ASTM F1473-24

Standard Test Method for Notch Tensile Test to Measure the Resistance to Slow Crack Growth of Polyethylene Pipes and Resins

SIGNIFICANCE AND USE
5.1 This test method is useful to measure the slow crack growth resistance of molded plaques of polyethylene materials at accelerated conditions such as 80 °C, 2.4 MPa stress, and with a sharp notch.  
5.2 The testing time or time to failure depends on the following test parameters: temperature; stress; notch depth; and specimen geometry. Increasing temperature, stress, and notch depth decrease the time to failure. Material parameters, not controlled by the laboratory, that could impact the test results (time to failure) are: pigment (color or carbon black) and the carrier resin for the pigment, or both. Thus, in reporting the test time or time to failure, all the conditions of the test shall be specified.  
Note 4: Time to failure can also be affected by the degree of pigment (color or carbon black) dispersion and distribution within the test specimen. Test Method D5596 and ISO 18553 provide methods for assessing the degree of dispersion and distribution of the pigment
SCOPE
1.1 This test method determines the resistance of polyethylene materials to slow crack growth under conditions specified within.
Note 1: This test method is known as PENT (Pennsylvania Notch Test) test.  
1.2 The standard test is performed at 80 °C and at 2.4 MPa, but it shall be acceptable to conduct tests at a temperature below 80 °C and with other stresses low enough to preclude ductile failure and thereby eventually induce brittle type of failure. The standard test is conducted in an air environment; however, it shall be acceptable to immerse test specimens in an alternate environment such as water or a water/detergent solution, or other liquid or a different environment such as an inert gas to evaluate slow crack growth performance in different environments. Generally, polyethylenes will ultimately fail in a brittle manner by slow crack growth at 80 °C if the stress is at or below 2.4 MPa
Note 2: When testing in environments other than air, it is recommended to consider maintaining the efficacy of the test media (for example, a detergent solution) to minimize any effect of aging.  
1.3 The test method is for specimens cut from compression molded plaques.2 See Appendix X1 for information relating to specimens from pipe.  
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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-Mar-2024
• ICS: 23.040.20 - Plastics pipes
• Technical Committee: F17 - Plastic Piping Systems
• Drafting Committee: F17.40 - Test Methods

Relations

• Replaces: ASTM F1473-23 - Standard Test Method for Notch Tensile Test to Measure the Resistance to Slow Crack Growth of Polyethylene Pipes and Resins
• Effective Date: 01-Apr-2024
• Referred By: ASTM F2769-24 - Standard Specification for Polyethylene of Raised Temperature (PE-RT) Plastic Hot and Cold-Water Tubing and Distribution Systems
• Effective Date: 01-Apr-2024
• Referred By: ASTM F3123-22 - Standard Specification for Metric Outside Diameter Polyethylene (PE) Plastic Pipe (DR-PN)
• Effective Date: 01-Apr-2024
• Referred By: ASTM D6068-10(2018) - Standard Test Method for Determining <emph type="bdit">J-R </emph>Curves of Plastic Materials
• Effective Date: 01-Apr-2024
• Referred By: ASTM F3524/F3524M-23 - Standard Specification for Polyamide-12 (PA12) Line Pipe
• Effective Date: 01-Apr-2024
• Referred By: ASTM D4976-12a(2020) - Standard Specification for Polyethylene Plastics Molding and Extrusion Materials
• Effective Date: 01-Apr-2024
• Referred By: ASTM F2785-21 - Standard Specification for Polyamide 12 Gas Pressure Pipe, Tubing, and Fittings
• Effective Date: 01-Apr-2024
• Referred By: ASTM D3350-21 - Standard Specification for Polyethylene Plastics Pipe and Fittings Materials
• Effective Date: 01-Apr-2024
• Referred By: ASTM F3373-21 - Standard Specification for Polyethylene (PE) Electrofusion Fittings for Outside Diameter Controlled Crosslinked Polyethylene (PEX) Pipe
• Effective Date: 01-Apr-2024
• Referred By: ASTM F1055-16a(2022) - Standard Specification for Electrofusion Type Polyethylene Fittings for Outside Diameter Controlled Polyethylene and Crosslinked Polyethylene (PEX) Pipe and Tubing
• Effective Date: 01-Apr-2024
• Referred By: ASTM D2513-20 - Standard Specification for Polyethylene (PE) Gas Pressure Pipe, Tubing, and Fittings
• Effective Date: 01-Apr-2024
• Referred By: ASTM F2818-10(2023) - Standard Specification for Specification for Crosslinked Polyethylene (PEX) Material Gas Pressure Pipe and Tubing
• Effective Date: 01-Apr-2024
• Referred By: ASTM F412-23 - Standard Terminology Relating to Plastic Piping Systems
• Effective Date: 01-Apr-2024
• Referred By: ASTM F2619/F2619M-20 - Standard Specification for High-Density Polyethylene (PE) Line Pipe
• Effective Date: 01-Apr-2024
• Referred By: ASTM D3261-24 - Standard Specification for Butt Heat Fusion Polyethylene (PE) Plastic Fittings for Polyethylene (PE) Plastic Pipe and Tubing
• Effective Date: 01-Apr-2024

