1、Designation: D1598 15aStandard Test Method forTime-to-Failure of Plastic Pipe Under Constant InternalPressure1This standard is issued under the fixed designation D1598; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the time-to-failure of both thermoplastic and reinforced thermosetting/res
3、in pipe under constant internal pressure.1.2 This test method provides a method of characterizingplastics in the form of pipe under the conditions prescribed.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI uni
4、ts that are provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of 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
5、the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D2122 Test Method for Determining Dimensions of Ther-moplastic Pipe and FittingsD2837 Test Method for Obtaining Hydrostatic Design Basisfor Thermoplastic Pipe Materials or Pressure Design Basisfor Th
6、ermoplastic Pipe ProductsD2992 Practice for Obtaining Hydrostatic or Pressure De-sign Basis for “Fiberglass” (Glass-Fiber-ReinforcedThermosetting-Resin) Pipe and FittingsD2517 Specification for Reinforced Epoxy Resin Gas Pres-sure Pipe and FittingsD3567 Practice for Determining Dimensions of “Fiberg
7、lass”(Glass-Fiber-Reinforced Thermosetting Resin) Pipe andFittings3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 failure, noccurrence of ballooning, rupture, seepageor weeping.3.1.1.1 ballooning, nany localized expansion of a pipewhile under internal pressure. This is sometim
8、es referred to asductile failure.3.1.1.1.1 DiscussionOverall distention caused by appliedstress is not considered to be a failure.3.1.1.2 rupture, na break in the pipe wall with immediateloss of test fluid and continued loss at essentially no pressure.If rupture is not preceded by some yielding, thi
9、s may be termeda non-ductile failure.3.1.1.3 seepage or weeping, ntest fluid passing throughcracks in the pipe wall to an extent detectable visually orelectronically. A reduction in pressure will frequently enablethe pipe to carry fluid without apparent evidence of loss offluid.3.1.2 free (unrestrai
10、ned) end closure, na pipe specimenend closure(cap) that seals the end of the pipe against loss ofinternal fluid and is fastened to the pipe specimen.3.1.3 restrained end closure, na pipe specimen end clo-sure (cap) that seals the end of the specimen against loss ofinternal fluid and pressure, but is
11、 not fastened to the pipespecimen. Retained end closures rely on tie-rod(s) through thepipe specimen or on an external structure to resist internalpressure end thrust.4. Summary of Test Method4.1 This test method consists of exposing specimens of pipeto a constant internal pressure while in a contro
12、lled environ-ment. Such a controlled environment may be accomplished by,but is not limited to, immersing the specimens in a controlledtemperature water or air bath. The time-to-failure is measured.NOTE 1Dimensional changes should be measured on specimensundergoing long-term strength tests. Measureme
13、nts using circumferentialtapes, strain gages, or mechanical extensometers provide useful informa-tion.1This test method is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.40 on TestMethods.Current edition approved Dec. 1, 201
14、5. Published December 2015. Originallyapproved 1958. Last previous edition approved in 2015 as D1598 15. DOI:10.1520/D1598-15A2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
15、 refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 The data obtained by this tes
16、t method are useful forestablishing stress versus failure time relationships in a con-trolled environment from which the hydrostatic design basisfor plastic pipe materials can be computed. (Refer to TestMethod D2837 and Practice D2992.)5.2 In order to determine how plastics will perform as pipe,it i
17、s necessary to establish the stress-failure time relationshipsfor pipe over 2 or more logarithmic decades of time (hours) ina controlled environment. Because of the nature of the test andspecimens employed, no single line can adequately representthe data, and therefore the confidence limits should b
18、e estab-lished.NOTE 2Some materials may exhibit a nonlinear relationship betweenlog-stress and log-failure time, usually at short failure times. In such cases,the 105-hour stress value computed on the basis of short-term test datamay be significantly different than the value obtained when a distribu
19、tionof data points in accordance with Test Method D2837 is evaluated.However, these data may still be useful for quality control or otherapplications, provided correlation with long-term data has been estab-lished.5.3 The factors that affect creep and long-term strengthbehavior of plastic pipe are n
