1 Scope

NOTE This specification covers the materials, application, jacketing, and finishing of field-applied thermal insulation for mechanical piping, ductwork, and equipment. (1.1)

1.2 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.

1.3 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.

NOTE 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, while on cold service 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. (1.4)

NOTE A hot pipe drives heat and moisture outward, away from itself, so a small gap in hot insulation wastes a little energy but does no lasting harm; a cold pipe pulls moisture inward, and a small gap or a single unsealed seam 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. (1.5)

NOTE 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. (1.6)

1.7 Insulation shall not be applied until the system it covers has been tested and accepted.

1.8 Factory-applied insulation furnished as part of packaged equipment shall not be duplicated in the field.

1.9 Where a service is excluded above — refrigerant line sets, plumbing pipe insulation, buried pre-insulated systems — that service shall be insulated under its own standard and not here.

2 Referenced Standards

2.1 Materials, fabrication, and installation shall comply with the latest adopted editions of the following standards and codes.

2.2 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.

2.3 ASHRAE 90.1 and the adopted energy code establish minimum thicknesses; the contract documents may require more but shall not specify less.

2.4 Referenced Standards List

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)

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for the Engineer's review and return before procurement and installation:

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

Action Submittals Requiredcheckbox

☐ 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

3.1.2 Submittals shall be coordinated so that the proposed material, jacket, and thickness for each service are presented together, not piecemeal.

3.2 Closeout Submittals

3.2.1 At substantial completion the Contractor shall provide the following:

Manufacturer maintenance data for jacketed and weatherproofed systems
Recommended inspection intervals for outdoor metal jacket and field-applied mastics
As-installed documentation of any system where the installed thickness or material differs from the schedule by approved substitution

Required Closeout Submittalscheckbox

☑ Manufacturer maintenance data for jacketed and weatherproofed systems

☑ Recommended inspection intervals for outdoor metal jacket and field-applied mastics

☑ As-installed documentation of approved thickness or material substitutions

4 Quality Assurance

4.1 Workmanship Standard

4.1.1 All insulation work shall be performed to the applicable details and tolerances of the MICA National Commercial & Industrial Insulation Standards.

NOTE 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. (4.1.2)

4.1.3 Where this standard, the drawings, and MICA are silent on a detail, the manufacturer's published detail shall govern.

4.2 Installer Qualifications

4.2.1 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.

NOTE 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. (4.2.2)

4.3 Mockups

Field Mockup Requiredradio

● No mockup required (standard for typical commercial projects)

○ Mockup required for below-ambient vapor-seal and outdoor-jacketed assemblies

4.3.1 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.

NOTE The accepted mockup establishes the standard of workmanship for the project. (4.3.2)

5 Environmental and Service Conditions

5.1 Service Temperature

NOTE The insulation material and thickness for each system are governed first by the temperature of the fluid or air it carries. (5.1.1)

5.1.2 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.

Service Temperature Classificationselect

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

NOTE 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. (5.1.3)

5.1.4 The Contractor shall confirm the design operating temperature of each service from the equipment schedules before selecting material and thickness.

5.2 Installation Environment

NOTE 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. (5.2.1)

5.2.2 Outdoor and mechanical-room-low locations shall be provided with a weather- and abuse-resistant metal jacket; concealed interior runs need only the basic factory jacket.

Installation Environmentselect

Concealed indoor, conditioned (above ceilings, in chases)

Exposed indoor, occupied space

Mechanical/equipment room (impact and personnel exposure)

Exposed outdoor (weather and UV exposure)

5.3 Ambient Design Humidity for Cold Service

NOTE 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. (5.3.1)

NOTE 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. (5.3.2)

5.3.3 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.

6 Insulation Materials by Service

6.1 The material for each service shall be selected for its service-temperature range, its moisture behavior, and its location.

NOTE The following are the materials this standard recognizes; each option below maps to products available from multiple manufacturers. (6.2)

6.3 Mineral or Glass Fiber for Hot Piping and Equipment

Hot Piping Insulation Materialradio

● Mineral fiber preformed pipe insulation, ASTM C547 (standard for hot water and steam)

○ Glass fiber preformed pipe insulation, ASTM C547

6.3.1 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.

NOTE 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. (6.3.2)

6.3.3 Fibrous insulation 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.

6.4 Closed-Cell Elastomeric for Below-Ambient Piping

Below-Ambient Piping Insulation Materialradio

● 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)

6.4.1 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.

NOTE 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. (6.4.2)

6.4.3 Closed-cell elastomeric shall not be used on hot lines above its rated service-temperature limit.

6.5 Rigid Cellular Phenolic

6.5.1 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.

6.5.2 Phenolic is closed-cell and low-permeance and shall be jacketed with a vapor-retarder jacket on cold service.

6.6 Cellular Glass

6.6.1 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.

NOTE 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. (6.6.2)

6.7 Calcium Silicate for High Temperature

High-Temperature Insulation Material (steam, breechings)radio

● 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)

6.7.1 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.