Overview

ASTM F1473-24: Standard Test Method for Notch Tensile Test to Measure the Resistance to Slow Crack Growth of Polyethylene Pipes and Resins establishes a widely recognized procedure for assessing the slow crack growth (SCG) resistance of polyethylene (PE) materials, specifically pipes and resins. Commonly known as the Pennsylvania Notch Test (PENT), this standard is essential for quality assurance and research in the plastic piping industry.

Polyethylene pipes are vital in water, gas, and industrial applications, and their long-term performance is influenced by their ability to resist brittle failure from slow crack growth. ASTM F1473-24 provides guidelines for notched tensile testing under accelerated conditions, offering a standardized approach to determine the durability and reliability of PE pipes and resin products.

Key Topics

• Scope and Principle:

  • Measures SCG resistance of polyethylene materials using notched test specimens subjected to constant tensile stress at elevated temperatures (typically 80°C, 2.4 MPa).
  • Standard testing involves specimens cut from compression-molded plaques; guidance is also provided for specimens prepared from PE pipe.

• Test Parameters Impacting Results:

  • Temperature, applied stress, notch depth, and specimen geometry significantly affect testing duration and mode of failure.
  • Material variables such as pigment (color or carbon black) and dispersion influence SCG results and must be reported for reliability.

• Test Environments:

  • While standard tests occur in air, alternate media like water, detergent solutions, or inert gases may be used to evaluate environmental effects on slow crack growth.

• Reporting and Evaluation:

  • Accurate reporting of specimen source, stress, notch depth, load, test temperature, time to failure, and testing media is required.
  • Failure mode is visually assessed to distinguish between brittle and ductile fractures.

Applications

• Pipe Manufacturing and Quality Control:
  Polyethylene pipe producers employ ASTM F1473-24 to qualify materials and finished pipe products for resistance to slow crack growth, ensuring compliance with industry standards for potable water, gas distribution, and other critical applications.

• Material Development:
  Resin manufacturers use PENT testing to screen and develop higher-performance PE grades, particularly those engineered for enhanced SCG resistance in demanding environments.

• Research and Comparative Studies:
  The method supports research into additives, pigments, and processing techniques that affect the long-term integrity of PE pipes. Comparing results from standard and modified test conditions enables evaluation of PE products for specific service environments.

• Field Failure Analysis:
  Testing specimens cut from failed or aged pipe assists engineers and asset managers in understanding SCG-related failures and predicting service life.

