ASTM WK65117

    New Specification for Cross-Linkable Polyethylene (CX-PE) Pipe

    (What is a Work Item?)

    Developed by Subcommittee: F17.68 | Committee F17 | Contact Staff Manager



    WK65117

    1. Scope

    1.1 This specification covers outside diameter-controlled cross-linkable polyethylene (CX-PE) pipe produced in sizes DN 25 to 630 and NPS 1 to 24 in various dimension ratios. Included in this specification are requirements and test methods for long-term hydrostatic strength, hydrostatic design basis, hydrostatic burst pressure, hydrostatic sustained pressure, ultraviolet (UV) weathering resistance, initial and ultimate degree of cross-linking, workmanship, and marking. 1.2 This specification shall not be applied to cross-linked products, specifically PEX pipe or tubing. NOTE 1For avoidance of doubt, CX-PE is a different product than PEX, specifically with regard to the cross-linking rate, installation, and commissioning processes. The two are not to be confused by the reader of this specification. 1.3 The pipe covered by this specification is intended for pressure and non-pressure applications. Fluids such as water, water solutions, multi-phase mixtures, crude oil, gases, and chemical solutions containing some water are permitted to be transported in pipe made in accordance with this specification before or after cross-linking. Water aids in the cross-linking process. After CX-PE pipe is field cross-linked (commissioned) water content is not a consideration, and additional fluids such as dry gas and chemically compatible fluids that do not contain water are permitted. Consult the pipe manufacturers recommendations for information regarding compatible fluids. The maximum continuous service temperature for pipe made in accordance with this specification is 200F or 93C, however, during commissioning only higher temperatures are permitted for a limited duration. Pipe made in accordance with this specification is not intended for use with potable water, distribution of natural gas, or use with liquefied petroleum gas. 1.4 Pipe produced in accordance with this specification is intended to be cross-linked after installation; however, the procedures and practices to be used for the installation and cross-linking of the CX-PE pipe are not within the scope of this specification. Accordingly, the scope of this specification does not include requirements for cross-linking pressures or temperatures nor requirements for testing the degree of cross-linking after installation. Manufacturers recommendations for the commissioning of CX-PE pipe are used to ensure that the performance of the completed piping system meets design expectations. NOTE 2The critical difference between pipes made in accordance with this specification and PEX pipes made in accordance with standards such as Specification F2905 is that the final cross-linking process is completed as part of installation and commissioning as opposed to cross-linking taking place in a pipe manufacturers facility. The critical difference between pipe made in accordance with this specification and PE pipe made in accordance with Specification F2619 is that after field commissioning the cross-linked pipe has a higher maximum operating temperature. 1.5 This specification includes requirements to mitigate the risk of internal pressure failure during incidental pre-cross-linking use, the commissioning process, and use after commissioned. This specification also includes information on the determination of the maximum allowable operating pressure (MAOP) for the commissioned piping system. Manufacturers recommendations will offer guidance on how to cross-link CX-PE pipe during system commissioning. NOTE 3 Manufacturers recommendations set forth requirements for the cross-linking of CX-PE piping as well as other requirements that are intended to ensure that piping system performance meets expectations when in service. The compounds used to make CX-PE pipe per this specification are uniquely formulated to control the rate of cross-linking. Performance requirements for CX-PE pipe are intended to assure that pressure capacity before cross-linking is sufficient to preclude short-term failure and assure full performance after commissioning. CX-PE pipe will not actively cross-link over its entire usable temperature range. The cross-linking process for CX-PE pipe involves the introduction of heat and moisture to piping to invoke cross-linking, preferably but not necessarily with internal pressure. 1.6 Joining of CX-PE pipes made in accordance with this specification is outside the scope of this specification. Joining in accordance with manufacturers recommendations shall be observed. Any requirements for the performance of joints made with CX-PE pipe are outside the scope of this specification. 1.7 The text of this specification references notes, footnotes, and appendixes that provide nonmandatory explanatory material. Excluding table footnotes which are mandatory, notes, footnotes and information in parentheses shall not be considered as requirements of this specification. 1.8 Units--The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Nonconformance with this specification is possible if values from the two systems are combined. Values in parentheses are conversions that are appropriately rounded for accuracy and precision; that are not exact equivalents, and that are for nonmandatory informational purposes. 1.9 This standard does not purport to address all the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.10 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.


    Keywords

    cross-linkable polyethylene; CX-PE; cross-linked polyethylene; hydrostatic stress; PEX; pipe; pressure; energy piping

    Rationale

    Cross-linkable PE pipe has no specification at this time. There are users who take advantage of the properties of cross-linkable PE to cross-link pipes after they have been installed or perform butt fusion on the pipe to join it. The most pressing need for this standard is to provide standardized stock material that may be converted into fittings, which then may be cross-linked. It is very difficult to produce large dimension fittings from PEX but much easier to do so using PE or cross-linkable PE.

    The title and scope are in draft form and are under development within this ASTM Committee.

    Citing ASTM Standards
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    Work Item Status

    Date Initiated:
    09-12-2018

    Technical Contact:
    Robert Samplonius

    Item:
    030

    Ballot:
    F17 (20-07)

    Status:
    Negative Votes Need Resolution