1、Designation: F2968/F2968M 14a An American National StandardStandard Specification forBlack Crosslinked Polyethylene (PEX) Pipe, Fittings andJoints For Gas Distribution Applications1This standard is issued under the fixed designation F2968/F2968M; the number immediately following the designation indi
2、cates the yearof original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification covers outside diamete
3、r controlled,black metric-sized and IPS-sized crosslinked polyethylene(PEX) pipe, fittings and joints, made in pipe dimension ratiosranging from 6 to 17, and pressure rated for gas distribution.Included are requirements and test methods for material,workmanship, dimensions, burst pressure, hydrostat
4、ic sus-tained pressure, stabilizer functionality, bent-pipe hydrostaticpressure, degree of crosslinking, chemical resistance, andsqueeze-off. Requirements for pipe and fittings markings arealso given. The pipe, fittings and joints covered by thisspecification are intended for buried gas distribution
5、 and gastransmission pressure piping applications.1.2 The 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 UnitsT
6、he values stated in either SI units or inch-pound units are to be regarded separately as standard. Thevalues stated in each system may not be exact equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in non-conformance with the
7、 standard.NOTE 1Metric sized (SI units) pipe should only be joined withcorresponding metric sized fittings, and inch sized pipe should only bejoined with corresponding inch sized fittings. Inch sized fittings should notbe used for metric sized pipe, and metric sized fittings should not be usedfor in
8、ch sized pipe.1.4 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 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2
9、. Referenced Documents2.1 ASTM Standards:2D543 Practices for Evaluating the Resistance of Plastics toChemical ReagentsD618 Practice for Conditioning Plastics for TestingD792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD1505 Test Method for Density of
10、Plastics by the Density-Gradient TechniqueD1598 Test Method for Time-to-Failure of Plastic PipeUnder Constant Internal PressureD1599 Test Method for Resistance to Short-Time HydraulicPressure of Plastic Pipe, Tubing, and FittingsD1600 Terminology forAbbreviated Terms Relating to Plas-ticsD1603 Test
11、Method for Carbon Black Content in OlefinPlasticsD2122 Test Method for Determining Dimensions of Ther-moplastic Pipe and FittingsD2290 Test Method for Apparent Hoop Tensile Strength ofPlastic or Reinforced Plastic PipeD2765 Test Methods for Determination of Gel Content andSwell Ratio of Crosslinked
12、Ethylene PlasticsD2837 Test Method for Obtaining Hydrostatic Design Basisfor Thermoplastic Pipe Materials or Pressure Design Basisfor Thermoplastic Pipe ProductsD4218 Test Method for Determination of Carbon BlackContent in Polyethylene Compounds By the Muffle-Furnace TechniqueF412 Terminology Relati
13、ng to Plastic Piping SystemsF876 Specification for Crosslinked Polyethylene (PEX) Tub-ingF1041 Guide for Squeeze-Off of Polyolefin Gas PressurePipe and TubingF1055 Specification for Electrofusion Type PolyethyleneFittings for Outside Diameter Controlled Polyethyleneand Crosslinked Polyethylene (PEX)
14、 Pipe and Tubing1This specification 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 Nov. 1, 2014. Published December 2014. Originallyapproved in 2014. Last previous edition approved in 20
15、14 as D2968/D2968M14.DOI: 10.1520/F296814A.2For referenced ASTM standards, visit the ASTM website, 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.*A Summary of Chan
16、ges section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Dec
17、ision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1F1563 Specification for Tools to Squeeze-off Polyethylene(PE) Gas Pipe or TubingF1948 Specification for Metallic Mechanica
18、l Fittings forUse on Outside Diameter Controlled Thermoplastic GasDistribution Pipe and TubingF2897 Specification for Tracking and Traceability EncodingSystem of Natural Gas Distribution Components (Pipe,Tubing, Fittings, Valves, and Appurtenances)2.2 Federal Standard:3FED-STD-123 Marking for Shipme
19、nt (Civil Agencies)2.3 Military Standard:3MIL-STD-129 Marking for Shipment and Storage2.4 ISO Standards:4ISO 1167 Thermoplastics pipes, fittings and assemblies forthe conveyance of fluids Determination of the resis-tance to internal pressure Part 1: General methodISO 14531-2 Plastics pipes and fitti
20、ngs Crosslinkedpolyethylene (PE-X) pipe systems for the conveyance ofgaseous fuels Metric series Specifications Part 2:Fittings for heat-fusion jointingISO 14531-3 Plastics pipes and fittings Crosslinkedpolyethylene (PE-X) pipe systems for the conveyance ofgaseous fuels Metric series Specifications
