard of workmanship for the project.
+
+```datasheet
+label: Field Mockup Required
+type: radio
+options:
+ - "No mockup required (standard for typical commercial projects)"
+ - "Mockup required for below-ambient vapor-seal and outdoor-jacketed assemblies"
+default: "No mockup required (standard for typical commercial projects)"
+```
+
+# Environmental and Service Conditions
+
+## Service Temperature
+
+The insulation material and thickness for each system are governed first by the temperature of the fluid or air it carries. Each insulated service shall be classified by its design operating temperature, because that temperature determines both the minimum thickness required by the energy code and the material's suitability — an elastomeric foam that is ideal on a chilled-water line will not survive on a steam line, and a calcium-silicate block that is correct on a steam line is wholly unsuited to a cold line. The Contractor shall confirm the design operating temperature of each service from the equipment schedules before selecting material and thickness.
+
+```datasheet
+label: Service Temperature Classification
+type: select
+options:
+ - "Below-ambient (cold): chilled water, dual-temp, cold service — requires continuous vapor barrier"
+ - "Low-temperature hot: heating hot water and domestic hot water, up to ~250°F"
+ - "Medium-temperature hot: low-pressure steam and condensate, ~250–350°F"
+ - "High-temperature hot: high-pressure steam, breechings, ~350°F and above"
+default: "Below-ambient (cold): chilled water, dual-temp, cold service — requires continuous vapor barrier"
+```
+
+## Installation Environment
+
+Whether a run is concealed in a conditioned interior, exposed in an occupied space, located in a mechanical room, or exposed outdoors governs the choice of jacket and the need for weatherproofing and impact protection. Outdoor and mechanical-room-low locations need a weather- and abuse-resistant metal jacket; concealed interior runs need only the basic factory jacket.
+
+```datasheet
+label: Installation Environment
+type: select
+options:
+ - "Concealed indoor, conditioned (above ceilings, in chases)"
+ - "Exposed indoor, occupied space"
+ - "Mechanical/equipment room (impact and personnel exposure)"
+ - "Exposed outdoor (weather and UV exposure)"
+default: "Concealed indoor, conditioned (above ceilings, in chases)"
+```
+
+## Ambient Design Humidity for Cold Service
+
+The required vapor-retarder performance and, in severe cases, the insulation thickness on below-ambient systems depend on the ambient conditions the system will see. A chilled-water line in a humid, unconditioned space (a parking garage, a fan room with outdoor-air exposure, a coastal mechanical room) faces a far higher vapor drive than the same line in a dry conditioned office. Where the design ambient dew point can approach or exceed the pipe surface temperature, the insulation thickness shall be confirmed adequate to keep the jacket surface above the dew point, which may require more than the energy-code minimum.
+
+# Insulation Materials by Service
+
+The material for each service shall be selected for its service-temperature range, its moisture behavior, and its location. The following are the materials this standard recognizes; each option below maps to products available from multiple manufacturers.
+
+## Mineral or Glass Fiber for Hot Piping and Equipment
+
+Hot-service piping and equipment shall be insulated with mineral or glass fiber: preformed pipe insulation to ASTM C547, blanket to ASTM C553, or block and board to ASTM C612. Fibrous insulation is the workhorse of hot service because it tolerates high temperature, is inexpensive, is easy to fit to pipe and fittings, and — on hot service — does not need to resist vapor drive, since the heat flow is outward. It shall not be used on below-ambient service unless it is a closed-cell product, because fibrous insulation is absorbent and, if it ever wets on a cold line, loses its thermal value and stays wet.
+
+```datasheet
+label: Hot Piping Insulation Material
+type: radio
+options:
+ - "Mineral fiber preformed pipe insulation, ASTM C547 (standard for hot water and steam)"
+ - "Glass fiber preformed pipe insulation, ASTM C547"
+default: "Mineral fiber preformed pipe insulation, ASTM C547 (standard for hot water and steam)"
+```
+
+## Closed-Cell Elastomeric for Below-Ambient Piping
+
+Below-ambient piping shall be insulated with preformed flexible closed-cell elastomeric insulation to ASTM C534, or with another closed-cell material as specified below. Closed-cell elastomeric is the standard for chilled-water and dual-temperature lines because the material is itself a vapor retarder: its closed-cell structure resists the inward vapor drive that destroys fibrous insulation on cold service, so the vapor seal is built into the body of the insulation rather than depending solely on a surface jacket. Its limitation is service temperature; it is not used on hot lines above its rated limit.
