ASTM D2444-21

Standard Practice for Determination of the Impact Resistance of Thermoplastic Pipe and Fittings by Means of a Tup (Falling Weight)

SIGNIFICANCE AND USE
4.1 The impact resistance of thermoplastic pipe and fittings relates to suitability for service and to quality of processing. Impact resistance may also provide a relative measure of a material's resistance to breakage during handling and installation and, for non-buried applications, to in-service breakage. See Appendix X5 for guidelines for selecting testing combinations.  
4.2 Results obtained by use of this practice can be used in three ways:  
4.2.1 As the basis for establishing impact test requirements in product standards,  
4.2.2 To measure the effect of changes in materials or processing, and  
4.2.3 To measure the effect of the environment.
SCOPE
1.1 This practice covers the determination of the impact resistance of thermoplastic pipe and fittings under specified conditions of impact by means of a tup (falling weight). Three interchangeable striking noses are used on the tup, differing in geometrical configuration. Two specimen holders are described.
Note 1: Appendix X1 shows the procedure to determine impact strength.  
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 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-Jan-2021
• ICS: 23.040.20 - Plastics pipes
• ICS: 23.040.45 - Plastics fittings
• Technical Committee: F17 - Plastic Piping Systems
• Drafting Committee: F17.40 - Test Methods

Relations

• Refers: ASTM F412-20 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Apr-2020
• Refers: ASTM F412-19 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Jan-2019
• Refers: ASTM F725-03(2018) - Standard Practice for Drafting Impact Test Requirements In Thermoplastic Pipe And Fittings Standards
• Effective Date: 01-Aug-2018
• Refers: ASTM D1600-18 - Standard Terminology for Abbreviated Terms Relating to Plastics (Withdrawn 2024)
• Effective Date: 01-Jan-2018
• Refers: ASTM F412-17a - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Aug-2017
• Refers: ASTM F412-17 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Feb-2017
• Refers: ASTM F412-16a - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 15-Nov-2016
• Refers: ASTM F412-16 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Aug-2016
• Refers: ASTM F412-15 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Jun-2015
• Refers: ASTM D2122-15 - Standard Test Method for Determining Dimensions of Thermoplastic Pipe and Fittings
• Effective Date: 15-Mar-2015
• Refers: ASTM D1600-14 - Standard Terminology for Abbreviated Terms Relating to Plastics
• Effective Date: 01-Feb-2014
• Refers: ASTM F725-03(2013) - Standard Practice for Drafting Impact Test Requirements In Thermoplastic Pipe And Fittings Standards
• Effective Date: 01-Aug-2013
• Refers: ASTM D1600-13 - Standard Terminology for Abbreviated Terms Relating to Plastics
• Effective Date: 15-Apr-2013
• Refers: ASTM F412-13 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 15-Feb-2013
• Refers: ASTM F412-12 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Apr-2012

Overview

ASTM D2444-21 is the Standard Practice for Determination of the Impact Resistance of Thermoplastic Pipe and Fittings by Means of a Tup (Falling Weight). Developed by ASTM International, this practice provides a systematic approach for determining the impact resistance of thermoplastic pipes and fittings using a falling weight apparatus, commonly known as a tup. The primary goal is to assess a product’s resistance to breakage under specified impact conditions, which aids in evaluating suitability for end-use, quality of material processing, and resistance to damage during handling, installation, and use.

This standard guides manufacturers, quality control professionals, and testing laboratories to generate reproducible and meaningful impact resistance data, which is essential for product development, performance validation, and compliance with product standards.

Key Topics

• Scope of Testing
  The standard specifies the procedures for testing thermoplastic pipes and fittings using a falling weight with interchangeable striking noses and specimen holders to simulate real-world impact scenarios.

• Significance and Use
  The results from this practice:

  • Form the basis for impact test requirements in product standards
  • Help measure the effects of changes in materials, processing variables, or environmental factors
  • Provide a comparative measure of the material’s resistance to breakage

• Apparatus and Methodology

  • Uses a tup (falling weight) with various striking nose geometries (Tup A, B, C)
  • Supports specimens in either a V-block or flat-plate holder
  • Ensures controlled drop height and mass to deliver consistent impact energy

• Sample Preparation and Conditioning

  • Establishes standard specimen lengths and preparation methods
  • Specifies conditioning at defined temperature and humidity prior to testing

• Criteria for Failure

  • Considers visible shattering, cracks, or splits as failure
  • Records permanent deformation or specific failure types in the test report

• Reporting

  • Mandates detailed recording of test parameters, specimen details, conditioning, failures, and observations for full traceability

Applications

ASTM D2444-21 is widely applied in industries where thermoplastic pipe and fittings are produced, tested, or specified. Key applications include:

• Quality Control
  Manufacturers use this standard during production to ensure thermoplastic pipes and fittings meet impact resistance requirements for safe handling, installation, and service life.

