Abstract This specification covers establishes requirements for coextruded crosslinked polyethylene multi-layer pressure tubing with a continuously welded aluminum tube construction between inner and outer layers of plastic. The inner and outer crosslinked polyethylene layers are bonded to the aluminum by a melt adhesive. The tubing is outside diameter controlled and made in one standard dimension ratio, SDR9 and is intended to be used for hot and cold water conveyance in applications up to a certain temperature. The tubing is intended for use in potable water distribution systems for residential and commercial applications, water service, hydronic radiant heating (HRH), radiant panel heating, baseboard, and snow melt systems. PEX-AL-PEX tubing is comprised of one metallic layer, two layers of polymeric adhesive and two-layers of crosslinked polyethylene. The metallic layer is aluminum and the cross-linked polyethylene plastics used to make the PEX layers of the PEX-AL-PEX tubing shall be made from virgin resin. Different tests and measurements shall be conducted in order to determine the following properties: out-of-roundness, pipe wall thickness, outer and inner PEX layer thickness, adhesion, burst pressure, sustained pressure, gel content, and apparent ring tensile strength. The tubing shall be free of visible cracks, blisters, holes, foreign inclusions and other known injurious defects. The tubing shall be as uniform as practical in color, opacity, density and other physical properties.Scope1.1 This specification covers establishes requirements for coextruded crosslinked polyethylene multi-layer pressure tubing with a continuously welded aluminum tube construction between inner and outer layers of plastic. The inner and outer crosslinked polyethylene layers are bonded to the aluminum by a melt adhesive. The tubing is outside diameter controlled and made in one standard dimension ratio, SDR9 and is intended to be used for hot and cold water conveyance in applications up to 180°F (82.2°C). Included in this specification is a system of nomenclature for crosslinked polyethylene-aluminum-crosslinked polyethylene (PEX-AL-PEX) tubes, and the requirements and test methods for materials, dimensions of component layers and the finished tubing, layer adhesion test, weld strength, short-term burst pressure, long-term sustained pressure and marking requirements. The tubing covered by this specification is intended for use in potable water distribution systems for residential and commercial applications, water service, hydronic radiant heating (HRH), radiant panel heating, baseboard, and snow melt systems. 1.2 This specification covers only plastic-metal-plastic multi-layer tubes incorporating a continuous welded aluminum tube. Tubing consisting of metallic layers not welded together is outside the scope of this specification. 1.3 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.4 Specifications for connectors for use with pipe meeting the requirements of this specification are given in Annex A1. 1.5 The following precautionary caveat pertains only to the test method portion, Section 9, of this specification. 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 and health practices and determine the applicability of regulatory requirements prior to use.