20、ot completely known at this time.This procedure takes into account those factors that are knownto have important influences and provides a tool for investi-gating others.5.4 Creep, or nonrecoverable deformation for pipe made ofsome plastics, is as important as actual leakage in decidingwhether or no
21、t a pipe has failed. Specimens that exhibitlocalized ballooning, however, may lead to erroneous interpre-tation of the creep results unless a method of determining creepis established that precludes such a possibility. Circumferentialmeasurements at two or three selected positions on a specimenmay n
22、ot be adequate.5.5 Great care must be used to ensure that specimens arerepresentative of the pipe under evaluation. Departure fromthis assumption may introduce discrepancies as great as, if notgreater than, those due to departure from details of procedureoutlined in this test method.6. Apparatus6.1
23、Constant-Temperature SystemA water bath or otherfluid bath equipped so that uniform temperature is maintainedthroughout the bath. This may require agitation. If an air orother gaseous environment is used, provision shall be made foradequate circulation.The test may be conducted at 23C (73F)or other
24、selected temperatures as required and the temperaturetolerance requirements shall be 62C (63.6F).6.2 Pressurizing SystemAny device that is capable ofcontinuously applying constant internal pressure on the speci-men may be used. The device shall be capable of reaching thetest pressure without exceedi
25、ng it and of holding the pressurewithin the tolerance shown in 6.6 for the duration of the test.6.3 Pressure GageA pressure gage or pressure transducerhaving an accuracy sufficient to meet the pressure tolerancerequirements of 6.6 is required.6.4 Timing DeviceA time meter connected to the pressur-iz
26、ed fluid side of the system through a pressure or flow switch,or both.The timing device and pressure or flow switch, or both,together shall be capable of measuring the time when thespecimen is at 98 % or more of test pressure with sufficientaccuracy to meet the tolerance requirements of 6.6.6.5 Spec
27、imen End ClosuresEither free-end or restrained-end closures that will withstand the maximum test pressuresmay be used. Closures shall be designed so that they do notcause failure of the specimen. Free-end closures shall be usedfor referee tests for thermoplastic pipe.NOTE 3Free-end closures fasten t
28、o the specimen so that internalpressure produces longitudinal tensile stress in addition to hoop. Com-pared to free end closure specimens, stresses in the wall of restrained-endclosure specimens act in the hoop and radial directions only. Because ofthis difference in loading, the equivalent hoop str
29、ess in free-end closurespecimens of solid wall thermoplastic pipe are approximately 11 % lowerthan in restrained-end closure specimens tested at the same pressure. Thetest results for each specimen and the LTHS will reflect this difference intest method.6.6 Time and Pressure ToleranceWhen added toge
30、ther,the tolerance for the timing device and the tolerance for thepressure gage shall not exceed 62%.7. Test Specimens7.1 Pipe Specimen LengthFor pipe sizes of 6 in. (150 mm)or less, the specimen length between end closures shall be notless than five times the nominal outside diameter of the pipe,bu
31、t in no case less than 12 in. (300 mm). The 12 in. (300 mm)minimum specimen length requirement shall not apply tomolded specimens. For larger sizes of pipe, the minimumlength between end closures shall be not less than three timesthe nominal outside diameter but in no case less than 30 in.(760 mm).7
32、.2 MeasurementsDimensions shall be determined in ac-cordance with Test Method D2122 or Practice D3567.8. Conditioning8.1 Specimens to be tested at 23C shall be conditioned attest temperatures in a liquid bath for a minimum of 1 h or in agaseous medium for a minimum of 16 h before pressurizing.8.2 Wh
33、en specimens are to be tested at higher temperatures,condition them in the elevated temperature environment untilthey have reached test temperature.NOTE 4Conditioning time is a function of pipe size wall thickness,temperature differential, the film heat transfer coefficient and whether theelevated t
34、emperature environment is applied to one or both sides of thespecimen. One-hour conditioning of 1-in. and smaller pipe at 82C(180F) in a water environment has been found to be sufficient.8.3 Unless otherwise agreed upon, the test temperature shallbe 23 6 2C (73 6 3.6F) for thermoplastics. For thermo
