ANSI Standards NSF ANSI 359-2018 pdf free download – Valves for crosslinked polyethylene (PEX) water distribution tubing systems NSF ANSI 359-2018 pdf free download - Valves for crosslinked polyethylene (PEX) water distribution tubing systems. 3.3 fitting: A piping component used to join, terminate, or provide changes of direction in a piping system. 3.4 plastic: A... 02-20 Download Now