ASTM C165 - 07(2012)

    Standard Test Method for Measuring Compressive Properties of Thermal Insulations

    Active Standard ASTM C165 | Developed by Subcommittee: C16.32

    Book of Standards Volume: 04.06


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    Significance and Use

    4.1 In providing Procedures A and B, it is recognized that different types of thermal insulation will exhibit significantly different behavior under compressive load. Data must usually be obtained from a complete load-deformation curve, and the useful working range normally corresponds to only a portion of the curve. The user is cautioned against use of the product in the range beyond which the product is permanently damaged or properties are adversely affected.

    4.2 Load-deformation curves provide useful data for research and development, quality control, specification acceptance or rejection, and for other special purposes. Standard loading rates shall not be used arbitrarily for all purposes; the effects of impact, creep, fatigue, and repeated cycling must be considered. All load-deformation data shall be reviewed carefully for applicability prior to acceptance for use in engineering designs differing widely in load, load application rate, and material dimensions involved.

    1. Scope

    1.1 This test method covers two procedures for determining the compressive resistance of thermal insulations.

    1.1.1 Procedure A covers thermal insulations having an approximate straight-line portion of a load-deformation curve, with or without an identifiable yield point as shown in Figs. 1 and 2. Such behavior is typical of most rigid board or block-type insulations.

     Procedure A—Straight Line Portion with Definite
Yield Point
    FIG. 1 Procedure A—Straight Line Portion with Definite Yield Point
     Procedure A—Straight Line Portion but no Definite
Yield Point
    FIG. 2 Procedure A—Straight Line Portion but no Definite Yield Point

    1.1.2 Procedure B covers thermal insulations that become increasingly more stiff as load is increased, as shown in Fig. 3. Such behavior is typical of fibrous batt and blanket insulations that have been compressed previously to at least the same deformation by compression packaging or mechanical softening.

     Procedure B—Increasing Stiffness
    FIG. 3 Procedure B—Increasing Stiffness

    1.2 It is recognized that the classification of materials under Procedures A and B shall not hold in all cases. For example, some batt or blanket materials that have not been compression packaged will exhibit behavior more typical of Procedure A for their first loadings. Also, some higher density fibrous insulation boards that have been precompressed will exhibit load-deformation curves more typical of Procedure B. There will also be thermal insulations with load-deformation curves that follow none of the three types shown here; that is, curves with no straight-line portion, curves with compaction areas, and curves that change from negative to positive slope.

    1.3 This test method does not cover reflective or loose fill insulations.

    1.4 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.

    1.5 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 and health practices and determine the applicability of regulatory limitations prior to use.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    C167 Test Methods for Thickness and Density of Blanket or Batt Thermal Insulations

    C168 Terminology Relating to Thermal Insulation

    C240 Test Methods of Testing Cellular Glass Insulation Block

    E4 Practices for Force Verification of Testing Machines

    E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods

    E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method


    ICS Code

    ICS Number Code 91.100.60 (Thermal and sound insulating materials)

    UNSPSC Code

    UNSPSC Code 30141500(Thermal insulation)


    DOI: 10.1520/C0165-07R12

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