ASTM F725-03e1

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An American National Standard
e1
Designation:F 725–03
Standard Practice for
Drafting Impact Test Requirements In Thermoplastic Pipe
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And Fittings Standards
This standard is issued under the fixed designation F 725; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
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e NOTE—Keywords editorially added in November 2003.
1. Scope 3.1.4 OC curve (operating characteristic curve)—a graph
that illustrates the chance of success or failure when a given
1.1 Thispracticedescribesaprocedureforsettingupimpact
specification format is employed, given any quality level from
test requirements on the basis of test data obtained by Test
0to1(0to100%passinginthelotfromwhichtestspecimens
Method D2444.
are selected).
1.2 This practice is applicable to thermoplastic pipe and
3.1.5 probability graph paper—commercially available
fittings.
graph paper that provides straight-line plots when the distribu-
1.3 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 D 2444Appendix 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:
D2444 Test Method for Impact Resistance of Thermoplas-
NOTE 2—The terms “mean,” “normal distribution,” and “standard
2
tic Pipe and Fittings by Means of a Tup (Falling Weight)
deviation” are dealt with in elementary statistics textbooks.
3. Terminology
4. Summary of Practice
3.1 Definitions of Terms Specific to This Standard:
4.1 Round-robin tests of representative pipe and fittings
3.1.1 binomial probability equation—the equation that de- specimens are performed to identify the energy levels at which
fines the chance for exactly r specimens to pass, when n are
90% or more of the specimens in acceptable lots will pass.A
tested, given p, the chance that a single specimen chosen at preferred test format is listed. The B-tup and the V-block
random will pass. It is expressed as follows:
holder, and room-temperature conditioning and tests are pre-
ferred choices.
n!
r n2r
P 5 p ~1 2 p! (1)
r n
r!~n–r!!
5. Significance and Use
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
3.1.2 binomial test—atestthathasonlytwopossibleresults
with statistical methods. It provides for specification values
(for example, pass or fail, heads or tails, true or false).
that will pass acceptable lots with a high degree of certainty.
3.1.3 mean strength—the average strength of the total
The impact test requirement is intended to discriminate be-
population (see Note 2).
tween acceptable materials and manufacturing methods and
those which are not; it is not a simulated service test.
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This practice is under the jurisdiction of ASTM Committee F17 on Plastic
6. Procedure
Piping Systems and is the direct responsibility of Subcommittee F17.40 on Test
Methods.
6.1 Test thermoplastic pipe or fittings specimens in accor-
Current edition approved April 10, 2003. Published May 2003. Originally
dance with Test Method D2444, and plot the test results on
approved in 1981. Last previous edition approved in 1996 as F725–89 (1996).
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probability graph paper.
Annual Book of ASTM Standards, Vol 08.04.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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F725–03
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 rej
...