• Product Development and Improvement
  R&D teams utilize impact resistance testing to compare material formulations or processing modifications, allowing for optimization of product durability and performance.

• Compliance and Certification
  Testing labs reference ASTM D2444-21 to verify compliance with customer specifications and national or international product standards for thermoplastic piping.

• Assessment of Environmental Effects
  The standard provides a method for measuring how exposure to different environments impacts material impact resistance, supporting decisions about suitability in various service conditions.

Related Standards

ASTM D2444-21 is part of a larger framework of standards relevant to testing, manufacturing, and specifying plastic piping systems, such as:

• ASTM D618 – Conditioning Plastics for Testing
• ASTM D1600 – Terminology for Abbreviated Terms Relating to Plastics
• ASTM D2122 – Test Method for Determining Dimensions of Thermoplastic Pipe and Fittings
• ASTM F412 – Terminology Relating to Plastic Piping Systems
• ASTM F725 – Practice for Drafting Impact Test Requirements in Thermoplastic Pipe and Fittings Standards

These related standards ensure that test results from ASTM D2444-21 are consistent, accurate, and applicable across the thermoplastic piping industry.

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Keywords: ASTM D2444-21, impact resistance, thermoplastic pipe, pipe fittings, falling weight test, tup, quality control, plastic piping standards, product compliance, material testing

