ANSI ASTM F1734-2003 Standard Practice for Qualification of a Combination of Squeeze Tool Pipe and Squeeze-Off Procedures to Avoid Long-Term Damage in Polyethylene (PE) Gas Pipe《为避.pdf

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1、Designation: F1734 03 (Reapproved 2009) An American National StandardStandard Practice forQualification of a Combination of Squeeze Tool, Pipe, andSqueeze-Off Procedures to Avoid Long-Term Damage inPolyethylene (PE) Gas Pipe1This standard is issued under the fixed designation F1734; the number immed

2、iately following the designation 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This

3、practice covers qualifying a combination of asqueeze tool, a polyethylene gas pipe, and a squeeze-offprocedure to avoid long-term damage in polyethylene gas pipe.Qualifying is conducted by examining the inside and outsidesurfaces of pipe specimens at and near the squeeze to deter-mine the existence

4、of features indicative of long-term damage.If indicative features are absent, sustained pressure testing inaccordance with Specification D2513 is conducted to confirmthe viability of the squeeze-off process. For assistance withspecimen examination, an Adjunct, ADJF17342, is availablefrom ASTM.1.2 Th

5、is practice is appropriate for any combination ofsqueeze tool, PE gas pipe and squeeze-off procedure, and isparticularly appropriate for pre-1975 Polyethylene (PE) pipe,and for pipe sizes of 8 in. or above, because of a greaterpossibility of long-term damage.1.3 This practice is for use by squeeze-t

6、ool manufacturers,pipe manufacturers and gas utilities to qualify squeeze toolsmade in accordance with Specification F1563; and squeeze-offprocedures in accordance with Guide F1041 with pipe manu-factured in accordance with Specification D2513.1.4 Governing codes and project specifications should be

7、consulted. Nothing in this practice should be construed asrecommending practices or systems at variance with governingcodes and project specifications.1.5 Where applicable in this guide, “pipe” shall mean “pipeand tubing.”1.6 UnitsThe values stated in inch-pound units are to beregarded as standard.

8、The values given in parentheses aremathematical conversions to SI units that are provided forinformation only and are not considered standard.1.7 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

9、 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:3D2513 Specification for Polyethylene (PE) Gas PressurePipe, Tubing, and FittingsD3350 Specification for Polyethylene Plastics Pipe

10、 and Fit-tings MaterialsF1041 Guide for Squeeze-Off of Polyolefin Gas PressurePipe and TubingF1563 Specification for Tools to Squeeze-off Polyethylene(PE) Gas Pipe or Tubing2.2 ASTM Adjuncts:Interpretation Aid for Squeeze-Off Damage23. Terminology3.1 Definitions:3.1.1 squeeze-off, na technique used

11、to temporarily con-trol the flow of gas in a polyethylene gas pipe by flattening thepipe with a mechanical or hydraulic device.3.1.2 squeeze process, nthe combination of the squeezetool, the pipe being squeezed, and the squeeze-off procedurebeing used.3.1.3 wall compression (WC), nthe percentage ext

12、ent towhich the pipe walls are compressed when the pipe issqueezed. (See Fig. 1.) It is defined as:WC,%5S1 2L2tD3100 (1)1This practice is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.60 on Gas.Current edition approved Aug.

13、 1, 2009. Published September 2009. Originallyapproved in 1996. Last previous edition approved in 2003 as F1734 03. DOI:10.1520/F1734-03R09.2Available from ASTM International Headquarters. Order Adjunct No.ADJF1734. Original adjunct produced in 1995.3For referenced ASTM standards, visit the ASTM web

14、site, 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 Conshohocken, PA 19428-2959. United Stat

15、esThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Tra

16、de (TBT) Committee.1where:L = distance between the squeeze tool bars as shown in Fig.1, andt = uncompressed pipe wall thickness, expressed in thesame units as L.3.1.3.1 DiscussionWhen the distance between the squeezetool bars is greater than twice the wall thickness, the pipe wallsare not compressed

17、, which yields a negative value for the wallcompression percentage. The value becomes positive when theL value is less than the 2t value. Typical squeeze tool stops areset for 30 % or less wall compression based on maximum wallthickness (a distance that is 70 % of twice maximum wallthickness when th

18、e squeeze tool is closed to the stops).Maximum wall thickness is the minimum wall thickness plusthe wall thickness tolerance.4. Summary of Practice4.1 Pipe of the size and material of interest is cut intospecimens at least 1 ft long or 3 diameters long whichever isgreater, and attached to a supply o

19、f pressurized gas. Withpressurized gas flowing through the specimen, the specimensare squeezed with the tool of interest, using the procedure ofinterest, until the desired level of flow control is achieved.Using Eq 1, the wall compression percentage at the desiredlevel of flow control is determined.

