ASTM C534/C534M-23

Standard Specification for Preformed Flexible Elastomeric Cellular Thermal Insulation in Sheet and Tubular Form

ABSTRACT
This specification covers sheet and tubular preformed flexible elastomeric cellular thermal insulation. The materials are classified into three grades according to the operating temperature range of the industrial systems that each material is used for. The non-thermoplastic, thermoset products should be made of natural or synthetic rubber that may be modified using various thermoplastic or thermosetting resins, plasticizers, modifiers, antioxidants, curatives, blowing agents, and other additives. All products should be tested using the prescribed procedures and conform to the specified values of apparent thermal conductivity, water absorption, water-vapor permeability, and linear shrinkage.
SCOPE
1.1 This specification covers preformed flexible elastomeric cellular-thermal insulation in sheet and tubular form. Grade 1 covers materials to be used on commercial or industrial systems with operating temperatures from –183 to 104°C [–297 to 220°F], Grade 2 covers material used on industrial systems with operating temperatures from –183 to 150°C [–297 to 300°F], and Grade 3 covers material used on industrial systems with operating temperatures from –183 to 120°C [–297 to 250°F] where halogens are not permitted.  
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Dec-2022
• ICS: 83.100 - Cellular materials
• ICS: 91.100.60 - Thermal and sound insulating materials
• Technical Committee: C16 - Thermal Insulation
• Drafting Committee: C16.22 - Organic and Nonhomogeneous Inorganic Thermal Insulations

Relations

• Refers: ASTM C168-24 - Standard Terminology Relating to Thermal Insulation
• Effective Date: 15-Apr-2024
• Refers: ASTM E96/E96M-24 - Standard Test Methods for Gravimetric Determination of Water Vapor Transmission Rate of Materials
• Effective Date: 01-Mar-2024
• Refers: ASTM C390-08(2024) - Standard Practice for Sampling and Acceptance of Thermal Insulation Lots
• Effective Date: 01-Mar-2024
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM E84-23d - Standard Test Method for Surface Burning Characteristics of Building Materials
• Effective Date: 01-Dec-2023
• Refers: ASTM E96/E96M-23 - Standard Test Methods for Gravimetric Determination of Water Vapor Transmission Rate of Materials
• Effective Date: 15-Nov-2023
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM E84-23c - Standard Test Method for Surface Burning Characteristics of Building Materials
• Effective Date: 01-Sep-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D1622-20 - Standard Test Method for Apparent Density of Rigid Cellular Plastics
• Effective Date: 15-Jul-2020
• Refers: ASTM C1763-20 - Standard Test Method for Water Absorption by Immersion of Thermal Insulation Materials
• Effective Date: 01-May-2020
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM C1763-19e1 - Standard Test Method for Water Absorption by Immersion of Thermal Insulation Materials
• Effective Date: 15-Oct-2019
• Refers: ASTM C1763-19 - Standard Test Method for Water Absorption by Immersion of Thermal Insulation Materials
• Effective Date: 15-Oct-2019
• Refers: ASTM C390-08(2019) - Standard Practice for Sampling and Acceptance of Thermal Insulation Lots
• Effective Date: 01-Sep-2019

Overview

ASTM C534/C534M-23: Standard Specification for Preformed Flexible Elastomeric Cellular Thermal Insulation in Sheet and Tubular Form establishes requirements for flexible, closed-cell elastomeric insulation materials supplied in sheet and tubular forms. Developed by ASTM International, this specification is essential for manufacturers, specifiers, and installers working with thermal insulation designed to control heat gain and loss in piping and equipment across a broad range of commercial and industrial applications.

This standard classifies the insulation into three grades based on their operating temperature ranges and provides guidance on material composition, physical properties, performance criteria, tolerances, and inspection methods. Adhering to ASTM C534/C534M-23 ensures reliable thermal performance, resilience, and compatibility with industrial systems.