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: D2444 − 21
Standard Practice for
Determination of the Impact Resistance of Thermoplastic
Pipe and Fittings by Means of a Tup (Falling Weight)
This standard is issued under the fixed designation D2444; 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* F412 Terminology Relating to Plastic Piping Systems
F725 Practice for Drafting Impact Test Requirements In
1.1 This practice covers the determination of the impact
Thermoplastic Pipe And Fittings Standards
resistance of thermoplastic pipe and fittings under specified
conditions of impact by means of a tup (falling weight). Three
3. Terminology
interchangeable striking noses are used on the tup, differing in
3.1 Definitions—Definitions are in accordance with Termi-
geometrical configuration. Two specimen holders are de-
nology F412, and abbreviations are in accordance with Termi-
scribed.
nology D1600, unless otherwise specified.
NOTE 1—Appendix X1 shows the procedure to determine impact
strength.
3.2 Definitions of Terms Specific to This Standard:
1.2 The values stated in inch-pound units are to be regarded
3.2.1 tup—Thestrikingpartofafallinghammerlikemecha-
as standard. The values given in parentheses are mathematical
nism.
conversions to SI units that are provided for information only
4. Significance and Use
and are not considered standard.
1.3 This standard does not purport to address all of the 4.1 The impact resistance of thermoplastic pipe and fittings
relates to suitability for service and to quality of processing.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- Impact resistance may also provide a relative measure of a
material’s resistance to breakage during handling and installa-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. tion and, for non-buried applications, to in-service breakage.
See Appendix X5 for guidelines for selecting testing combi-
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard- nations.
ization established in the Decision on Principles for the
4.2 Results obtained by use of this practice can be used in
Development of International Standards, Guides and Recom-
three ways:
mendations issued by the World Trade Organization Technical
4.2.1 As the basis for establishing impact test requirements
Barriers to Trade (TBT) Committee.
in product standards,
4.2.2 To measure the effect of changes in materials or
2. Referenced Documents
processing, and
2.1 ASTM Standards:
4.2.3 To measure the effect of the environment.
D618 Practice for Conditioning Plastics for Testing
5. Apparatus
D1600 Terminology forAbbreviatedTerms Relating to Plas-
tics
5.1 General—One type of impact tester is illustrated in Fig.
D2122 Test Method for Determining Dimensions of Ther-
1.
moplastic Pipe and Fittings
5.2 Tup:
5.2.1 The tup nose shall be as shown in Fig. 2. When used
with the 0.50 in. (12.7 mm) radius nose, it is designated as Tup
This practice is under the jurisdiction of ASTM Committee F17 on Plastic
A. When used with the 2.00 in. (51 mm) radius nose, it is
Piping Systems and is the direct responsibility of Subcommittee F17.40 on Test
Methods. designated as Tup B. When used with the 0.25 in. (6.3 mm)
Current edition approved Feb. 1, 2021. Published February 2021. Originally
radius nose, it is designated as Tup C.
approved in 1965. Last previous edition approved in 2019 as D2444 – 19. DOI:
10.1520/D2444-21.
NOTE 2—It is suggested that tups be made of scratch-resistant steel to
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
reduce damage to the nose. Badly scarred noses may affect test results.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.2.2 The mass of the tup shall be 6, 12, 20, or 30 lb (2.7,
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 5.4, 9.1, or 13.6 kg).
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2444 − 21
5.3 Drop Tube:
5.3.1 The drop tube shall be of sufficient length (approxi-
mately 12 ft (3.7 m)) to provide for a fall of at least 10 ft (3.0
m) and shall be mounted so that the lengthwise direction is
vertical as measured with a plumb bob or a spirit level at least
2 ft (610 mm) in length.
5.3.2 Care must be taken to ensure that the tup falls freely;
it must not “chatter” down the tube.
NOTE 3—No material for the drop tube is specified. However, a
colddrawn seamless steel tubing with an inside diameter of 2.563 6 0.003
in. (65.10 6 0.08 mm), or acrylonitrile-butadiene-styrene (ABS) or
poly(vinyl chloride) (PVC) plastic pipe, 2 ⁄2 in. nominal pipe size, with a
standard dimension ratio (SDR) of 21, have been found to be satisfactory.
NOTE 4—Provided equivalent results are obtained, the tup may be
dropped without a drop tube or guided by other means. The drop tube is
used to reduce the hazard to operators and property that may occur when
the tup rebounds. It also helps guide and center the tup so that it will be
more likely to strike the top of the test specimen. It may also be necessary
to provide a protective barrier around the specimen, particularly for larger
sizesofpipeandfittings,toprotecttheoperatorfromflyingbrokenpieces.
NOTE 5—The tup may not fall freely if the clearance between the tup
and tube is too large or too small, or if it is restrained by a partial vacuum
above the tup, such as can be caused by the hold and release device.
5.3.3 Means shall be provided (1) to hold the tup at steps of
2 in. (50.8 mm) for a distance of 2 to 10 ft (610 mm to 3.0 m)
above the specimen holder, (2) to release the tup in a
reproducible manner, (3) to allow the tup to fall freely, and (4)
to catch the tup on the first rebound. Refer to Fig. 1.
FIG. 1 One Type of Tup Impact Tester
5.4 SpecimenHolder—Twospecimenholdersaredescribed:
the V-block (Holder A) and the flat-plate (Holder B).
5.4.1 The V-block holder shall be at least as long as the
