Piping and fittings.

(a) The piping between the cylinders and the appliances must be seamless annealed copper tubing or such other seamless tubing as may be approved by the Commandant. (b) All high-pressure tubing between the cylinders and the regulators must have a minimum wall thickness of 0.049 inch. All low-pressure tubing between the regulator and appliances must have a minimum wall thickness of 0.032 inch. (c) Tubing connecting fittings must be of the flare type; or connections may be soldered or brazed with material having a melting point in excess of 1,000 °F.