Key Topics

• Material Types and Grades
  • Type I: Tubular forms for pipes and similar applications
  • Type II: Sheet forms for equipment, ducts, and flat surfaces
  • Grade 1: Suitable for systems from -183 to 104°C (-297 to 220°F)
  • Grade 2: Suitable for systems from -183 to 150°C (-297 to 300°F)
  • Grade 3: Used where halogens are not permitted; for systems from -183 to 120°C (-297 to 250°F)
• Material Composition
  • Insulation products are a blend of natural or synthetic rubber enhanced with a variety of additives for improved performance
  • The closed-cell structure inhibits water absorption and offers consistent thermal insulating properties
• Performance Requirements
  • Apparent thermal conductivity limits at various temperatures
  • Water absorption capped at 0.20% by volume
  • Maximum water vapor permeability specified for each grade
  • Dimensional stability, with linear shrinkage limited to 7% after thermal cycling
  • Leachable chloride and fluoride content strictly controlled in Grade 3 for use in sensitive environments
  • Rigorous testing for odor emission, surface burning characteristics, and workmanship
• Dimension and Tolerances
  • Precise tolerances set for both diameters and wall thickness in tubular forms
  • Detailed dimensional accuracy for sheet material, facilitating proper installation and function

Applications

Flexible elastomeric cellular thermal insulation meeting ASTM C534/C534M-23 is widely used in:

• Commercial and Industrial HVAC Systems
  • Insulation of chilled water, steam, and hot water piping
  • Thermal insulation on air conditioning systems to prevent condensation and energy losses
• Process Industry Installations
  • Insulating pipes, ducts, tanks, and vessels operating at varied temperature ranges
  • Protecting sensitive equipment and lines from temperature fluctuations and environmental exposure
• Halogen-Free Environments
  • Grade 3 materials are specified for environments-such as electronics and clean rooms-where halogenated compounds are strictly prohibited
• Stainless Steel Systems
  • Insulation for austenitic stainless steel applications with controlled leachable halide content, compatible with best practices for stress corrosion prevention
• Cold and Cryogenic Systems
  • Suitable for sub-ambient and cryogenic process lines requiring consistent thermal performance and minimal water vapor permeability

Proper installation is critical for maintaining long-term thermal efficiency and preventing water vapor intrusion. Seam sealing and correct material selection based on temperature range and application environment enhance system durability and energy savings.

Related Standards

Professionals referencing ASTM C534/C534M-23 should also review related ASTM standards addressing terminology, testing, and other aspects of thermal insulation, including:

• ASTM C168 – Terminology Relating to Thermal Insulation
• ASTM C177, C518, C335, C1114 – Test Methods for Thermal Transmission Properties
• ASTM C390 – Practice for Sampling and Acceptance of Thermal Insulation Lots
• ASTM C411 – Hot-Surface Performance of High-Temperature Insulation
• ASTM C795 – Specification for Insulation Use in Contact with Austenitic Stainless Steel
• ASTM C871 – Test Methods for Leachable Ion Content
• ASTM E84 – Test Method for Surface Burning Characteristics

