ASTM F876-2008b Standard Specification for Crosslinked Polyethylene (PEX) Tubing.pdf

1、Designation: F 876 08bAn American National StandardStandard Specification forCrosslinked Polyethylene (PEX) Tubing1This standard is issued under the fixed designation F 876; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year

2、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. Scope*1.1 This specification covers crosslinked polyethylene(PEX) tubing that incorporates an optional polymeric inner,middl

3、e or outer layer and that is outside diameter controlled,made in nominal SDR9 tubing dimension ratios except werenoted, and pressure rated for water at three temperatures (seeAppendix X1). Included are requirements and test methods formaterial, workmanship, dimensions, burst pressure, hydrostaticsus

4、tained pressure, excessive temperature pressure, excessivetemperature-pressure, environmental stress cracking, stabilizerfunctionality, bent-tube hydrostatic pressure, oxidative stabilityin potable chlorinated water, and degree of crosslinking.Requirements for tubing markings are also given.1.2 The

5、text of this specification references notes, footnotes,and appendixes which provide explanatory material. Thesenotes and footnotes (excluding those in tables and figures) shallnot be considered as requirements of the specification.1.3 The values stated in inch-pound units are to be regardedas standa

6、rd. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 The following safety hazards caveat pertains only to thetest methods portion, Section 7, of this specification: Thisstandard does not purport to addre

7、ss all of the safety concerns,if any, associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice fo

8、r Conditioning Plastics for TestingD 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 1505 Test Method for Density of Plastics by the Density-Gradient TechniqueD 1598 Test Method for Time-to-Failure of Plastic PipeUnder Constant Internal PressureD 15

9、99 Test Method for Resistance to Short-Time Hydrau-lic Pressure of Plastic Pipe, Tubing, and FittingsD 1600 Terminology for Abbreviated Terms Relating toPlasticsD 1898 Practice for Sampling of Plastics3D 2122 Test Method for Determining Dimensions of Ther-moplastic Pipe and FittingsD 2765 Test Metho

10、ds for Determination of Gel Content andSwell Ratio of Crosslinked Ethylene PlasticsD 2837 Test Method for Obtaining Hydrostatic DesignBasis for Thermoplastic Pipe Materials or Pressure DesignBasis for Thermoplastic Pipe ProductsD 3895 Test Method for Oxidative-Induction Time of Poly-olefins by Diffe

11、rential Scanning CalorimetryF 412 Terminology Relating to Plastic Piping SystemsF 1281 Specification for Crosslinked Polyethylene/Aluminum/Crosslinked Polyethylene (PEX-AL-PEX)Pressure PipeF 2023 Test Method for Evaluating the Oxidative Resis-tance of Crosslinked Polyethylene (PEX) Tubing andSystems

12、 to Hot Chlorinated Water2.2 ANSI Standard:B36.10 Standards Dimensions of Steel Pipe (IPS)42.3 Federal Standard:FED-STD-123 Marking for Shipment (Civil Agencies)52.4 Military Standard:MIL-STD-129 Marking for Shipment and Storage52.5 NSF Standard:NSF/ANSI 14 for Plastic Piping Components and RelatedM

13、aterials62.6 ISO Standards:4ISO 1167 Thermoplastics pipes, fittings and assemblies forthe conveyance of fluids - Determination of the resistanceto internal pressure - Part 1: General method1This specification is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct

14、responsibility of Subcommittee F17.26 on OlefinBased Pipe.Current edition approved Dec. 1, 2008. Published January 2009. Originallyapproved in 1984. Last previous edition approved 2008 as F 876 08a.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service

15、at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.4Available from American National Standards Institute (ANSI), 25 W.

16、43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.5Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/www.dodssp.daps.mil.6Available from NSF International, P.O. Box 130140, 789 N. Dixboro Rd., AnnArbor, MI 48

17、113-0140, http:/www.nsf.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.ISO 13760 Plastics pipes for the conveyance of fluids underpressure - Miners rule - Calcula

18、tion method for cumu-lative damageISO R 161-1690 Pipes of Plastic Materials for the Transportof Fluids (Outside Diameters and Nominal Pressures) Part1, Metric Series2.7 PPI Standard:7PPI TR-4 PPI Listing of Hydrostatic Design Basis (HDB),Strength Design Basis (SDB), Pressure Design Basis(PDB) and Mi

19、nimum Required Strength (MRS) Ratingsfor Thermoplastic Piping Materials or Pipe3. Terminology3.1 DefinitionsDefinitions are in accordance with Termi-nology F 412, and abbreviations are in accordance with Ter-minology D 1600, unless otherwise specified. The abbreviationfor crosslinked polyethylene is

