1、Designation: D2444 99 (Reapproved 2010)D2444 17Standard Test Method Practice 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 indi
2、cates 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 () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of
3、 the U.S. Department of Defense.1. Scope1.1 This test method covers the determination of the impact resistance of thermoplastic pipe and fittings under specifiedconditions of impact by means of a tup (falling weight). Three interchangeable striking noses are used on the tup, differing ingeometrical
4、configuration. Two specimen holders are described.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.1.3 This standard does not purpor
5、t to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D618 Pr
6、actice for Conditioning Plastics for TestingD2122 Test Method for Determining Dimensions of Thermoplastic Pipe and Fittings3. Significance and Use3.1 The impact resistance of thermoplastic pipe and fittings relates to suitability for service and to quality of processing. Impactresistance may also pr
7、ovide a relative measure of a materials resistance to breakage during handling and installation and, fornon-buried applications, to in-service breakage. See Appendix X4 for guidelines for selecting testing combinations.3.2 Results obtained by use of this test method can be used in three ways:3.2.1 A
8、s the basis for establishing impact test requirements in product standards,3.2.2 To measure the effect of changes in materials or processing, 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 b
9、e as shown in Fig. 2. When used with the 0.50-in. (12.7-mm) radius nose, it is designated as Tup A.When used with the 2.00-in. (51-mm) radius nose, it is designated 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
10、-resistant steel to reduce 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:1 This test method pracitce is under the jurisdiction of ASTM Committee F17 on Plastic Piping Systems and is the
11、 direct responsibility of Subcommittee F17.40 on TestMethods.Current edition approved Aug. 1, 2010Nov. 15, 2017. Published November 2010February 2018. Originally approved in 1965. Last previous edition approved in 20052010as D2444 99(2005).(2010). DOI: 10.1520/D2444-99R10.10.1520/D2444-17.2 For refe
12、rencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide t
13、he user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit 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 versionof the stand
14、ard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1FIG. 1 One Type of Tup Impact TesterNOTE 1Dimensions are in inches (millimetres).FIG. 2 Tup Nose DetailD2444 1724.3.1 T
15、he drop tube shall be of sufficient length (approximately 12 ft (3.7 m) to provide for a fall of at least 10 ft (3.0 m) andshall be mounted so that the lengthwise direction is vertical as measured with a plumb bob or a spirit level at least 2 ft (610 mm)in length.4.3.2 Care must be taken to ensure t
16、hat the tup falls freely; it must not “chatter” down the tube.NOTE 2No material for the drop tube is specified. However, a colddrawn seamless steel tubing with an inside diameter of 2.563 6 0.003 in. (65.106 0.08 mm), or acrylonitrile-butadiene-styrene (ABS) or poly(vinyl chloride) (PVC) plastic pip
17、e, 212 in. nominal pipe size, with a standard dimensionratio (SDR) of 21, have been found to be satisfactory.NOTE 3Provided equivalent results are obtained, the tup may be dropped without a drop tube or guided by other means. The drop tube is used toreduce the hazard to operators and property that m
18、ay occur when the tup rebounds. It also helps guide and center the tup so that it will be more likelyto strike the top of the test specimen. It may also be necessary to provide a protective barrier around the specimen, particularly for larger sizes of pipeand fittings, to protect the operator from f
19、lying broken pieces.NOTE 4The tup may not fall freely if the clearance between the tup and tube is too large or too small, or if it is restrained by a partial vacuum abovethe 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 of 2 in.
20、 (50.8 mm) for a distance of 2 to 10 ft (610 mm to 3.0 m)above the specimen holder, (2) to release the tup in a reproducible manner, (3) to allow the tup to fall freely, and (4) to catch thetup on the first rebound. Refer to Fig. 1.4.4 Specimen HolderTwo specimen holders are described. The V-block (
21、HolderA) is usually used with TupsAand C; the flatplate (Holder B) is often used with Tup B or for testing fittings.4.4.1 The V-block holder shall be at least as long as the specimen being tested and shall have a 90-deg included angle. It maybe fabricated or of solid construction. The side supports
22、shall be of sufficient depth to support the specimen in the V and not onthe top edges of the V-block.NOTE 5Both aluminum and steel have been found suitable for the holders.4.4.2 The flat-plate holder shall consist of a plate approximately 8 by 12 by 1 in. (203 by 305 by 25.4 mm) in which a grooveto
23、position the pipe specimen shall be cut. This groove shall be about 0.12 in. (3 mm) in depth with the edges rounded to a radiusof about 0.06 in. (1.5 mm). Fittings that do not contact the plate directly under the point of impact shall be supported at this pointby a flat steel plate or shim. The spec
24、imen holder shall be mounted on a rigid base fastened to a concrete slab. Means shall beprovided to center the specimens under the drop tube. A bar or rod placed inside the specimen and retained by a light spring maybe employed if difficulty is encountered in holding the specimen in position.5. Test
25、 Specimens5.1 The pipe specimens shall be equal in length to the nominal outside diameter but not less than 6 in. (152 mm) in length. Burrsshall be removed.5.2 Fittings shall be tested either unassembled or assembled to pieces of pipe each 6 in. in length.6. Number of Test Specimens6.1 A minimum of
26、20 specimens are required for preliminary tests.6.2 A minimum of 100 specimens are required for final tests, and 50 additional specimens may be required.7. Conditioning7.1 Condition the test specimens at 40 h, 23C, 50 % RH and 50 6 5 % relative humidity for not less than 40 h prior to testin accorda
27、nce with Procedure A of Practice D618, for those tests where conditioning is required.7.2 Test ConditionsConduct the test in a room maintained at the test temperature or, if the test is made in an atmosphere orat a temperature other than that at which the specimens are conditioned, conduct the test