By complying with ASTM C534/C534M-23, users ensure their preformed flexible elastomeric cellular thermal insulation delivers proven performance, safety, and compatibility for a range of demanding commercial and industrial applications.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C534/C534M − 23
Standard Specification for
Preformed Flexible Elastomeric Cellular Thermal Insulation
in Sheet and Tubular Form
This standard is issued under the fixed designation C534/C534M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope ments and Thermal Transmission Properties by Means of
the Guarded-Hot-Plate Apparatus
1.1 This specification covers preformed flexible elastomeric
C390 Practice for Sampling and Acceptance of Thermal
cellular-thermal insulation in sheet and tubular form. Grade 1
Insulation Lots
covers materials to be used on commercial or industrial
C335 Test Method for Steady-State Heat Transfer Properties
systems with operating temperatures from –183 to 104°C
of Pipe Insulation
[–297 to 220°F], Grade 2 covers material used on industrial
C411 Test Method for Hot-Surface Performance of High-
systems with operating temperatures from –183 to 150°C
Temperature Thermal Insulation
[–297 to 300°F], and Grade 3 covers material used on
C447 Practice for Estimating the Maximum Use Tempera-
industrial systems with operating temperatures from –183 to
ture of Thermal Insulations
120°C [–297 to 250°F] where halogens are not permitted.
C518 Test Method for Steady-State Thermal Transmission
1.2 The values stated in either SI units or inch-pound units
Properties by Means of the Heat Flow Meter Apparatus
are to be regarded separately as standard. The values stated in
C534 Specification for Preformed Flexible Elastomeric Cel-
each system may not be exact equivalents; therefore, each
lular Thermal Insulation in Sheet and Tubular Form
system shall be used independently of the other. Combining
C585 Practice for Inner and Outer Diameters of Thermal
values from the two systems may result in non-conformance
Insulation for Nominal Sizes of Pipe and Tubing
with the standard.
C692 Test Method for Evaluating the Influence of Thermal
1.3 This standard does not purport to address all of the
Insulations on External Stress Corrosion Cracking Ten-
safety concerns, if any, associated with its use. It is the
dency of Austenitic Stainless Steel
responsibility of the user of this standard to establish appro-
C795 Specification for Thermal Insulation for Use in Con-
priate safety, health, and environmental practices and deter-
tact with Austenitic Stainless Steel
mine the applicability of regulatory limitations prior to use.
C871 Test Methods for Chemical Analysis of Thermal Insu-
1.4 This international standard was developed in accor-
lation Materials for Leachable Chloride, Fluoride, Silicate,
dance with internationally recognized principles on standard-
and Sodium Ions
ization established in the Decision on Principles for the
C1045 Practice for Calculating Thermal Transmission Prop-
Development of International Standards, Guides and Recom-
erties Under Steady-State Conditions
mendations issued by the World Trade Organization Technical
C1058 Practice for Selecting Temperatures for Evaluating
Barriers to Trade (TBT) Committee.
and Reporting Thermal Properties of Thermal Insulation
C1114 Test Method for Steady-State Thermal Transmission
2. Referenced Documents
Properties by Means of the Thin-Heater Apparatus
2.1 ASTM Standards:
C1304 Test Method for Assessing the Odor Emission of
C168 Terminology Relating to Thermal Insulation
Thermal Insulation Materials
C177 Test Method for Steady-State Heat Flux Measure-
C1427 Specification for Extruded Preformed Flexible Cel-
lular Polyolefin Thermal Insulation in Sheet and Tubular
Form
This specification is under the jurisdiction of ASTM Committee C16 on
Thermal Insulation and is the direct responsibility of Subcommittee C16.22 on
C1763 Test Method for Water Absorption by Immersion of
Organic and Nonhomogeneous Inorganic Thermal Insulations.
Thermal Insulation Materials
Current edition approved Jan. 1, 2023. Published February 2023. Originally
D883 Terminology Relating to Plastics
approved in 1964. Last previous edition approved in 2020 as C0534/C534M – 20a.
DOI: 10.1520/C0534_C0534M-23.
D1622 Test Method for Apparent Density of Rigid Cellular
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Plastics
