CFR /  Title 46  /  Part 154  /  Sec. 154.665 Welding procedures.

Welding procedure tests for cargo tanks for a design temperature colder than 0 [deg]C (32 [deg]F), process pressure vessels, and piping must meet Sec. 54.05-15 and Subpart 57.03 of this chapter.

Cargo Pressure and Temperature Control