ASTM D4968-19a

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: D4968 − 19 D4968 − 19a
Standard Practice for
Annual Review of Test Methods and Specifications for
Plastics
This standard is issued under the fixed designation D4968; 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 is intended to assist the subcommittees and sections of Committee D20 on Plastics with the process of
standards evaluation during the five-year review mandated by ASTM or when changes to test methods and specifications are
required. It is intended to complement the Form and Style for ASTM Standards (“Blue Book”) not replace it.
NOTE 1—There is no known ISO equivalent to this standard.
1.2 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:
D883 Terminology Relating to Plastics
D5740 Guide for Writing Material Standards in the Classification Format
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E2653 Practice for Conducting an Interlaboratory Study to Determine Precision Estimates for a Fire Test Method with Fewer
Than Six Participating Laboratories
E2935 Practice for Conducting Equivalence Testing in Laboratory Applications
Form and Style for ASTM Standards (Blue Book)
3. Terminology
3.1 Definitions—For definitions of terms that appear in this practice relating to plastics, refer to Terminology D883.
3.2 For definitions of terms that appear in this practice relating to quality and statistics, refer to Terminology E456.
3.2.1 Repeatability—precision under repeatability conditions. (E456)
3.2.2 repeatability conditions, n—conditions where independent test results are obtained with the same method on identical test
items in the same laboratory by the same operator using the same equipment within short intervals of time. (E456)
3.2.3 Reproducibility—precision under reproducibility conditions. (E456)
3.2.4 reproducibility conditions, n—conditions where test results are obtained with the same method on identical test items in
different laboratories with different operators using different equipment. (E456)
3.3 The International Code Council (ICC) has issued guidelines for standards that are appropriate for reference in ICC codes,
which include the requirement that they shall be written in mandatory language.
3.3.1 In practice, the key issue is to avoid using the terms “may” and “should,” except within definitions, appendixes and
non-mandatory notes.
This guide is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.90 on Executive.
Current edition approved May 1, 2019Aug. 1, 2019. Published May 2019August 2019. Originally approved in 1989. Last previous edition approved in 20172019 as
D4968 - 17.D4968 - 19. DOI: 10.1520/D4968-19.10.1520/D4968-19A.
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.
*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
D4968 − 19a
4. Significance and Use
4.1 It is the intention of this practice, in addition to the Form and Style for ASTM Standards, to assist persons revising test
methods and specifications in Committee D20 to ensure that all required elements are included and that the revised document is
presented in the most user-friendly manner possible.
4.2 This practice is intended for use by Committee D20 when test methods and specifications under its jurisdiction are revised
because of technical changes or upon five-year review.
4.3 The figures in Annex A1 contain three flowcharts. Fig. A1.1 is a flowchart that shows the review process for standards that
have been revised or reapproved recently. Fig. A1.2 is a flowchart for standards that have neither been revised nor reapproved
within five years of a new review. Fig. A1.3 is a flowchart for the precision and bias process in outline form.
4.4 Specific instructions to be followed when revising Committee D20 documents are given in this practice.
4.5 The model precision and bias (P and B) statements included in Annex A3 were developed to standardize the presentation
of data.
5. Evaluating the Need for Revisions
5.1 Society regulations require that all Committee D20 standards be reviewed in detail every five years. Ballots to revise
individual sections of a document (which have the potential to change the date of issue) do not absolve the responsible D20
subcommittee from the requirement to conduct the detailed review every five years. Begin the review for revision, reapproval, or
withdrawal at least one year prior to the required revision year, that is, four years after the last full review. The date of the last
complete document review must be listed in the Summary of Changes section at the end of the document.
5.2 The goal of the review process is to determine if the document under review is to be balloted for:
5.2.1 Reapproval without change,
5.2.2 Reapproval with editorial changes,
5.2.3 Revision with technical changes, or
5.2.4 Withdrawal.
5.3 Two figures with flowcharts for review of plastics standard test methods or specifications are found in Annex A1.
5.3.1 The flowchart in Fig. A1.1 applies only to reviews of standards that have either been revised or have been reapproved less
than five years before any new review.
5.3.2 When a standard test method or a standard specification has neither been revised nor reapproved for at least five years a
new ballot is required, in accordance with Fig. A1.2 and the flowchart in Fig. A1.1 does not apply.
5.3.3 The following sections describe the details for each step of the flowcharts.
5.3.4 With the permission of the Section or Subcommittee chairman, as appropriate, a task group is formed with a task group
chairman to head it. The task group shall be composed of either one person or a small group. The subcommittee chairman generates
a project number to help track the progress. The task group chairman registers the project with ASTM through the website and
an ASTM Work Item number is generated. This WK number will appear on ballots.