Related Standards

For comprehensive characterization and testing, ASTM F1473-24 is often used alongside these key standards:

• ASTM D4703: Practice for Compression Molding Thermoplastic Materials into Test Specimens, Plaques, or Sheets - for specimen preparation.
• ASTM D5596: Test Method for Microscopic Evaluation of the Dispersion of Carbon Black in Polyolefin Geosynthetics - for assessing pigment dispersion.
• ASTM F412: Terminology Relating to Plastic Piping Systems - for industry-standard terms and definitions.
• ISO 18553: Method for assessment of pigment/carbon black dispersion in polyolefin pipes and compounds.

Practical Value

Adhering to ASTM F1473-24 ensures standardized evaluation of slow crack growth resistance in polyethylene materials. This directly influences product reliability, safety, and longevity in infrastructure projects. The method's flexibility in test environment and material selection supports innovation in PE material design while maintaining industry benchmarks for quality and performance.

Keywords: ASTM F1473-24, slow crack growth, polyethylene pipe, resin, notch tensile test, PENT, plastic piping, SCG resistance, brittle failure, 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: F1473 − 24
Standard Test Method for
Notch Tensile Test to Measure the Resistance to Slow Crack
Growth of Polyethylene Pipes and Resins
This standard is issued under the fixed designation F1473; 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* 1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This test method determines the resistance of polyeth-
ization established in the Decision on Principles for the
ylene materials to slow crack growth under conditions speci-
Development of International Standards, Guides and Recom-
fied within.
mendations issued by the World Trade Organization Technical
NOTE 1—This test method is known as PENT (Pennsylvania Notch
Barriers to Trade (TBT) Committee.
Test) test.
1.2 The standard test is performed at 80 °C and at 2.4 MPa, 2. Referenced Documents
but it shall be acceptable to conduct tests at a temperature
2.1 ASTM Standards:
below 80 °C and with other stresses low enough to preclude
D1600 Terminology for Abbreviated Terms Relating to Plas-
ductile failure and thereby eventually induce brittle type of 4
tics (Withdrawn 2024)
failure. The standard test is conducted in an air environment;
D4703 Practice for Compression Molding Thermoplastic
however, it shall be acceptable to immerse test specimens in an
Materials into Test Specimens, Plaques, or Sheets
alternate environment such as water or a water/detergent
D5596 Test Method for Microscopic Evaluation of the
solution, or other liquid or a different environment such as an
Dispersion of Carbon Black in Polyolefin Geosynthetics
inert gas to evaluate slow crack growth performance in
F412 Terminology Relating to Plastic Piping Systems
different environments. Generally, polyethylenes will ulti-
2.2 ISO Standard:
mately fail in a brittle manner by slow crack growth at 80 °C
ISO 18553 Method for the assessment of the degree of
if the stress is at or below 2.4 MPa
pigment or carbon black dispersion in polyolefin pipes,
NOTE 2—When testing in environments other than air, it is recom-
fittings and compounds
mended to consider maintaining the efficacy of the test media (for
example, a detergent solution) to minimize any effect of aging.
3. Terminology
1.3 The test method is for specimens cut from compression
3.1 Definitions are in accordance with Terminology F412.
molded plaques. See Appendix X1 for information relating to
Abbreviations are in accordance with Terminology D1600,
specimens from pipe.
unless otherwise indicated.
1.4 The values stated in SI units are to be regarded as
3.2 Definitions of Terms Specific to This Standard:
standard. The values given in parentheses after SI units are
3.2.1 brittle failure, n—a failure mode which exhibits no
provided for information only and are not considered standard.
visible (to the naked eye) permanent material deformation
1.5 This standard does not purport to address all of the
(stretching, elongation, or necking down) in the area of the
safety concerns, if any, associated with its use. It is the
break.
responsibility of the user of this standard to establish appro-
3.2.2 slow crack growth, n—the slow extension of the crack
priate safety, health, and environmental practices and deter-
with time.
mine the applicability of regulatory limitations prior to use.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee F17 on Plastic contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Piping Systems and is the direct responsibility of Subcommittee F17.40 on Test Standards volume information, refer to the standard’s Document Summary page on
