1、Designation: D 2837 04e1An American National StandardStandard Test Method forObtaining Hydrostatic Design Basis for Thermoplastic PipeMaterials or Pressure Design Basis for Thermoplastic PipeProducts1This standard is issued under the fixed designation D 2837; the number immediately following the des
2、ignation 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.e1NOTEEquation X4.5 was editorially corrected in November 2006.1. Scope1.1 This test method describes two essentially equivalentprocedures: one for obtaining a long-term hydrostatic strengthcategory based on stress, referred to herein as the hydrostaticdesign
4、 basis (HDB); and the other for obtaining a long-termhydrostatic strength category based on pressure, referred toherein as the pressure design basis (PDB). The HDB is basedon the materials long-term hydrostatic strength (LTHS),andthe PDB is based on the products long-term hydrostaticpressure-strengt
5、h (LTHSP). The HDB is a material propertyand is obtained by evaluating stress rupture data derived fromtesting pipe made from the subject material. The PDB is aproduct specific property that reflects not only the properties ofthe material(s) from which the product is made, but also theinfluence on p
6、roduct strength by product design, geometry, anddimensions and by the specific method of manufacture. ThePDB is obtained by evaluating pressure rupture data. TheLTHS is determined by analyzing stress versus time-to-rupture(that is, stress-rupture) test data that cover a testing period ofnot less tha
7、n 10 000 h and that are derived from sustainedpressure testing of pipe made from the subject material. Thedata are analyzed by linear regression to yield a best-fitlog-stress versus log time-to-fail straight-line equation. Usingthis equation, the materials mean strength at the 100 000-hintercept (LT
8、HS) is determined by extrapolation. The resultantvalue of the LTHS determines the HDB strength category towhich the material is assigned. The LTHSPis similarlydetermined except that the determination is based on pressureversus time data that are derived from a particular product. Thecategorized valu
9、e of the LTHSPis the PDB. An HDB/PDB isone of a series of preferred long-term strength values. This testmethod is applicable to all known types of thermoplastic pipematerials and thermoplastic piping products. It is also appli-cable for any practical temperature and medium that yieldsstress-rupture
10、data that exhibit an essentially straight-linerelationship when plotted on log stress (pound-force per squareinch) or log pressure (pound-force per square in. gage) versuslog time-to-fail (hours) coordinates, and for which this straight-line relationship is expected to continue uninterrupted through
11、at least 100 000 h.1.2 Unless the experimentally obtained data approximate astraight line, when calculated using log-log coordinates, it isnot possible to assign an HDB/PDB to the material. Data thatexhibit high scatter or a “knee” (a downward shift, resulting ina subsequently steeper stress-rupture
12、 slope than indicated bythe earlier data) but which meet the requirements of this testmethod tend to give a lower forecast of LTHS/LTHSP.Inthecase of data that exhibit excessive scatter or a pronounced“knee,” the lower confidence limit requirements of this testmethod are not met and the data are cla
13、ssified as unsuitable foranalysis.1.3 A fundamental premise of this test method is that whenthe experimental data define a straight-line relationship inaccordance with this test methods requirements, this straightline may be assumed to continue beyond the experimentalperiod, through at least 100 000
14、 h (the time intercept at whichthe materials LTHS/LTHSPis determined). In the case ofpolyethylene piping materials, this test method includes asupplemental requirement for the “validating” of this assump-tion. No such validation requirements are included for othermaterials (see Note 1). Therefore, i
15、n all these other cases, it isup to the user of this test method to determine based on outsideinformation whether this test method is satisfactory for theforecasting of a materials LTHS/LTHSPfor each particularcombination of internal/external environments and tempera-ture.NOTE 1Extensive long-term d
16、ata that have been obtained on com-mercial pressure pipe grades of polyvinyl chloride (PVC), polybutlene(PB), and cross linked polyethlene (PEX) materials have shown that thisassumption is appropriate for the establishing of HDBs for these1This test method is under the jurisdiction of ASTM Committee
17、 F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.40 on TestMethods.Current edition approved June 1, 2004. Published July 2004. Originally approvedin 1969. Last previous edition approved in 2002 as D 2837 02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Bo