20、 Let this level of wallcompression be called WCnom. Additional specimens aresqueezed to obtain squeeze levels that are 5 % greater, 10 %greater, 5 % less and 10 % less than WCnom. This squeezerange brackets levels of wall compression for flow control.NOTE 1For example, if the desired level of flow c

21、ontrol wereachieved at 25 % wall compression, additional specimens would beprepared at 35 %, 30 %, 20 % and 15 % wall compression. In researchtests, a flow of 0.1 ft3/h was considered equivalent to stopping the flow.4,54.2 The squeezed samples are split along their length at 90degrees to the squeeze

22、 “ears” (See Fig. 1). The area containingthe ears is examined visually using the unaided eye, thenmagnification. Features such as crazing, small voids, or cracksindicate permanent damage and disqualify the squeeze-offprocess.4.3 Where the results of the visual screening do not indicatepermanent dama

23、ge, additional specimens are squeezed at theWC level where damage is not indicated, and sustainedpressure tests in accordance with Specification D2513 areperformed. When sustained pressure test specimens meet therequirements of Specification D2513, the squeeze-off processhas been verified.4.3.1 When

24、 damage is identified at WCnom less 5 % orWCnom less 10 % levels, a wall compression percentage wheredamage does not occur should be identified. Prepare additionalspecimens by lessening wall compression in 5 % increments,and then examine the specimens to identify a wall compressionpercentage that do

25、es not indicate damage.NOTE 2This practice uses flow through the squeezed-off pipe as aparameter. For some combinations of tool, pipe and procedure, it is notpossible to stop flow completely without causing permanent damage to thepipe, particularly for pipes greater than 2 in, nominal size.4.4 Using

26、 a desired squeeze-off procedure, tests conductedat different pipe temperatures with various sizes of tools andpipes can be used to verify a range of temperatures, tool sizes,and pipe sizes for which the squeeze-off process is applicable.5. Significance and Use5.1 Squeeze-off is widely used to tempo

27、rarily control theflow of gas in PE pipe. Squeeze tools vary depending on thesize of the pipe and the design of the tool. Squeeze-offprocedures vary depending on the tool design, pipe material,and environmental conditions.5.2 Experience indicates that some combinations of poly-ethylene material, tem

28、perature, tool design, wall compressionpercentage and procedure can cause damage leading to failure.5.3 Studies of polyethylene pipe extruded in the late 1980sand thereafter show that damage typically does not developwhen the wall compression percentage is 30 % or less, whentemperatures are above 50

29、F (10C), and when closure andrelease rates are typical of field conditions for screw-driventools.4With tools meeting Specification F1563, acceptableflow control at typical gas service pressures is achieved at wallcompression percentages between 10 and 20 % for pipe diam-eters less than 6 in.4,5Becau

30、se damage does not develop inthese materials at such squeeze levels, the references citedindicate that squeeze-off flow control practices using toolsmeeting Specification F1563 and qualified procedures meetingPractice F1041 are effective for smaller pipe sizes.4,5NOTE 3Specification F1563 provides a

31、 procedure for evaluating toolflow control performance.4Stephens, D. R., Leis, B. N., Francini, R. B., and Cassady, M. J., Volume 1:Users Guide on Squeeze-Off of Polyethylene Gas Pipes, Topical Report GRI-92/0147.1, NTIS PB93-161032, Battelle Columbus for Gas Research Institute, Febru-ary 1992.5Step

32、hens, D. R., Leis, B. N., Francini, R. B., and Cassady, M. J., Volume 2:Technical Reference on Squeeze-Off of Polyethylene Gas Pipes, Topical ReportGRI-92/0147.2, NTIS PB93-161040, Battelle Columbus for Gas Research Institute,October 1992.FIG. 1 Definition of Wall CompressionF1734 03 (2009)25.4 This

33、 practice provides a method to qualify a combina-tion of squeeze tool, pipe size and material, and squeeze-offprocedure to ensure that long-term damage does not occur.This practice is useful for polyethylene gas pipe manufacturedbefore 1975, for new or revised polyolefin gas pipe materials,for pipe

34、diameters of 8 in. or above, for new or revised squeezetool designs, and for new or revised squeeze-off procedures.6. Interpretation of Results6.1 This practice relies on a screening process using visualinspection followed by sustained pressure testing as describedin Specification D2513 to qualify a

