【国外标准】 Standard Specification for Metric and Inch-sized Crosslinked Polyethylene (PEX) Pipe

This specification details the physical and performance requirements, and the corresponding test methods, for the evaluation of crosslinked polyethylene (PEX) pipes that are outside diameter controlled, made in nominal pipe dimension ratios, and pressure rated for water at different temperatures. Crosslinked PEX pipes covered here shall be made from polyethylene compounds that have been crosslinked by peroxides, Azo compounds, or silane compounds in extrusion, or by electron beam after extrusion, and are primarily defined by means of three criteria, namely, nominal density, degree of crosslinking, and long-term strength tests. Sampled pipe specimens shall be tested for conformance with workmanship, dimension (out-of-roundness, outside diameter, and wall thickness), density, hydrostatic burst pressure, hydrostatic sustained pressure strength, excessive temperature-pressure capacity, environmental stress cracking, stabilizer functionality, bent-pipe hydrostatic sustained pressure strength, oxidative stability in potable chlorinated water, and degree of crosslinking requirements.1.1 This specification covers crosslinked polyethylene (PEX) pipe that is outside diameter controlled in metric pipe sizes of DN 16 to DN 1000 (approximate outside diameters of 16 mm to 1005 mm) and inch pipe sizes NPS 3 to NPS 54 (approximate outside diameters of 3.5 in. to 54 in.), made in nominal pipe dimension ratios, and pressure rated for water at three temperatures (see Appendix X1). Included are requirements and test methods for material, workmanship, dimensions, burst pressure, hydrostatic sustained pressure, excessive temperature-pressure, environmental stress cracking, stabilizer functionality, bent-pipe hydrostatic pressure, oxidative stability in potable chlorinated water, degree of crosslinking, and minimum operating temperature. Requirements for pipe markings are also specified. The pipe covered by this specification is intended for pressure applications, such as, industrial and general-purpose pipelines, potable water pipelines, and fire–extinguishing pipelines1.2 The text of this specification references notes, footnotes, and appendixes, which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the specification.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.1.4 This standard does not purport to address all of 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.1.5 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.