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
D1667 Specification for Flexible Cellular Materials—Poly
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. (Vinyl Chloride) Foam (Closed-Cell)
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C534/C534M − 23
E84 Test Method for Surface Burning Characteristics of 4.3 Grade 1 is flexible elastomeric material for use on
Building Materials typical commercial systems.
E96/E96M Test Methods for Gravimetric Determination of
4.4 Grade 2 is a high temperature flexible elastomeric
Water Vapor Transmission Rate of Materials
material.
E177 Practice for Use of the Terms Precision and Bias in
4.5 Grade 3 is an elastomeric material that does not contain
ASTM Test Methods
any leachable chlorides, fluorides or polyvinyl chloride.
E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to
NOTE 2—Continuous long-term exposure at or above the upper use
Determine the Precision of a Test Method temperature may cause degradation in the form of loss of flexibility
E2231 Practice for Specimen Preparation and Mounting of
5. Materials
Pipe and Duct Insulation Materials to Assess Surface
Burning Characteristics
5.1 These products shall be made of a homogeneous blend
2.2 Other Standards:
of natural or synthetic rubber that is permitted to be modified
CAN/ULC-S102 Standard Method of Test for Surface Burn-
with various thermoplastic or thermosetting resins, plasticizers,
ing Characteristics of Building Materials and Assemblies
modifiers, antioxidants, curatives, blowing agents and other
additives. These products are thermoset and are not thermo-
3. Terminology
plastic in nature.
3.1 Definitions—Terms used in this specification are defined
5.2 These products are expanded with chemical blowing
in Terminology C168 and in Terminology D883.
agents that decompose with the application of heat. The gases
produced by these blowing agents are similar to those found in
3.2 Definitions of Terms Specific to This Standard:
the atmosphere and thus the diffusion rate is not significant.
3.2.1 cellular elastomeric foam—a closed-cell foam made
These gases do not change over time and the thermal conduc-
of natural or synthetic rubber, or a mixture of the two, and
tivity of the insulation is stable over time.
containing other polymers, other chemicals, or both, which is
permitted to be modified by organic or inorganic additives.
5.3 Flexible, elastomeric, cellular thermal insulations shall
These foams have properties similar to those of vulcanized
be of uniform core density and have closed cells. Even though
rubber, namely, (1) the ability to be converted from a thermo-
these insulation materials are permitted to have a smooth skin
plastic to a thermosetting state by cross-linking (vulcanization)
surface on one or both sides, they are to be considered
and (2) the ability to recover substantially its original shape
homogeneous for the purposes of determining thermal perfor-
when strained or elongated.
mance.
3.2.2 flexible cellular—a flexible cellular organic polymeric
6. Physical Requirements
material shall not rupture within 60 s when a specimen 200 by
25 by 25 mm [8 by 1 by 1 in.] is bent around a 25-mm [1-in.]
6.1 Qualification Requirements—Thermal conductivity, wa-
diameter mandrel at a uniform rate of one lap in 5 s in the form
ter vapor permeability and dimensional stability physical
of a helix at a temperature between 18 and 29°C [65 and 85°F].
properties listed in Table 1, are defined as qualification
requirements (refer to Practice C390, Section 5, Classification
NOTE 1—The flexibility of these materials may decrease at lower
temperatures.
of Requirements and Section 6, Acceptance for Qualification
Requirements).
4. Classification
6.2 Inspection Requirements:
4.1 When referencing Specification C534/C534M, type and
6.2.1 The requirements for water absorption listed in Table
grade shall always be specified.
1 is defined as an inspection requirement (refer to Practice
C390, Section 5, Classification of Requirements, and Section 7,
4.2 The types are designated below:
Acceptance for Inspection Requirements).
4.2.1 Type I—Tubular.
6.2.2 All dimensional requirements shall be as described in
Grade 1 Use temperature (minimum/maximum values) -183 to
104°C [-297 to 220°F]. Section 6 and Table 2.
Grade 2 Use temperature (minimum/maximum values) -183 to
6.2.3 All workmanship, finish and appearance requirements
150°C [-297 to 300°F].