+
+```datasheet
+label: Below-Ambient Piping Insulation Material
+type: radio
+options:
+ - "Closed-cell flexible elastomeric, ASTM C534 (standard for chilled water and dual-temp)"
+ - "Rigid cellular phenolic, ASTM C1126 (where higher R per inch is required)"
+ - "Cellular glass, ASTM C552 (where non-combustible, impermeable, abuse-resistant required)"
+default: "Closed-cell flexible elastomeric, ASTM C534 (standard for chilled water and dual-temp)"
+```
+
+## Rigid Cellular Phenolic
+
+Rigid cellular phenolic to ASTM C1126 may be used on below-ambient and moderate-temperature service where its higher thermal resistance per inch of thickness allows a thinner insulation profile in space-constrained runs. Phenolic is closed-cell and low-permeance and shall be jacketed with a vapor-retarder jacket on cold service.
+
+## Cellular Glass
+
+Cellular glass to ASTM C552 may be used where a rigid, non-combustible, completely impermeable, abuse-resistant insulation is required — for example on cold piping subject to traffic or mechanical abuse, at supports carrying high load, or where a true vapor-impermeable material is preferred for critical below-ambient service. Cellular glass does not absorb water and does not support combustion. It is more expensive and more brittle than the alternatives and is reserved for the conditions that justify it.
+
+## Calcium Silicate for High Temperature
+
+Calcium silicate to ASTM C533 shall be used on high-temperature service above the range of fibrous pipe insulation — high-pressure steam, breechings, and other surfaces approaching or exceeding the upper limit of mineral fiber. Calcium silicate is rigid, non-combustible, and high-compressive-strength, which also makes it the standard insert material at pipe supports on hot systems. Type I is rated to 1200°F and Type II to 1700°F.
+
+```datasheet
+label: High-Temperature Insulation Material (steam, breechings)
+type: radio
+options:
+ - "Calcium silicate, ASTM C533 Type I (to 1200°F)"
+ - "Calcium silicate, ASTM C533 Type II (to 1700°F)"
+ - "Mineral fiber, ASTM C547 (within its rated service temperature)"
+default: "Calcium silicate, ASTM C533 Type I (to 1200°F)"
+```
+
+## Duct Insulation
+
+Supply, return, outside-air, and exhaust ductwork shall be insulated with glass-fiber duct wrap (blanket) to ASTM C553 on concealed round and rectangular duct, or with rigid glass-fiber board to ASTM C612 where a firm surface, a finished exposed appearance, or a higher installed thickness without compression is required. Concealed supply and return duct is normally wrapped; exposed duct in occupied spaces and outdoor duct are normally board-insulated and jacketed. Insulation used inside ducts as acoustical lining, where specified, is part of the ductwork work and is not covered here.
+
+```datasheet
+label: Concealed Duct Insulation
+type: radio
+options:
+ - "Glass-fiber duct wrap (blanket), ASTM C553, faced with vapor retarder (standard, concealed)"
+ - "Rigid glass-fiber board, ASTM C612, faced (where firm surface or no-compression thickness needed)"
+default: "Glass-fiber duct wrap (blanket), ASTM C553, faced with vapor retarder (standard, concealed)"
+```
+
+## Fire Performance
+
+Insulation, jackets, facings, mastics, and adhesives installed in or exposed to building spaces, plenums, and concealed locations shall have a flame-spread index of 25 or less and a smoke-developed index of 50 or less when tested to ASTM E84, as required by NFPA 90A and the building code, or shall be otherwise listed for the location. The 25/50 limit classifies the assembly as limited-combustible; it is not the same as non-combustible. Duct insulation in air-handling plenums shall additionally comply with the applicable UL 181 classification.
+
+```datasheet
+label: Fire Performance Requirement
+type: radio
+options:
+ - "Flame spread ≤25 / smoke developed ≤50 per ASTM E84 (standard, all building spaces and plenums)"
+ - "Non-combustible material required (specific code-driven locations)"
+default: "Flame spread ≤25 / smoke developed ≤50 per ASTM E84 (standard, all building spaces and plenums)"
+```
+
+# Insulation Thickness Schedule
+
+Minimum insulation thickness shall be not less than the value required by the adopted edition of ASHRAE 90.1 for the service temperature and pipe size, and not less than any greater thickness shown in the contract documents. The thicknesses in the energy-code tables are keyed to a stated range of insulation thermal conductivity at a stated mean rating temperature; where the selected material's conductivity falls outside the table's range, the thickness shall be adjusted by the energy code's conductivity-correction method so the installed system meets the same heat-flow basis. The Contractor shall not reduce thickness below the code minimum; on below-ambient systems the Contractor shall confirm that the code-minimum thickness also keeps the jacket surface above the design dew point and shall increase thickness where it does not.
