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

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1、Designation: F 876 08aAn 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 is outside diameter controlled, made innominal

3、 SDR9 tubing dimension ratios except were noted, andpressure rated for water at three temperatures (see AppendixX1). Included are requirements and test methods for material,workmanship, dimensions, burst pressure, hydrostatic sus-tained pressure, excessive temperature pressure, excessivetemperature-

4、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 text of this specification references notes, footnotes,and appendixes

5、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 standard. The values given in parentheses are mathematicalconversions to SI

6、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 address all of the safety concerns,if any, associated with its use. It is t

7、he 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 for Conditioning Plastics for TestingD 792 Test Methods for Density and

8、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 1599 Test Method for Resistance to Short-Time Hydrau-lic Pressure of Pla

9、stic 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 Methods for Determination of Gel Content andSwell Ratio of Crosslinked Ethy

10、lene 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 Differential Scanning CalorimetryF 412 Terminology Relating to Plastic Pipi

11、ng SystemsF 2023 Test Method for Evaluating the Oxidative Resis-tance of Crosslinked Polyethylene (PEX) Tubing andSystems 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 Stan

12、dard:MIL-STD-129 Marking for Shipment and Storage52.5 NSF Standard:NSF/ANSI 14 for Plastic Piping Components and RelatedMaterials62.6 ISO Standards:4ISO 1167 Thermoplastics pipes, fittings and assemblies forthe conveyance of fluids - Determination of the resistanceto internal pressure - Part 1: Gene

13、ral methodISO 13760 Plastics pipes for the conveyance of fluids underpressure - Miners rule - Calculation method for cumu-lative damage1This specification is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.26 on OlefinBased P

14、ipe.Current edition approved Sept. 1, 2008. Published September 2008. Originallyapproved in 1984. Last previous edition approved 2008 as F 876 08.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards

15、 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. 43rd St.,4th Floor, New York, NY 10036, http:/www.an

16、si.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 48113-0140, http:/www.nsf.org.1*A Summary of Changes s

17、ection 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 R 161-1690 Pipes of Plastic Materials for the Transportof Fluids (Outside Diameters and Nominal Pressures) Part1, Metric Series2.7 PPI Stan

18、dard:7PPI TR-4 PPI Listing of Hydrostatic Design Basis (HDB),Strength Design Basis (SDB), Pressure Design Basis(PDB) and Minimum Required Strength (MRS) Ratingsfor Thermoplastic Piping Materials or Pipe3. Terminology3.1 DefinitionsDefinitions are in accordance with Termi-nology F 412, and abbreviati

19、ons are in accordance with Ter-minology D 1600, unless otherwise specified. The abbreviationfor crosslinked polyethylene is 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 dia

20、meter schedule conforms to ANSIB36.10.3.2 Definitions of Terms Specific to This Standard:3.2.1 crosslinked polyethylene plasticsplastics preparedby crosslinking (curing) polyethylene compounds.3.2.2 hydrostatic design stress (HDS)the estimated maxi-mum tensile stress the material is capable of withs

21、tandingcontinuously with a high degree of certainty that failure of thetube will not occur. This stress is circumferential 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 fa

22、ctor 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 ofestablished stress values (specified in Test Method D 2837) fora plastic compound obtained by categorizing the long-termhydrostatic strength determined in accordance with TestMeth

23、od D 2837.3.2.3.1 DiscussionA listing of HDB and HDS values arecontained in PPI publication PPI TR43.2.4 pressure rating (PR)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 betw

24、een dimensions, hydrostatic designstress, and pressure ratingthe following expression, com-monly known as the ISO equation,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 M

25、Pa),P = pressure rating, psi (or MPa),DO= average outside diameter, in. (or mm),t = minimum wall thickness, in. (or mm), andR = 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 ou

26、tside diameter of the tubing in inches orin millimetres by the minimum wall thickness in inches ormillimetres. If the wall 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. T

27、he SDR values shall be rounded to the nearest 0.5.3.2.7 standard thermoplastic tubing materials designationcodeThe tubing material designation code shall consist ofthe abbreviation for the type of plastic (PEX) followed by fourArabic digits that describe short-term properties in accordancewith appli

28、cable ASTM standards and as shown in Table 2.3.2.7.1 DiscussionThe first digit is for chlorine resistancetested in accordance 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 requir