specimen being tested and shall have a 90° included angle. It
may be fabricated or of solid construction. The side supports
shallbeofsufficientdepthtosupportthespecimenintheVand
not on the top edges of the V-block.
NOTE 6—Both aluminum and steel have been found suitable for the
holders.
5.4.2 The flat-plate holder shall consist of a 1 in. (25.4 mm)
minimum thick plate at least as long as the specimen being
tested, in which a groove to position the pipe specimen shall be
cut. This groove shall be about 0.12 in. (3 mm) in depth with
the edges rounded to a radius of about 0.06 in. (1.5 mm).
Fittings that do not contact the plate directly under the point of
impact shall be supported at this point by a flat steel plate or
shim. The specimen holder shall be mounted on a rigid base
fastened to a concrete slab. Means shall be provided to center
the specimens under the drop tube. A bar or rod placed inside
the specimen and retained by a light spring may be employed
if difficulty is encountered in holding the specimen in position.
6. Test Specimens
6.1 The pipe specimens shall be equal in length to the
nominal outside diameter but not less than 6 in. (152 mm) in
length. Burrs shall be removed.
6.2 Fittings shall be tested either unassembled or assembled
to pieces of pipe each 6 in. (152 mm) in length.
7. Number of Test Specimens
NOTE 1—Dimensions are in inches (millimetres).
7.1 Thenumberoftestspecimensshallbeasspecifiedinthe
FIG. 2 Tup Nose Detail
product standard. If the number of test specimens are not
D2444 − 21
specifiedintheproductstandard,thefollowingshallapply;test 10.2.2.2 If all four specimens fail, test four more specimens
20 sample specimens. When 4 or more of 20 specimens tested with a lighter tup.
fail, test 20 additional specimens. 17 or more of 20 specimens
10.2.2.3 If all four specimens pass, test the same specimens
passingor32ormoreof40specimenspassingshallindicatean
with a heavier tup, at a drop height of 5 ft (1.5 m).
acceptable pass rate for the test.
10.2.2.4 Once a weight has been used that results in the
failure of some, but not all, specimens at a height of 5 ft (1.5
NOTE 7—See F725 Practice for Drafting Impact Test Requirements in
Thermoplastic Pipe and Fittings Standards.
m), continue the test as described in 10.2.3. If no failures occur
with the heaviest tup at a drop height of 5 ft (1.5 m), test at the
8. Conditioning
maximum drop height. If no failures occur with the maximum
8.1 Condition the test specimens at 40 h, 73 °F (23 °C), and
weight at the maximum drop height, test a total of 50
50 6 5 % relative humidity for not less than 40 h prior to test
specimens at this drop height, record the results, and discon-
in accordance with Procedure A of Practice D618, for those
tinue testing. If one or more of the preliminary test specimens
tests where conditioning is required.
passes with the maximum weight at the maximum drop height,
proceed to 10.2.3.
8.2 Test Conditions—Conduct the test in a room maintained
at the test temperature or, if the test is made in an atmosphere 10.2.3 After the optimum tup weight has been determined,
divide the remaining group of preliminary test specimens into
or at a temperature other than that at which the specimens are
conditioned, conduct the test as soon as possible after removal two equal lots. Each group shall contain at least eight speci-
mens. Test one lot at a lesser drop height so that substantially
from the conditioning atmosphere, but in any case within 15 s.
Incaseofdisagreement,conductthetestsinaroommaintained less than 50 % failures result. Test the second lot at a greater
dropheightsothatsubstantiallymorethan50 %failuresresult.
at the test temperature.
Plot these results on probability graph paper to serve as the
8.3 The test conditions shall be as specified in the product
basis for estimating the proper drop heights for the final test.
standard.
10.2.4 If the 6 lb (2.7 kg) tup produces 100 % failures at 5
9. Procedure—General
ft (1.5 m), use lesser drop heights for the procedures outlined
in 10.2.3.
9.1 Measure the dimensions of the test specimens in accor-
dance with Test Method D2122.
NOTE 10—Because there must be both failures and nonfailures in this
test, conditions that result in 100 % failures or 100 % passes are of limited
9.2 The point of impact for all specimens shall be at the top
value in the development of information. When all specimens pass, the
of the vertical diameter.
problem can be helped by (1) changing from the flat-plate holder to the
9.3 Test unsymmetrical fittings with the specimen lying on V-block holder (in the case of pipe specimens), (2) changing from Tup B
to Tup A, and finally to Tup C, and (3) lowering the test temperature.
its side.
When all specimens fail, the sequence is reversed.
9.4 Position the pipe specimens at random angular orienta-
10.3 Final Test:
tions.
10.3.1 Divide 100 test specimens into two equal sets.
9.5 Impact each specimen only once.
10.3.2 On the basis of the preliminary test, trial and error, or
9.6 Conduct the test and record the results as described in
judgment, estimate the drop height at which 85 % of the
Sections 10 and 11.
specimens will pass and test the first set of 50 specimens at this
height. Record the value of the mass, the drop height, and the
10. Procedure—Details
number of passes.
10.1 Impact one of the sets using an energy estimated to
10.3.3 Estimate the drop height at which 85 % of the
cause15 %ofthespecimenstofail;impactthesecondsetatan
specimens will fail and, if it is 10 ft (3.0 m) or more, use this
energy estimated to cause 85 % to fail. Record the actual
height. Test 50 specimens and record the number of passes and
percentage that fail and plot on normal probability graph paper.
the drop height.
10.2 Preliminary Tests:
10.3.4 Acceptable Data:
10.2.1 The purpose of the preliminary tests is to identify the
