ASTM F1588-1996(2002) Standard Test Method for Constant Tensile Load Joint Test (CTLJT)《恒定拉伸载荷连接试验的标准试验方法》.pdf

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1、Designation: F 1588 96 (Reapproved 2002)An American National StandardStandard Test Method forConstant Tensile Load Joint Test (CTLJT)1This standard is issued under the fixed designation F 1588; the number immediately following the designation indicates the year oforiginal adoption or, in the case of

2、 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.1. Scope1.1 The constant tensile load joint test (CTLJT) is designedto demonstrate that a joint in a plast

3、ic piping system is resistantto the effects of long-term creep.1.1.1 The joint is subjected to an internal pressure at leastequal to its operating pressure and a sustained axial tensile loadfor a specified time period, usually 1000 h. The joint shall notleak, nor may the pipe completely pull out for

4、 the test duration.The total axial stress is set by the referencing document.1.1.2 Some typical conditions for testing of joints on poly-ethylene pipe are described in Appendix X1.1.2 This test is usually performed at 73F (22.8C).1.3 The CTLJT was developed to demonstrate the long-termresistance to

5、pullout of mechanical joints on polyethylene gaspipe. The CTLJT has also been successfully applied to theevaluation of other components of plastic piping systems.These applications are discussed in Appendix X1.1.4 This standard does not purport to address all of thesafety concerns, if any, associate

6、d 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:D 638 Test Method for Tensile Properties of Plastics2D 1600 Ter

7、minology for Abbreviated Terms Relating toPlastics2D 2122 Test Method for Determining Dimensions of Ther-moplastic Pipe and Fittings3D 2513 Specification for Thermoplastic Gas Pressure Pipe,Tubing, and Fittings3F 412 Terminology Relating to Plastic Piping Systems32.2 ANSI Standard:B31.8 Gas Transmis

8、sion and Distribution Piping Systems42.3 Code of Federal Regulations:OPS Part 192, Title 4953. Terminology3.1 Definitions:3.1.1 GeneralDefinitions are in accordance with TestMethod D 638 and Terminology F 412, unless otherwise speci-fied. Abbreviations are in accordance with TerminologyD 1600.3.1.2

9、The gas industry terminology used in this test methodis in accordance with the definitions given in ANSI B31.8 orOPS Part 192, Title 49, unless otherwise indicated.3.2 Definitions of Terms Specific to This Standard:3.2.1 mechanical joint, Category 1a mechanical jointdesign that provides a seal plus

10、a resistance to force on the pipeend, equal to or greater than that which will cause a permanentdeformation of the pipe or tubing. (D 2513)3.2.2 mechanical joint, Category 3a mechanical jointdesign that provides a seal plus a pipe restraint rating equiva-lent to the anticipated thermal stresses occu

11、rring in a pipeline.This category has a manufacturers pipe-end restraint thatallows slippage at less than the value required to yield the pipe.(D 2513)3.2.3 piperefers to both pipe and tubing.4. Summary of Test Method4.1 A joint is subjected to a sustained axial load for aspecified period of time (u

12、sually 1000 h). The test duration andthe actual test conditions (axial stress, internal pressure, testduration, and test temperature) are either specified by areferencing document or, for new or unique applications,agreed upon between the user and the manufacturer. X1.2contains a background discussi

13、on of axial stress values andaxial load determination.4.2 The joint is made to plastic pipe of the type, grade, size,and dimension ratio to be used in the final application. Theaxial tensile stress should be as high as possible, but shall belower than the stress at which the plastic material continu

14、es tostretch and finally yields (the long-term yield strength) (seeNote 1).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 March 10, 1996. Published May 1996. Or

15、iginallypublished as F 1588 95. Last previous edition F 1588 95.2Annual Book of ASTM Standards, Vol 08.01.3Annual Book of ASTM Standards, Vol 08.04.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.5Available from Superintendent of Documents,

16、Government Printing Office,Washington, DC 20402.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 1During the first hours of a test, the pipe elongates measurably.Elongation continues for the duration of the test at a decaying rat

17、e.4.3 A joint passes this test if it does not leak and does notpull out or allow slippage in excess of the manufacturersspecified design slippage during the test duration.4.4 If a pipe in the test assembly yields before the specifiedminimum test time is attained, the total stress is above thelong-te

18、rm yield strength of that pipe and the test shall beperformed again at a stress level calculated to be below thelong-term yield strength of the pipe.5. Significance and Use5.1 This test method was designed to be used to validate thelong-term resistance to pullout of joints designed for use inplastic

19、 natural gas piping systems.5.2 This test method is used in addition to the short-termtests required by OPS Part 192.283b, Title 49. Informalversions of this test method are used by manufacturers andutilities to demonstrate that a joint is resistant to the effects oflong-term creep and meets the req

20、uirements for classificationas a Category 1 or a Category 3 joint in accordance withSpecification D 2513.5.3 This test method may also be applicable for the deter-mination of the effects of a sustained axial load on joints orother components of plastic piping systems designed for otherapplications.

