PEX, in particular the B-type silane PEX in SESTA pipes, is a polyethylene derivative in which certain hydrogen atoms are replaced by chemical groups that bind the polymer macromolecules together in a process called cross-linking. Thus, while in polyethylene the polymer chains can flow with increasing temperature and the product becomes deformable, in PEX this flow is not possible and the product remains stable.
For this reason, it can also be used, coupled with aluminium, for pipes in high-temperature heating systems.
The SESTA PE-Xb/AI/PE-Xb multilayer pipe consists of 5 layers: PEX on the inside and outside bonded via two special adhesive layers to a longitudinally welded (TIG butt-welded) aluminium alloy intermediate layer. It guarantees a high level of mouldability of the structure, total hygiene and absolute resistance to corrosion thanks to the fact that the aluminium cannot come into contact with the masonry because it is protected by the plastic layers.