Code of Federal Regulations Title 46. Shipping § 46.108.447 Piping

(a) Each pipe, valve, and fitting in a CO₂ system must have a bursting pressure of at least 420 kilograms per square centimeter (6,000 pounds per square inch).

(b) All piping for a CO₂ system of nominal size of 19.05 millimeters ( 3/4 inch) inside diameter or less must be at least Schedule 40 (standard weight) and all piping of nominal size over 19.05 millimeters ( 3/4 inch) inside diameter must be at least Schedule 80 (extra heavy).

(c) Each pipe, valve, and fitting made of ferrous materials in a CO₂ system must be protected inside and outside from corrosion.

(d) Each CO₂ system must have a pressure relief valve set to relieve between 168 and 196 kilograms per square centimeter (2,400 and 2,800 pounds per square inch) in the distribution manifold or other location that protects the piping when all branch line shut off valves are closed.

(e) The end of each branch line in a CO₂ system must extend at least 50 millimeters (2 inches) beyond the last discharge outlet and be closed with a cap or plug.

(f) Piping, valves, and fittings in a CO₂ system must be securely supported and protected from damage.

(g) Each CO₂ system must have drains and dirt traps located where dirt or moisture can accumulate in the system.

(h) Discharge piping in a CO₂ system may not be used for any other purpose except as part of a fire detection system.

(i) Piping in a CO₂ system that passes through accommodation spaces must not have drains or other openings within these spaces.