1、Designation: D2444 99 (Reapproved 2010)Standard Test Method forDetermination of the Impact Resistance of ThermoplasticPipe and Fittings by Means of a Tup (Falling Weight)1This standard is issued under the fixed designation D2444; the number immediately following the designation indicates the year of
2、original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Departm
3、ent of Defense.1. Scope1.1 This test method covers the determination of the impactresistance of thermoplastic pipe and fittings under specifiedconditions of impact by means of a tup (falling weight). Threeinterchangeable striking noses are used on the tup, differing ingeometrical configuration. Two
4、specimen holders are de-scribed.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of
5、thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditi
6、oning Plastics for TestingD2122 Test Method for Determining Dimensions of Ther-moplastic Pipe and Fittings3. Significance and Use3.1 The impact resistance of thermoplastic pipe and fittingsrelates to suitability for service and to quality of processing.Impact resistance may also provide a relative m
7、easure of amaterials resistance to breakage during handling and installa-tion and, for non-buried applications, to in-service breakage.See Appendix X4 for guidelines for selecting testing combi-nations.3.2 Results obtained by use of this test method can be usedin three ways:3.2.1 As the basis for es
8、tablishing impact test requirementsin product standards,3.2.2 To measure the effect of changes in materials orprocessing, and3.2.3 To measure the effect of the environment.4. Apparatus4.1 GeneralOne type of impact tester is illustrated in Fig.1.4.2 Tup:4.2.1 The tup nose shall be as shown in Fig. 2.
9、 When usedwith the 0.50-in. (12.7-mm) radius nose, it is designated as TupA. When used with the 2.00-in. (51-mm) radius nose, it isdesignated as Tup B. When used with the 0.25-in. (6.3-mm)radius nose, it is designated as Tup C.NOTE 1It is suggested that tups be made of scratch-resistant steel toredu
10、ce damage to the nose. Badly scarred noses may affect test results.4.2.2 The mass of the tup shall be 6, 12, 20, or 30 lb (2.7,5.4, 9.1, or 13.6 kg).4.3 Drop Tube:4.3.1 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 (3.0m) and shall
11、be mounted so that the lengthwise direction isvertical as measured with a plumb bob or a spirit level at least2 ft (610 mm) in length.4.3.2 Care must be taken to ensure that the tup falls freely;it must not “chatter” down the tube.NOTE 2No material for the drop tube is specified. However, acolddrawn
12、 seamless steel tubing with an inside diameter of 2.563 6 0.003in. (65.10 6 0.08 mm), or acrylonitrile-butadiene-styrene (ABS) orpoly(vinyl chloride) (PVC) plastic pipe, 212 in. nominal pipe size, with astandard dimension ratio (SDR) of 21, have been found to be satisfactory.NOTE 3Provided equivalen
13、t results are obtained, the tup may bedropped without a drop tube or guided by other means. The drop tube isused to reduce the hazard to operators and property that may occur whenthe tup rebounds. It also helps guide and center the tup so that it will bemore likely to strike the top of the test spec
14、imen. It may also be necessaryto provide a protective barrier around the specimen, particularly for largersizes of pipe and fittings, to protect the operator from flying broken pieces.NOTE 4The tup may not fall freely if the clearance between the tup1This test method is under the jurisdiction of AST
15、M Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.40 on TestMethods.Current edition approved Aug. 1, 2010. Published November 2010. Originallyapproved in 1965. Last previous edition approved in 2005 as D2444 99(2005).DOI: 10.1520/D2444-99R10.2For reference
16、d ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
17、hohocken, PA 19428-2959. United States1and tube is too large or too small, or if it is restrained by a partial vacuumabove the tup, such as can be caused by the hold and release device.4.3.3 Means shall be provided (1) to hold the tup at steps of2 in. (50.8 mm) for a distance of 2 to 10 ft (610 mm t
18、o 3.0 m)above the specimen holder, (2) to release the tup in areproducible manner, (3) to allow the tup to fall freely, and (4)to catch the tup on the first rebound. Refer to Fig. 1.4.4 Specimen HolderTwo specimen holders are described.The V-block (Holder A) is usually used with Tups A and C; thefla