+
+## Governing Energy Code Edition
+
+```datasheet
+label: Governing Energy Code Edition for Insulation Thickness
+type: select
+options:
+ - "ASHRAE 90.1-2022"
+ - "ASHRAE 90.1-2019"
+ - "ASHRAE 90.1-2016"
+ - "IECC (as adopted, references ASHRAE 90.1 thicknesses)"
+default: "ASHRAE 90.1-2022"
+```
+
+## Hot Piping Thickness Selection
+
+The values below follow the structure of the ASHRAE 90.1 minimum-thickness table for heating and hot-water systems. The thickness increases with both fluid temperature and pipe size; the larger of the code value and any drawing requirement governs.
+
+```datasheet
+label: Heating Hot Water Insulation Thickness (105–200°F service)
+type: select
+unit: in.
+drawing_ref: true
+options:
+ - "1.0 in. — pipe under 1.5 in. (105–140°F)"
+ - "1.5 in. — pipe 1.5 in. and larger (105–140°F)"
+ - "1.5 in. — pipe under 1.5 in. (141–200°F)"
+ - "2.0 in. — pipe 1.5 in. and larger (141–200°F)"
+default: "1.5 in. — pipe under 1.5 in. (141–200°F)"
+```
+
+```datasheet
+label: Steam and Steam Condensate Insulation Thickness (201–350°F service)
+type: select
+unit: in.
+drawing_ref: true
+options:
+ - "2.5 in. — 201–250°F service"
+ - "3.0 in. — pipe under 1.5 in. (251–350°F)"
+ - "4.0 in. — pipe 1.5 in. to 4 in. (251–350°F)"
+ - "4.5 in. — pipe 4 in. and larger (251–350°F)"
+default: "2.5 in. — 201–250°F service"
+```
+
+## Cold Piping Thickness Selection
+
+The values below follow the structure of the ASHRAE 90.1 minimum-thickness table for cooling systems. Cold-service minimum thicknesses are smaller than hot-service values, but the vapor barrier — not the thickness alone — is what makes a cold system work; thickness shall never be reduced to the point that the jacket surface falls below the dew point.
+
+```datasheet
+label: Chilled Water and Dual-Temperature Insulation Thickness (40–60°F service)
+type: select
+unit: in.
+drawing_ref: true
+options:
+ - "0.5 in. — pipe under 1.5 in."
+ - "1.0 in. — pipe 1.5 in. and larger"
+ - "1.0 in. — all sizes in high-humidity or unconditioned space (condensation control)"
+default: "1.0 in. — pipe 1.5 in. and larger"
+```
+
+```datasheet
+label: Below-40°F Service Insulation Thickness
+type: select
+unit: in.
+drawing_ref: true
+options:
+ - "0.5 in. — pipe under 1 in."
+ - "1.0 in. — pipe 1 in. to 8 in."
+ - "1.5 in. — pipe 8 in. and larger"
+default: "1.0 in. — pipe 1 in. to 8 in."
+```
+
+# Jacketing and Vapor Retarders
+
+The jacket is the outer skin of the insulation system. It serves three jobs that vary by location: it protects the insulation from mechanical damage and moisture, it provides a finished and cleanable surface, and on below-ambient systems it is part of the continuous vapor retarder. The jacket is selected by location, not by the insulation underneath it.
+
+## All-Service Jacket Indoors
+
+Indoor concealed and exposed piping shall be finished with a factory-applied all-service jacket (ASJ) — a kraft/foil/scrim facing meeting the vapor-retarder requirements of ASTM C1136 — with a self-sealing longitudinal lap and matching butt strips. ASJ is the standard indoor jacket because it provides the vapor retarder and a clean white finish in one factory-applied layer at low cost. On below-ambient service the ASJ is the vapor retarder, so every lap and butt joint shall be sealed continuously.
