PEX tubing comes in nominal sizes ranging from 1/4 to 3 in. copper tube size (CTS), and pipe sizes in both inch and metric sizes. PEX tubing is SDR9 with standard hydrostatic pressure ratings of 160 psi at 73°F (1105 kPa at 23°C) and 100 psi at 180°F (690 kPa at 82°C). Consult the specific PEX manufacturer's literature and listings for appropriate pressure ratings. PEX tubing and pipe are sold in coils and straight lengths.
PEX is a polyethylene material which has undergone a change in molecular structure using a chemical or a physical process whereby the polymer chains are chemically linked. Crosslinking of polyethylene into PEX for pipes results in improved properties such as elevated temperature strength and performance, chemical resistance and resistance to slow crack growth.