19、t plate (Holder B) is often used with Tup B or for testingfittings.4.4.1 The V-block holder shall be at least as long as thespecimen being tested and shall have a 90-deg included angle.It may be fabricated or of solid construction. The side supportsshall be of sufficient depth to support the specime
20、n in the V andnot on the top edges of the V-block.NOTE 5Both aluminum and steel have been found suitable for theholders.4.4.2 The flat-plate holder shall consist of a plate approxi-mately 8 by 12 by 1 in. (203 by 305 by 25.4 mm) in which agroove to position the pipe specimen shall be cut. This groov
21、eshall be about 0.12 in. (3 mm) in depth with the edges roundedto a radius of about 0.06 in. (1.5 mm). Fittings that do notcontact the plate directly under the point of impact shall besupported at this point by a flat steel plate or shim. Thespecimen holder shall be mounted on a rigid base fastened
22、toa concrete slab. Means shall be provided to center the speci-mens under the drop tube. A bar or rod placed inside thespecimen and retained by a light spring may be employed ifdifficulty is encountered in holding the specimen in position.5. Test Specimens5.1 The pipe specimens shall be equal in len
23、gth to thenominal outside diameter but not less than 6 in. (152 mm) inlength. Burrs shall be removed.5.2 Fittings shall be tested either unassembled or assembledto pieces of pipe each 6 in. in length.6. Number of Test Specimens6.1 A minimum of 20 specimens are required for prelimi-nary tests.6.2 A m
24、inimum of 100 specimens are required for finaltests, and 50 additional specimens may be required.7. Conditioning7.1 Condition the test specimens at 40 h, 23C, 50 % RHand 50 6 5 % relative humidity for not less than 40 h prior totest in accordance with ProcedureAof Practice D618, for thosetests where
25、 conditioning is required.7.2 Test ConditionsConduct the test in a room maintainedat the test temperature or, if the test is made in an atmosphereor at a temperature other than that at which the specimens areconditioned, conduct the test as soon as possible after removalfrom the conditioning atmosph
26、ere, but in any case within 15 s.In case of disagreement, conduct the tests in a room maintainedat the test temperature.FIG. 1 One Type of Tup Impact TesterNOTE 1Dimensions are in inches (millimetres).FIG. 2 Tup Nose DetailD2444 99 (2010)28. ProcedureGeneral8.1 Measure the dimensions of the test spe
27、cimens in accor-dance with Test Method D2122.8.2 The point of impact for all specimens shall be at the topof the vertical diameter.8.3 Test unsymmetrical fittings with the specimen lying onits side.8.4 Position the pipe specimens at random angular orienta-tions.8.5 Impact each specimen only once.9.
28、ProcedureDetails9.1 Impact one of the sets using an energy estimated tocause 15 % of the specimens to fail; impact the second set at anenergy estimated to cause 85 % to fail. Record the actualpercentage that fail and plot on normal probability graph paper.9.2 Preliminary Tests:9.2.1 The purpose of t
29、he preliminary tests is to identify theoptimum tup mass and to determine the drop heights to be usedfor the final tests.NOTE 6The use of this preliminary procedure is optional. Trial anderror, previous experience with the material, or guesswork may serve aswell. Also, see Appendix X3.NOTE 7The chief
30、 source of problems in conducting impact tests is theratio of the standard deviation to the mean strength. Use of Tup C withpipe specimens will reduce the size of the problem.9.2.2 Select a tup estimated to cause failure of somespecimens when dropped from a height of 5 ft (1.5 m) and useit to test f
31、our specimens.9.2.2.1 If at least one but not all four specimens fail with thefirst tup selected, continue the test as described in 9.2.3.9.2.2.2 If all four specimens fail, test four more specimenswith a lighter tup.9.2.2.3 If all four specimens pass, test the same specimenswith a heavier tup, at a
32、 drop height of 5 ft (1.5 m).9.2.2.4 Once a weight has been used that results in thefailure of some, but not all, specimens at a height of 5 ft (1.5m), continue the test as described in 9.2.3. If no failures occurwith the heaviest tup at a drop height of 5 ft (1.5 m), test at themaximum drop height.