+
+```datasheet
+label: Indoor Pipe Jacket
+type: radio
+options:
+ - "Factory-applied all-service jacket (ASJ), ASTM C1136, self-sealing lap (standard indoor)"
+ - "Field-applied vapor-retarder mastic over insulation (cellular glass, irregular surfaces)"
+default: "Factory-applied all-service jacket (ASJ), ASTM C1136, self-sealing lap (standard indoor)"
+```
+
+## PVC Fitting Covers
+
+Fittings, valves, and other irregular shapes on jacketed indoor piping shall be finished with preformed PVC fitting covers over insulating inserts. Preformed covers give a fitting the same clean, sealable, cleanable finish as the straight-pipe jacket, which hand-applied mastic at every elbow cannot match in either appearance or vapor integrity. On cold service the fitting cover shall be sealed to the adjoining pipe jacket so the vapor retarder is continuous around the fitting.
+
+```datasheet
+label: Fitting and Valve Finish (indoor jacketed piping)
+type: radio
+options:
+ - "Preformed PVC fitting covers over insulating inserts (standard)"
+ - "Field-fabricated insulation with vapor-retarder mastic and reinforcing membrane"
+default: "Preformed PVC fitting covers over insulating inserts (standard)"
+```
+
+## Metal Jacket Outdoors and in Mechanical Rooms
+
+Piping and equipment exposed outdoors, and piping in mechanical rooms within reach of personnel and traffic (generally below about 7 ft), shall be jacketed with a metal jacket — aluminum or stainless steel — over the insulation and its vapor retarder. Metal jacket is used in these locations because it resists weather, ultraviolet degradation, impact, and abuse that would quickly destroy an ASJ or PVC finish. Outdoors the metal jacket is the weatherproofing layer and shall be installed to shed water; it is not itself the vapor retarder, which must be provided by the insulation or an underlying retarder, because metal jacket laps are not vapor-tight.
+
+```datasheet
+label: Outdoor and Low-Mechanical-Room Jacket
+type: radio
+options:
+ - "Aluminum metal jacket with integral moisture barrier (standard outdoor and abuse-prone)"
+ - "Stainless steel metal jacket (corrosive, coastal, or high-abuse environments)"
+default: "Aluminum metal jacket with integral moisture barrier (standard outdoor and abuse-prone)"
+```
+
+## Stainless Steel Compatibility
+
+Where insulation is applied in contact with austenitic stainless steel piping or equipment, the insulation and all jacketing, mastics, and adhesives in contact with the stainless surface shall comply with ASTM C795, verified by the stress-corrosion test of ASTM C692 and the leachable-ion chemical analysis of ASTM C871. Ordinary insulation can carry enough soluble chloride to cause external chloride stress-corrosion cracking of austenitic stainless steel under insulation — a cracking failure that initiates invisibly beneath the jacket and can rupture a pressurized line. Low-chloride, inhibited insulation is required wherever stainless is insulated, regardless of service temperature.
+
+```datasheet
+label: Stainless-Steel Chloride Stress-Corrosion Compliance
+type: radio
+options:
+ - "Not applicable — no austenitic stainless steel insulated"
+ - "Insulation and accessories meet ASTM C795 (C692 / C871) where in contact with austenitic stainless"
+default: "Not applicable — no austenitic stainless steel insulated"
+```
+
+# Insulation of Specific Systems
+
+## Ducts
+
+Concealed supply and return ductwork shall be insulated with faced duct wrap, applied with the facing outward as the vapor retarder, with all seams and the longitudinal lap stapled and sealed and the facing not compressed at corners; duct wrap compressed at a sharp corner loses thickness and R-value exactly where it is thinnest. Exposed indoor duct and outdoor duct shall be insulated with rigid board and finished with a jacket appropriate to the location. Outside-air and cold supply ducts carry surfaces below the dew point and shall be treated as below-ambient: their facing or jacket is a continuous vapor retarder with every seam sealed. Exhaust and relief duct downstream of a damper exposed to outdoor air may sweat and shall be insulated where it is in conditioned space and subject to condensation.
+
+```datasheet
+label: Concealed Supply/Return Duct Insulation R-Value
+type: range
+unit: h·ft²·°F/Btu
+drawing_ref: true
+options:
+ min: 4.2
+ max: 12
+ setpoints: [4.2, 6, 8, 12]
+default: 6
+```
+
+## Hot Piping
+
+Hot piping shall be insulated continuously, with insulation butted tightly at joints and fittings insulated to the full thickness of the adjoining pipe. Personnel-protection is a governing requirement: where hot piping or equipment is within reach of personnel, the insulation thickness shall be sufficient to hold the jacket surface at or below 140°F so that incidental contact does not burn. On hot service no vapor retarder is required, but the jacket shall still be continuous for appearance, cleanliness, and protection. Insulation shall not be applied over un-tested pipe, and shall be held back from flanges, unions, and valve bonnets enough to permit disassembly, then insulated with removable covers where the connection must be serviced.
