ASTM C421 - 08 (2020)

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Designation: C421 −08 (Reapproved 2020)
Standard Test Method for
Tumbling Friability of Preformed Block-Type and Preformed
Pipe-Covering-Type Thermal Insulation
1
This standard is issued under the ﬁxed designation C421; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This test method covers determination of the mass loss
of preformed block-type and preformed pipe-covering-type
thermal insulation as a result of a combination of abrasion and
impact produced by a laboratory tumbling mechanism.
1.2 The values stated in inch-pound units are to be regarded
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
and are not considered 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 appro-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
2
C168 Terminology Relating to Thermal Insulation
C302 Test Method for Density and Dimensions of Pre-
formed Pipe-Covering-Type Thermal Insulation
C303 Test Method for Dimensions and Density of Pre-
formed Block and Board–Type Thermal Insulation
3. Terminology
3.1 Deﬁnitions—Deﬁnitions pertaining to thermal insulat-
ing materials are deﬁned in Terminology C168.
4. Signiﬁcance and Use
4.1 Several test methods for measuring mass loss by abra-
sion and impact of preformed block-type and preformed
pipe-covering-type thermal insulation have been used previ-
ously. It is believed that no single test method completely
covers all factors involving such forces for different kinds of
materials, but this test method is intended to provide a
procedure that gives reproducible results. It is used for com-
paring the mass loss by tumbling before and after a speciﬁc
treatment of the insulation, as agreed upon by the purchaser
and the manufacturer.
5. Apparatus
5.1 Box—A cubical box of oak wood, having inside dimen-
sions of 7
1
⁄
2
by 7
3
⁄
4
by 7
3
⁄
4
in. (190 by 197 by 197 mm),
mounted rigidly at the center of one 7
3
⁄
4
by 7
3
⁄
4
in. (197 by 197
mm) end, so that the axis normal to a face of the box is that of
a rotatable horizontal shaft. One side of the box shall be hinged
as a door and shall be gasketed to be dust-tight. The box shaft
shall be motor driven at a constant speed of 60 62 r/min.
5.2 Cubes—Twenty-four room-dry, solid oak,
3
⁄
4
6
1
⁄
32
-in.
(19 60.8-mm) cubes shall be placed in the box with the test
specimens. The speciﬁc gravity of the oak cubes shall be
approximately 0.65; white oak meets this requirement.
NOTE 1—Number each group of wood cubes 1 through 24. At the end
of every 600-revolution test, remove one “used” cube (follow the number
sequence and remove the oldest cube) and replace with a correspondingly
numbered “new” cube. In this manner, cube wear is eliminated as an
uncontrolled variable in the test method. When the corners of the wood
cubes have been worn so that the radius of curvature is greater than
1
⁄
16
in.
(1.6 mm) or the cubes have become altered so as not to be comparable
with new cubes, they shall be discarded and new ones used. A conven-
tional machinist’s radius gage is used for checking the edge wear.
6. Test Specimens
6.1 Cut the insulation with a ﬁne-tooth saw (similar to a
16-tooth band saw) into 1 6
1
⁄
16
-in. (25.4 61.6-mm) cubes.
6.2 Test twelve cubes at a time cut from one piece of
insulation. When ﬂat insulation has special surfaces due to
treatment or molding, cut each cube to include such special
1
This test method is under the jurisdiction of ASTM Committee C16 on Thermal
Insulation and is the direct responsibility of Subcommittee C16.32 on Mechanical
Properties.
Current edition approved March 1, 2020. Published March 2020. Originally
approved in 1958. Last previous edition approved in 2014 as C421 – 08 (2014).
DOI: 10.1520/C0421-08R20.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. 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
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.

surfaces as one face, except that the edges and corners of the

insulation shall not be used.

6.3 Dry and condition specimens prior to test, following

applicable speciﬁcations for the material. If the material is

adversely affected by oven temperatures, then condition speci-

mens for not less than 40 h at 73.461.8°F (23 61°C), and 50

65 % relative humidity before testing. In the absence of

deﬁnitive drying speciﬁcations, dry specimens in an oven at

215 to 250°F (102 to 121°C) to constant mass, and hold in a

desiccator to cool to room temperature before testing. Where

circumstances or requirements preclude compliance with these

conditioning procedures, exceptions agreed upon by the pur-

chaser and the manufacturer are acceptable, but they shall be

speciﬁcally listed in the test report.