shall be as described in Section 9.
Grade 3 Use temperature (minimum/maximum values) -183 to
120°C [-297 to 250°F].
6.2.4 Compliance with inspection requirements shall be in
accordance with Practice C390.
4.2.2 Type II—Sheet.
Grade 1 Use temperature (minimum/maximum values) -183 to
6.3 Both Type I and Type II insulations shall conform to the
104°C [-297 to 220°F].
physical property requirements listed in Table 1.
Grade 2 Use temperature (minimum/maximum values) -183 to
150°C [-297 to 300°F].
6.4 The material shall be free of objectionable odors at all
Grade 3 Use temperature (minimum/maximum values) -183 to
temperatures within the recommended use range when tested
120°C [-297 to 250°F].
according to Test Method C1304.
6.5 Surface Burning Characteristics—The material shall be
tested to assess its surface burning characteristics, at the
Available from Underwriters Laboratories (UL), 2600 N.W. Lake Rd., Camas,
WA 98607-8542, http://www.ul.com. thickness supplied, in accordance with Test Method E84 with
C534/C534M − 23
A
TABLE 1 Physical Requirements for Type I (Tubular) and Type II (Sheet)
Property Unit Grade 1 Grade 2 Grade 3
(higher temperature) (non-chloride/non-fluoride containing)
Apparent thermal conductivity, max., W/m·K [Btu·in./h·ft ·°F]
at a mean temperature of:
-150°C [-238°F] 0.023[0.16] 0.023 [0.16] 0.023 [0.16]
-100°C [-148°F] 0.028 [0.18] 0.028 [0.18] 0.028 [0.18]
-29°C [-20°F] 0.036 [0.25] 0.036 [0.25] 0.036 [0.25]
-18°C [0°F] 0.038 [0.26] 0.038 [0.26] 0.038 [0.26]
24°C [75°F] 0.040 [0.28] 0.043 [0.30] 0.040 [0.28]
50°C [120°F] 0.043 [0.30] 0.047 [0.32] 0.043 [0.30]
86°C [150°F] 0.045 [0.31] 0.049 [0.34] 0.045 [0.31]
150°C [300°F] NA 0.061 [0.42] NA
Water absorption, max. % by volume 0.20 0.20 0.20
-10 -10 -10
Water-vapor permeability, max. g/Pa·s·m [perm-in.] 1.44 × 10 [0.10] 4.32 × 10 [0.30] 4.32 × 10 [0.30]
Linear shrinkage, % linear change 7.0 % 7.0 % 7.0 %
max after soak at maximum
use temperature
A
Table 1 describes two types of flexible elastomeric cellular thermal insulation. The values stated in Table 1 may not always be appropriate as design values. For specific
design recommendations using a particular product and for supporting documentation, consult the manufacturer.
TABLE 2 Dimensional Tolerances, mm [in.]
Insulation is manufactured for diameters up to 200 mm [8 in.
Tolerances nominal pipe size (NPS)] with wall thickness up to 50 mm [2
Type I—Tubular Material
in.].
Inside diameter, mm [in.]:
3 3
Up to 10 [ ⁄8 ], incl. +2.5 [ ⁄32 ], -0
7.2 Type II—Sheet material is manufactured in thicknesses
1 7 1
13 [ ⁄2 ] to 22 [ ⁄8 ], incl. +3 [ ⁄8 ], -0
up to 50 mm [2 in.]. Sheets are manufactured in sizes up to
1 3
25 [1] to 38 [1 ⁄2 ], incl. +5 [ ⁄16 ], -0
5 3 1
41 [1- ⁄8 ] to 60 [2- ⁄8 ], incl. +6 [ ⁄4 ], -0 1.22 m [48 in.] in width and in continuous lengths. Other sizes
3 3
Over 60 [2- ⁄8 ] +10 [ ⁄8 ], -0
are available upon request. Individual dimensions shall con-
Wall thicknesses, mm [in.]:
form to those specified by the manufacturer.
3 1
Up to 19 [ ⁄4 ], incl. +3 [ ⁄8 ], -0
3 3
19 and over [ ⁄4 ] +5 [ ⁄16 ], -0
7.3 Actual dimensions shall be agreed upon between the
Length, mm [in.] +75 [3], -25 [1]
Type II—Sheet Material manufacturer and the purchaser. The procedure section and the
Thickness, mm [in.]:
pipe and tubing diameter information of Practice C585 is
1 1
Up to 13 [ ⁄2 ], incl. ± 2 [± ⁄16 ]
1 3 beneficial in determining these actual dimensions.
Over 13 [ ⁄2 ] ± 3 [± ⁄32 ]
Length and width, mm [in.]:
1 7.4 The insulation tolerances shall conform to Table 2.
Up to 150 [6], incl. ± 6 [± ⁄4 ]
Over 150 [6] to 300 [12], incl. ± 10 [± ⁄8 ]
Over 300 [12] ± 3%
8. Surface
8.1 Type I—All surfaces (except ends and slits that are
mechanically cut) shall have natural skins.
mounting according to Practice E2231. The results shall be
8.2 Type II—Sheet material is manufactured either with skin
reported. In Canada, use Test Method CAN/ULC-S102 and
on one side or with skin on two sides. The surface shall be at
report the results.
the manufacturer’s option, unless otherwise specified.
6.5.1 This test method does not always define the hazard
potentially presented by preformed flexible elastomeric cellular
9. Workmanship, Finish, and Appearance
thermal insulation under actual fire conditions. It is retained for
reference in this standard as test data are required by some
9.1 The insulation shall be free of visual defects that will
