Asahi/America Chem ProlineAsahi/America, Inc.’s Chem Proline® and Chem Prolok™ piping systems have been certified by NSF to NSF/ANSI Standard 61-G. Made from PE resin, Chem Proline pipe and fittings possess great resistance to slow crack growth and are a lower cost alternative to metal, fiberglass reinforced plastic pipe and lined steel pipe. Chem Prolok™ is a fabricated double wall piping system manufactured from Chem Proline single wall pipe. Chem Prolok provides a low installed cost and safe long-term, maintenance-free service.