1、Designation: F2968/F2968M 14F2968/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 d
2、esignation indicates 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 Scope*1.1 This specification c
3、overs outside diameter controlled, black metric-sized and IPS-sized crosslinked polyethylene (PEX)pipe, fittings and joints, made in pipe dimension ratios ranging from 6 to 17, and pressure rated for gas distribution. Included arerequirements and test methods for material, workmanship, dimensions, b
4、urst pressure, hydrostatic sustained pressure, stabilizerfunctionality, bent-pipe hydrostatic pressure, degree of crosslinking, chemical resistance, and squeeze-off. Requirements for pipeand fittings markings are also given. The pipe, fittings and joints covered by this specification are intended fo
5、r buried gasdistribution and gas transmission pressure piping applications.1.2 The text of this specification references notes, footnotes, and appendixes, which provide explanatory material. These notesand footnotes (excluding those in tables and figures) shall not be considered as requirements of t
6、he specification.1.3 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard. The values statedin each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining valuesfrom the two systems may result
7、 in non-conformance with the standard.NOTE 1Metric sized (SI units) pipe should only be joined with corresponding metric sized fittings, and inch sized pipe should only be joined withcorresponding inch sized fittings. Inch sized fittings should not be used for metric sized pipe, and metric sized fit
8、tings should not be used for inch sizedpipe.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulato
9、rylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D543 Practices for Evaluating the Resistance of Plastics to Chemical ReagentsD618 Practice for Conditioning Plastics for TestingD792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by DisplacementD1505
10、 Test Method for Density of Plastics by the Density-Gradient TechniqueD1598 Test Method for Time-to-Failure of Plastic Pipe Under Constant Internal PressureD1599 Test Method for Resistance to Short-Time Hydraulic Pressure of Plastic Pipe, Tubing, and FittingsD1600 Terminology for Abbreviated Terms R
11、elating to PlasticsD1603 Test Method for Carbon Black Content in Olefin PlasticsD2122 Test Method for Determining Dimensions of Thermoplastic Pipe and FittingsD2290 Test Method for Apparent Hoop Tensile Strength of Plastic or Reinforced Plastic PipeD2765 Test Methods for Determination of Gel Content
12、 and Swell Ratio of Crosslinked Ethylene PlasticsD2837 Test Method for Obtaining Hydrostatic Design Basis for Thermoplastic Pipe Materials or Pressure Design Basis forThermoplastic Pipe ProductsD4218 Test Method for Determination of Carbon Black Content in Polyethylene Compounds By the Muffle-Furnac
13、e TechniqueF412 Terminology Relating to Plastic Piping SystemsF876 Specification for Crosslinked Polyethylene (PEX) Tubing1 This specification is under the jurisdiction of ASTM Committee F17 on Plastic Piping Systems and is the direct responsibility of Subcommittee F17.60 on Gas.Current edition appr
14、oved April 15, 2014Nov. 1, 2014. Published June 2014December 2014. Originally approved in 2014. Last previous edition approved in 2014 asD2968/D2968M14. DOI: 10.1520/F296814.10.1520/F296814A.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at servi
15、ceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. B
16、ecauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section ap
17、pears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1F1041 Guide for Squeeze-Off of Polyolefin Gas Pressure Pipe and TubingF1055 Specification for Electrofusion Type Polyethylene Fittings for Outside Diamet
18、er Controlled Polyethylene and CrosslinkedPolyethylene (PEX) Pipe and TubingF1563 Specification for Tools to Squeeze-off Polyethylene (PE) Gas Pipe or TubingF1948 Specification for Metallic Mechanical Fittings for Use on Outside Diameter Controlled Thermoplastic Gas DistributionPipe and TubingF2897
19、Specification for Tracking and Traceability Encoding System of Natural Gas Distribution Components (Pipe, Tubing,Fittings, Valves, and Appurtenances)2.2 Federal Standard:3FED-STD-123 Marking for Shipment (Civil Agencies)2.3 Military Standard:3MIL-STD-129 Marking for Shipment and Storage2.4 ISO Stand
