1、Designation: D 2444 99 (Reapproved 2005)An American National StandardStandard 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 D 2444; the number immediately following the de
2、signation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use
3、 by agencies of the Department 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 ingeom
4、etrical configuration. Two specimen holders are de-scribed.1.2 The values stated in inch-pound units are to be regardedas the standard. The values in parentheses are provided forinformation purposes only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with
5、 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:2D 618 Practice for Conditioning Plastics for TestingD 2122 Test Meth
6、od 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 measure of amaterials resistance to breaka
7、ge during handling and installa-tion and, for non-buried applications, to in-service breakage.See Appendix X4 for guidelines for selecting testing combina-tions.3.2 Results obtained by use of this test method can be usedin three ways:3.2.1 As the basis for establishing impact test requirementsin pro
8、duct 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. When usedwith the 0.50-in. (12.7-mm) rad
9、ius 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)1This test method is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.40 on Tes
10、tMethods.Current edition approved May 1, 2005. Published June 2005. Originallyapproved in 1965. Last previous edition approved in 1999 as D 2444 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandar
11、ds volume information, refer to the standards Document Summary page onthe ASTM website. FIG. 1 One Type of Tup Impact Tester1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.radius nose, it is designated as Tup C.NOTE 1It is suggested
12、that tups be made of scratch-resistant steel toreduce 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 pro
13、vide for a fall of at least 10 ft (3.0m) and shall 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
14、for the drop tube is specified. However, acolddrawn 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 bee
15、n found to be satisfactory.NOTE 3Provided equivalent 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 wi
16、ll bemore likely to strike the top of the test specimen. 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 tu
17、pand 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 to 3.0 m)above the specimen holder, (2)
18、 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 de-scribed. The V-block (Holder A) is usually used with Tups Aand C; the flat plate (Holder B) is often used wit
19、h Tup B or fortesting fittings.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 specimen in the V andnot on the top edges o
20、f 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 grooveshall be about 0.12 in. (3 mm) in d
21、epth 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 toa concrete slab. Means shall be pr
22、ovided 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 length to thenominal outside diameter b
23、ut 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 minimum of 100 specimens are required
24、 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 Procedure A of Practice D 618, forthose tests where conditioning is required.7.2 Tes
25、t 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 atmosphere, but in any case within 15 s.
26、In case of disagreement, conduct the tests in a room maintainedat the test temperature.8. ProcedureGeneral8.1 Measure the dimensions of the test specimens in accor-dance with Test Method D 2122.NOTE 1Dimensions are in inches (millimetres).FIG. 2 Tup Nose DetailD 2444 99 (2005)28.2 The point of impac
27、t 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. ProcedureDetails9.1 Impact one of the sets using an energy estimate
28、d 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 the preliminary tests is to identify theoptimum tup mass and to dete
29、rmine 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 source of problems in conducting impact tests is theratio of the s
30、tandard 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 four specimens.9.2.2.1 If at least one but not all four specimens fa
31、il 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 drop height of 5 ft (1.5 m).9.2.2.4 Once a weight has been used th
32、at 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. If no failures occur with the maximumweight at the maximum drop he
33、ight, 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 After the optimum tup weight has been determined,divide the remaining
34、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 greaterdrop height so that substantially more than 50 % failures result.Plot
35、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 outlined in9.2.3.NOTE 8Because there must be both failures and non
36、failures 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 theV-block holder (in the case of pipe specimens), (2) changing from T
37、up 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, trial and error, orjudgment, estimate the drop height at which 85
38、 % 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, if it is 10 ft (3.0 m) or more, use this height.Test 50 specimens an
39、d 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 of passes in the two setsshould differ by at least 20.9.3.4.2 If t
40、he 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 were con-ducted at the same drop height as the final tests shall be
41、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 the set as measured by the test.9.3.7 The intercept of the plot at
42、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 the impact and that can be seen by thenaked eye. Lighting devices may
43、 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 shall include the following:11.1.1 Complete identification of pipe
44、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 were made, and the positionof the weld mark in relation to the poi
45、nt 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,11.1.8 Types of failure and any deformation observed,11.1.9 Date of test, and11.1.10 Copy of probability plot, including number o
46、fspecimens tested at each drop height.D 2444 99 (2005)312. 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 employed. Therefore, no state-ment of bias can be made.NOTE 9A brief trea
47、tment 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 DETERMINING PRECISION AND ACCURACY BY APPLYING BINOMIAL PROBABILITY
48、TECHNIQUESX1.1 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 success is known. When a fair coinis tossed, for example, the probabilit
49、y 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!n 2 r(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 equation is mathematically exact.X1.5 A complication exists when the