NOTE Calcium silicate is rigid, non-combustible, and high-compressive-strength, which also makes it the standard insert material at pipe supports on hot systems. (6.7.2)

NOTE Type I is rated to 1200°F and Type II to 1700°F. (6.7.3)

6.8 Duct Insulation

Concealed Duct Insulationradio

● 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)

6.8.1 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.

NOTE Concealed supply and return duct is normally wrapped; exposed duct in occupied spaces and outdoor duct are normally board-insulated and jacketed. (6.8.2)

NOTE Insulation used inside ducts as acoustical lining, where specified, is part of the ductwork work and is not covered here. (6.8.3)

6.9 Fire Performance

Fire Performance Requirementradio

● Flame spread ≤25 / smoke developed ≤50 per ASTM E84 (standard, all building spaces and plenums)

○ Non-combustible material required (specific code-driven locations)

6.9.1 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.

NOTE The 25/50 limit classifies the assembly as limited-combustible; it is not the same as non-combustible. (6.9.2)

6.9.3 Duct insulation in air-handling plenums shall additionally comply with the applicable UL 181 classification.

7 Insulation Thickness Schedule

7.1 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.

7.2 Where the selected material's conductivity falls outside the energy-code table's stated range, the thickness shall be adjusted by the energy code's conductivity-correction method so the installed system meets the same heat-flow basis.

7.3 The Contractor shall not reduce thickness below the code minimum.

7.4 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.

7.5 Governing Energy Code Edition

Governing Energy Code Edition for Insulation Thicknessselect

ASHRAE 90.1-2022

ASHRAE 90.1-2019

ASHRAE 90.1-2016

IECC (as adopted, references ASHRAE 90.1 thicknesses)

7.6 Hot Piping Thickness Selection

NOTE The values below follow the structure of the ASHRAE 90.1 minimum-thickness table for heating and hot-water systems. (7.6.1)

NOTE The thickness increases with both fluid temperature and pipe size; the larger of the code value and any drawing requirement governs. (7.6.2)

7.6.3 The insulation thickness for heating hot water piping in the 105–200°F range shall be specified for each pipe size, not less than the governing code value.

Heating Hot Water Insulation Thickness (105–200°F service)select

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)

Per drawings

7.6.4 The insulation thickness for steam and steam condensate piping in the 201–350°F range shall be specified for each pipe size, not less than the governing code value.

Steam and Steam Condensate Insulation Thickness (201–350°F service)select

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)

Per drawings

7.7 Cold Piping Thickness Selection

NOTE The values below follow the structure of the ASHRAE 90.1 minimum-thickness table for cooling systems. (7.7.1)

7.7.2 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.

Chilled Water and Dual-Temperature Insulation Thickness (40–60°F service)select

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)

Per drawings

Below-40°F Service Insulation Thicknessselect

0.5 in. — pipe under 1 in.

1.0 in. — pipe 1 in. to 8 in.

1.5 in. — pipe 8 in. and larger

Per drawings

8 Jacketing and Vapor Retarders

NOTE The jacket is the outer skin of the insulation system. (8.1)

NOTE 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. (8.2)

8.3 The jacket shall be selected by location, not by the insulation underneath it.

8.4 All-Service Jacket Indoors

Indoor Pipe Jacketradio

● Factory-applied all-service jacket (ASJ), ASTM C1136, self-sealing lap (standard indoor)

○ Field-applied vapor-retarder mastic over insulation (cellular glass, irregular surfaces)

8.4.1 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.

NOTE 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. (8.4.2)

8.4.3 On below-ambient service the ASJ is the vapor retarder, so every lap and butt joint shall be sealed continuously.

8.5 PVC Fitting Covers

Fitting and Valve Finish (indoor jacketed piping)radio

● Preformed PVC fitting covers over insulating inserts (standard)

○ Field-fabricated insulation with vapor-retarder mastic and reinforcing membrane

8.5.1 Fittings, valves, and other irregular shapes on jacketed indoor piping shall be finished with preformed PVC fitting covers over insulating inserts.

NOTE 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. (8.5.2)

8.5.3 On cold service the fitting cover shall be sealed to the adjoining pipe jacket so the vapor retarder is continuous around the fitting.

8.6 Metal Jacket Outdoors and in Mechanical Rooms

Outdoor and Low-Mechanical-Room Jacketradio

● Aluminum metal jacket with integral moisture barrier (standard outdoor and abuse-prone)

○ Stainless steel metal jacket (corrosive, coastal, or high-abuse environments)

8.6.1 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.

NOTE 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. (8.6.2)

8.6.3 Outdoors the metal jacket is the weatherproofing layer and shall be installed to shed water.

8.6.4 The metal jacket is not itself the vapor retarder, which shall be provided by the insulation or an underlying retarder, because metal jacket laps are not vapor-tight.