20、ards:4ISO 1167 Thermoplastics pipes, fittings and assemblies for the conveyance of fluids Determination of the resistance tointernal pressure Part 1: General methodISO 14531-2 Plastics pipes and fittings Crosslinked polyethylene (PE-X) pipe systems for the conveyance of gaseous fuels Metric series S
21、pecifications Part 2: Fittings for heat-fusion jointingISO 14531-3 Plastics pipes and fittings Crosslinked polyethylene (PE-X) pipe systems for the conveyance of gaseous fuels Metric series Specifications Part 3: Fittings for mechanical jointing (including PE-X/metal transitions)2.5 PPI Standards:5P
22、PI TR-3 Policies and Procedures for Developing Hydrostatic Design Basis (HDB), Pressure Design Basis (PDB), StrengthDesign Basis (SDB), and Minimum Required Strength (MRS) Ratings for Thermoplastic Piping Materials or PipePPI TR-4 PPI Listing of Hydrostatic Design Basis (HDB), Strength Design Basis
23、(SDB), Pressure Design Basis (PDB) andMinimum Required Strength (MRS) Ratings for Thermoplastic Piping Materials or Pipe3. Terminology3.1 DefinitionsDefinitions are in accordance with Terminology F412, and abbreviations are in accordance with TerminologyD1600, unless otherwise specified. The abbrevi
24、ation for crosslinked polyethylene is PEX. Plastic pipe denotes a particular diameterschedule of plastic pipe that is outside diameter controlled.3.2 Definitions of Terms Specific to This Standard:3.2.1 crosslinked polyethylene, nmolecular chains chemically connected through irradiation with high-en
25、ergy electron beams,or chemical agents such as organic peroxides or silanes.a polyethylene material that has undergone a change in molecular structureusing a chemical or a physical process whereby the polymer chains are chemically linked.3.2.2 PEX pipe material designation codeThe PEX pipe material
26、designation code shall consist of the abbreviation forcrosslinked polyethylene (PEX) followed by four Arabic digits as shown in Table 1, and as defined in Terminology F412 for PEXpipe materials.4. Pipe Classification4.1 GeneralThis standard covers black PEX pipe that is pressure rated based on HDB a
27、t 73F 23C and 200F 93C.Pressure ratings for temperatures between 73F 23C and 200F 93C are determined by temperature interpolation in accordancewith PPI TR-3.4.2 ClassificationPEX pipes are classified by their PEX pipe material designation codes as shown in Table 1.3 DLA Document Services Building 4/
28、D 700 Robbins Avenue Philadelphia, PA 19111-5094 http:/quicksearch.dla.mil/4 Available from International Organization for Standardization (ISO), 1, ch. de la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http:/www.iso.org.5 Available from Plastics Pipe Institute (PPI), 105 Decker Court, Suite
29、 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 1800 12.41 630 4.34F2968/F2968M 14a25. Materials5.1 GeneralPEX pipes, mee
30、ting the requirements of this specification, are defined by means of (1) degree of crosslinking per6.7, and (2) long-term strength tests per Test Method D2837 to determine HDB per Table 1. The HDB is a property of the PEXcompound, which is used to make the PEX pipe.5.2 Basic MaterialsPEX pipe and fi
31、ttings shall be made from PE compounds, which have been crosslinked by peroxides, azocompounds, or silane compounds in extrusion, or by electron beam after extrusion, such that the pipe meets the performancerequirements of Section 6. The materials, procedure for mixing, and the process for crosslink
32、ing shall result in a product withHydrostatic Design Basis ratings equal to or better than those shown in Table 1, when determined in accordance with proceduresno less restrictive than those of Test Method D2837, and the PEX material shall have a Plastics Pipe Institute (PPI) long-termhydrostatic de
33、sign stress and hydrostatic design basis rating per PPI TR-3. See Appendix X1 for additional information on PPIhydrostatic stress ratings.5.3 Pipe Material Designation CodeThe PEX material meeting the requirements of this specification shall be designated PEX0006, PEX 0008 or PEX 0009.NOTE 2The firs
34、t two digits in the pipe material designation code are for chlorine resistance and UV resistance. A “0” indicates “not tested”. If eitherof these properties has been tested, then the “0” is replaced by the appropriate digit.5.4 DensityWhen determined in accordance with 7.5, the PE base resin used fo