28、as soon as possible after removal fromthe conditioning atmosphere, but in any case within 15 s. In case of disagreement, conduct the tests in a room maintained at thetest temperature.8. ProcedureGeneral8.1 Measure the dimensions of the test specimens in accordance with Test Method D2122.8.2 The poin
29、t of impact for all specimens shall be at the top of the vertical diameter.8.3 Test unsymmetrical fittings with the specimen lying on its side.8.4 Position the pipe specimens at random angular orientations.8.5 Impact each specimen only once.9. ProcedureDetails9.1 Impact one of the sets using an ener
30、gy estimated to cause 15 % of the specimens to fail; impact the second set at an energyestimated to cause 85 % to fail. Record the actual percentage that fail and plot on normal probability graph paper.D2444 1739.2 Preliminary Tests:9.2.1 The purpose of the preliminary tests is to identify the optim
31、um tup mass and to determine the drop heights to be used forthe final tests.NOTE 6The use of this preliminary procedure is optional. Trial and error, previous experience with the material, or guesswork may serve as well.Also, see Appendix X3.NOTE 7The chief source of problems in conducting impact te
32、sts is the ratio of the standard deviation to the mean strength. Use of Tup C with pipespecimens will reduce the size of the problem.9.2.2 Select a tup estimated to cause failure of some specimens when dropped from a height of 5 ft (1.5 m) and use it to testfour specimens.9.2.2.1 If at least one but
33、 not all four specimens fail with the first tup selected, continue the test as described in 9.2.3.9.2.2.2 If all four specimens fail, test four more specimens with a lighter tup.9.2.2.3 If all four specimens pass, test the same specimens with a heavier tup, at a drop height of 5 ft (1.5 m).9.2.2.4 O
34、nce a weight has been used that results in the failure of some, but not all, specimens at a height of 5 ft (1.5 m), continuethe test as described in 9.2.3. If no failures occur with the heaviest tup at a drop height of 5 ft (1.5 m), test at the maximum dropheight. If no failures occur with the maxim
35、um weight at the maximum drop height, test a total of 50 specimens at this drop height,record the results, and discontinue testing. If one or more of the preliminary test specimens passes with the maximum weight atthe maximum drop height, proceed to 9.2.3.9.2.3 After the optimum tup weight has been
36、determined, divide the remaining group of preliminary test specimens into twoequal lots. Each group shall contain at least eight specimens. Test one lot at a lesser drop height so that substantially less than 50 %failures result. Test the second lot at a greater drop height so that substantially mor
37、e than 50 % failures result. Plot these resultson probability graph paper to serve as the basis 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 in 9.2.3.NOTE 8Because
38、 there must be both failures and nonfailures in this test, conditions that result in 100 % failures or 100 % passes are of limited valuein the development of information. When all specimens pass, the problem can be helped by (1) changing from the flat-plate holder to the V-block holder(in the case o
39、f pipe specimens), (2) changing from Tup B to 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, or judgme
40、nt, estimate the drop height at which 85 % of the specimenswill pass and test the first set of 50 specimens at this height. Record the value of the mass, the drop height, and the number ofpasses.9.3.3 Estimate the drop height at which 85 % of the specimens will fail and, if it is 10 ft (3.0 m) or mo
41、re, use this height. Test50 specimens and record the number of passes and the drop height.9.3.4 Acceptable Data:9.3.4.1 To be acceptable, there must be at least one pass and at least one fail in each set of data; one set of data should list lessthan 50 % failures; the number of passes in the two set
42、s should differ by at least 20.9.3.4.2 If the requirements of 9.3.4.1 have not been met, test 50 additional specimens at a drop height chosen to rectify thedeficiency.9.3.5 Construct a straight-line plot of the test results on normal probability paper. Preliminary tests which were conducted atthe sa
43、me drop height as the final tests shall be used to compute the percent passing at that height. All other preliminary test resultsare ignored for purposes of obtaining the final plot.9.3.6 The intercept of the plot with the 50 % pass/fail line is the average impact resistance of the set as measured b
44、y 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 practical purposes)one standard deviation.10. Definition of Failure10.1 Failure in the test specimens shall be shattering or any crack or split created by the impact and that c
45、an be seen by the nakedeye. Lighting devices may be used to assist in examining the specimens. A crease visible on the surface shall not be construed asfailure. If criteria of failure other than those cited here are used, they shall be listed in the report.11. Report11.1 The report shall include the
46、 following:11.1.1 Complete identification of pipe or fittings tested, including type of plastic, source, manufacturers code, size, averagedimensions and minimum wall thickness, and history,11.1.2 In the case of fittings, the dimensions of pipe used to prepare the specimens, how joints were made, and
47、 the position ofthe weld mark in relation to the point of impact,11.1.3 Test temperature and conditioning procedure,11.1.4 Tup used,D2444 17411.1.5 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
48、test, and11.1.10 Copy of probability plot, including number of specimens tested at each drop height.12. Precision and Bias12.1 This test method is neither precise nor accurate within the limits usually associated with those terms unless larger numbersof test specimens are employed. Therefore, no sta
49、tement of bias can be made.NOTE 9A brief treatment of the subject of precision and accuracy for binomial 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 TECH-NIQUESX1.1 Tests that have only two possible results (pass or fail, heads or tails, black or white) are governed by the rules of probability.X1.2 The most elementary application of the rules occurs when the tru
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