21、Test parameters and the internal pressurizingfluid, if any, should be listed in the referencing document.5.4 Documents that reference this test method for productsother than joints shall specify test conditions and performancerequirements. In general, such products pass this test if theymaintain the

22、ir structural integrity, do not leak, and perform tospecification during and after the test.6. Apparatus6.1 Loading Methods:6.1.1 Any loading method that maintains the correct, in-linetensile load on the joint (within 62 %) for the test duration isacceptable. Loading methods successfully employed fo

23、r allsize loads include lever arms, hydraulic cylinders, and aircylinders.6.1.2 Dead weight (a pile of scrap steel or iron) has workedwell for loads up to 1 ton (907 kg) (see Note 2).NOTE 2To provide an adequate stress level for58 in. DR 7 PE tubing,about 200 lb (90 kg) are required. Pipe 2 in. SDR1

24、1 PE requires about2000 lb (907 kg).6.1.3 Hydraulic and air-powered loading frames have beenconstructed to provide up to 50 000 lb (22 680 kg) for tests on3-in. IPS through 8-in. IPS joints. The stroke of the cylindershould be adequate for the material being tested.6.2 Applied Axial Load Determinati

25、on MonitoringTheapplied axial load shall be maintained to within 62 % of thecalculated value.6.2.1 Dead weight is weighed before the start of a test.6.2.2 In systems with air or hydraulic cylinders, a load-celland indicator may be used between the cylinder and the testassembly. An alternative is to

26、accurately establish the relation-ship between inlet pressure and the force generated by acylinder and then to monitor a pressure gage placed in thepressurization line to the cylinder during the test.6.3 Pressure GageEach assembly shall have a pressuregage to monitor internal pressure on the test as

27、sembly. Thegage shall be able to measure the test pressure to within anaccuracy of 1 % or better.6.4 Test Assembly:6.4.1 The test assembly is capped and verified to be leaktight. Attachment devices that ensure straight line axial loadingshall be used at each end to attach the test assembly to theloa

28、ding device. The test assembly may contain more than onejoint of the size under evaluation (see Note 3).NOTE 3There are many configurations possible with the wide varietyof joints that are available. If the mechanical joint to be tested is suitablefor the purpose, it can be used to cap the pipe ends

29、.6.4.2 The minimum length is three pipe diameters betweenfittings (stiffener ends). Elongation is proportional to specimenlength. It is important to allow sufficient space in the apparatusto provide for anticipated elongation of the test specimen forthe duration of the test.7. Precautions and Safety

30、 Considerations7.1 Each test fixture and joint assembly shall be designed tosafely accommodate a sudden unexpected failure in any part ofthe test assembly. Both fixture and joint(s) shall be regularlyinspected for safety. Joint pullouts usually occur unexpectedlyand proceed from start to finish in s

31、econds. Failure may beaccompanied by the sudden release of the internal pressure ora falling test assembly, or both.7.2 It is strongly recommended that water be used as thepressurizing fluid when testing systems that may fail in a brittlemanner (specifically PVC systems). If that is not possible, th

32、etest specimens shall be placed in a strong chamber at all timeswhen pressurized (see Note 4).NOTE 4For example, after 938 h of uneventful testing, one 6-in. IPStransition joint rapidly pulled apart. There was no indication of pipemovement when inspected 5 min before failure.8. Test Specimens8.1 Pip

33、e Specimen Selection:8.1.1 For tests of fittings intended for use in natural gasdistribution systems, the pipe supply used for the tests shallhave a print line signifying that it was manufactured to therequirements of Specification D 2513.8.1.2 Pipe specimens used for fittings tests shall meet thedi

34、mensional requirements of the referencing document. (SeeNote 5.) The dimensions of the pipe specimens selected for usein an evaluation shall be known and reported.NOTE 5Some fittings may perform well with pipe of the nominaloutside diameter and wall thickness and fail if assembled to pipe at thelimi

35、ts of the dimensional tolerances. To ensure good performance on thefull range of pipe dimensions that meet specifications, it may be necessaryto procure or to manufacture specimens at the extremities of both wallthickness and outside diameter and to perform verification tests on one ormore sizes of

