Section 154.522 - Materials for piping(a) The materials for piping systems must meet § 154.625 for the minimum design temperature of the piping, except the material for open ended vent piping may be specially approved by the Commandant (CG-ENG) if:(1) The temperature of the cargo at the pressure relief valve setting is -55 °C (-67 °F) or warmer; and(2) Liquid cannot discharge to the vent piping.(b) Materials for piping outside the cargo tanks must have a melting point of at least 925 °C (1697 °F), except for short lengths of pipes with fire resisting insulation that are attached to the cargo tanks.CGD 74-289, 44 FR 26009, May 3, 1979, as amended by USCG-2014-0688, 79 FR 58285, Sept. 29, 2014