The pressure vessels for low temperature operation must be as required by Section VIII of the ASME BPVC (incorporated by reference; see § 54.01-1) as modified by this subpart.

(a) Requirements for ferritic steels, high alloy steels, and heat-treated ferritic steels are contained in §§ 54.25-10, 54.25-15, and 54.25-20, respectively.

(b) Requirements for toughness testing of material product forms and weldments (including weld procedure qualification and production toughness tests) are contained in subpart 54.05.

(c) Materials suitable for a given minimum service temperature may be used in warmer service. Steels differing in chemical composition, mechanical properties, or heat treatments from those specified may be specially approved by the Commandant. Similarly, aluminum alloys and other nonferrous materials not intended to be covered by these sections may be specially considered by the Commandant for service at any low temperature.