Methods. the ASTM website.
Current edition approved April 1, 2024. Published April 2024. Originally The last approved version of this historical standard is referenced on
approved in 1997. Last previous edition approved in 2023 as F1473 – 23. DOI: www.astm.org.
10.1520/F1473-24. Available from International Organization for Standardization (ISO), ISO
Lu, X., and Brown, N., “A Test for Slow Crack Growth Failure in Polyethylene Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
Under a Constant Load,” Journal of Polymer Testing, Vol 11, pp. 309–319, 1992. Geneva, Switzerland, http://www.iso.org.
*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
F1473 − 24
4. Summary of Test Method 6.3 Temperature Controller, shall be able to control the
temperature within 6 0.5 °C with respect to the set point.
4.1 Specimens are prepared from compression molded
plaques, precisely notched and then exposed to a constant 6.4 Temperature-Measuring Device, a thermometer or a
tensile stress at elevated temperatures in air. Time on test is thermocouple which can measure the temperature with an
recorded for tests conducted against a minimum time before accuracy of 6 0.1 °C.
failure requirement or the time to complete failure is recorded.
6.5 Timer, shall have an accuracy of at least 1 % and shall
automatically stop when the specimen fails.
NOTE 3—Minimum time before failure requirements are found in
material or product specifications, codes, etc.
6.6 Alignment Jig, as shown in Fig. 1, which aligns the grips
and the specimen when the specimen is being tightened in the
5. Significance and Use
grips. Alternate alignment jigs which produce the same func-
5.1 This test method is useful to measure the slow crack
tion may be used.
growth resistance of molded plaques of polyethylene materials
6.7 Notching Machine, for notching the specimen is shown
at accelerated conditions such as 80 °C, 2.4 MPa stress, and
in Fig. 2 or other machines which produce the same results
with a sharp notch.
shall be acceptable. The notching machine presses a razor
5.2 The testing time or time to failure depends on the
blade into the specimen at a speed less than 0.25 mm/min. The
following test parameters: temperature; stress; notch depth; and
depth of the notch is controlled within 60.01 mm. The
specimen geometry. Increasing temperature, stress, and notch
machine is designed so that the main notch and the side notches
depth decrease the time to failure. Material parameters, not
will be coplanar and the plane of the notching is perpendicular
controlled by the laboratory, that could impact the test results
to the tensile axis of the specimen. The thickness of the razor
(time to failure) are: pigment (color or carbon black) and the
blade is approximately 0.2 mm.
carrier resin for the pigment, or both. Thus, in reporting the test
time or time to failure, all the conditions of the test shall be
7. Precautions
specified.
7.1 The load shall be carefully added to avoid shocking the
NOTE 4—Time to failure can also be affected by the degree of pigment
specimen. When the specimen is inserted in the grips, bending
(color or carbon black) dispersion and distribution within the test
and twisting shall be avoided in order to prevent the premature
specimen. Test Method D5596 and ISO 18553 provide methods for
activation of the notch. For standard testing in air, avoid
assessing the degree of dispersion and distribution of the pigment
exposure to fluids such as detergents.
6. Apparatus
8. Test Specimens
6.1 Lever Loading Machine, with a lever arm ratio of about
8.1 Specimens are machined from a compression molded
5:1 to produce a constant tensile load on the specimen. The
plaque of the polyethylene material.
tensile load may also be applied directly using dead weights or
any other method for producing a constant load. The pull rods 8.2 Specimen Geometry—A representative geometry for
on the grips shall have universal action to prevent bending. The compression molded plaque specimens is shown in Fig. 3.
grips shall be serrated to prevent slippage. The load on the
8.3 Dimensional Requirements:
specimen shall be accurate to 60.5 %.
8.3.1 The side groove shall be 1.0 mm 6 0.10 mm for all
6.2 Furnace, a chamber of sufficient size to house one or plaque thicknesses.
more samples for testing and heated by ordinary incandescent 8.3.2 The overall length is not critical except that the
light bulbs covered with aluminum foil or any other suitable distance between the notch and the end of a grip should be
heating element. more than 10 mm. Thicker specimens should have a greater
FIG. 1 Alignment Jig
F1473 − 24
FIG. 2 Notching Machine
Legend:
Arrows designate direction of tensile stress.