18、x C700, West Conshohocken, PA 19428-2959, United States.materials for water and for ambient temperatures. Refer to Note 2 andAppendix X1 for additional information.1.4 The experimental procedure to obtain individual datapoints shall be as described in Test Method D 1598, whichforms a part of this te
19、st method. When any part of this testmethod is not in agreement with Test Method D 1598, theprovisions of this test method shall prevail.1.5 General references are included at the end of this testmethod.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with
20、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.1.7 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are
21、 forinformation only and are not considered the standard.NOTE 2Over 3000 sets of data, obtained with thermoplastic pipe andpiping assemblies tested with water, natural gas, and compressed air, havebeen analyzed by the Plastic Pipe Institutes2(PPI) Hydrostatic StressBoard. None of the currently comme
22、rcially offered compounds includedin PPI TR-4, “PPI Listing of Hydrostatic Design Bases (HDB), PressureDesign Bases (PDB), Strength Design Bases (SDB), and MinimumRequired Strength (MRS) Ratings for Thermoplastic Piping Materials orPipe” exhibit knee-type plots at the listed temperature, that is, de
23、viatefrom a straight line in such a manner that a marked drop occurs in stressat some time when plotted on equiscalar log-log coordinates. Ambienttemperature stress-rupture data that have been obtained on a number of thelisted materials and that extend for test periods over 120 000 h give noindicati
24、on of “knees.” However, stress-rupture data which have beenobtained on some thermoplastic compounds that are not suitable orrecommended for piping compounds have been found to exhibit adownward trend at 23C (73F) in which the departure from linearityappears prior to this test methods minimum testing
25、 period of 10 000 h. Inthese cases, very low results are obtained or the data are found unsuitablefor extrapolation when they are analyzed by this test method.Extensive evaluation of stress-rupture data by PPI and others has alsoindicated that in the case of some materials and under certain testcond
26、itions, generally at higher test temperatures, a departure fromlinearity, or “down-turn”, may occur beyond this test methods minimumrequired data collection period of 10 000 h.APPI study has shown that inthe case of polyethylene piping materials that are projected to exhibit a“down-turn” prior to 10
27、0 000 h at 73F, the long-term field performanceof these materials is prone to more problems than in the case of materialswhich have a projected “down-turn” that lies beyond the 100 000-hintercept. In response to these observations, a supplemental “validation”requirement for PE materials has been add
28、ed to this test method in 1988.This requirement is designed to reject the use of this test method for theestimating of the long-term strength of any PE material for whichsupplemental elevated temperature testing fails to validate this testmethods inherent assumption of continuing straight-line stres
29、s-rupturebehavior through at least 100 000 h at 23C (73F).When applying this test method to other materials, appropriate consid-eration should be given to the possibility that for the particular grade ofmaterial under evaluation and for the specific conditions of testing,particularly, when higher te
30、st temperatures and aggressive environmentsare involved, there may occur a substantial “down-turn” at some pointbeyond the data collection period. The ignoring of this possibility maylead to an overstatement by this test method of a materials actualLTHS/LTHSP. To obtain sufficient assurance that thi
31、s test methodsinherent assumption of continuing linearity through at least 100 000 h isappropriate, the user should consult and consider information outside thistest method, including very long-term testing or extensive field experiencewith similar materials. In cases for which there is insufficient
32、 assurance ofthe continuance of the straight-line behavior that is defined by theexperimental data, the use of other test methods for the forecasting oflong-term strength should be considered (see Appendix X1).2. Referenced Documents2.1 ASTM Standards:3D 1243 Test Method for Dilute Solution Viscosit
33、y of VinylChloride PolymersD 1598 Test Method for Time-to-Failure of Plastic PipeUnder Constant Internal PressureE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 ISO/DIS Standard:ISO/DIS 9080 Plastic Piping and Ducting Systems, Deter-mination of L
