Crosslinked polyethylene/aluminum/crosslinked polyethylene (PEX-AL-PEX) composite pressure-pipe systems
This Standard covers crosslinked polyethylene/aluminum/crosslinked polyethylene (PEX-AL-PEX) macrocomposite pipe consisting of a welded aluminum (AL) tube laminated by a melt adhesive to layers of crosslinked polyethylene (PEX) inside and outside the aluminum tube. This Standard also covers fittings (connectors) for use with PEX-AL-PEX pipe. The pipes covered in this Standard are pressure rated for 1380 kPa at 23 °C or 860 kPa at 82 °C, or both.
Systems are intended for use in potable water distribution systems or other applications, including municipal water service lines, reclaimed water distribution, radiant panel heating systems, hydronic baseboard heating systems, snow and ice melting systems, building services piping, compressed air distribution, ground source geothermal systems, underground irrigation, and compressed gas distribution (not including fuel gases), provided that the PEX-AL-PEX systems comply with the applicable code requirements. Residential and commercial systems are included.
Note: The complete structure, consisting of the aluminum, melt adhesive, and layers of crosslinked polyethylene intimately bonded together, is known as pipe. For the purposes of this Standard, the layer of welded aluminum, or the internal and external layer of crosslinked polyethylene, is known as a tube. Tubes, intimately bonded together by the melt adhesive, form a pipe.
This Standard specifies requirements for materials, quality of work, dimensions, thermocycling resistance, sustained pressure performance, delamination resistance, and marking.
In developing the hydrostatic design basis for PEX-AL-PEX pipes, in accordance with CSA B137.0, pressure has been substituted for fibre stress.
The pressure rating of PEX-AL-PEX pipes is contingent on the thickness of the aluminum metal reinforcing layer. Pipes having the same dimension ratio but different metal reinforcing layer thicknesses will have different pressure ratings. The dimension ratio therefore cannot be used, as it is with homogeneous walled pipes, to assess changes in pressure rating with wall thickness variation.
In this Standard, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the Standard; “should” is used to express a recommendation or that which is advised but not required; and “may” is used to express an option or that which is permissible within the limits of the Standard.
Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.
Notes to tables and figures are considered part of the table or figure and may be written as requirements.
Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.