All dimensions are in millimetres.
FIG. 3 Representative Geometry for Compression-Molded Specimen
overall length so that the gripped area will be greater in order resin, that is, a higher temperature for a lower melt index. The
to avoid slippage in the grip. purpose of applying and removing the pressure is to eliminate
voids. Turn off the heat and apply pressure. The time to cool
8.4 Preparation of Compression Molded Plaques—
between 130 °C and 90 °C shall be greater than 80 min.
8.4.1 Polyethylene resins shall be evaluated by using
Alternatively, the time to cool from the molding temperature to
specimens that are machined from compression molded
about room temperature shall be greater than 5 h. During
plaques using Practice D4703, except for the following proce-
cooling the pressure is allowed to decrease naturally.
dures. After the resin is heated to 140 °C to 160 °C, apply and
remove the pressure three times. Increase the temperature to 8.5 Specimen Notching—The specimen has two types of
170 °C to 190 °C for 10 min to 15 min without pressure. Then notches, the main notch and two side notches. The side notches
apply and remove the pressure three times. The specific are usually referred to as “side grooves.” The depth require-
temperatures that are used depend on the melt index of the ments for these notches are given in Table 1. The main notch
F1473 − 24
A
TABLE 1 Notch Depth as a Function of Specimen Thickness
10.3 Loading the Specimen—When the specimen in the
This table is based on the stress intensity being the same for all
grips is removed from the alignment jig and transferred to the
thicknesses.
testing machine, take care that the notch is not activated by
Thickness, mm Notch Depth, mm
bending the specimen. Apply the load after the specimen has
been held for at least 1 h at the test temperature. Apply the load
4.00 1.90
gradually within a period of about 5 s to 10 s without any
5.00 2.28
6.00 2.50
impact on the specimen.
7.00 2.80
8.00 3.09
10.4 Temperature Measurement—Place the thermocouple or
9.00 3.30
thermometer near the notched part of the specimen. Periodi-
10.00 3.50
11.00 3.70 cally record the temperature with a frequency that depends on
12.00 3.90
the length of the test.
13.00 4.18
14.00 4.39
10.5 When testing is stopped before failure or when the
15.00 4.48
specimen fails, record the time on test, or the time to failure.
16.00 4.65
17.00 4.88
Failure occurs when the two halves of the specimen separate
18.00 4.95
completely or extensive deformation occurs in the remaining
19.00 5.09
ligament. Failure mode shall be visually examined and shall be
20.00 5.20
A brittle only except for the remaining ligament (opposite of the
For an intermediate thickness, linearly interpolate to obtain the notch depth. The
notch depth in the specimen shall be within± 0.05 mm of the interpolated value. face notch) where ductility is allowed.
NOTE 6—A failure that is majority ductile may indicate that either the
test temperature or applied stress is too high.
is produced by pressing a razor blade into the specimen at a
speed of less than 0.25 mm/min. A fresh razor blade shall not
11. Report
be used for more than three specimens and shall be used within
one day. The rate of notching for the side grooves is not 11.1 Compression-molded test specimens shall be identified
important. It is important to make the side grooves coplanar
by the polyethylene material source (resin manufacturer or
with the main notch. Specimens shall be notched at room other source) lot number as well as information of the color
temperature. (for example, natural, black, blue etc.) of the specimen being
tested.
9. Conditioning
11.2 Stress based on the unnotched area.
9.1 Unless otherwise specified, condition the test specimens
for at least 1 h at the test temperature prior to loading. The 11.3 Depth of main notch and side grooves.
length of time between notching and testing is not important.
11.4 Calculated load and cross-sectional dimensions of the
specimen.
10. Procedure
10.1 Calculation of Test Load: 11.5 Test temperature.
10.1.1 Calculate the test load, P, as follows:
11.6 Time on test or time to failure.
P 5 σ × w × t (1)
11.7 Date and time for the beginning and ending of the test.
where:
11.8 Media type (for example, air, water, etc.) used for
σ = stress,
testing. If a media other than air is used, a description of steps
w = specimen width, and
to maintain the composition of the media throughout the period
t = specimen thickness.
of testing shall be included.
The variables w and t are based on the specimens prior to
notching.
12. Precision and Bias
10.1.2 If σ has the units of megapascals and w and t are in
millimetres, and A is in square millime
...