34、ong-Term Hydrostatic Strength of Thermo-plastics Materials in Pipe Form by Extrapolation42.3 Plastics Pipe Institute:PPI TR-3 Policies and Procedures for Developing HDB,SDB, PDB, and MRS Ratings for Thermoplastic PipingMaterials or PipePPI TR-4 PPI Listing of Hydrostatic Design Bases (HDB),Strength
35、Design Bases (SDB), Pressure Design Bases(PDB) and Minimum Required Strength (MRS) Ratingsfor Thermoplastic Piping Materials or Pipe3. Terminology3.1 Definitions:3.1.1 failurebursting, cracking, splitting, or weeping(seepage of liquid) of the pipe during test.3.1.2 hoop stressthe tensile stress in t
36、he wall of the pipein the circumferential orientation due to internal hydrostaticpressure.3.1.3 hydrostatic design basis (HDB)one of a series ofestablished stress values for a compound. It is obtained bycategorizing the LTHS in accordance with Table 1.3.1.4 hydrostatic design stress (HDS)the estimat
37、ed maxi-mum tensile stress the material is capable of withstandingcontinuously with a high degree of certainty that failure of thepipe will not occur. This stress is circumferential when internalhydrostatic water pressure is applied.3.1.5 long-term hydrostatic strength (LTHS)the estimatedtensile str
38、ess in the wall of the pipe in the circumferentialorientation that when applied continuously will cause failure ofthe pipe at 100 000 h. This is the intercept of the stressregression line with the 100 000-h coordinate.3.1.6 long-term hydrostatic pressure-strength (LTHSP)the estimated internal pressu
39、re that when applied continu-ously will cause failure of the pipe at 100 000 h. This is theintercept of the pressure regression line with the 100 000-hinterce2Plastics Pipe Institute, 1825 Connecticut Avenue N.W., Suite 680, Washington,DC 20009.3For referenced ASTM standards, visit the ASTM website,
40、 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.4Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 10036.D283704e123.1.7
41、pressurethe force per unit area exerted by themedium in the pipe.3.1.8 pressure rating (PR)the estimated maximum waterpressure the pipe is capable of withstanding continuously witha high degree of certainty that failure of the pipe will not occur.3.1.8.1 The PR and HDS/HDB are related by the followi
42、ngequation.PR 5 2 HDB! DF!/SDR21! 5 2 HDS!/SDR21! (1)3.1.8.2 The PR and PDB are related by the followingequation:PR 5 PDB! DF! (2)3.1.9 pressure design basis (PDB)one of a series ofestablished pressure values for plastic piping components(multilayer pipe, fitting, valve, etc.) obtained by categorizi
43、ngthe LTHSPin accordance with Table 2.3.1.10 service (design) factor (DF)a number less than1.00 (which takes into consideration all the variables anddegree of safety involved in a thermoplastic pressure pipinginstallation) which is multiplied by the HDB to give the HDS,or multiplied by the PDB to gi
44、ve the pressure rating.3.1.11 The following equations shall be used for the relationbetween stress and pressure:S 5 PD 2 t!/2t for outside diameter controlled pipe (3)orS 5 Pd 1 t!/2t for inside diameter controlled pipe (4)where:S = stress,P = pressure,D = average outside diameter,d = average inside
45、 diameter, andt = minimum wall thickness.4. Significance and Use4.1 The procedure for estimating long-term hydrostaticstrength or pressure-strength is essentially an extrapolationwith respect to time of a stress-time or pressure-time regressionline based on data obtained in accordance with Test Meth
46、odD 1598. Stress or pressure-failure time plots are obtained forthe selected temperature and environment: the extrapolation ismade in such a manner that the long-term hydrostatic strengthor pressure strengthis estimated for these conditions.NOTE 3Test temperatures should preferably be selected from
47、thefollowing: 40C; 50C; 60C; 80C; 100C. It is strongly recommendedthat data also be generated at 23C for comparative purposes.4.2 The hydrostatic or pressure design basis is determinedby considering the following items and evaluating them inaccordance with 5.4.4.2.1 Long-term hydrostatic strength or
48、 hydrostaticpressure-strength at 100 000 h,4.2.2 Long-term hydrostatic strength or hydrostaticpressure-strength at 50 years, and4.2.3 Stress that will give 5 % expansion at 100 000 h.4.2.4 The intent is to make allowance for the basic stress-strain characteristics of the material, as they relate to
49、time.4.3 Results obtained at one temperature cannot, with anycertainty, be used to estimate values for other temperatures.Therefore, it is essential that hydrostatic or pressure designbases be determined for each specific kind and type of plasticcompound and each temperature. Estimates of long-termstrengths of materials can be made for a specific temperatureprovided that calculated values, based on experimental data,are available for temperatures both above and below thetemperature of interest.4.4 Hydrostatic design stresses are obtained