7. Procedure

7.1 Conduct the test in the Standard Laboratory Atmosphere

at 73.4 61.8°F (23 61°C) and 50 65 % relative humidity.

NOTE 2—Other specimen conditioning procedures or test conditions

may be selected to simulate actual-use conditions, upon agreement

between the purchaser and the manufacturer.

7.2 Weigh the twelve conditioned test specimens on a

balance to within 61%.

7.3 Place the twelve specimens together with the 24 oak

cubes in the clean test box and secure the lid tightly.

7.4 Rotate the box at 60 62 r/min for 600 63 revolutions.

7.5 Immediately after the test period, carefully empty the

contents of the box onto a

⁄

-in. (9.5-mm) mesh screen and tap

gently to remove dust and small particles. Carefully remove the

twelve largest pieces of insulation from the screen and weigh

promptly.

7.6 Clean out the box between runs.

7.7 If an additional test period is to be run, replace the

twelve weighed pieces into the box and repeat steps 7.3 – 7.5.

8. Calculation

8.1 Calculate the percent mass loss to two signiﬁcant ﬁgures

using Eq 1:

Mass loss, % 5

3100 (1)

where:

= original mass, and

= ﬁnal mass.

9. Report

9.1 The report shall include the following:

9.1.1 Complete description of the material tested, including

type, source, and density, in accordance with Test Methods

C302 and C303, and special surfaces if any,

9.1.2 Conditioning or drying procedures followed and spe-

cial conditions employed in the test, if any,

9.1.3 Date of test,

9.1.4 Percent mass loss, and

9.1.5 Comments on the mode and extent of abrasion,

erosion, crumbling, cracking, etc.

10. Precision and Bias

10.1 Precision—The precision of this test method is given in

Table 1.

10.1.1 Repeatability—The difference between successive

results obtained by the same operator with the same apparatus

under constant operating conditions on identical test materials

would exceed the values given for repeatability in Table 1 only

in one case in twenty.

10.1.2 Reproducibility—The difference between two single

and independent results obtained by different operators work-

ing in different laboratories on identical material would exceed

the values given for reproducibility in Table 1 only in one case

in twenty.

10.2 Bias—No information can be presented on the bias of

the procedure in this test method because no material having an

accepted reference value is available.

11. Keywords

11.1 mass loss; thermal insulating materials—block/board;

tumbling friability

Supporting data have been ﬁled at ASTM Headquarters. Request Research

Report RR:C16-1006.

TABLE 1 Precision

Material Mass

Loss (%)

Repeatability Reproducibility

±2.0Sr ±2.0Sr

(%) ±2.0SR

±2.0

(%)

Rigid cellular A 0.11 0.34 309 0.40 364

plastic B 1.00 0.65 65.0 0.83 83.0

(Specimens = 3, C 5.3 1.6 30.9 4.2 79.3

Laboratories = 6) D 31.4 2.6 8.2 8.5 27.1

E 48.9 4.5 9.1 11.3 23.2

F 49.6 5.3 10.7 10.8 21.8

Calcium silicate

15 lb/ft

(240 kg/m

)

maximum

(Specimen = 6,

Laboratories = 4)

... 9.3 1.3 14.0 1.1 11.8

Perlite

14 lb/ft

(224 kg/m

)

maximum

(Specimens = 3,

Laboratories = 5)

... 54.4 4.2 7.6 9.5 17.5

Sr=repeatability standard deviation

SR=reproducibility standard deviation

C421 − 08 (2020)

ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned

in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk

of infringement of such rights, are entirely their own responsibility.

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every ﬁve years and

if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards

and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the

responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should

make your views known to the ASTM Committee on Standards, at the address shown below.

This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,

United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above

address or at 610-832-9585 (phone), 610-832-9555 (fax), or service@astm.org (e-mail); or through the ASTM website

(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222

Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/

C421 − 08 (2020)

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摘要：

ASTM C421 - 08 (2020) 是由美国材料与试验协会发布的一项标准测试方法，主要用于评估松散填充型隔热材料在机械抖动作用下的耐久性与降解特性。该标准通过模拟运输、安装及使用过程中材料可能受到的反复震动与摩擦，测定材料颗粒的破碎、粉化及质量损失程度，从而为建筑保温工程中松散填充材料的性能评估提供科学依据。适用于矿物棉、纤维素、玻璃纤维等常用松散型隔热产品，帮助生产商、检测机构及工程设计人员确保材料在长期使用中保持稳定的热工性能和结构完整性。标准版本号中的“08 (2020)”表示最初

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