5.3.5 Is it Recommended that the Standard Be Withdrawn?—If the examination of the standard indicates that it is obsolete or
basically flawed in light of more recent knowledge, ballot for withdrawal. Ballot for withdrawal is also in order if the standard has
been replaced by a more current standard.
5.3.6 Are changes required?—If the review of the standard using the instructions in this document and the current version of
the ASTM Form and Style for ASTM Standards (Blue Book) indicate that no changes are needed, it is recommended that the
standard be balloted for reapproval without change.
5.3.7 Are Changes Editorial?—If the subcommittee, section, or task group considers the intended changes to be editorial in
nature, the appropriate standards editor at ASTM Headquarters shall be consulted. If the changes meet the qualifications for
editorial revision, within a five-year period since last publication, the standard can be editorially changed without balloting, as
shown in Fig. A1.1. Such a revised standard will be published with an indication that it has been reissued with editorial changes.
However the document must still be balloted for revision or reapproval at least every five years regardless of whether it has been
reissued with editorial changes, and the process shown in Fig. A1.2 shall be followed.
5.3.8 Is Technical Revision Necessary?—If it is decided that the changes needed in the standard modify the technical content
in any way, or if the review using this practice finds missing elements, technical changes shall be balloted. If major changes are
needed, a subcommittee ballot is recommended. Otherwise a concurrent subcommittee, Main Committee, and Society ballot is
recommended, providing this approach is approved by the main committee chairman and the subcommittee chairman or by a
simple majority vote of the membership of the main committee and subcommittees.
5.3.9 Model Precision and Bias (P and B) Statement:
5.3.9.1 It is a requirement of ASTM that all test methods have a precision and bias section. For test methods that produce a
numerical test result, an interlaboratory study (ILS, round robin) shall be conducted. Practice E691 describes the recommended
practice for conducting an ILS to determine the precision of a test method, when six or more laboratories are involved.
D4968 − 19a
5.3.9.2 Practice E691 requires a minimum number of six laboratories generating usable data for a round robin for an acceptable
round robin. As a result, Practice E691 is not applicable in all cases. Other statistical practices are appropriate for use if they yield
equivalent information. It is recommended that the statistical practice used be reviewed by Subcommittee D20.13 on Statistics.
5.3.9.3 If an ILS (round robin) cannot be accomplished prior to initial balloting of a test method, single-laboratory data must
be used in the P and B statement. Use the model statement in Annex A3 as a model for such statements and follow the guidance
from the ASTM Form and Style for ASTM Standards. No test method shall remain a valid ASTM standard without at least a
single-laboratory P and B statement after a five year period from publication.
5.3.9.4 ASTM International requires that an ILS study (round robin) be performed, if possible, within five years of the test
method’s initial publication. If an insufficient number of laboratories is available to complete a round robin by the five-year review,
the model statement in Annex A3 is still acceptable, but a statement modeled after the “Type B” statement in Annex A3 shall be
added.
5.3.9.5 When acceptable ILS (round-robin) data has been developed, it shall be written using a statement modeled after the
“Type C” statement in Annex A3 and it shall be balloted for approval as a technical change. Documentation for the round robin
shall be assembled in a technical report and submitted to the staff manager. A footnote documenting the report number shall be
included in the standard.
6. Revising the Standard
6.1 Keep the audience in mind.
6.1.1 There are many different users of ASTM standards. When revising documents, write the standard to be of use to the proper
audience. A standard can be used by such diverse users as design engineers, product specifiers, quality control persons, testing
laboratory managers, and technicians who will perform tests and all of their requirements need to be taken into account.
6.1.2 Keep in mind, however, that certain sections of the documents are directed at specific audiences. For example, the
procedures section of a test method will primarily be used by the technician who does the test. It is recommended that this section
be written in an imperative mood giving direct instructions on how to do the test, just as it would be done if the standard were
speaking to the person. It is recommended not to add unnecessary explanations in the mandatory sections of the standard but to
give clear and concise instructions. It is recommended that explanations that are not needed for conducting the test be, preferably,
included in an appendix or in an explanatory note.
6.1.3 Sections such as the scope are to give direction to the user on how and for what the standard is to be used. Setup and
calibration will be used by a test laboratory manager, and so forth. For each section, it is essential to consider the potential user
and to write that section to give the most direct and usable information to that potential user in the most concise and understandable
manner possible.