21、Part 3:Fittings for mechanical jointing (including PE-X/metaltransitions)2.5 PPI Standards:5PPI TR-3 Policies and Procedures for Developing Hydro-static Design Basis (HDB), Pressure Design Basis (PDB),Strength Design Basis (SDB), and Minimum RequiredStrength (MRS) Ratings for Thermoplastic Piping Ma
22、te-rials or PipePPI 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 F412, and a
23、bbreviations are in accordance with Termi-nology D1600, unless otherwise specified. The abbreviation forcrosslinked polyethylene is PEX. Plastic pipe denotes a par-ticular diameter schedule of plastic pipe that is outside diam-eter controlled.3.2 Definitions of Terms Specific to This Standard:3.2.1
24、crosslinked polyethylene, na polyethylene materialthat has undergone a change in molecular structure using achemical or a physical process whereby the polymer chains arechemically linked.3.2.2 PEX pipe material designation codeThe PEX pipematerial designation code shall consist of the abbreviation f
25、orcrosslinked polyethylene (PEX) followed by four Arabic digitsas shown in Table 1, and as defined in Terminology F412 forPEX pipe materials.4. Pipe Classification4.1 GeneralThis standard covers black PEX pipe that ispressure rated based on HDB at 73F 23C and 200F 93C.Pressure ratings for temperatur
26、es between 73F 23C and200F 93C are determined by temperature interpolation inaccordance with PPI TR-3.4.2 ClassificationPEX pipes are classified by their PEXpipe material designation codes as shown in Table 1.5. Materials5.1 GeneralPEX pipes, meeting the requirements of thisspecification, are define
27、d by means of (1) degree of crosslink-ing per 6.7, and (2) long-term strength tests per Test MethodD2837 to determine HDB per Table 1. The HDB is a propertyof the PEX compound, which is used to make the PEX pipe.5.2 Basic MaterialsPEX pipe and fittings shall be madefrom PE compounds, which have been
28、 crosslinked byperoxides, azo compounds, or silane compounds in extrusion,or by electron beam after extrusion, such that the pipe meetsthe performance requirements of Section 6. The materials,procedure for mixing, and the process for crosslinking shallresult in a product with Hydrostatic Design Basi
29、s ratings equalto or better than those shown in Table 1, when determined inaccordance with procedures no less restrictive than those ofTest Method D2837, and the PEX material shall have a PlasticsPipe Institute (PPI) long-term hydrostatic design stress andhydrostatic design basis rating per PPI TR-3
30、. See Appendix X1for additional information on PPI hydrostatic stress ratings.5.3 Pipe Material Designation CodeThe PEX materialmeeting the requirements of this specification shall be desig-nated PEX 0006, PEX 0008 or PEX 0009.NOTE 2The first two digits in the pipe material designation code arefor c
31、hlorine resistance and UV resistance. A “0” indicates “not tested”. Ifeither of these properties has been tested, then the “0” is replaced by theappropriate digit.5.4 DensityWhen determined in accordance with 7.5, thePE base resin used for PEX pipe, without carbon black, usedfor PEX pipe shall have
32、a minimum average density of 0.926g/cm3.5.5 Carbon BlackPE compounds used to make PEX pipeshall contain 2.0 to 3.0 percent well dispersed carbon black asmeasured in the PEX pipe by Test Methods D1603 or D4218.5.6 Rework MaterialPEX rework shall not be used in themanufacture of PEX pipes and fittings
33、 made in accordance tothis specification.3DLA Document Services Building 4/D 700 Robbins Avenue Philadelphia, PA19111-5094 http:/quicksearch.dla.mil/4Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http:/www.iso.org
34、.5Available from Plastics Pipe Institute (PPI), 105 Decker Court, Suite 825,Irving, TX 75062, http:/www.plasticpipe.org.TABLE 1 PEX Pipe Material Designation CodesPEX Pipe MaterialDesignation Code73F 23C HDBPsi MPa200F 93C HDBPsi MPaPEX 0006 1250 8.62 630 4.34PEX 0008 1600 11.03 630 4.34PEX 0009 180
35、0 12.41 630 4.34F2968/F2968M 14a25.7 Chemical ResistanceThe PEX material shall not in-crease in weight more than 0.5 % (1.0 % for toluene inmethanol). Where the test specimen is a pipe ring, the materialshall not change more than 612 % in apparent tensile yieldstrength when measured in accordance wi
36、th 7.11.NOTE 3This test is only an indication of what will happen as a resultof short-term exposure to these chemicals. For long-term results, addi-tional testing is required.6. Requirements6.1 WorkmanshipThe pipe shall be homogeneousthroughout and free of visible cracks, holes, foreign inclusions,o
37、r 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 2 and Table 3 for pipe apply tothe average measured diameter in accordance with 7.4.1.6.3 Di
38、mensions and Tolerances:6.3.1 Outside DiametersThe outside diameters and toler-ances shall be as shown in Table 2 or Table 3, when measuredin accordance with 7.4 and 7.4.1.6.3.2 Wall ThicknessThe wall thickness and tolerancesshall be as shown in Table 4 or Table 5, when measured inaccordance with 7.