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: F1473 − 23 F1473 − 24
Standard Test Method for
Notch Tensile Test to Measure the Resistance to Slow Crack
Growth of Polyethylene Pipes and Resins
This standard is issued under the fixed designation F1473; 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 test method determines the resistance of polyethylene materials to slow crack growth under conditions specified within.
NOTE 1—This test method is known as PENT (Pennsylvania Notch Test) test.
1.2 The standard test is performed at 80 °C and at 2.4 MPa, but it shall be acceptable to conduct tests at a temperature below 80 °C
and with other stresses low enough to preclude ductile failure and thereby eventually induce brittle type of failure. The standard
test is conducted in an air environment; however, it shall be acceptable to immerse test specimens in an alternate environment such
as water or a water/detergent solution, or other liquid or a different environment such as an inert gas to evaluate slow crack growth
performance in different environments. Generally, polyethylenes will ultimately fail in a brittle manner by slow crack growth at
80 °C if the stress is at or below 2.4 MPa
NOTE 2—When testing in environments other than air, it is recommended to consider maintaining the efficacy of the test media (for example, a detergent
solution) to minimize any effect of aging.
1.3 The test method is for specimens cut from compression molded plaques. See Appendix X1 for information relating to
specimens from pipe.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered standard.
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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.6 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:
This test method 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 July 1, 2023April 1, 2024. Published July 2023April 2024. Originally approved in 1997. Last previous edition approved in 20182023 as
F1473 – 18.F1473 – 23. DOI: 10.1520/F1473-23.10.1520/F1473-24.
Lu, X., and Brown, N., “A Test for Slow Crack Growth Failure in Polyethylene Under a Constant Load,” Journal of Polymer Testing, Vol 11, pp. 309–319, 1992.
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
F1473 − 24
D1600 Terminology for Abbreviated Terms Relating to Plastics (Withdrawn 2024)
D4703 Practice for Compression Molding Thermoplastic Materials into Test Specimens, Plaques, or Sheets
D5596 Test Method for Microscopic Evaluation of the Dispersion of Carbon Black in Polyolefin Geosynthetics
F412 Terminology Relating to Plastic Piping Systems
2.2 ISO Standard:
ISO 18553 Method for the assessment of the degree of pigment or carbon black dispersion in polyolefin pipes, fittings and
compounds
3. Terminology
3.1 Definitions are in accordance with Terminology F412. Abbreviations are in accordance with Terminology D1600, unless
otherwise indicated.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 brittle failure, n—a failure mode which exhibits no visible (to the naked eye) permanent material deformation (stretching,
elongation, or necking down) in the area of the break.
3.2.2 slow crack growth, n—the slow extension of the crack with time.
4. Summary of Test Method
4.1 Specimens are prepared from compression molded plaques, precisely notched and then exposed to a constant tensile stress at
elevated temperatures in air. Time on test is recorded for tests conducted against a minimum time before failure requirement or
the time to complete failure is recorded.
NOTE 3—Minimum time before failure requirements are found in material or product specifications, codes, etc.
5. Significance and Use
5.1 This test method is useful to measure the slow crack growth resistance of molded plaques of polyethylene materials at
accelerated conditions such as 80 °C, 2.4 MPa stress, and with a sharp notch.
5.2 The testing time or time to failure depends on the following test parameters: temperature; stress; notch depth; and specimen
geometry. Increasing temperature, stress, and notch depth decrease the time to failure. Material parameters, not controlled by the