20、 PEX. Plastic tubing denotes aparticular diameter schedule of plastic pipe in which outsidediameter of the tubing is equal to the nominal size plus18 in.Plastic pipe outside diameter schedule conforms to ANSIB36.10.3.2 Definitions of Terms Specific to This Standard:3.2.1 crosslinked polyethylene pla

21、sticsplastics preparedby crosslinking (curing) polyethylene compounds.3.2.2 hydrostatic design stress (HDS)the estimated maxi-mum tensile stress the material is capable of withstandingcontinuously with a high degree of certainty that failure of thetube will not occur. This stress is circumferential

22、when internalhydrostatic water pressure is applied. The HDS is equal to thehydrostatic design basis (HDB) times the design factor (DF)for water. For this standard, the design factor is equal to 0.50.HDS 5 HDB 3 DF5 HDB 3 0.50 for this standard!3.2.3 hydrostatic design basis (HDB)one of a series ofes

23、tablished stress values (specified in Test Method D 2837) fora plastic compound obtained by categorizing the long-termhydrostatic strength determined in accordance with TestMethod D 2837.3.2.3.1 DiscussionA listing of HDB and HDS values arecontained in PPI publication PPI TR43.2.4 pressure rating (P

24、R)the estimated maximum waterpressure the tube is capable of withstanding continuously witha high degree of certainty that failure of the tube will not occur.3.2.5 relation between dimensions, hydrostatic designstress, and pressure ratingthe following expression, com-monly known as the ISO equation,

25、8is used in this specificationto relate dimensions, hydrostatic design stress, and pressurerating:2S/P 5DO/t! 2 1 (1)or2S/P 5 R 2 1where:S = hydrostatic design stress, psi (or MPa),P = pressure rating, psi (or MPa),DO= average outside diameter, in. (or mm),t = minimum wall thickness, in. (or mm), an

26、dR = standard dimension ratio, SDR.3.2.6 standard dimension ratio (SDR)the ratio of outsidediameter to wall thickness. For PEX-tubing, it is calculated bydividing the average outside diameter of the tubing in inches orin millimetres by the minimum wall thickness in inches ormillimetres. If the wall

27、thickness calculated by this formula isless than 0.070 in. (1.78 mm) it shall be arbitrarily increased to0.070 in. except for sizes516 in. and smaller, as specified inTable 1. The SDR values shall be rounded to the nearest 0.5.3.2.7 standard thermoplastic tubing materials designationcodeThe tubing m

28、aterial designation code shall consist ofthe abbreviation for the type of plastic (PEX) followed by fourArabic digits that describe short-term properties in accordancewith applicable ASTM standards and as shown in Table 2.3.2.7.1 DiscussionThe first digit is for chlorine resistancetested in accordan

29、ce with Test Method F 2023.(1) A digit “0” indicates that the PEX tubing either has notbeen tested for chlorine resistance or that the PEX tubing doesnot meet the minimum requirement for chlorine resistance.(2) A digit “1” indicates the PEX tubing has been testedand meets the F 876 requirement for m

30、inimum chlorine resis-tance at the end use condition of 25% at 140F (60C) and 75%at 73F (23C).(3) A digit “2” is reserved for future application.(4) A digit “3” indicates that the PEX tubing has beentested and meets the F 876 requirement for minimum chlorineresistance at end use condition of 50% at

31、140F and 50% at73F.7Plastics Pipe Institute (PPI), 105 Decker Court, Suite 825 Irving TX, 75062.http:/www.plasticpipe.org8ISO R 161-1690.TABLE 1 Wall Thickness and Tolerances for Nominal PEX SDR9 PlasticTubingANominal TubingMinimum WallThicknessTolerancein. mm in. mm in. mm18 3 0.047B1.19B+0.007 +0.

32、1814 7 0.062B1.57B+0.010 +0.25516516 8 0.064 1.63 +0.010 +0.2538 10 0.070B1.78B+0.010 +0.2512 13 0.070B1.78B+0.010 +0.2558 16 0.083 2.12 +0.010 +0.2534 19 0.097 2.47 +0.010 +0.251 25 0.125 3.18 +0.013 +0.33114 32 0.153 3.88 +0.015 +0.38112 38 0.181 4.59 +0.019 +0.482 51 0.236 6.00 +0.024 +0.61212 64

33、 0.292 7.41 +0.030 +0.763 76 0.347 8.82 +0.033 +0.84312 89 0.403 10.23 +0.035 +0.894 102 0.458 11.64 +0.040 +1.02412 114 0.514 13.05 +0.045 +1.145 127 0.569 14.46 +0.050 +1.276 152 0.681 17.29 +0.060 +1.52AThe minimum is the lowest wall thickness of the pipe at any cross section. Themaximum permitte

