1、Designation: D 2837 08An 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 desig
2、nation 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.This standard has been approved for use by
3、agencies of the Department of Defense.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 basis (HDB); and the other for obtaining a long-termhydrostatic s
4、trength 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-strength (LTHSP). The HDB is a material propertyand is obtained by evalua
5、ting 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 product strength by product design, geometry, anddimensions and by
6、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 than 10 000 h and that are derived from sustainedpressure testing of
7、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 (LTHS) is determined by extrapolation. The resultantvalue of the LTHS
8、 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 value of the LTHSPis the PDB. An HDB/PDB isone of a series of preferre
9、d 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 data that exhibit an essentially straight-linerelationship when pl
10、otted 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 throughat least 100 000 h.1.2 Unless the experimentally obtained data app
11、roximate 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 slope than indicated bythe earlier data) but which meet the requi
12、rements 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 classified as unsuitable foranalysis.1.3 A fundamental premise of thi
13、s 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 h (the time intercept at whichthe materials LTHS/LTHSPis determin
14、ed). 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, in all these other cases, it isup to the user of this test method t
15、o 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 data that have been obtained on com-mercial pressure pipe grades of
16、 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 F17 on PlasticPiping Systems and is the direct responsibility of
17、Subcommittee F17.40 on TestMethods.Current edition approved May 1, 2008. Published June 2008. Originallyapproved in 1969. Last previous edition approved in 2004 as D 2837 041.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.materials
18、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 test method. When any part of this testmethod is not in agreement wi
19、th 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 its use. It is theresponsibility of the user of this standard to e
20、stablish 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 forinformation only and are not considered the standard.NOTE 2Ove
21、r 3000 sets of data, obtained with thermoplastic pipe andpiping assemblies tested with water, natural gas, and compressed air, havebeen analyzed by the Plastic Pipe Institutes (PPI) Hydrostatic StressBoard2. None of the currently commercially offered compounds includedin PPI TR-4, “PPI Listing of Hy
22、drostatic 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, deviatefrom a straight line in such a manner that a marked drop occ
23、urs 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 noindication of “knees.” However, stress-rupture data which have beenobtain
24、ed 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 period of 10 000 h. Inthese cases, very low results are obtained
25、 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 testconditions, generally at higher test temperatures, a departure fromli
26、nearity, 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 100 000 h at 73F, the long-term field performanceof these materials
27、 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 added to this test method in 1988.This requirement is designed to re
28、ject 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 stress-rupturebehavior through at least 100 000 h at 23C (73F).When ap
29、plying 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 test temperatures and aggressive environmentsare involved, there ma
30、y 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 this test methodsinherent assumption of continuing linearity through
31、 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 assurance ofthe continuance of the straight-line behavior that i
32、s 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 Viscosity of VinylChloride PolymersD 1598 Test Method for Time-to-Failure
33、 of Plastic PipeUnder Constant Internal PressureE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 ISO Standard:ISO 9080 Plastic Piping and Ducting Systems, Determina-tion of Long-Term Hydrostatic Strength ofThermoplasticsMaterials in Pipe Form by E
34、xtrapolation42.3 Plastics Pipe Institute:2PPI 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 Design Bases (SDB), Pressure Design Bases(PDB) and Minimum Required Strengt
35、h (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 the wall of the pipein the circumferential orientation due to internal hydro
36、staticpressure.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 estimated maxi-mum tensile stress the material is capable of withstandingcontinuou
37、sly 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 stress in the wall of the pipe in the circumferentialorientation that when app
38、lied 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 pressure that when applied continu-ously will cause failure of the pipe at 100 00
39、0 h. This is theintercept of the pressure regression line with the 100 000-hinterce2Available from Plastics Pipe Institute (PPI), 105 Decker Court, Suite 825,Irving, TX 75062, http:/www.plasticpipe.org.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Serv
40、ice 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 (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.orgD28370823.1.7 pressurethe force p
41、er 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 followingequation.PR 5 2 H
42、DB! 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 categorizingthe LTHSPin accor
43、dance 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 give the pressure rat
44、ing.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 diameter, andt = m
45、inimum 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 MethodD 1598. Stress or
46、 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 thefollowing: 40C;
47、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 hydrostaticpressur
48、e-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 time.4.3 Results ob
49、tained 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 by multiplyingth
