1、Designation: F2968/F2968M 14 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 indic
2、ates 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. Scope1.1 This specification covers outside diameter
3、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, hydrostatic
4、 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 p
5、ressurepiping 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 UnitsThe values stated in eit
6、her 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 standard.NOTE 1Metric
7、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 inch sized pipe.1.4 This
8、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. Referenced Documents2
9、.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 Plastics by the Density
10、-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 Method for Carbon Black
11、 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 Ethylene PlasticsD2837
12、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 Relating to Plastic Piping Sy
13、stemsF1041 Guide for Squeeze-Off of Polyolefin Gas PressurePipe and TubingF1055 Specification for Electrofusion Type PolyethyleneFittings for Outside Diameter Controlled Polyethylene1This specification is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct respons
14、ibility of Subcommittee F17.60 on Gas.Current edition approved April 15, 2014. Published June 2014. DOI: 10.1520/F296814.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refe
15、r to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1and Crosslinked Polyethylene (PEX) Pipe and TubingF1563 Specification for Tools to Squeeze-off Polyethylene(PE) Gas Pipe or Tu
16、bingF1948 Specification for Metallic Mechanical 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 Fe
17、deral Standard:3FED-STD-123 Marking for Shipment (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: Gene
18、ral methodISO 14531-2 Plastics pipes and fittings 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
19、 ofgaseous fuels Metric series Specifications 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 RequiredStre
20、ngth (MRS) Ratings for Thermoplastic Piping Mate-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 a
21、re in accordance with Termi-nology F412, and abbreviations 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 Definit
22、ions of Terms Specific to This Standard:3.2.1 crosslinked polyethylene, nmolecular chains chemi-cally connected through irradiation with high-energy electronbeams, or chemical agents such as organic peroxides or silanes.3.2.2 PEX pipe material designation codeThe PEX pipematerial designation code sh
23、all consist of the abbreviation forcrosslinked 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 93
24、C.Pressure ratings for temperatures 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
25、 of thisspecification, are defined 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 madef
26、rom PE compounds, which have been 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 pro
27、duct with Hydrostatic Design Basis 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
28、 design basis rating per PPI TR-3. 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 m
29、aterial designation code arefor chlorine 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 bl
30、ack, usedfor PEX pipe shall have 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 themanu
31、facture of PEX pipes and fittings 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 2
32、0, Switzerland, http:/www.iso.org.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 000
33、8 1600 11.03 630 4.34PEX 0009 1800 12.41 630 4.34F2968/F2968M 1425.7 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 yieldstrengt
34、h when measured in accordance with 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 cra
35、cks, holes, 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 2 and Table 3 for pipe apply tothe average measured diameter
36、 in accordance with 7.4.1.6.3 Dimensions 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, wh
37、en measured inaccordance with 7.4 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 p
38、si 14.1 MPa. Piping intended for 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 inaccord
39、ance with 7.7. For pipe sizes above 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 minimumof 3000 ps
40、i 20.7 MPa for PEX 0006, 3700 psi 25.5 MPa forPEX 0008, 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 shallTABLE 2 Metric-sized Outside Diameters and Tolerances for PEX PipePipe Size Average Outside Di
41、ameter 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 0.40 2.5140 140.45 0.45 2.8160 160.50 0.50 3.2180 1
42、80.55 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 22.1TABLE 3 Inch-sized Outside Diameters and Tolerances for PEXPipePipe Si
43、ze 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 14.000 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.
44、000 0.14434 34.000 0.15336 36.000 0.16242 42.000 0.18948 48.000 0.21654 54.000 0.243F2968/F2968M 143be within the range from 65 to 89 % inclusive. Depending onthe process used, the following minimum percentage crosslink-ing values shall be achieved: 73 % by peroxides, 65 % byelectron beam, or 65 % b
45、y 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 Pressure Strength:6.9.1 GeneralPEX pipe sizes and DRs
46、deemed suitablefor bending by the pipe manufacturer shall meet the require-ments in 6.9.2.6.9.2 Cold-bent pipe, with a radius of six (6) times theoutside diameter and consisting of a continuous bend lengthinducing not less than 90 angle, shall meet the minimumhydrostatic sustained pressure strength
47、requirements in 6.4when tested in accordance with 7.6.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 11 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
48、.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
49、 7.4 8.3140 23.3 19.2 15.7 12.7 10.3 8.7 8.3 9.3160 26.6 21.9 17.9 14.6 11.8 9.9 9.5 10.6180 29.9 24.6 20.1 16.4 13.3 11.1 10.7 11.9200 33.2 27.4 22.4 18.2 14.7 12.4 11.9 13.2225 37.4 30.8 25.2 20.5 16.6 13.9 13.4 14.9250 41.5 34.2 27.9 22.7 18.4 15.5 14.8 16.4280 46.5 38.3 31.3 25.4 20.6 17.3 16.6 18.4315 52.3 43.1 35.2 28.6 23.2 19.5 18.7 20.7355 59.0 48.5 39.7 32.2 26.1 21.9 21.1 23.4400 . 54.7 44.7 36.3 29.4 24.7 26.2 23.7450 . 61.5 50
