Code of Federal Regulations Title 46. Shipping § 46.58.20–20 Refrigeration piping

(a) All piping materials shall be suitable for handling the primary refrigerant, brine, or fluid used, and shall be of such chemical and physical properties as to remain ductile at the lowest operating temperature.

(b) Piping systems shall be designed in accordance with ANSI B31.5 (incorporated by reference;  see 46 CFR 58.03–1). Piping used for cargo reliquefaction systems shall also comply with the applicable requirements found in low temperature piping, § 56.50–105 of this subchapter.

(c) A relief valve shall be fitted on or near the compressor on the gas discharge side between the compressor and the first stop valve with the discharge therefrom led to the suction side. A check valve shall be fitted in the atmospheric discharge line if it is led through the side of the vessel below the freeboard deck, or a shutoff valve may be employed if it is locked in the open position.