ASTM International has published F3346-26, the new edition of its specification for polyethylene of raised temperature / aluminium / polyethylene of raised temperature composite pressure pipe. It replaces the 2024 edition. The standard describes a coextruded polyethylene pipe reinforced by a butt-welded aluminium tube, with the inner and outer PE-RT layers bonded to the aluminium by a melt adhesive.
The scope is deliberately narrow. Pipe with a non-welded metal layer, or with plastic layers other than polyethylene, falls outside it, and PEX-AL-PEX remains under ASTM F1281. Within its scope the standard sets a nomenclature, material requirements and test methods, the dimensions and strength of the component tubes and the finished pipe, adhesion tests, burst and sustained pressure performance, and marking. Fittings are covered in an annex.
The listed applications show where North America uses this pipe: air conditioning and refrigeration lines, underground irrigation, radiant panel and baseboard heating, snow- and ice-melt systems, and gases compatible with composite pipe.
Butt-welding is becoming the reference
In an overlap-welded pipe the edges of the aluminium strip lie on top of each other, leaving a small step in the wall. In a butt-welded pipe they meet edge to edge, so the aluminium wall is even all the way round. F3346 accepts only the second construction, and China’s new HVAC group standard T/ZZB 2125-2025 also treats butt-welded pipe as a category of its own. Both point the same way: specifiers increasingly name the welding method, not just the materials.
The SUSLiD view
If your project or market names ASTM F3346, specify butt-welded construction. Our butt-welded PE-RT/AL/PE-RT models end in -B, from 16 to 32 mm.
Source: ASTM F3346-26 Standard Specification for PE-RT/AL/PE-RT Composite Pressure Pipe · ASTM International, 2026-09-16