6.2 Whenever a new standard is developed, or revisions to an existing standard are prepared for ballot, a Work Item must be
registered with ASTM at the ASTM web-site (www.astm.org). When the Work Item is registered with ASTM an e-mail will be
sent to the technical contact with a link that permits the download of an electronic copy of the current standard. It is recommended
to use the “track changes” function in MS Word to show changes. Deleted text will be shown as struck out. New text will be shown
as underlined. Be aware that it is possible that the paragraph numbers and their references will change as a result of these edits.
6.3 Whenever a document is revised and circulated for ballot, it must be accompanied by a cover letter that explains the purpose
of the ballot.
6.4 When circulating a standard for ballot, the standard shall have the following working caveat in bold print on the front page
of the revision draft:
THIS DOCUMENT IS NOT AN ASTM STANDARD; IT IS UNDER CONSIDERATION WITHIN AN ASTM
TECHNICAL COMMITTEE BUT HAS NOT RECEIVED ALL APPROVALS REQUIRED TO BECOME AN ASTM
STANDARD. IT SHALL NOT BE REPRODUCED OR CIRCULATED OR QUOTED, IN WHOLE OR IN PART,
OUTSIDE OF ASTM COMMITTEE ACTIVITIES EXCEPT WITH THE APPROVAL OF THE CHAIRMAN OF THE
COMMITTEE HAVING JURISDICTION AND THE PRESIDENT OF THE SOCIETY. COPYRIGHT ASTM, 100 Barr
Harbor Drive, WEST CONSHOHOCKEN, PA, 19428-2959 ALL RIGHTS RESERVED.
6.5 Reference the Form and Style for ASTM Standards for detailed information regarding the form and style for the document.
6.6 The standard shall be reviewed to ensure that all procedures, directions, instructions, etc. are written as mandatory
requirements. Explanatory material, intended either for emphasis or for offering informative suggestions not properly part of the
standard, shall be incorporated as notes or appendixes and is not required to be written in mandatory language.
6.7 Documents that have been developed for, or have the potential of being referenced in, model codes such as those from the
International Code Council (ICC) and from the National Fire Protection Association (NFPA) shall be written completely in
mandatory language (except for terminology, notes and appendixes). Explanatory material shall only be used in appendixes, notes
and footnotes unless the footnote is integral to a table and the document shall contain the following statement:
“The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes (excluding
those in tables and figures) shall not be considered as requirements of the standard.”
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7. Reviewing Test Methods
7.1 Use the following assessment sections as an aid in test method review. Strive to ensure that the Committee D20 test methods
are not more complex than necessary. One of the goals of a five-year review is to make test methods as user friendly as possible.
Read each section. If it is not clear and does not contain the points mentioned in this section, rewrite it!
7.1.1 Note that, in order to provide uniformity in standardization, Practice D4968 makes mandatory the inclusion in standard
test methods under the jurisdiction of Committee D20 sections that are not necessarily required by the ASTM Form and Style of
ASTM Standards (Blue Book).
7.2 Title (Mandatory)—Determine if the title accurately defines the test method described. Change it if it does not.
7.3 Scope (Mandatory)—The scope shall contain the following essential items:
7.3.1 Clearly state the purpose of the test method in one or two sentences.
7.3.2 If there are any cautions or concerns regarding the use of the results of the test method or how it is performed, insert the
following sentence in the Scope: See the Significance and Use section for cautions in using this test method.
7.3.3 Committee D20 considers SI units to be primary. The scope shall include the sentence shown in 7.3.3.1 in accordance with
instructions in the ASTM Form and Style of ASTM Standards (Blue Book). In some instances a statement such as that shown in
7.3.3.2 is an acceptable alternative. Make these numbered paragraphs in either case.
7.3.3.1 “The values stated in SI units are to be regarded as standard.”
7.3.3.2 “The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in
each system are not necessarily exact equivalents; therefore, each system shall be used independently of the other. It is possible
that combining values from the two systems will result in nonconformance with the standard.”
7.3.4 Ensure that the test method has the following mandatory caveat included as a numbered paragraph in the scope. “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.”
7.3.5 If specific hazards are known, put them in a Hazards section and cite any appropriate additional warnings.
7.3.6 All test methods shall have an ISO equivalency statement. A note must be included to the end of the scope section with
an ISO equivalency statement. See Annex A2 of this practice for the proper formats and instructions.
7.4 Referenced Documents (Mandatory):
7.4.1 Ensure that all ASTM standards (including the document designation and title) that are cited in the text of the standard
are referenced in this section.