codes.
adversely affect the service quality. For example, blisters, blow
6.5.2 Preformed flexible cellular elastomeric thermal insu-
holes and tears when occurring to an excessive degree shall be
lation is an organic material and is combustible. Do not
judged to adversely affect the service quality of the material.
exposed it to flames or other ignition sources. In some
applications, the fire test response characteristics of the mate-
10. Sampling
rial are addressed through requirements established by the
appropriate governing documents. 10.1 The insulation shall be sampled in accordance with
Practice C390. Details shall be agreed upon between the buyer
6.6 Leachable Chloride/Fluoride Content—Grade 3 shall be
and seller.
below the detectable limit of the test procedure used for
leachable chlorides or fluorides when tested according to T
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C534/C534M − 20a C534/C534M − 23
Standard Specification for
Preformed Flexible Elastomeric Cellular Thermal Insulation
in Sheet and Tubular Form
This standard is issued under the fixed designation C534/C534M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers preformed flexible elastomeric cellular-thermal insulation in sheet and tubular form. Grade 1 covers
materials to be used on commercial or industrial systems with operating temperatures from –183 to 104°C [–297 to 220°F], Grade
2 covers material used on industrial systems with operating temperatures from –183 to 150°C [–297 to 300°F], and Grade 3 covers
material used on industrial systems with operating temperatures from –183 to 120°C [–297 to 250°F] where halogens are not
permitted.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C168 Terminology Relating to Thermal Insulation
C177 Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the
Guarded-Hot-Plate Apparatus
C390 Practice for Sampling and Acceptance of Thermal Insulation Lots
C335 Test Method for Steady-State Heat Transfer Properties of Pipe Insulation
C411 Test Method for Hot-Surface Performance of High-Temperature Thermal Insulation
C447 Practice for Estimating the Maximum Use Temperature of Thermal Insulations
C518 Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus
C534 Specification for Preformed Flexible Elastomeric Cellular Thermal Insulation in Sheet and Tubular Form
C585 Practice for Inner and Outer Diameters of Thermal Insulation for Nominal Sizes of Pipe and Tubing
This specification is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.22 on Organic and
Nonhomogeneous Inorganic Thermal Insulations.
Current edition approved Nov. 1, 2020Jan. 1, 2023. Published November 2020February 2023. Originally approved in 1964. Last previous edition approved in 2020 as
C0534/C534M – 20.C0534/C534M – 20a. DOI: 10.1520/C0534_C0534M-20A.10.1520/C0534_C0534M-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C534/C534M − 23
C692 Test Method for Evaluating the Influence of Thermal Insulations on External Stress Corrosion Cracking Tendency of
Austenitic Stainless Steel
C795 Specification for Thermal Insulation for Use in Contact with Austenitic Stainless Steel
C871 Test Methods for Chemical Analysis of Thermal Insulation Materials for Leachable Chloride, Fluoride, Silicate, and
Sodium Ions
C1045 Practice for Calculating Thermal Transmission Properties Under Steady-State Conditions
C1058 Practice for Selecting Temperatures for Evaluating and Reporting Thermal Properties of Thermal Insulation
C1114 Test Method for Steady-State Thermal Transmission Properties by Means of the Thin-Heater Apparatus
C1304 Test Method for Assessing the Odor Emission of Thermal Insulation Materials
C1427 Specification for Extruded Preformed Flexible Cellular Polyolefin Thermal Insulation in Sheet and Tubular Form
C1763 Test Method for Water Absorption by Immersion of Thermal Insulation Materials
D883 Terminology Relating to Plastics
D1622 Test Method for Apparent Density of Rigid Cellular Plastics
D1667 Specification for Flexible Cellular Materials—Poly (Vinyl Chloride) Foam (Closed-Cell)
E84 Test Method for Surface Burning Characteristics of Building Materials
E96/E96M Test Methods for Gravimetric Determination of Water Vapor Transmission Rate of Materials
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E2231 Practice for Specimen Preparation and Mounting of Pipe and Duct Insulation Materials to Assess Surface Burning
Characteristics
