Non-metallic underground pipe - with fine metallic particles added to the non-metallic material, to render it responsive to a metal detector

摘要

Underground pipe is made of non-metallic material, pref. PVC or polyethylene, to which are added fine metallic particles pref. Al, Cu and/or Fe powder, and pref. only in a surface layer of the pipe. The pipe pref. consists of an internal non-metallic pipe, surrounded by a sheath consisting of a mixt. of non-metallic material and fine metallic particles. The non-metallic material of the sheath and the material of the internal pipe corresponds to each other. The pipe responds to a conventional metal detector without losing the advantages of non-metallic pipes.