10.3.4.1 To be acceptable, there must be at least one pass
optimum tup mass and to determine the drop heights to be used
and at least one fail in each set of data; one set of data should
for the final tests.
listlessthan50 %failures;thenumberofpassesinthetwosets
NOTE 8—The use of this preliminary procedure is optional. Trial and
should differ by at least 20.
error, previous experience with the material, or guesswork may serve as
10.3.4.2 If the requirements of 10.3.4.1 have not been met,
well. Also, see Appendix X4.
test 50 additional specimens at a drop height chosen to rectify
NOTE 9—The chief source of problems in conducting impact tests is the
the deficiency.
ratio of the standard deviation to the mean strength. Use of Tup C with
pipe specimens will reduce the size of the problem.
10.3.5 Construct a straight-line plot of the test results on
10.2.2 Select a tup estimated to cause failure of some normal probability paper. Preliminary tests which were con-
specimens when dropped from a height of 5 ft (1.5 m) and use ducted at the same drop height as the final tests shall be used
it to test four specimens. to compute the percent passing at that height. All other
10.2.2.1 If at least one but not all four specimens fail with preliminary test results are ignored for purposes of obtaining
the first tup selected, continue the test as described in 10.2.3. the final plot.
D2444 − 21
10.3.6 The intercept of the plot with the 50 % pass/fail line 12.1.3 Test temperature and conditioning procedure,
is the average impact resistance of the set as measured by the
12.1.4 Tup used,
test.
12.1.5 Holder used,
10.3.7 The intercept of the plot at the 16 % or the 84 %
12.1.6 The mass of the tup, lb (kg),
pass/fail line differs from the average strength by (for practical
12.1.7 Point of impact for fittings,
purposes) one standard deviation.
12.1.8 Types of failure and any deformation observed, each
11. Criteria for Specimen Failure
specimen tested should be recorded as “pass” or “fail” in
11.1 Failure in the test specimens shall be shattering or any
accordance with the description in Section 10.
crack or split created by the impact and that can be seen by the
12.1.9 Date of test, and
nakedeye.Lightingdevicesmaybeusedtoassistinexamining
the specimens. A crease visible on the surface shall not be
13. Precision and Bias
construed as specimen failure. If criteria of failure in the test
13.1 This practice is neither precise nor accurate within the
specimens other than those cited here are used, they shall be
listed in the report. limits usually associated with those terms unless larger num-
bers of test specimens are employed. Therefore, no statement
12. Report
of bias can be made.
12.1 The report shall include the following:
NOTE 11—Abrief treatment of the subject of precision and accuracy for
12.1.1 Complete identification of pipe or fittings tested,
binomial tests is provided in Appendix X2.
including type of plastic, source, manufacturer’s code, size,
average dimensions and minimum wall thickness, and history,
14. Keywords
12.1.2 In the case of fittings, the dimensions of pipe used to
prepare the specimens, how joints were made, and the position 14.1 fittings; flat-plate; impact resistance; groove; pipe;
of the weld mark in relation to the point of impact, thermoplastic; thickness; tup (falling weight)
APPENDIXES
(Nonmandatory Information)
X1. DETERMINATION OF IMPACT STRENGTH
X1.1 Impact one of the sets using an energy estimated to m),continuethetestasdescribedinX1.2.3.Ifnofailuresoccur
cause15 %ofthespecimenstofail;impactthesecondsetatan with the heaviest tup at a drop height of 5 ft (1.5 m), test at the
energy estimated to cause 85 % to fail. Record the actual maximum drop height. If no failures occur with the maximum
percentage that fail and plot on normal probability graph paper.
weight at the maximum drop height, test a total of 50
specimens at this drop height, record the results, and discon-
X1.2 Preliminary Tests:
tinue testing. If one or more of the preliminary test specimens
passes with the maximum weight at the maximum drop height,
X1.2.1 Thepurposeofthepreliminarytestsistoidentifythe
proceed to X1.2.3.
optimum tup mass and to determine the drop heights to be used
for the final tests.
X1.2.3 After the optimum tup weight has been determined,
divide the remaining group of preliminary test specimens into
NOTE X1.1—The use of this preliminary practice is optional. Trial and
error, previous experience with the material, or professional judgement two equal lots. Each group shall contain at least eight speci-
may serve as well. Also, see Appendix X3.
mens. Test one lot at a lesser drop height so that substantially
NOTE X1.2—The chief source of problems in conducting impact tests is
less than 50 % failures result. Test the second lot at a greater
the ratio of the standard deviation to the mean strength. Use ofTup C with
dropheightsothatsubstantiallymorethan50 %failuresresult.
pipe specimens will reduce the size of the problem.
Plotthese results on probability graph paper to serve as the
X1.2.2 Select a tup estimated to cause failure of some
basis for estimating the proper drop heights for the final test.
specimens when dropped from a height of 5 ft (1.5 m) and use
X1.2.4 If the 6 lb (2.7 kg) tup produces 100 % failures at 5
it to test four specimens.
ft (1.5 m), use lesser drop heights for the practices outlined in
X1.2.2.1 If at least one but not all four specimens fail with
X1.2.3.
the first tup selected, continue the test as described in X1.2.3.
X1.2.2.2 If all four specimens fail, test four more specimens
NOTE X1.3—Because there must be both failures and nonfailures in this
with a lighter tup. test, conditions that result in 100 % failures or 100 % passes are of limited
value in the development of info
...