7.4.2 Also list other organizations’ standards if they are referenced in the text.
7.5 Terminology (Mandatory):
7.5.1 A terminology section is mandatory. If the document does not have this section, it must be added.
7.5.2 Include a section that references to Terminology D883 and that states as follows: “For definitions of terms used in this
test method and associated with plastics issues refer to the terminology contained in D883.” Include also a reference to
Terminology D883 in the section on referenced ASTM standards.
7.5.3 Check Terminology D883 for terms relevant to the test method. If any terms from the test method which appear in
Terminology D883, would be helpful to the user of the standard, include a definition identical to that in Terminology D883.
7.5.4 Determine from the text a list of terms used which are potentially unclear to the user of the standard. Add definitions of
those terms into the terminology section of the test method.
7.5.5 Determine whether specific terminology documents apply to the standard. Reference any terminology standard if a term
from it is included in the terminology section.
7.5.6 If a term is listed in the document which is not found in the terminology documents, develop a definition and include the
term in the Terminology section of the update to be balloted. In addition, if the term is of general interest to Committee D20
standards, submit the definition to the chairperson of Subcommittee D20.92 for review and possible inclusion in Terminology
D883.
7.6 Summary of Test Method (Mandatory)—Include a brief outline of the test method. Describe essentially how the test method
is performed without any details of the procedure or sequence.
7.7 Significance and Use (Mandatory)—Examine the Significance and Use section. Ensure that it includes the following:
7.7.1 State when, where, and why the test method is to be used.
7.7.2 State how the test method is to be used by industry.
7.7.3 State how suitable the test method is for use in specifications.
7.7.4 For test methods where appropriate, add the following statement:
“Before proceeding with this test method, if appropriate, make reference to the specification associated with the material or
product being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters, or combination thereof,
covered in the relevant ASTM material or product specification shall take precedence over those mentioned in this test method.
If there are no relevant ASTM specifications, then the default conditions apply.”
D4968 − 19a
7.7.5 State what are the significant features of the test method.
7.7.6 State any appropriate warnings which restrict the use of the results of the test method.
7.8 Interferences—If the successful execution of the test method requires explanatory statements on interference effects, briefly
list the constituents or properties that are most likely to cause interference, and the amounts that they are known to interfere.
7.9 Apparatus:
7.9.1 If the required equipment for performing the test method is no longer available, ballot the test method for withdrawal.
7.9.2 If the equipment is available from only one manufacturer, the source for obtaining the equipment shall be listed in a
footnote that clarifies that information. Use language such as the following:
“The sole source of supply of the apparatus known to the committee at this time is (name and address of the supplier). If you
are aware of alternative suppliers, please provide this information to ASTM International Headquarters.”
7.9.3 If there are two or more sources of the equipment for performing the test method, no mention of the equipment
manufacturer or where the equipment can be obtained is permitted.
7.9.4 In some cases, when there is interest in retaining the test method, the following statement is acceptable:
“It is believed that the instrument specified in this test method is no longer commercially available.”
7.10 Hazards:
7.10.1 Point out safety precautions in this section or in the notes where appropriate in the text if specific hazards are known.
7.10.2 Cite any precautions or warnings at the end of the generic safety hazards caveat.
7.11 Sampling, Test Specimens, and Test Units—Give mandatory instructions for any sampling techniques.
7.12 Preparation of Apparatus—Give mandatory instructions.
7.13 Calibration and Standardization—Give mandatory instructions.
7.14 Conditioning:
7.14.1 Specify, in the imperative mood, the conditioning atmosphere required during the test and the time of exposure to the
atmosphere.
7.14.2 If the wording of the conditioning section contains the term “. for those tests where conditioning is required .,” replace
this wording with “. unless otherwise specified .”
7.15 Procedure (Mandatory)—Give mandatory instructions. It is important that this be a step-by-step instruction on how to
perform the test method.
7.16 Calculation—State the directions for calculating the results in mandatory form.
7.17 Report (Mandatory)—State detailed information required in reporting the results of the tests.
7.18 Precision and Bias (Mandatory):
7.18.1 All test methods must have a statement on precision (P) and a statement on bias (B) in a precision and bias section.
7.18.2 The precision data presented in the test method shall be representative of the conditions defined in the standard. However,
in some cases it is possible that the material preparation and specific test conditions included in the ASTM material specification
will result in a deviation from the P and B statement. In such cases this would require additional study.