39、4 and 7.4.2.6.4 Sustained Pressure 73F 23CThe PEX pipe shallnot fail in less than 1000 h when tested in accordance with 7.6.For PEX 0006 the stress shall be 1320 psi 9.1 MPa, for PEX0008 the stress shall be 1650 psi 11.3 MPa, and for PEX 0009the stress shall be 2050 psi 14.1 MPa. Piping intended for
40、 useat temperatures of 100F 38C and higher shall be tested atboth 73F 23C and the maximum design temperature. Thetest fiber stress shall be 90 % of the HDB.6.5 Minimum Hydrostatic Burst Pressure (Quick Burst)The pipe shall fail in a ductile manner when tested inaccordance with 7.7. For pipe sizes ab
41、ove 4 in 110 mmnominal diameter, the testing lab shall be allowed to replace thequick burst test by the apparent ring tensile strength test in 6.6.6.6 Apparent Tensile Strength at YieldWhen tested inaccordance to 7.8, the PEX pipe shall demonstrate a minimumTABLE 2 Metric-sized Outside Diameters and
42、 Tolerances for PEX PipePipe Size Average Outside Diameter Tolerances for Average Diameter Out-of-Roundnessmm mm mm mm16 16.15 0.15 1.220 20.15 0.15 1.225 25.15 0.15 1.232 32.15 0.15 1.340 40.20 0.20 1.450 50.20 0.20 1.463 63.20 0.20 1.575 75.25 0.25 1.690 90.30 0.30 1.8110 110.35 0.35 2.2125 125.40
43、 0.40 2.5140 140.45 0.45 2.8160 160.50 0.50 3.2180 180.55 0.55 3.6200 200.60 0.60 4.0225 225.70 0.70 4.5250 250.75 0.75 5.0280 280.85 0.85 9.8315 315.95 0.95 11.1355 356.10 1.10 12.5400 410.20 1.20 14.0450 451.35 1.35 15.6500 501.50 1.50 17.5560 561.70 1.70 19.6630 631.90 1.90 22.1710 713.20 3.20 24
44、.8800 813.00 3.60 28.0900 904.05 4.05 31.51000 1004.50 4.50 35.0TABLE 3 Inch-sized Outside Diameters and Tolerances for PEXPipePipe Size Outside Diameter Tolerances for OutsideDiameter ()in. in. in.3 3.500 0.0164 4.500 0.0205 5.563 0.0256 6.625 0.0308 8.625 0.03910 10.750 0.04812 12.750 0.05714 14.0
45、00 0.06316 16.000 0.07218 18.000 0.08120 20.000 0.09022 22.000 0.09924 24.000 0.10826 26.000 0.11728 28.000 0.12630 30.000 0.13532 32.000 0.14434 34.000 0.15336 36.000 0.16242 42.000 0.18948 48.000 0.21654 54.000 0.243F2968/F2968M 14a3of 3000 psi 20.7 MPa for PEX 0006, 3700 psi 25.5 MPa forPEX 0008,
46、 and 4600 psi 31.7 MPa for PEX 0009.6.7 Degree of CrosslinkingWhen tested in accordancewith 7.9, the degree of crosslinking for PEX pipe material shallbe within the range from 65 to 89 % inclusive. Depending onthe process used, the following minimum percentage crosslink-ing values shall be achieved:
47、 73 % by peroxides, 65 % byelectron beam, or 65 % by silane compounds.6.8 Stabilizer FunctionalityStabilizer Functionality shallbe tested in accordance with 7.10. The test need only beperformed for the original validation of pipe made from aparticular compound.6.9 Bent Pipe Hydrostatic Sustained Pre
48、ssure Strength:6.9.1 GeneralPEX pipe sizes and DRs deemed suitablefor bending by the pipe manufacturer shall meet the require-ments in 6.9.2.TABLE 4 Metric-sized Wall Thickness and Tolerances for PEX Plastic PipeMinimum Wall Thickness (t), mm (tolerance is plus 12%)Pipe Size mm DR 6 DR 7.4 DR 9 DR 1
49、1 DR 13.6 DR 16.2 DR 17 DR 2116 3.0 2.3 2.0 . . . . .20 3.4 3.0 2.3 2.0 . . . .25 5.4 3.5 3.0 2.3 2.0 . . .32 5.4 4.4 3.6 3.0 2.4 2.0 2.0 2.340 6.7 5.5 4.5 3.7 3.0 2.5 2.4 2.850 8.3 6.9 5.6 4.6 3.7 3.1 3.0 3.463 10.5 8.6 7.1 5.8 4.7 3.9 3.8 4.375 12.5 10.3 8.4 6.8 5.6 4.6 4.5 5.190 15.0 12.3 10.1 8.2 6.7 5.6 5.4 6.1110 18.3 15.1 12.3 10.0 8.1 7.7 6.6 7.4125 20.8 17.1 14.0 11.4 9.2 7.7 7.4 8.3140 23.3 19.2 15.7 12.7 10.3 8.7 8.3 9.3160