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: D2444 − 19 D2444 − 21
Standard Practice for
Determination of the Impact Resistance of Thermoplastic
Pipe and Fittings by Means of a Tup (Falling Weight)
This standard is issued under the fixed designation D2444; 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 practice covers the determination of the impact resistance of thermoplastic pipe and fittings under specified conditions
of impact by means of a tup (falling weight). Three interchangeable striking noses are used on the tup, differing in geometrical
configuration. Two specimen holders are described.
NOTE 1—Appendix X1 shows the procedure to determine impact strength.
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 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:
D618 Practice for Conditioning Plastics for Testing
D1600 Terminology for Abbreviated Terms Relating to Plastics
D2122 Test Method for Determining Dimensions of Thermoplastic Pipe and Fittings
F412 Terminology Relating to Plastic Piping Systems
F725 Practice for Drafting Impact Test Requirements In Thermoplastic Pipe And Fittings Standards
3. Terminology
3.1 Definitions—Definitions are in accordance with Terminology F412, and abbreviations are in accordance with Terminology
D1600, unless otherwise specified.
3.2 Definitions of Terms Specific to This Standard:
This practice is under the jurisdiction of ASTM Committee F17 on Plastic Piping Systems and is the direct responsibility of Subcommittee F17.40 on Test Methods.
Current edition approved Aug. 1, 2019Feb. 1, 2021. Published September 2019February 2021. Originally approved in 1965. Last previous edition approved in 20172019
as D2444 – 17.D2444 – 19. DOI: 10.1520/D2444-19.10.1520/D2444-21.
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.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2444 − 21
3.2.1 tup—The striking part of a falling hammer like mechanism.
4. Significance and Use
4.1 The impact resistance of thermoplastic pipe and fittings relates to suitability for service and to quality of processing. Impact
resistance may also provide a relative measure of a material’s resistance to breakage during handling and installation and, for
non-buried applications, to in-service breakage. See Appendix X5 for guidelines for selecting testing combinations.
4.2 Results obtained by use of this practice can be used in three ways:
4.2.1 As the basis for establishing impact test requirements in product standards,
4.2.2 To measure the effect of changes in materials or processing, and
4.2.3 To measure the effect of the environment.
5. Apparatus
5.1 General—One type of impact tester is illustrated in Fig. 1.
5.2 Tup:
5.2.1 The tup nose shall be as shown in Fig. 2. When used with the 0.50 in. (12.7 mm) radius nose, it is designated as Tup A. When
used with the 2.00 in. (51 mm) radius nose, it is designated as Tup B. When used with the 0.25 in. (6.3 mm) radius nose, it is
designated as Tup C.
NOTE 2—It is suggested that tups be made of scratch-resistant steel to reduce damage to the nose. Badly scarred noses may affect test results.
FIG. 1 One Type of Tup Impact Tester
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NOTE 1—Dimensions are in inches (millimetres).
FIG. 2 Tup Nose Detail
5.2.2 The mass of the tup shall be 6, 12, 20, or 30 lb (2.7, 5.4, 9.1, or 13.6 kg).
5.3 Drop Tube:
5.3.1 The drop tube shall be of sufficient length (approximately 12 ft (3.7 m)) to provide for a fall of at least 10 ft (3.0 m) and
shall be mounted so that the lengthwise direction is vertical as measured with a plumb bob or a spirit level at least 2 ft (610 mm)
in length.
5.3.2 Care must be taken to ensure that the tup falls freely; it must not “chatter” down the tube.
NOTE 3—No material for the drop tube is specified. However, a colddrawn seamless steel tubing with an inside diameter of 2.563 6 0.003 in. (65.10 6
0.08 mm), or acrylonitrile-butadiene-styrene (ABS) or poly(vinyl chloride) (PVC) plastic pipe, 2 ⁄2 in. nominal pipe size, with a standard dimension ratio
(SDR) of 21, have been found to be satisfactory.
NOTE 4—Provided equivalent results are obtained, the tup may be dropped without a drop tube or guided by other means. The drop tube is used to reduce
the hazard to operators and property that may occur when the tup rebounds. It also helps guide and center the tup so that it will be more likely to strike
the top of the test specimen. It may also be necessary to provide a protective barrier around the specimen, particularly for larger sizes of pipe and fittings,
to protect the operator from flying broken pieces.
NOTE 5—The tup may not fall freely if the clearance between the tup and tube is too large or too small, or if it is restrained by a partial vacuum above
the tup, such as can be caused by the hold and release device.
5.3.3 Means shall be provided (1) to hold the tup at steps of 2 in. (50.8 mm) for a distance of 2 to 10 ft (610 mm to 3.0 m) above
the specimen holder, (2) to release the tup in a reproducible manner, (3) to allow the tup to fall freely, and (4) to catch the tup on
the first rebound. Refer to Fig. 1.
5.4 Specimen Holder—Two specimen holders are described: the V-block (Holder A) and the flat-plate (Holder B).
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5.4.1 The V-block holder shall be at least as long as the specimen being tested and shall have a 90-deg90° included angle. It may
be fabricated or of solid construction. The side supports shall be of sufficient depth to support the specimen in the V and not on
the top edges of the V-block.
NOTE 6—Both aluminum and steel have been found suitable for the holders.