34、d wall thickness, at any cross section, is the minimum wallthickness plus the stated tolerance. All tolerances are on the plus side of theminimum requirement.BFor tubing sizes of12 in. and below, wall thickness minimums are notfunctions of SDR.F 876 08b2(5) A digit “4” is reserved for future applica

35、tion.(6) A digit “5” indicates that the PEX tubing has beentested and meets the requirement for minimum chlorine resis-tance at end use conditions of 100% of the time at 140F3.2.7.2 DiscussionThe second digit is a “0”. This digit isreserved for a currently unspecified PEX tubing property.3.2.7.3 Dis

36、cussion The last two digits are the hydrostaticdesign stress for water at 73F (23C) in units of 100 psi withany decimal figures dropped. Where the hydrostatic designstress code contains less than two figures, a zero is used beforethe number. Thus, a complete material designation code forPEX tubing s

37、hall consist of the three letters “PEX” and fourdigits.4. Tubing Classification4.1 GeneralThis specification covers one PEX tubingmaterial in one standard dimension ratio and having pressureratings for water of three temperatures. The pressure ratingsdecrease as the temperature is increased.4.2 Stan

38、dard Thermoplastic Pipe Dimension Ratio (SDR)This specification covers PEX tubing in one standard dimen-sion ratio (SDR 9) for nominal diameters58 in. and larger, andwith a specified wall thickness for smaller diameters. Thepressure ratings are uniform for all nominal tubing sizes.5. Materials5.1 Ge

39、neralCrosslinked polyethylene tubing, meeting therequirements of this specification, are primarily defined bymeans of three criteria, namely, (1) nominal density, (2) degreeof crosslinking, and (3) long-term strength tests. There is astrong correlation between nominal density and results ofshort-ter

40、m strength tests.NOTE 1PEX tubing intended for use in the transport of potable watershould be evaluated and certified as safe for this purpose by a testingagency acceptable to the local health authority. The evaluation should bein accordance with requirements for chemical extraction, taste, and odor

41、that are no less restrictive than those included in NSF/ANSI 14. The sealor mark of the laboratory making the evaluation should be included on thetubing.5.2 Basic MaterialsPEX tubing shall be made from poly-ethylene compounds which have been crosslinked by perox-ides, Azo compounds, or silane compou

42、nds in extrusion, or byelectron beam after extrusion, or by other means such that thetubing meets the performance requirements of Section 6. Forthe use temperatures that the tubing will be marked for, thematerials, procedure for mixing, and the process for crosslink-ing shall result in a product wit

43、h long term hydrostatic stressratings equal to or better than those shown in Table 3, whendetermined in accordance with procedures no less restrictivethan those of PPI TR-3.9Tubing incorporating an optionallayer shall also meet the requirement of PPI TR-39. SeeAppendix X1 for additional information

44、on PPI hydrostaticstress ratings.NOTE 2Tubing produced by crosslinking by peroxides, Azo com-pounds, or silane compounds in extrusion, or by electron beam afterextrusion have met the requirements of Section 6. There are several otherprocesses for producing crosslinked polyethylene tubing. However, e

45、achprocess must be established as meeting the requirements of this specifi-cation.5.3 Tubing Material DesignationThe tubing meeting therequirements of this specification shall be designated PEX.6. Requirements6.1 WorkmanshipThe tubing shall be homogeneousthroughout and free of visible cracks, holes,

46、 foreign inclusions,or other defects. The pipe shall be as uniform as commerciallypracticable in color, opacity, density, and other physical prop-erties.6.2 Out-of RoundnessThe maximum out-of roundnessrequirements, shown in Table 4 for tubing, apply to theaverage, measured diameter after rounding wi

47、th a roundingtool recommended by the manufacturer.6.3 Dimensions and Tolerances:6.3.1 Outside DiametersThe outside diameters and toler-ances of the tubing including the layers shall be as shown inTable 4, when measured in accordance with 7.4 and 7.4.1.6.3.1.1 LayerTubing that incorporates an inner,

48、middle orouter layer have to meet the minimum wall thickness andtolerances requirements as specified in Table 1. In addition, thelayer shall not result in the reduction of the total PEX materialbelow that specified in Table 1. In the case of tubing with amiddle layer, the total base PEX material wal

49、l thickness shallbe the sum of the inner and outer base PEX material wallthicknesses.9PPI Technical Report TR-3, Policies and Procedures for Developing Recom-mended Hydrostatic Design Stresses for Thermoplastic Pipe Materials.TABLE 2 Material Designation Code CellsProperty Standard 0 1 2 3 4 5 6789ChlorineResistanceF 2023 Not testedor rated75 %at 73Fand 25 %at 140FReserved 50 %at 73Fand 50 %at 140FReserved 100 %at 140F. . . .Reserved . . . . . . . . . . .HDSfor water at73F. . . . . . . 630 . 800 .TABLE 3 Hydrostatic