+
+```datasheet
+label: Personnel-Protection Surface Temperature Limit
+type: range
+unit: °F
+options:
+ min: 120
+ max: 140
+ setpoints: [120, 130, 140]
+default: 140
+```
+
+## Cold and Dual-Temperature Piping
+
+Cold and dual-temperature piping shall be insulated as a continuous vapor-sealed system. Every longitudinal seam, every butt joint, every fitting, every valve, and every termination shall be sealed so that no path exists for humid air to reach the cold pipe surface. The single most important rule of this section is that the vapor barrier is continuous and unbroken; a cold system with excellent insulation and one unsealed seam will fail at that seam. Dual-temperature piping that runs cold in the cooling season shall be insulated and vapor-sealed as a cold system year-round, because it only takes one cold season to wet insulation that was treated as hot.
+
+### Continuous Vapor Barrier
+
+```datasheet
+label: Below-Ambient Vapor Barrier
+type: radio
+options:
+ - "Continuous, sealed vapor retarder over entire cold system including fittings, valves, supports, and terminations (required)"
+default: "Continuous, sealed vapor retarder over entire cold system including fittings, valves, supports, and terminations (required)"
+```
+
+### Insulated Supports and Saddles
+
+At every support, hanger, and anchor on a cold line the insulation shall be continuous through the support, carried on a rigid insulating insert (a high-density insulation segment or a cellular-glass or calcium-silicate saddle) sized to carry the pipe load, with a metal protection shield distributing the load, and with the vapor retarder continuous over the insert. A bare clamp or a crushed section of insulation at a support is a thermal bridge: the cold metal of the support reaches through to a point outside the vapor barrier, that point sweats, and water runs back into the insulation. Insulated supports exist precisely to keep the cold surface inside the continuous vapor barrier at the one place — the support — where it is most tempting to interrupt it.
+
+```datasheet
+label: Cold-Line Support Treatment
+type: radio
+options:
+ - "Rigid insulating insert (saddle) with load-distributing shield and continuous vapor seal at every support (standard)"
+ - "Pre-insulated pipe support assemblies with integral vapor barrier"
+default: "Rigid insulating insert (saddle) with load-distributing shield and continuous vapor seal at every support (standard)"
+```
+
+### Vapor Stops
+
+On long cold runs and at the ends of cold piping, vapor stops (a full seal of the insulation to the pipe with vapor-retarder mastic) shall be installed at terminations, at equipment connections, and at intervals on long runs so that if the vapor retarder is breached, moisture intrusion is confined to one segment rather than wicking the length of the line.
+
+## Equipment
+
+Tanks, breechings, heat exchangers, pumps, and other equipment requiring insulation shall be insulated with material suited to the surface temperature — fibrous or calcium-silicate board on hot equipment, closed-cell or cellular-glass on cold equipment — finished with a jacket suited to the location and, on cold equipment, with a continuous vapor retarder. Equipment that must be opened for service (pump volutes, heat-exchanger heads, manways, valve bonnets) shall be insulated with removable, reusable insulation covers so the equipment can be serviced and re-insulated without destroying the insulation. Factory-insulated equipment shall not be field-insulated; the insulation furnished with packaged boilers, chillers, and similar equipment is complete as furnished.
+
+```datasheet
+label: Serviceable Equipment Insulation
+type: radio
+options:
+ - "Removable/reusable insulation covers at all serviceable connections (pumps, heads, bonnets, manways)"
+ - "Permanent insulation only (equipment not requiring service access)"
+default: "Removable/reusable insulation covers at all serviceable connections (pumps, heads, bonnets, manways)"
+```
+
+# Installation
+
+## Surface Preparation
+
+Surfaces to be insulated shall be clean, dry, and free of loose scale, rust, oil, and dirt, and the piping or duct system shall have been pressure-tested and accepted before insulation is applied. Insulation applied over a wet, dirty, or untested surface traps the condition it covers: moisture on a cold pipe is sealed in, and an untested joint that later leaks must have its insulation destroyed to reach it.
+
+## Application and Joints
+
+Pipe insulation shall be applied with longitudinal joints sealed and butt joints tightly butted, the self-sealing lap rolled down firmly, and butt strips applied over every transverse joint. On below-ambient systems every seam, lap, and butt joint shall be sealed continuously with the manufacturer's adhesive, mastic, or sealing system so the vapor retarder is unbroken. Insulation shall not be stretched at bends or fittings; stretched insulation thins, and stretched elastomeric eventually pulls apart and opens the vapor seal.