36、such material.8.2 Specimen Preparation:F 1588 96 (2002)28.2.1 Cut the required number of thermoplastic pipe speci-mens to length. Make each pipe specimen a minimum of threepipe diameters long plus the length needed for insertion intothe fitting(s).8.2.2 To obtain dimensions and to verify that pipe u

37、sed forthe test meets ASTM dimensional requirements, perform thefollowing measurements on each specimen, a representativesample from a coil, or 40-ft (12-m) long straight length.8.2.2.1 Measure the outside diameter (OD) at the center ofa specimen, using a circumferential wrap tape, in accordancewith

38、 Test Method D 2122.8.2.2.2 Using the procedures for wall thickness measure-ment and calculation of the average wall thickness in TestMethod D 2122, measure the wall thickness at each end of aspecimen and calculate the average wall thickness (AWT).9. Assembly9.1 Install the fittings on the pipe spec

39、imens in accordancewith the manufacturers instructions.9.2 With a marking pen or similar device, place an indexmark on the pipe directly adjacent to the ends of all mechanicalfittings, so that any slippage can be measured and compared tothat which may be allowed by the manufacturers specifica-tions.

40、 Some displacement of this mark under load is normaldue to the stretching of the material in the joint.10. Procedure10.1 The test assembly shall be conditioned to the testtemperature for a minimum of 12 h before the load is applied.10.2 Install the test assembly into the long-term loadingdevice.10.3

41、 Inspect all parts of the test assembly and the loadingmechanism for safety before applying the tensile load.10.4 After 24 h of loading, examine all joints in theassembly for signs of slippage. If the slippage does not exceedthat specified by the manufacturer for the joint under test,slowly introduc

42、e the pressurizing fluid into the assembly to thefull operating pressure 61%.10.5 Monitor for leaks and record the ambient temperature,the tensile load, the amount of slippage (if any), and theinternal pressure for the duration of the test.11. Calculation11.1 Load Calculation Method 1:11.1.1 Calcula

43、te the cross sectional area, A, of the pipe wall,as follows:A5p3AWT 3 OD 2 AWT! (1)11.1.2 Calculate the tensile load, P, as follows:11.1.2.1 Calculate the total load, PT, as follows:PTlb!5stress psi!3 A in.2! (2)11.1.2.2 Calculate the axial loading generated by the inter-nal pressure, P1, as follows

44、:P15p/4 3 OD2in.2!3 test pressure psig! (3)11.1.2.3 Calculate the load (lb) to be applied by the loadingmechanism, P2, as follows:P25 PT2 P1(4)11.2 Load Calculation Method 2:11.2.1 This alternative load calculation method has beenincluded to accommodate producers who use this test methodfor large nu

45、mbers of developmental tests. The procedure in11.1 is recommended for referee-type tests because the error inthe calculated cross-sectional area of in-specification pipe mayexceed 10 % if this alternative method is used.11.2.2 Calculate the cross-sectional area of the pipe wall, A,as follows:A5p3MW

46、3 MOD 2 MW! (5)where:MW = maximum wall from Table 2 or 3 of SpecificationD 2513, andMOD = maximum outside diameter from Table 2 or 3 ofSpecification D 2513.11.2.3 Calculation of Tensile Load, P:11.2.3.1 Calculate the total load as follows:PTlb!5stress psi!3A in.2! (6)11.2.3.2 Calculate the axial loa

47、ding generated by the inter-nal pressure, P1, as follows:P15p/4 3 OD2in.2!3 test pressure psig! (7)11.2.3.3 Calculate the load (lb) to be applied by the loadingmechanism, P2, as follows:P25 PT2 P1(8)12. Report and Documentation12.1 Report the following information for each product orjoint under eval

48、uation:12.1.1 Test duration (h),12.1.2 Axial tensile stress (psi) in the pipe wall for the pipesection in that particular joint,12.1.3 Cross-sectional area (in.2) of pipe wall and the load(lb),12.1.4 Name the pressurization fluid: air or water,12.1.5 Leakage,12.1.6 Ambient temperature range, and12.1

49、.7 Any slippage detected between pipe and fitting up toand including a pullout. Compare this to the manufacturersallowable slippage, if any, and to the appropriate standards andspecifications. Indicate whether the joint passed or failed.13. Precision and Bias13.1 Products subjected to this test either leak, slip beyondthe manufacturers design, or pull out and fail the test. Orproducts subjected to this test do not pull out, slip within thelimits set by the manufacturer, and do not leak and pass the test.Therefore, no precision or bias statement is nece