2.2 Other Standards:
CAN/ULC-S102 Standard Method of Test for Surface Burning Characteristics of Building Materials and Assemblies
3. Terminology
3.1 Definitions—Terms used in this specification are defined in Terminology C168 and in Terminology D883.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 cellular elastomeric foam—a closed-cell foam made of natural or synthetic rubber, or a mixture of the two, and containing
other polymers, other chemicals, or both, which is permitted to be modified by organic or inorganic additives. These foams have
properties similar to those of vulcanized rubber, namely, (1) the ability to be converted from a thermoplastic to a thermosetting
state by cross-linking (vulcanization) and (2) the ability to recover substantially its original shape when strained or elongated.
3.2.2 flexible cellular—a flexible cellular organic polymeric material shall not rupture within 60 s when a specimen 200 by 25 by
25 mm [8 by 1 by 1 in.] is bent around a 25-mm [1-in.] diameter mandrel at a uniform rate of one lap in 5 s in the form of a helix
at a temperature between 18 and 29°C [65 and 85°F].
NOTE 1—The flexibility of these materials may decrease at lower temperatures.
4. Classification
4.1 When referencing Specification C534/C534M, type and grade shall always be specified.
4.2 The types are designated below:
4.2.1 Type I—Tubular.
Grade 1 Use temperature (minimum/maximum values) -183 to
104°C [-297 to 220°F].
Grade 2 Use temperature (minimum/maximum values) -183 to
150°C [-297 to 300°F].
Grade 3 Use temperature (minimum/maximum values) -183 to
120°C [-297 to 250°F].
Available from Underwriters Laboratories (UL), 2600 N.W. Lake Rd., Camas, WA 98607-8542, http://www.ul.com.
C534/C534M − 23
A
TABLE 1 Physical Requirements for Type I (Tubular) and Type II (Sheet)
Property Unit Grade 1 Grade 2 Grade 3
(higher temperature) (non-chloride/non-fluoride containing)
Apparent thermal conductivity, max., W/m·K [Btu·in./h·ft ·°F]
at a mean temperature of:
-150°C [-238°F] 0.023[0.16] 0.023 [0.16] 0.023 [0.16]
-100°C [-148°F] 0.028 [0.18] 0.028 [0.18] 0.028 [0.18]
-29°C [-20°F] 0.036 [0.25] 0.036 [0.25] 0.036 [0.25]
-18°C [0°F] 0.038 [0.26] 0.038 [0.26] 0.038 [0.26]
24°C [75°F] 0.040 [0.28] 0.043 [0.30] 0.040 [0.28]
50°C [120°F] 0.043 [0.30] 0.047 [0.32] 0.043 [0.30]
86°C [150°F] 0.045 [0.31] 0.049 [0.34] 0.045 [0.31]
150°C [300°F] NA 0.061 [0.42] NA
Water absorption, max. % by volume 0.20 0.20 0.20
-10 -10 -10
Water-vapor permeability, max. g/Pa·s·m [perm-in.] 1.44 × 10 [0.10] 4.32 × 10 [0.30] 4.32 × 10 [0.30]
Linear shrinkage, % linear change 7.0 % 7.0 % 7.0 %
max after soak at maximum
use temperature
A
Table 1 describes two types of flexible elastomeric cellular thermal insulation. The values stated in Table 1 may not always be appropriate as design values. For specific
design recommendations using a particular product and for supporting documentation, consult the manufacturer.
4.2.2 Type II—Sheet.
Grade 1 Use temperature (minimum/maximum values) -183 to
104°C [-297 to 220°F].
Grade 2 Use temperature (minimum/maximum values) -183 to
150°C [-297 to 300°F].
Grade 3 Use temperature (minimum/maximum values) -183 to
120°C [-297 to 250°F].
4.3 Grade 1 is flexible elastomeric material for use on typical commercial systems.
4.4 Grade 2 is a high temperature flexible elastomeric material.
4.5 Grade 3 is an elastomeric material that does not contain any leachable chlorides, fluorides or polyvinyl chloride.
NOTE 2—Continuous long-term exposure at or above the upper use temperature may cause degradation in the form of loss of flexibility
5. Materials
5.1 These products shall be made of a homogeneous blend of natural or synthetic rubber that is permitted to be modified with
various thermoplastic or thermosetting resins, plasticizers, modifiers, antioxidants, curatives, blowing agents and other additives.
These products are thermoset and are not thermoplastic in nature.
5.2 These products are expanded with chemical blowing agents that decompose with the application of heat. The gases produced
by these blowing agents are similar to those found in the atmosphere and thus the diffusion rate is not significant. These gases do
not change over time and the thermal conductivity of the insulation is stable over time.
5.3 Flexible, elastomeric, cellular thermal insulations shall be of uniform core density and have closed cells. Even though these