35、 squeeze-off process.6.2 The area of wrinkling at the ears on the inside diameter(ID) of the pipe and the area on the outside of the pipe oppositethe ears are examined . Evidence of any one or a combinationof void formation, cracks or extensive localized stresswhitening, or failure during sustained

36、pressure testing disquali-fies the squeeze-off process.6.3 Unacceptable features implying long-term damage areshown in the photographs in adjunct, ADJF17342.7. Apparatus7.1 Squeeze-off Tools, meeting Specification F1563 that areto be covered by the squeeze-off process.7.2 Pipe Cutters and Saws, capa

37、ble of cutting the PE pipe.7.3 Jewelers Loupe or (Stereo) Optical Microscope, pro-viding 10 or higher magnification.7.4 Vernier Caliper or Ball-End Micrometer, with an accu-racy of at least 0.001 in.7.5 Stopwatch, that can indicate time to at least the nearestsecond.8. Materials8.1 Polyethylene pipe

38、 meeting Specification D2513.9. Safety Precautions9.1 Care should be taken and appropriate protective equip-ment for eyes and persons is required when working withhydraulic and power tools that may be used in the squeeze-offprocess. Personal hearing protection is required when com-pressed gas is dis

39、charged from open-ended specimens.10. Preparation of the Sample and Equipment10.1 Select pipe samples at least 3 pipe diameters long butnot less than 1 ft long.10.2 Measure the pipe wall thickness at 15 incrementsaround the pipe, and identify the location of maximum wallthickness.10.3 Condition samp

40、les to the temperature of interest.Studies show that at very low temperatures or on thicker-walled pipe significant hold times are necessary to reachthermal equilibrium. Experience with smaller-diameter, lowerSDR pipe (for example, 2 to 6-in. SDR 11 pipe) indicates thata minimum of 24 h is required

41、for the sample to reachequilibrium.11. Procedure11.1 Orient the sample in the squeeze tool so that thethickest portion of the pipe wall forms one of the squeeze-offears. Locate the squeeze tool at the midpoint of the samplelength so that the tool is centered on the sample and square tothe centerline

42、 of the sample.11.2 The squeeze bar shims or stops, or both, must be within1 % of the target level.11.3 Operate the tool in accordance with the procedure ofinterest, close the bars to the distance required for the desiredwall compression, and hold for at least 30 min. Closure stopsmay need to be rem

43、oved or smaller stops or shims may beneeded to obtain the closure distance required.11.4 Release the squeeze in accordance with the procedureof interest.11.5 If re-rounding is included in the procedure of interest,re-round the sample accordingly.11.6 Allow the sample to sit undisturbed without exter

44、nalforce at the desired temperature for 24 h.11.7 Cut a ring from the pipe sample. The ring is to be atleast 2 pipe diameters in length with the squeeze in the middleof the ring. Cut the ring lengthwise with the squeeze-earsoriented 90 to the plane of the cut.11.8 Visual ExaminationWith the unaided

45、eye, and thenwith magnification, examine the interior of the sample at eachsqueeze ear for stress whitening, crazing, or cracking. Examinethe exterior of the sample at the squeeze ears for evidence of adimple centered at the ear. Examine first with the unaided eye.Samples that pass unaided eye visua

46、l examination are thenvisually examined under 10 magnification.11.8.1 Unaided-Eye Visual Examination:11.8.1.1 Wrinkling of the interior of the squeeze-off ear isexpected to occur. Some stress whitening along the ridges andin the valleys of wrinkles is also expected to occur. Stresswhitening should b

47、e limited to these ridges and valleys in theregion where wall thinning occurs in response to the squeezeprocess. Stress whitening should be diffuse in appearancerather than an intense white band.11.8.1.2 Cracking or voids on the inside or a dimple on theoutside disqualify the squeeze-off process.11.

48、8.1.3 A dimple on the outside of the pipe, or stresswhitening strung out along a severe wrinkle on the inside of thepipe, at WCnom plus 5 %, WCnom, WCnom less 5 % orWCnom less 10 % levels disqualify the squeeze-off process.11.8.2 Magnified Visual Examination :11.8.2.1 At 10 magnification, examine th

49、e interior of thesqueeze ear of samples that pass the unaided-eye examination,Cracking or voids disqualify the squeeze-off process.11.8.2.2 At 10 magnification, stress whitening strung outalong a wrinkle is evidence of damage that can grow with time.Judgment, depending on the severity of the features, the serviceconditions, and the utilitys service record for that pipe, candisqualify the squeeze procedure if such features are found.11.8.2.3 General widespread evidence of changes in color,such as intense stress whitening or crazing, is evidence ofF1734 03 (2009)