29、ement for chlorine resistance.(2) A digit “1” indicates the PEX tubing has been testedand meets the F 876 requirement for minimum 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 t

30、he PEX tubing has beentested and meets the F 876 requirement for minimum chlorineresistance at end use condition of 50% at 140F and 50% at73F.(5) A digit “4” is reserved for future application.(6) A digit “5” indicates that the PEX tubing has beentested and meets the requirement for minimum chlorine

31、 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 Discussion The last two digits are the hydrostaticdesign stress for water at 73F (23C) in units of 100 psi withany

32、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 shall consist of the three letters “PEX” and fourdigits.4. Tubing Classification4.1 GeneralThis specification cov

33、ers 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 Standard Thermoplastic Pipe Dimension Ratio (SDR)This specification covers PEX tubing in one standard dimen-sion rat

34、io (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 GeneralCrosslinked polyethylene tubing, meeting therequirements of this specification, are primarily defined bymea

35、ns of three criteria, namely, (1) nominal density, (2) degree7Plastics Pipe Institute (PPI), 105 Decker Court, Suite 825 Irving TX, 75062.http:/www.plasticpipe.org8ISO R161-1690.F 876 08a2of crosslinking, and (3) long-term strength tests. There is astrong correlation between nominal density and resu

36、lts ofshort-term 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,

37、taste, and odorthat 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, o

38、r silane compounds 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 i

39、n a product with 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-3.9See Appendix X1 for additionalinformation on PPI hydrostatic stress ratings.NOTE 2Tubing produced by crosslinki

40、ng 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, eachprocess must be established as meeting the requirements of this s

41、pecifi-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, foreign inclusions,or other defects. The pipe shall be as uniform a

42、s 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 with a roundingtool recommended by the manufacturer.6.3 Dimensions and

43、 Tolerances:6.3.1 Outside DiametersThe outside diameters and toler-ances shall be as shown in Table 4, when measured inaccordance with 7.4 and 7.4.1.6.3.2 Wall ThicknessThe wall thickness and tolerancesshall be as shown in Table 1, when measured in accordancewith 7.4 and 7.4.2.NOTE 3Tubing diameters

44、 less than58 in. diameter have minimumwall thicknesses based on both hydrostatic and mechanical strength.6.4 DensityWhen determined in accordance with 7.5, thecrosslinked polyethylene tubing material shall have a minimumdensity of 0.926 Mg/m3.6.5 Hydrostatic Sustained Pressure StrengthThe tubingshal

45、l not fail, balloon, burst, or weep as defined in Test MethodD 1598, at the test pressures shown in Table 5 when tested inaccordance with 7.6.6.6 Hydrostatic Burst PressureThe minimum burst pres-sure for PEX plastic tubing shall be as shown in Table 6, whendetermined in accordance with 7.7.6.7 Envir

46、onmental Stress Cracking There shall be no lossof pressure in the tubing, when tested in accordance with 7.8.6.8 Degree of CrosslinkingWhen tested in accordancewith 7.9, the degree of crosslinking for PEX tubing materialshall be within the range from 65 to 89 % inclusive. Dependingon the process use

47、d, the following minimum percentagecrosslinking values shall be achieved: 70 % by peroxides, 65 %by Azo compounds, 65 % by electron beam, or 65 % by silanecompounds.NOTE 4Techniques as found in Test Methods D 2765.6.9 Stabilizer Functionality Stabilizer Functionality shallbe tested in accordance wit

48、h 7.10.NOTE 5 For example ASTM F 876 PEX tubing marked with thematerial designation code PEX 1006 is a PEX tubing meeting the chlorineresistance requirement for 25% of the time at 140F and 75% of the timeat 73F and having an HDS for water at 73F of 630psi (HDB of 1250 psi)as follows:6.10 Oxidative S

49、tability in Potable Chlorinated Water9PPI Technical Report TR-3, Policies and Procedures for Developing Recom-mended Hydrostatic Design Stresses for Thermoplastic Pipe Materials.TABLE 1 Wall Thickness and Tolerances for Nominal PEX SDR9 PlasticTubingANominal TubingMinimum WallThicknessTolerancein. mm in. mm in. mm18 3 0.047B1.19B+0.007 +0.1814 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