insulation materials are permitted to have a smooth skin surface on one or both sides, they are to be considered homogeneous for
the purposes of determining thermal performance.
6. Physical Requirements
6.1 Qualification Requirements—Thermal conductivity, water vapor permeability and dimensional stability physical properties
listed in Table 1, are defined as qualification requirements (refer to Practice C390, Section 5, Classification of Requirements and
Section 6, Acceptance for Qualification Requirements).
6.2 Inspection Requirements:
C534/C534M − 23
TABLE 2 Dimensional Tolerances, mm [in.]
Tolerances
Type I—Tubular Material
Inside diameter, mm [in.]:
3 3
Up to 10 [ ⁄8 ], incl. +2.5 [ ⁄32 ], -0
1 7 1
13 [ ⁄2 ] to 22 [ ⁄8 ], incl. +3 [ ⁄8 ], -0
1 3
25 [1] to 38 [1 ⁄2 ], incl. +5 [ ⁄16 ], -0
5 3 1
41 [1- ⁄8 ] to 60 [2- ⁄8 ], incl. +6 [ ⁄4 ], -0
3 3
Over 60 [2- ⁄8 ] +10 [ ⁄8 ], -0
Wall thicknesses, mm [in.]:
3 1
Up to 19 [ ⁄4 ], incl. +3 [ ⁄8 ], -0
3 3
19 and over [ ⁄4 ] +5 [ ⁄16 ], -0
Length, mm [in.] +75 [3], -25 [1]
Type II—Sheet Material
Thickness, mm [in.]:
1 1
Up to 13 [ ⁄2 ], incl. ± 2 [± ⁄16 ]
1 3
Over 13 [ ⁄2 ] ± 3 [± ⁄32 ]
Length and width, mm [in.]:
Up to 150 [6], incl. ± 6 [± ⁄4 ]
Over 150 [6] to 300 [12], incl. ± 10 [± ⁄8 ]
Over 300 [12] ± 3%
6.2.1 The requirements for water absorption listed in Table 1 is defined as an inspection requirement (refer to Practice C390,
Section 5, Classification of Requirements, and Section 7, Acceptance for Inspection Requirements).
6.2.2 All dimensional requirements shall be as described in Section 6 and Table 2.
6.2.3 All workmanship, finish and appearance requirements shall be as described in Section 9.
6.2.4 Compliance with inspection requirements shall be in accordance with Practice C390.
6.3 Both Type I and Type II insulations shall conform to the physical property requirements listed in Table 1.
6.4 The material shall be free of objectionable odors at all temperatures within the recommended use range when tested according
to Test Method C1304.
6.5 Surface Burning Characteristics—The material shall be tested to assess its surface burning characteristics, at the thickness
supplied, in accordance with Test Method E84 with mounting according to Practice E2231. The results shall be reported. In
Canada, use Test Method CAN/ULC-S102 and report the results.
6.5.1 This test method does not always define the hazard potentially presented by preformed flexible elastomeric cellular thermal
insulation under actual fire conditions. It is retained for reference in this standard as test data are required by some codes.
6.5.2 Preformed flexible cellular elastomeric thermal insulation is an organic material and is combustible. Do not exposed it to
flames or other ignition sources. In some applications, the fire test response characteristics of the material are addressed through
requirements established by the appropriate governing documents.
6.6 Leachable Chloride/Fluoride Content—Grade 3 shall be below the detectable limit of the test procedure used for leachable
chlorides or fluorides when tested according to Test Method C871.
7. Standard Shapes, Sizes and Dimensions
7.1 Type I—Tubular materials are manufactured in 1.83 m [72 in.] standard lengths, as well as in continuous lengths. Insulation
is manufactured for diameters up to 200 mm [8 in. nominal pipe size (NPS)] with wall thickness up to 50 mm [2 in.].
7.2 Type II—Sheet material is manufactured in thicknesses up to 50 mm [2 in.]. Sheets are manufactured in sizes up to 1.22 m
[48 in.] in width and in continuous lengths. Other sizes are available upon request. Individual dimensions shall conform to those
specified by the manufacturer.
C534/C534M − 23
7.3 Actual dimensions shall be agreed upon between the manufacturer and the purchaser. The procedure section and the pipe and
tubing diameter information of Practice C585 is beneficial in determining these actual dimensions.
7.4 The insulation tolerances shall conform to Table 2.
8. Surface
8.1 Type I—All surfaces (except ends and slits that are mechanically cut) shall have natural skins.
8.2 Type II—Sheet material is manufactured either with skin on one side or with skin on two sides. The surface shall be at the
manufacturer’s option, unless otherwise specified.
9. Workmanship, Finish, and Appearance
9.1 The insulation shall be free of visual defects that will adversely affect the service qual
...