7.18.3 If the test result is a non-numerical report of success or failure or other categorization or classification based on criteria
specified in the procedure, use the following statement of P and B:
“No information is presented about either the precision or bias of Test Method XXXX for measuring (insert here the name of
the property) since the test result is non-quantitative.”
7.18.4 If a round robin has been conducted, refer to the instructions for including the P and B statement in Annex A3 of this
practice, included recommended wording.
7.19 Keywords (Mandatory)—List in alphabetical order appropriate terms for indexing, selected from both the title and body
of the document and including general, vernacular, and trade items.
7.20 Tables—Tables shall be referenced in the text. Number tables in the order in which they are cited in the text. Make sure
that the tables contain titles.
7.21 Figures—Figures shall be referenced in the text. Number figures in the order in which they are cited in the text. Make sure
that the figures contain titles. The subcommittee is responsible for providing camera-ready artwork that does not require retouching
or corrections.
7.22 Annexes (for Mandatory Information)—Include detailed information on apparatus, materials, and other items when such
information is too lengthy to include in the text but is essential to the test method.
7.22.1 Examples of such information are as follows: glossary of terms used in the applicable specification, list of symbols, and
instructions for calibrating and standardizing apparatus.
7.23 Appendixes (for non-mandatory information)—An appendix is informative only and is not a mandatory part of the
specification.
D4968 − 19a
7.23.1 Examples of such information are as follows: example calculations, report forms, and rationale used in the development
of the specification.
7.24 Summary of Changes (Mandatory for ASTM D20 Standards):
7.24.1 List all changes from the last revision so that persons reading the standard will know what items are different from
previous additions. If multiple revisions occur within a 12 month span include all changes made within those 12 months.
7.24.2 List of changes shall be in numerical form and be limited to one sentence for each item.
7.24.3 List the year of the last complete review/revision of the standard
8. Reviewing Specifications
8.1 Use the following assessment sections as an aid in review of a specification. Strive to ensure that the Committee D20
specifications are not more complex than necessary. One of the goals of a five-year review is to make specifications as user friendly
as possible. Read each section. If it is not clear and does not contain the points mentioned in this section, rewrite it!
8.1.1 Note that, in order to provide uniformity in standardization, Practice D4968 makes mandatory the inclusion in standard
specifications under the jurisdiction of Committee D20 sections that are not necessarily required by the ASTM Form and Style of
ASTM Standards (Blue Book).
8.2 Title (Mandatory)—Determine if the title accurately defines the specification. Change it if it does not.
8.3 Scope (Mandatory)—Clearly state the purpose of the specification, preferably in one or two sentences.
8.3.1 State whether SI units or other units are preferred.
8.3.2 If the specification contains test methods within the body of the document include the following caveat in the scope:
“The following safety hazards caveat pertains only to the test method or test methods described in this specification. 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.”
8.3.3 All specifications must have an ISO equivalency statement. A note must be included to the end of the scope with an ISO
equivalency statement. See Annex A2 for the proper formats and instructions.
8.3.4 If the specification includes recycled plastics, insert a sentence in the scope which mentions the extent to which the
document deals with these materials. It is also potentially appropriate to include reference to recycled plastics in the title, the
Referenced Documents section, and in the Keywords section.
8.4 Referenced Documents—Ensure all ASTM standards cited in the text are referenced in this section. Include the ASTM
designation and title. Also list other organizations’ standards if they are referenced in the text and are available to the public.
8.5 Terminology (Mandatory):
8.5.1 A terminology section is mandatory. If the document does not have this section, it must be added.
8.5.2 Include a section that references to Terminology D883 and that states as follows: “For definitions of terms used in this
specification and associated with plastics issues refer to the terminology contained in D883.” Include also a reference to
Terminology D883 in the section on referenced ASTM standards.
8.5.3 Check Terminology D883 for terms relevant to the specification. If any terms from the specification which appear in
Terminology D883, would be helpful to the user of the standard, include a definition identical to that in Terminology D883.
8.5.4 Determine from the text a list of terms used which are potentially unclear to the user of the standard. Add definitions of
those terms into the terminology section of the specification.
8.5.5 Determine whether specific terminology documents apply to the specification. Reference any terminology standard if a
term from that terminology is included in the standard.
8.5.6 If a term is listed in the document which is not found in the terminology documents, develop a definition and include the
term in the Terminology section of the update to be balloted. In addition, if of the term is of general interest to Committee D20
standards, submit the definition to the chairperson of Subcommittee D20.92 for review and possible inclusion in Terminology
D883.
8.6 Classification (Optional):
8.6.1 If required, use an appropriate classification system for the corresponding types of plastic materia
...