33、 If no failures occur with the maximumweight at the maximum drop height, test a total of 50specimens at this drop height, record the results, and discon-tinue testing. If one or more of the preliminary test specimenspasses with the maximum weight at the maximum drop height,proceed to 9.2.3.9.2.3 Aft
34、er the optimum tup weight has been determined,divide the remaining group of preliminary test specimens intotwo equal lots. Each group shall contain at least eight speci-mens. Test one lot at a lesser drop height so that substantiallyless than 50 % failures result. Test the second lot at a greaterdro
35、p height so that substantially more than 50 % failures result.Plot these results on probability graph paper to serve as thebasis for estimating the proper drop heights for the final test.9.2.4 If the 6-lb (2.7-kg) tup produces 100 % failures at 5 ft(1.5 m), use lesser drop heights for the procedures
36、 outlined in9.2.3.NOTE 8Because there must be both failures and nonfailures in thistest, conditions that result in 100 % failures or 100 % passes are of limitedvalue in the development of information. When all specimens pass, theproblem can be helped by (1) changing from the flat-plate holder to the
37、V-block holder (in the case of pipe specimens), (2) changing from Tup Bto Tup A, and finally to Tup C, and (3) lowering the test temperature.When all specimens fail, the sequence is reversed.9.3 Final Test:9.3.1 Divide 100 test specimens into two equal sets.9.3.2 On the basis of the preliminary test
38、, trial and error, orjudgment, estimate the drop height at which 85 % of thespecimens will pass and test the first set of 50 specimens at thisheight. Record the value of the mass, the drop height, and thenumber of passes.9.3.3 Estimate the drop height at which 85 % of the speci-mens will fail and, i
39、f it is 10 ft (3.0 m) or more, use this height.Test 50 specimens and record the number of passes and thedrop height.9.3.4 Acceptable Data:9.3.4.1 To be acceptable, there must be at least one pass andat least one fail in each set of data; one set of data should listless than 50 % failures; the number
40、 of passes in the two setsshould differ by at least 20.9.3.4.2 If the requirements of 9.3.4.1 have not been met, test50 additional specimens at a drop height chosen to rectify thedeficiency.9.3.5 Construct a straight-line plot of the test results onnormal probability paper. Preliminary tests which w
41、ere con-ducted at the same drop height as the final tests shall be usedto compute the percent passing at that height. All otherpreliminary test results are ignored for purposes of obtainingthe final plot.9.3.6 The intercept of the plot with the 50 % pass/fail line isthe average impact resistance of
42、the set as measured by the test.9.3.7 The intercept of the plot at the 16 % or the 84 %pass/fail line differs from the average strength by (for practicalpurposes) one standard deviation.10. Definition of Failure10.1 Failure in the test specimens shall be shattering or anycrack or split created by th
43、e impact and that can be seen by thenaked eye. Lighting devices may be used to assist in examiningthe specimens. A crease visible on the surface shall not beconstrued as failure. If criteria of failure other than those citedhere are used, they shall be listed in the report.11. Report11.1 The report
44、shall include the following:11.1.1 Complete identification of pipe or fittings tested,including type of plastic, source, manufacturers code, size,average dimensions and minimum wall thickness, and history,11.1.2 In the case of fittings, the dimensions of pipe used toprepare the specimens, how joints
45、 were made, and the positionof the weld mark in relation to the point of impact,11.1.3 Test temperature and conditioning procedure,11.1.4 Tup used,11.1.5 Holder used,11.1.6 The mass of the tup, lb (kg),11.1.7 Point of impact for fittings,D2444 99 (2010)311.1.8 Types of failure and any deformation ob
46、served,11.1.9 Date of test, and11.1.10 Copy of probability plot, including number ofspecimens tested at each drop height.12. Precision and Bias12.1 This test method is neither precise nor accurate withinthe limits usually associated with those terms unless largernumbers of test specimens are employe
47、d. Therefore, no state-ment of bias can be made.NOTE 9A brief treatment of the subject of precision and accuracy forbinomial tests is provided in Appendix X1.13. Keywords13.1 fittings; impact resistance; pipe; thermoplastic; tup(falling weight)APPENDIXES(Nonmandatory Information)X1. GUIDELINES FOR D
48、ETERMINING PRECISION AND ACCURACY BY APPLYING BINOMIAL PROBABILITY TECH-NIQUESX1.1 Tests that have only two possible results (pass or fail,heads or tails, black or white) are governed by the rules ofprobability.X1.2 The most elementary application of the rules occurswhen the true probability of succ
49、ess is known. When a fair coinis tossed, for example, the probability for “heads” is known tobe exactly 0.5 chance out of 1.X1.3 The probability,rPn, for exactly r successes in n trieswhen the probability for success, p, is known for each try, isgiven by the equationrPn5n!r! n 2 r!pr!1 2 p!n2r(X1.1)Example The chance that one will obtain exactly 25 headswhen a fair coin is tossed 50 times is equal to50!25! 50 2 25!0.525! or 0.112 (X1.2)The factorial of zero (0) is one (1).X1.4 The total of the probabilities for all possible results isequal to 1. The eq
