ASTM WK68132

    New Practice for Commissioning of Cross-Linkable Polyethylene (CX-PE) Piping Systems

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



    WK68132

    1. Scope

    1.1 This practice covers the commissioning of pipe made in accordance with a cross-linkable polyethylene (CX-PE) pipe specification. 1.2 This practice is intended to provide information to users for the cross-linking of CX-PE pipe as an assembled system over a range of possible commissioning conditions. Limited advice regarding other matters, such as storage and handling of pipe before installation, layout of pipe, and recommended standard joining practices is offered but is intentionally limited to matters that are expected to affect the cross-linking processes. In general, joining practices used for installation of CX-PE piping systems are outside the scope of this practice; however, this practice requires that Practice F3507 be followed for butt-fusion joining of CX-PE pipe to ensure that the commissioned piping system hydrostatic pressure performance meets user requirements. 1.3 This practice is for the commissioning of pipe intended for pressure and non-pressure applications. Fluids such as water, water solutions, multi-phase mixtures, crude oil mixtures, gases, and chemical solutions containing small or large amounts of water are expected to fill the CX-PE pipe during the commissioning process. Consult the pipe manufacturers recommendations for information regarding compatible fluids. NOTE 1After CX-PE is cross-linked, water content is not a consideration, and chemically compatible fluids that do not contain water are permitted. The primary difference between commissioned CX-PE pipes and PEX pipes made in accordance with PEX line pipe 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. 1.4 CX-PE pipe commissioning per this practice is not intended to be applied to pipe installations for the transport of potable water, nor for the distribution of natural gas, nor for use with liquefied petroleum gas. 1.5 Qualified persons knowledgeable with the design, installation, and processes for cross-linking CX-PE pipe in accordance with this practice shall supervise the installation and commissioning of such projects. 1.6 CX-PE pipe commissioning in accordance with this practice is intended to result in completed systems with a high level of pressure-handling performance. This practice includes recommendations to mitigate the risk of internal pressure failure during incidental pre-cross-linking use, during the cross-linking process and after cross-linking is completed. 1.7 Commissioning per this practice requires the use of an appropriate cross-linking fluid. This practice sets out a method for determination if a cross-linking fluid is appropriate for cross-linking of the assembled CX-PE piping system. If the service fluid is determined to be an appropriate cross-linking fluid, commissioning only requires that an engineering evaluation be performed to determine that the risk of pressure or temperature or service fluid composition excursions for an initial term of service use be minimized. 1.8 If it is necessary for the cross-linking fluid to be different from the service fluid, this practice provides for methods to ensure that cross-linking is completed before the introduction of service fluids that potentially interfere with cross-linking and the development of the final properties of the cross-linked pipe. NOTE 2Compounds used to make CX-PE pipe are uniquely formulated to control the rate of cross-linking so that joining and installation may be performed, and the system will cross-link afterwards. The allowable temperature range for CX-PE pipe does not imply that it will actively cross-link over the entire 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. 1.9 The text of this practice references notes, footnotes, and appendixes that provide nonmandatory explanatory material. Excluding table footnotes that are mandatory, notes, footnotes and information in parentheses shall not be considered as requirements of this practice. 1.10 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 practice 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 non-mandatory informational purposes. 1.11 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. 1.12 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, Practices 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; PPI; pipe; pressure; in-service commissioning

    Rationale

    The commissioning of CX-PE pipelines and systems has additional considerations that shall be taken into account relative to the installation and commisioning of other plastic piping systems. The two most critical considerations are joining quality and completion of cross-linking. This practice will provide direction for the proper cross-linking of CX-PE piping so that, when it is completed, the piping system has the same performance as a system built from factory cross-linked PEX components. Users of this standard are expected to be workers in the oil and gas industries primarily who are assembling piping to transfer oilfield chemicals and water.

    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:
    05-09-2019

    Technical Contact:
    Robert Samplonius

    Status:
    Draft Under Development