35、setstest at 23 6 2C (73 6 3.6F) or at maximum rated tempera-ture depending on intended service. While every effort shouldbe made to meet the temperature tolerances listed, temporarilyexceeding the (+) temperature tolerance does not necessarilyrequire that all samples under test be abandoned. Data po
36、intsfrom such samples may still be acceptable. Refer also to TestMethod D2837 or Practice D2992 to determine the suitabilityof these data points.D1598 15a29. Procedure9.1 Attach end closures to the pipe test sections and fill eachspecimen completely with the test fluid conditioned to the testtempera
37、ture. Attach the specimens to the pressuring device,making certain no gas is entrapped when using liquids.Completely immerse the test specimens in the conditioningmedium.9.2 Support specimens in such a way as to prevent bendingor deflection by the weight of the pipe while under test. Thissupport sha
38、ll not constrain the specimen circumferentially orlongitudinally.9.3 After conditioning the specimens as specified in Section8, adjust the pressure to produce the desired loading.Apply thepressure to the specimens and make sure the timing deviceshave started.9.4 Record the time-to-failure of each sp
39、ecimen. The time-to-failure shall not include periods of time during which thespecimen was under depleted pressure or under no pressure.9.4.1 Any failure occurring within one pipe diameter of theend closure shall be examined carefully. If there is any reasonto believe that the failure is attributabl
40、e to the end closure, thevalue shall be discarded in computing averages or in plottingthe data.9.4.2 The failure value of a specimen that fails due tocolumn buckling shall be discarded in computing averages orin plotting the data.NOTE 5For certain materials creep measurements should be made inaccord
41、ance with Test Method D2837. It describes the procedure fordetermining when “circumferential expansion” must be used as a criterionfor establishing the hydrostatic design stress.9.5 Pressure ConnectionsEach specimen may be pres-sured individually or through a manifold system. If a manifoldsystem is
42、utilized, each pressure connection should include acheck valve to prevent pressure depletion of the system whenone specimen fails. Where the system is designed to preventone specimen failure from depressurizing the manifold, eachspecimen shall have its own timing device.9.6 Test FluidsWhile water is
43、 normally used inside thetest specimens, any fluid may be used. However, if a gas isused special care must be taken because of the potential energystored in any compressed gas.NOTE 6Test ApparatusAll the above components with some addi-tional features can be acquired as assembled stress rupture test
44、ers. Someunits utilize a liquid bath environment that can be adjusted from 20 to+150C. Other units offer a single pressure source with as many as 40manifolds that can each be set for a different pressure and 240 specimenpositions. A list of manufacturers of stress rupture test equipment can beobtain
45、ed from the ASTM Information Center.10. Calculation10.1 Hoop stress in the pipe specimens is calculated usingequations (approximation) for the hoop stress, as follows:S 5 PD 2 t!/2t (1)orS 5PDR 2 1!2(2)where:S = hoop stress, psi (MPa),P = internal pressure, psig (MPa),D = measured average outside di
46、ameter, in. (mm). Forreinforced thermosetting pipe, outside diameter shallnot include nonreinforced covers,t = measured minimum wall thickness, in. (mm). Forreinforced thermosetting pipe use minimum reinforcedwall thickness, andDR = dimension ratio, DR = D/t.NOTE 7An alternative method for calculati
47、ng the hoop stress ofreinforced pipe is given in the Annex of Specification D2517.10.2 Internal pressure in the pipe specimens is calculatedusing equations (approximate) for the internal pressure asfollows:P 52 StD 2 t!(3)or:P 52SDR 2 1!(4)where terms are as defined in 10.1.11. Report11.1 The report
48、 shall include the following:11.1.1 Complete identification of the specimens, includingmaterial type, manufacturers name and code number, andprevious history.11.1.2 Pipe dimensions including nominal size, minimumwall thickness, average outside diameter, length of test speci-men between end closures,
49、 and type of end closure. Forreinforced thermosetting pipe, wall thicknesses and outsidediameter shall be reinforced dimensions only. Unreinforcedthicknesses shall also be reported.11.1.3 Test temperature.11.1.4 Test environment, including conditioning time.11.1.5 Test fluid inside specimens.11.1.6 Test pressure, calculated hoop stress, and time-to-failure for each specimen.11.1.7 When pressure depletion is experienced, the time atwhich the pressure was depleted and time at which pressurewas restored shall be reported. The failure time in t
