46 CFR 56.97-25 - Preparation for testing (reproduces 137.2).
(a) Exposure of joints. All joints including welds must be left uninsulated and exposed for examination during the test.
(b) Addition of temporary supports. Piping systems designed for vapor or gas may be provided with additional temporary supports, if necessary, to support the weight of the test liquid.
(c) Restraint or isolation of expansion joints. Expansion joints must be provided with temporary restraint, if required for the additional pressure load under test, or they must be isolated from the test.
(d) Isolation of equipment not subjected to pressure test. Equipment that is not to be subjected to the pressure test must be either disconnected from the piping subassembly or system or isolated by a blank flange or similar means. Valves may be used if the valve with its closure is suitable for the proposed test pressure.
(e) Treatment of flanged joints containing blinds. Flanged joints at which blinds are inserted to blank off other equipment during the test need not be tested.
(f) Precautions against test medium expansion. If a pressure test is to be maintained for a period of time and the test medium in the system is subject to thermal expansion, precautions must be taken to avoid excessive pressure. A small relief valve set to 1 1/3 times the test pressure is recommended during the pressure test.