35、r PEX pipe, without carbon black, used forPEX pipe shall have a minimum average density of 0.926 g/cm3.5.5 Carbon BlackPE compounds used to make PEX pipe shall 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 rewo
36、rk shall not be used in the manufacture of PEX pipes and fittings made in accordance to thisspecification.5.7 Chemical ResistanceThe PEX material shall not increase in weight more than 0.5 % (1.0 % for toluene in methanol).Where the test specimen is a pipe ring, the material shall not change more th
37、an 612 % in apparent tensile yield strength whenmeasured in accordance with 7.11.NOTE 3This test is only an indication of what will happen as a result of short-term exposure to these chemicals. For long-term results, additionaltesting is required.6. Requirements6.1 WorkmanshipThe pipe shall be homog
38、eneous throughout and free of visible cracks, holes, foreign inclusions, or otherdefects. The pipe shall be as uniform as commercially practicable in color, opacity, density, and other physical properties.6.2 Out-of RoundnessThe maximum out-of roundness requirements shown in Table 2 and Table 3 for
39、pipe apply to theaverage measured diameter in accordance with 7.4.1.6.3 Dimensions and Tolerances:6.3.1 Outside DiametersThe outside diameters and tolerances shall be as shown in Table 2 or Table 3, when measured inaccordance with 7.4 and 7.4.1.6.3.2 Wall ThicknessThe wall thickness and tolerances s
40、hall be as shown in Table 4 or Table 5, when measured in accordancewith 7.4 and 7.4.2.6.4 Sustained Pressure 73F 23CThe PEX pipe shall not fail in less than 1000 h when tested in accordance with 7.6. ForPEX 0006 the stress shall be 1320 psi 9.1 MPa, for PEX 0008 the stress shall be 1650 psi 11.3 MPa
41、, and for PEX 0009 thestress shall be 2050 psi 14.1 MPa. Piping intended for use at temperatures of 100F 38C and higher shall be tested at both73F 23C and the maximum design temperature. The test fiber stress shall be 90 % of the HDB.6.5 Minimum Hydrostatic Burst Pressure (Quick Burst)The pipe shall
42、 fail in a ductile manner when tested in accordance with7.7. For pipe sizes above 4 in 110 mm nominal diameter, the testing lab shall be allowed to replace the quick burst test by theapparent ring tensile strength test in 6.6.6.6 Apparent Tensile Strength at YieldWhen tested in accordance to 7.8, th
43、e PEX pipe shall demonstrate a minimum of 3000psi 20.7 MPa for PEX 0006, 3700 psi 25.5 MPa for PEX 0008, and 4600 psi 31.7 MPa for PEX 0009.6.7 Degree of CrosslinkingWhen tested in accordance with 7.9, the degree of crosslinking for PEX pipe material shall bewithin the range from 65 to 89 % inclusiv
44、e. Depending on the process used, the following minimum percentage crosslinking valuesshall be achieved: 73 % by peroxides, 65 % by electron beam, or 65 % by silane compounds.6.8 Stabilizer FunctionalityStabilizer Functionality shall be tested in accordance with 7.10. The test need only be performed
45、for the original validation of pipe made from a particular compound.6.9 Bent Pipe Hydrostatic Sustained Pressure Strength:F2968/F2968M 14a36.9.1 GeneralPEX pipe sizes and DRs deemed suitable for bending by the pipe manufacturer shall meet the requirements in6.9.2.6.9.2 Cold-bent pipe, with a radius
46、of six (6) times the outside diameter and consisting of a continuous bend length inducingnot less than 90 angle, shall meet the minimum hydrostatic sustained pressure strength requirements in 6.4 when tested inaccordance with 7.6.6.10 Squeeze-OffThis requirement is limited to pipe sizes, wall thickn
47、esses, squeeze procedures, and conditions deemedsuitable for squeeze-off in service by the pipe manufacturer. Squeeze-off shall be performed per Guide F1041 using tools that meetSpecification F1563. There shall be no leakage or visual evidence of splitting, cracking, breaking or reduction in 1000-h
48、sustainedpressure category when pipe is tested in accordance with 7.12.TABLE 2 Metric-sized Outside Diameters and 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 1.34
49、0 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 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 24.8800 813.00 3.60 28.0900 90
