The silane method, also called the "moisture cure" method, results in PEX-B, where the cross-linking is performed in a secondary post-extrusion process, producing cross-links between a cross-linking agent.
The tubing may be installed in concrete, gypsum based lightweight concrete, sand, asphalt, in or under wood flooring or behind wallboard or plaster. Apollo APPW50012 Cross-Linked PEX-B Pipe, 1/2 in, 500 ft L, White The cross-linked bonds are formed through silanol condensation between two grafted vinyltrimethoxysilane (VTMS) units, connecting the polyethylene chains with C-C-Si-O-SiC-C bridges. The process is accelerated with heat and moisture. PEX tubing is for use in hot and cold potable water distribution systems.