laboratory, that could impact the test results (time to failure) are: pigment (color or carbon black) and the carrier resin for the
pigment, or both. Thus, in reporting the test time or time to failure, all the conditions of the test shall be specified.
NOTE 4—Time to failure can also be affected by the degree of pigment (color or carbon black) dispersion and distribution within the test specimen. Test
Method D5596 and ISO 18553 provide methods for assessing the degree of dispersion and distribution of the pigment
6. Apparatus
6.1 Lever Loading Machine, with a lever arm ratio of about 5:1 to produce a constant tensile load on the specimen. The tensile
load may also be applied directly using dead weights or any other method for producing a constant load. The pull rods on the grips
shall have universal action to prevent bending. The grips shall be serrated to prevent slippage. The load on the specimen shall be
accurate to 60.5 %.
6.2 Furnace, a chamber of sufficient size to house one or more samples for testing and heated by ordinary incandescent light bulbs
covered with aluminum foil or any other suitable heating element.
6.3 Temperature Controller, shall be able to control the temperature within 6 0.1 °C6 0.5 °C with respect to the set point.
The last approved version of this historical standard is referenced on www.astm.org.
Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
Switzerland, http://www.iso.org.
F1473 − 24
6.4 Temperature-Measuring Device, a thermometer or a thermocouple which can measure the temperature with an accuracy of
6 0.1 °C.
6.5 Timer, shall have an accuracy of at least 1 % and shall automatically stop when the specimen fails.
6.6 Alignment Jig, as shown in Fig. 1, which aligns the grips and the specimen when the specimen is being tightened in the grips.
Alternate alignment jigs which produce the same function may be used.
6.7 Notching Machine, for notching the specimen is shown in Fig. 2 or other machines which produce the same results shall be
acceptable. The notching machine presses a razor blade into the specimen at a speed less than 0.25 mm/min. The depth of the notch
is controlled within 60.01 mm. The machine is designed so that the main notch and the side notches will be coplanar and the plane
of the notching is perpendicular to the tensile axis of the specimen. The thickness of the razor blade is approximately 0.2 mm.
7. Precautions
7.1 The load shall be carefully added to avoid shocking the specimen. When the specimen is inserted in the grips, bending and
twisting shall be avoided in order to prevent the premature activation of the notch. For standard testing in air, avoid exposure to
fluids such as detergents.
8. Test Specimens
8.1 Specimens are machined from a compression molded plaque of the polyethylene material.
8.2 Specimen Geometry—A representative geometry for compression molded plaque specimens is shown in Fig. 3.
8.3 Dimensional Requirements:
8.3.1 The side groove shall be 1.0 mm 6 0.10 mm for all plaque thicknesses.
8.3.2 The overall length is not critical except that the distance between the notch and the end of a grip should be more than 10
mm. Thicker specimens should have a greater overall length so that the gripped area will be greater in order to avoid slippage in
the grip.
8.4 Preparation of Compression Molded Plaques—
8.4.1 Polyethylene resins shall be evaluated by using specimens that are machined from compression molded plaques using
Practice D4703, except for the following procedures. After the resin is heated to 140 °C to 160 °C, apply and remove the pressure
FIG. 1 Alignment Jig
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FIG. 2 Notching Machine
Legend:
Arrows designate direction of tensile stress.
All dimensions are in millimetres.
FIG. 3 Representative Geometry for Compression-Molded Specimen
three times. Increase the temperature to 170 °C to 190 °C for 1010 min to 15 min without pressure. Then apply and remove the
pressure three times. The specific temperatures that are used depend on the melt index of the resin, that is, a higher temperature