5.4.2 The flat-plate holder shall consist of a 1 in. (25.4 mm) minimum thick plate at least as long as the specimen being tested,
in which a groove to position the pipe specimen shall be cut. This groove shall be about 0.12 in. (3 mm) in depth with the edges
rounded to a radius of about 0.06 in. (1.5 mm). Fittings that do not contact the plate directly under the point of impact shall be
supported at this point by a flat steel plate or shim. The specimen holder shall be mounted on a rigid base fastened to a concrete
slab. Means shall be provided to center the specimens under the drop tube. A bar or rod placed inside the specimen and retained
by a light spring may be employed if difficulty is encountered in holding the specimen in position.
6. Test Specimens
6.1 The pipe specimens shall be equal in length to the nominal outside diameter but not less than 6 in. (152 mm) in length. Burrs
shall be removed.
6.2 Fittings shall be tested either unassembled or assembled to pieces of pipe each 6 in. (152 mm) in length.
7. Number of Test Specimens
7.1 The number of test specimens shall be as specified in the product standard. If the number of test specimens are not specified
in the product standard, the following shall apply; test 20 sample specimens. When 4 or more of 20 specimens tested fail, test 20
additional specimens. 17 or more of 20 specimens passing or 32 or more of 40 specimens passing shall indicate an acceptable pass
rate for the test.
NOTE 7—See F725 Practice for Drafting Impact Test Requirements in Thermoplastic Pipe and Fittings Standards.
8. Conditioning
8.1 Condition the test specimens at 40 h, 73 °F (23 °C), and 50 6 5 % relative humidity for not less than 40 h prior to test in
accordance with Procedure A of Practice D618, for those tests where conditioning is required.
8.2 Test Conditions—Conduct the test in a room maintained at the test temperature or, if the test is made in an atmosphere or at
a temperature other than that at which the specimens are conditioned, conduct the test as soon as possible after removal from the
conditioning atmosphere, but in any case within 15 s. In case of disagreement, conduct the tests in a room maintained at the test
temperature.
8.3 The test conditions shall be as specified in the product standard.
9. Procedure—General
9.1 Measure the dimensions of the test specimens in accordance with Test Method D2122.
9.2 The point of impact for all specimens shall be at the top of the vertical diameter.
9.3 Test unsymmetrical fittings with the specimen lying on its side.
9.4 Position the pipe specimens at random angular orientations.
9.5 Impact each specimen only once.
9.6 Conduct the test and record the results as described in Sections 10 and 11.
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10. Procedure—Details
10.1 Impact one of the sets using an energy estimated to cause 15 % of the specimens to fail; impact the second set at an energy
estimated to cause 85 % to fail. Record the actual percentage that fail and plot on normal probability graph paper.
10.2 Preliminary Tests:
10.2.1 The purpose of the preliminary tests is to identify the optimum tup mass and to determine the drop heights to be used for
the final tests.
NOTE 8—The use of this preliminary procedure is optional. Trial and error, previous experience with the material, or guesswork may serve as well. Also,
see Appendix X4.
NOTE 9—The chief source of problems in conducting impact tests is the ratio of the standard deviation to the mean strength. Use of Tup C with pipe
specimens will reduce the size of the problem.
10.2.2 Select a tup estimated to cause failure of some specimens when dropped from a height of 5 ft (1.5 m) and use it to test four
specimens.
10.2.2.1 If at least one but not all four specimens fail with the first tup selected, continue the test as described in 10.2.3.
10.2.2.2 If all four specimens fail, test four more specimens with a lighter tup.
10.2.2.3 If all four specimens pass, test the same specimens with a heavier tup, at a drop height of 5 ft (1.5 m).
10.2.2.4 Once a weight has been used that results in the failure of some, but not all, specimens at a height of 5 ft (1.5 m), continue
the test as described in 10.2.3. If no failures occur with the heaviest tup at a drop height of 5 ft (1.5 m), test at the maximum drop
height. If no failures occur with the maximum weight at the maximum drop height, test a total of 50 specimens at this drop height,
record the results, and discontinue testing. If one or more of the preliminary test specimens passes with the maximum weight at
the maximum drop height, proceed to 10.2.3.
10.2.3 After the optimum tup weight has been determined, divide the remaining group of preliminary test specimens into two
equal lots. Each group shall contain at least eight specimens. Test one lot at a lesser drop height so that substantially less than 50 %
failures result. Test the second lot at a greater drop height so that substantially more than 50 % failures result. Plot these results
on probability graph paper to serve as the basis for estimating the proper drop heights for the final test.
10.2.4 If the 6 lb (2.7 kg) tup produces 100 % failures at 5 ft (1.5 m), use lesser drop heights for the procedures outlined in 10.2.3.
NOTE 10—Because there must be both failures and nonfailures in this test, conditions that result in 100 % failures or 100 % passes are of limited value
in the development of information. When all specimens pass, the problem can be helped by (1) changing from the flat-plate holder to the V-block holder
(in the case of pipe specimens), (2) changing from Tup B to Tup A, and finally to Tup C, and (3) lowering the test temperature. When all specimens fail,
the sequence is reversed.
10.3 Final Test:
10.3.1 Divide 100 test specimens into two equal sets.
10.3.2 On the basis of the preliminary test, trial and error, or judgment, estimate the drop height at which 85 % of the specimens
will pass and test the first set of 50 specimens at this height. Record the value of the mass, the drop height, and the number of
passes.
10.3.3 Estimate the drop height at which 85 % of the specimens will fail and, if it is 10 ft (3.0 m) or more, use this height. Test
50 specimens and record the number of passes and the drop height.
10.3.4 Acceptable Data:
10.3.4.1 To be acceptable, there must be at least one pass and at least one fail in each set of data; one set of data should list less
than 50 % failures; the number of passes in the two sets should differ by at least 20.
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10.3.4.2 If the requirements of 10.3.4.1 have not been met, test 50 additional specimens at a drop height chosen to rectify the
deficiency.
10.3.5 Construct a straight-line plot of the test results on normal probability paper. Preliminary tests which were conducted at the
same drop height as the final tests shall be used to compute the percent passing at that height. All other preliminary test results
are ignored for purposes of obtaining the final plot.
10.3.6 The intercept of the plot with the 50 % pass/fail line is the average impact resistance of the set as measured by the test.
10.3.7 The intercept of the plot at the 16 % or the 84 % pass/fail line differs from the average strength by (for practical purposes)
one standard deviation.
11. Criteria for Specimen Failure
11.1 Failure in the test specimens shall be shattering or any crack or split created by the impact and that can be seen by the naked
eye. Lighting devices may be used to assist in examining the specimens. A crease visible on the surface shall not be construed as
specimen failure. If criteria of failure in the test specimens other than those cited here are used, they shall be listed in the report.
12. Report
12.1 The report shall include the following:
12.1.1 Complete identification of pipe or fittings tested, including type of plastic, source, manufacturer’s code, size, average
dimensions and minimum wall thickness, and history,
12.1.2 In the case of fittings, the dimensions of pipe used to prepare the specimens, how joints were made, and the position of
the weld mark in relation to the point of impact,
12.1.3 Test temperature and conditioning procedure,
12.1.4 Tup used,
12.1.5 Holder used,
12.1.6 The mass of the tup, lb (kg),
12.1.7 Point of impact for fittings,
12.1.8 Types of failure and any deformation observed, each specimen tested should be recorded as “pass” or “fail” in accordance
with the description in Section 10.
12.1.9 Date of test, and
13. Precision and Bias
13.1 This practice is neither precise nor accurate within the limits usually associated with those terms unless larger numbers of
test specimens are employed. Therefore, no statement of bias can be made.
NOTE 11—A brief treatment of the subject of precision and accuracy for binomial tests is provided in Appendix X2.
14. Keywords
14.1 fittings; flat-plate; impact resistance; groove; pipe; thermoplastic; thickness; tup (falling weight)
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APPENDIXES
(Nonmandatory Information)
X1. DETERMINATION OF IMPACT STRENGTH
X1.1 Impact one of the sets using an energy estimated to cause 15 % of the specimens to fail; impact the second set at an energy
estimated to cause 85 % to fail. Record the actual percentage that fail and plot on normal probability graph paper.
X1.2 Preliminary Tests:
X1.2.1 The purpose of the preliminary tests is to identify the optimum tup mass and to determine the drop heights to be used for
the final tests.
NOTE X1.1—The use of this preliminary practice is optional. Trial and error, previous experience with the material, or professional judgement may serve
as well. Also, see Appendix X3.
NOTE X1.2—The chief source of problems in conducting impact tests is the ratio of the standard deviation to the mean strength. Use of Tup C with pipe
specimens will reduce the size of the problem.
X1.2.2 Select a tup estimated to cause failure of some specimens when dropped from a height of 5 ft (1.5 m) and use it to test
four specimens.
X1.2.2.1 If at least one but not all four specimens fail with the first tup selected, continue the test as described in X1.2.3.
X1.2.2.2 If all four specimens fail, test four more specimens with a lighter tup.
X1.2.2.3 If all four specimens pass, test the same specimens with a heavier tup, at a drop height of 5 ft (1.5 m).
X1.2.2.4 Once a weight has been used that results in the failure of some, but not all, specimens at a height of 5 ft (1.5 m), continue
the test as described in X1.2.3. If no failures occur with the heaviest tup at a drop height of 5 ft (1.5 m), test at the maximum drop
height. If no failures occur with the maximum weight at the maximum drop height, test a total of 50 specimens at this drop height,
record the results, and discontinue testing. If one or more of the preliminary test specimens passes with the maximum weight at
the maximum drop height, proceed to X1.2.3.
X1.2.3 After the optimum tup weight has been determined, divide the remaining group of preliminary test specimens into two
equal lots. Each group shall contain at least eight specimens. Test one lot at a lesser drop height so that substantially less than 50 %
failures result. Test the second lot at a greater drop height so that substantially more than 50 % failures result. Plotthese results on
probability graph paper to serve as the basis for estimating the
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