8.7 Stainless Steel Compatibility

Stainless-Steel Chloride Stress-Corrosion Complianceradio

● Not applicable — no austenitic stainless steel insulated

○ Insulation and accessories meet ASTM C795 (C692 / C871) where in contact with austenitic stainless

8.7.1 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.

NOTE 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. (8.7.2)

8.7.3 Low-chloride, inhibited insulation shall be provided wherever stainless is insulated, regardless of service temperature.

9 Insulation of Specific Systems

9.1 Ducts

Concealed Supply/Return Duct Insulation R-Valuerange

h·ft²·°F/Btu

4.26812

Per drawings

9.1.1 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.

NOTE Duct wrap compressed at a sharp corner loses thickness and R-value exactly where it is thinnest. (9.1.2)

9.1.3 Exposed indoor duct and outdoor duct shall be insulated with rigid board and finished with a jacket appropriate to the location.

9.1.4 Outside-air and cold supply ducts carry surfaces below the dew point and shall be treated as below-ambient: their facing or jacket shall be a continuous vapor retarder with every seam sealed.

9.1.5 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.

9.2 Hot Piping

Personnel-Protection Surface Temperature Limitrange

°F

120130140

9.2.1 Hot piping shall be insulated continuously, with insulation butted tightly at joints and fittings insulated to the full thickness of the adjoining pipe.

9.2.2 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.

9.2.3 On hot service no vapor retarder is required, but the jacket shall still be continuous for appearance, cleanliness, and protection.

9.2.4 Insulation shall not be applied over un-tested pipe.

9.2.5 Insulation 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.

9.3 Cold and Dual-Temperature Piping

9.3.1 Cold and dual-temperature piping shall be insulated as a continuous vapor-sealed system.

9.3.2 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.

NOTE 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. (9.3.3)

9.3.4 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.

9.3.5 Continuous Vapor Barrier

Below-Ambient Vapor Barrierradio

● Continuous, sealed vapor retarder over entire cold system including fittings, valves, supports, and terminations (required)

9.3.6 Insulated Supports and Saddles

Cold-Line Support Treatmentradio

● 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

9.3.6.1 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.

NOTE 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. (9.3.6.2)

NOTE 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. (9.3.6.3)

9.3.7 Vapor Stops

9.3.7.1 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.

9.4 Equipment

Serviceable Equipment Insulationradio

● Removable/reusable insulation covers at all serviceable connections (pumps, heads, bonnets, manways)

○ Permanent insulation only (equipment not requiring service access)

9.4.1 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.

9.4.2 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.

9.4.3 Factory-insulated equipment shall not be field-insulated; the insulation furnished with packaged boilers, chillers, and similar equipment is complete as furnished.

10 Installation

10.1 Surface Preparation

10.1.1 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.

NOTE 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. (10.1.2)

10.2 Application and Joints

10.2.1 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.

10.2.2 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.

10.2.3 Insulation shall not be stretched at bends or fittings; stretched insulation thins, and stretched elastomeric eventually pulls apart and opens the vapor seal.

10.3 Fitting Covers and Inserts

10.3.1 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).

10.3.2 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.

10.4 Inserts at Supports

10.4.1 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.

NOTE Crushed insulation at a support loses thickness, conducts heat or cold through the support, and on cold service breaks the vapor seal. (10.4.2)

10.5 Outdoor Weatherproofing

10.5.1 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.

10.5.2 Elastomeric and other UV-sensitive insulation exposed outdoors shall be jacketed or coated against ultraviolet degradation.

10.5.3 Outdoor cold systems shall carry their continuous vapor retarder beneath the metal jacket, since the metal jacket alone is not vapor-tight.

10.6 Penetrations

10.6.1 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.

10.6.2 The annular space and any fire-rated assembly shall be firestopped under FirestoppingFirestoppingResolves to the current edition.sync/firestopping with a system listed for the insulated penetrant.

10.6.3 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.

10.6.4 Penetration locations are as indicated on the mechanical and architectural drawings.

11 Field Quality Control

Below-Ambient Vapor-Seal Inspectionradio

● Vapor seal inspected and accepted before jacketing/concealment (standard for cold systems)

○ Inspection waived (hot systems only)

11.1 The Engineer may inspect insulation work before it is concealed and before jacketing closes it from view.

11.2 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.

11.3 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.

12 Cleaning and Protection

12.1 Completed insulation, jackets, and finishes shall be left clean and undamaged.

12.2 Insulation shall be protected from weather, water, crushing, and mechanical damage during the remainder of construction.

12.3 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.

12.4 Jacketing soiled or dented during construction shall be cleaned or replaced before substantial completion.

13 Warranty

13.1 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.

13.2 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.

14 Delivery, Storage, and Handling

14.1 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.

14.2 Fibrous insulation is absorbent and shall be kept dry; insulation that arrives or becomes wet shall not be installed.

14.3 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.

14.4 Materials shall be handled to avoid crushing preformed pipe insulation and denting metal jacket stock.