for a lower melt index. The purpose of applying and removing the pressure is to eliminate voids. Turn off the heat and apply
pressure. The time to cool between 130 and 90°C130 °C and 90 °C shall be greater than 80 min. Alternatively, the time to cool
from the molding temperature to about room temperature shall be greater than 5 h. During cooling the pressure is allowed to
decrease naturally.
8.5 Specimen Notching—The specimen has two types of notches, the main notch and two side notches. The side notches are
usually referred to as “side grooves.” The depth requirements for these notches are given in Table 1. The main notch is produced
by pressing a razor blade into the specimen at a speed of less than 0.25 mm/min. A fresh razor blade shall not be used for more
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A
TABLE 1 Notch Depth as a Function of Specimen Thickness
This table is based on the stress intensity being the same for all
thicknesses.
Thickness, mm Notch Depth, mm
4.00 1.90
5.00 2.28
6.00 2.50
7.00 2.80
8.00 3.09
9.00 3.30
10.00 3.50
11.00 3.70
12.00 3.90
13.00 4.18
14.00 4.39
15.00 4.48
16.00 4.65
17.00 4.88
18.00 4.95
19.00 5.09
20.00 5.20
A
For an intermediate thickness, linearly interpolate to obtain the notch depth. The
notch depth in the specimen shall be within± 0.05 mm of the interpolated value.
than three specimens and shall be used within one day. The rate of notching for the side grooves is not important. It is important
to make the side grooves coplanar with the main notch. Specimens shall be notched at room temperature.
9. Conditioning
9.1 Unless otherwise specified, condition the test specimens for at least 1 h at the test temperature prior to loading. The length
of time between notching and testing is not important.
10. Procedure
10.1 Calculation of Test Load:
10.1.1 Calculate the test load, P, as follows:
P 5 σ ×w ×t (1)
where:
σ = stress,
w = specimen width, and
t = specimen thickness.
The variables w and t are based on the specimens prior to notching.
10.1.2 If σ has the units of megapascals and w and t are in millimetres, and A is in square millimetres, then P has the units of
Newtons. If a lever-loaded machine is used, divide P by the lever arm ratio. The load on the specimen shall be 60.5 % of the
calculated load.
NOTE 5—To convert the test load to pounds, multiply the load (in Newtons) by 0.225.
10.2 Gripping the Specimen—Using an alignment jig (Fig. 1), center the specimen in the grips so that the axis of the specimen
is aligned with the grips. When the grips are tightened, it is important not to activate the notch by bending or twisting the specimen.
The ends of the grips shall be at least 10 mm from the notch.
10.3 Loading the Specimen—When the specimen in the grips is removed from the alignment jig and transferred to the testing
machine, take care that the notch is not activated by bending the specimen. Apply the load after the specimen has been held for
at least 1 h at the test temperature. Apply the load gradually within a period of about 55 s to 10 s without any impact on the
specimen.
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10.4 Temperature Measurement—Place the thermocouple or thermometer near the notched part of the specimen. Periodically
record the temperature with a frequency that depends on the length of the test.
10.5 When testing is stopped before failure or when the specimen fails, record the time on test, or the time to failure. Failure occurs
when the two halves of the specimen separate completely or extensive deformation occurs in the remaining ligament. Failure mode
shall be visually examined and shall be brittle only except for the remaining ligament (opposite of the face notch) where ductility
is allowed.
NOTE 6—A failure that is majority ductile may indicate that either the test temperature or applied stress is too high.
11. Report
11.1 Compression-molded test specimens shall be identified by the polyethylene material source (
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