Section 153.294 - Marking of piping systems(a) Each cargo piping system must be marked with the designation number of the cargo tank it serves at each hose connection, valve, and blind in the piping system. The markings must be in characters at least 5 cm (approx. 2 in.) high.(b) Every hose connection of a cargo piping system must be marked with the cargo piping system's working pressure required by § 38.10-10(a) of this chapter.