ASTM F725-03(2013)
(Practice)Standard Practice for Drafting Impact Test Requirements In Thermoplastic Pipe And Fittings Standards
Standard Practice for Drafting Impact Test Requirements In Thermoplastic Pipe And Fittings Standards
SIGNIFICANCE AND USE
5.1 This practice is used for drafting impact test specification requirements, and it presupposes no special familiarity with statistical methods. It provides for specification values that will pass acceptable lots with a high degree of certainty. The impact test requirement is intended to discriminate between acceptable materials and manufacturing methods and those which are not; it is not a simulated service test.
SCOPE
1.1 This practice describes a procedure for setting up impact test requirements on the basis of test data obtained by Test Method D2444.
1.2 This practice is applicable to thermoplastic pipe and fittings.
1.3 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.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: F725 − 03 (Reapproved 2013)
Standard Practice for
Drafting Impact Test Requirements In Thermoplastic Pipe
And Fittings Standards
ThisstandardisissuedunderthefixeddesignationF725;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.2 binomial test—a test that has only two possible results
(for example, pass or fail, heads or tails, true or false).
1.1 Thispracticedescribesaprocedureforsettingupimpact
3.1.3 mean strength—theaveragestrengthofthetotalpopu-
test requirements on the basis of test data obtained by Test
lation (see Note 2).
Method D2444.
3.1.4 OC curve (operating characteristic curve)— a graph
1.2 This practice is applicable to thermoplastic pipe and
that illustrates the chance of success or failure when a given
fittings.
specification format is employed, given any quality level from
1.3 The values stated in inch-pound units are to be regarded
0to1(0to100%passinginthelotfromwhichtestspecimens
as standard. The values given in parentheses are mathematical
are selected).
conversions to SI units that are provided for information only
3.1.5 probability graph paper—commercially available
and are not considered standard.
graph paper that provides straight-line plots when the distribu-
1.4 This standard does not purport to address all of the
tion of attributes is normal. For a discussion on the use of
safety concerns, if any, associated with its use. It is the
proability graph paper, see Test Method D2444 Appendix X2.
responsibility of the user of this standard to establish appro-
3.1.6 specification format—the rules set forth by the test
priate safety and health practices and determine the applica-
requirement, including the number of specimens to be tested
bility of regulatory limitations prior to use.
and the minimum acceptable number of passes.
2. Referenced Documents
3.1.7 standard deviation—a statistical term that relates to
the size of the expected variation in test results.
2.1 ASTM Standards:
D2444Test Method for Determination of the Impact Resis-
NOTE 2—The terms “mean,” “normal distribution,” and “standard
deviation” are dealt with in elementary statistics textbooks.
tance of Thermoplastic Pipe and Fittings by Means of a
Tup (Falling Weight)
4. Summary of Practice
4.1 Round-robin tests of representative pipe and fittings
3. Terminology
specimens are performed to identify the energy levels at which
3.1 Definitions of Terms Specific to This Standard:
90% or more of the specimens in acceptable lots will pass.A
3.1.1 binomial probability equation—the equation that de-
preferred test format is listed. The B-tup and the V-block
fines the chance for exactly r specimens to pass, when n are
holder, and room-temperature conditioning and tests are pre-
tested, given p, the chance that a single specimen chosen at
ferred choices.
random will pass. It is expressed as follows:
5. Significance and Use
n!
r n2r
P 5 p ~1 2 p! (1)
r n
r!~n 2 r!! 5.1 This practice is used for drafting impact test specifica-
NOTE 1—The factorial of zero is one.
tion requirements, and it presupposes no special familiarity
with statistical methods. It provides for specification values
that will pass acceptable lots with a high degree of certainty.
This practice is under the jurisdiction of ASTM Committee F17 on Plastic
The impact test requirement is intended to discriminate be-
Piping Systems and is the direct responsibility of Subcommittee F17.40 on Test
tween acceptable materials and manufacturing methods and
Methods.
those which are not; it is not a simulated service test.
Current edition approved Aug. 1, 2013. Published October 2013. Originally
ε1
approved in 1981. Last previous edition approved in 2008 as F725–03(2008) .
6. Procedure
DOI: 10.1520/F0725-03R13.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.1 Test thermoplastic pipe or fittings specimens in accor-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
dance with Test Method D2444, and plot the test results on
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. probability graph paper.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F725 − 03 (2013)
6.2 It will be clear, from the probability paper plot, that the
energy level where 98% or 99% of all specimens would pass
willbelow.Ontheonehand,whenthetestformatrequiresthat
five of five, or six of six, or nine or ten of ten tested shall pass,
or the lot rejected, then the specified energy levels must
correspond to these levels (see Fig. 1, the operating character-
istic(OC)curveforthe“nineortenoften”testformat).Onthe
other hand, five of five, six of six, and nine or ten of ten tests
at low energy levels will not screen marginal or poor lots
effectively. (See Fig. 1 again).
6.3 Aformat which will accept reliably when 90% or more
of the specimens in acceptable lots would pass, and reject
reliably when 60% or fewer would pass, is as follows:
6.3.1 “X.X Test ten specimens. When nine or ten pass,
accept the lot. When six or fewer pass, reject the lot. When
seven or eight pass, test ten additional specimens. When 17 or
more of 20 pass, accept the lot. When 13 or fewer of 20 pass,
reject the lot. When 14, 15, or 16 pass, test 20 additional
FIG. 2 O.C. Curve for Section 6.3
specimens. When 32 or more of 40 pass, accept the lot. When
31 or fewer pass, reject the lot.”
6.3.2 The OC curve for this format is illustrated in Fig. 2.
choice (study Fig. 1 together with a data plot performed in
6.4 Specimen Length—The pipe specimen length should be
accordance with Test Method D2444 to fully grasp the merits
6 in. (150 mm) 6 ⁄4 in. (6mm). of this statement).
6.5 Choice of Tup and Holder—The B tup is preferred. It
7. Multiple-Product Standards
provides a good compromise between energy concentration in
7.1 Many thermoplastic pipe and fittings specifications list
the specimen (and therefore reduced test energy levels), and
large numbers of products.Test Method D2444 requires that at
resistance to damage in service. The V-block holder is pre-
least 100 test specimens shall be employed for each single test
ferred for pipe specimens; it provides for greater energy
run in order that the impact properties can be measured with
concentration, and for failures in a range of thin-walled
useful accuracy. The cost of round-robin tests on each size of
specimens which would merely flatten on the flat-plate holder.
the products in the standard may approach or exceed the value
6.6 Test Conditions—Room-temperature tests are preferred.
of the information to be obtained.
They can be performed by the manufacturer on a timely basis,
7.2 Testingcostscanbesignificantlyreducedbyperforming
so that the size of questionable or defective inventories is
preliminary tests on the largest sizes listed, to determine
minimized. Binomial tests are relatively crude, unless large
whetherornotacut-offpointexistsabovewhichallspecimens
numbers of specimens are subjected to test. The expense and
will pass at an energy level of 300 ft·lbf (407 J) (ordinarily the
inconvenienceoflow-temperatureconditioningrender
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