+
+## Fitting Covers and Inserts
+
+Fittings, valves, flanges, and irregular shapes shall be insulated to the full thickness of the adjoining straight pipe and finished with preformed covers (or field-fabricated insulation with sealed, reinforced mastic where preformed covers are not made for the shape). Inserts of the same or a denser insulation shall fill the cover so there is no uninsulated void at the fitting; a void at a cold fitting is a condensation point.
+
+## Inserts at Supports
+
+At pipe supports the insulation shall be carried continuously through the support on a rigid insert and protection shield as described for cold piping above; on hot piping the insert shall be a high-compressive-strength material (calcium silicate or cellular glass) sized to carry the load without crushing. Crushed insulation at a support loses thickness, conducts heat or cold through the support, and on cold service breaks the vapor seal.
+
+## Outdoor Weatherproofing
+
+Outdoor insulation shall be finished with a metal jacket installed to shed water: laps oriented downward and overlapped in the direction of drainage, longitudinal seams positioned away from upward-facing water collection, and all joints and terminations sealed against water entry. Elastomeric and other UV-sensitive insulation exposed outdoors shall be jacketed or coated against ultraviolet degradation. Outdoor cold systems shall carry their continuous vapor retarder beneath the metal jacket, since the metal jacket alone is not vapor-tight.
+
+## Penetrations
+
+Where insulated piping or duct passes through walls, floors, and roofs, the insulation shall be continuous through the penetration so the thermal envelope and, on cold service, the vapor barrier are not interrupted at the wall. The annular space and any fire-rated assembly shall be firestopped under [[sync/firestopping]] with a system listed for the insulated penetrant; the firestop and the insulation system shall be coordinated so that firestopping does not crush the insulation or breach the vapor retarder, and so that the insulation material at the penetration is compatible with the listed firestop system. Penetration locations are [[drawing: as indicated on the mechanical and architectural drawings]].
+
+# Field Quality Control
+
+The Engineer may inspect insulation work before it is concealed and before jacketing closes it from view. On below-ambient systems the Contractor shall make the continuous vapor seal — seams, fittings, supports, terminations, and vapor stops — available for inspection before the metal jacket or final finish is applied, because a vapor-seal defect cannot be found once the jacket is on. Insulation found wet, crushed, stretched, voided at fittings, or with an unsealed vapor seam shall be removed and replaced; patched mastic over a failed seam is not an acceptable repair on cold service.
+
+```datasheet
+label: Below-Ambient Vapor-Seal Inspection
+type: radio
+options:
+ - "Vapor seal inspected and accepted before jacketing/concealment (standard for cold systems)"
+ - "Inspection waived (hot systems only)"
+default: "Vapor seal inspected and accepted before jacketing/concealment (standard for cold systems)"
+```
+
+# Cleaning and Protection
+
+Completed insulation, jackets, and finishes shall be left clean and undamaged. Insulation shall be protected from weather, water, crushing, and mechanical damage during the remainder of construction; insulation that is wetted before the building is enclosed shall be dried and inspected, or removed and replaced if it cannot be restored, because wet fibrous insulation does not recover its thermal value and wet cold-service insulation is a future corrosion site. Jacketing soiled or dented during construction shall be cleaned or replaced before substantial completion.
+
+# Warranty
+
+The Contractor shall warrant the insulation work against defects in materials and workmanship for a period of not less than one year from substantial completion, or for the period stated in the contract documents if longer. Any condensation, sweating, dripping, mold, or corrosion-under-insulation attributable to a failed or discontinuous vapor barrier, and any insulation that has loosened, sagged, crushed at supports, or lost its jacket within the warranty period, shall be corrected at the Contractor's expense, including correction of any damage the failure caused to the piping, equipment, or surrounding construction.
+
+# Delivery, Storage, and Handling
+
+Insulation materials, jackets, mastics, and adhesives shall be delivered in the manufacturer's original packaging with labels intact and shall be stored indoors, off the ground, and protected from weather and moisture until installed. Fibrous insulation is absorbent and shall be kept dry; insulation that arrives or becomes wet shall not be installed. Mastics, adhesives, and sealants shall be stored within their rated temperature range and shall not be used past their shelf life, because cured-out or frozen mastic does not form a sound vapor seal. Materials shall be handled to avoid crushing preformed pipe insulation and denting metal jacket stock.