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ASME B31.3-2016 uninsulated and exposed for examination during leak 345.3.4 Limits of Tested Piping. Equipment that is testing. not to be tested shall be either disconnected from the (b) Joints previously tested in accordance with this piping or isolated by blinds or other means during the Code may be insulated or covered. test.A valve may be used provided the valve(including (c) At the owner's option,joints in Category D Fluid its closure mechanism) is suitable for the test pressure. Service that are subject to a hydrostatic leak test 345.4 Hydrostatic Leak Test (para. 345.4) or an initial service leak test (para. 345.7) may be insulated and have protective weather sheathing 345.4.1 Test Fluid. The fluid shall be water unless installed prior to leak testing. Consideration shall be there is the possibility of damage due to freezing or to given to increasing the test period to allow time for adverse effects of water on the piping or the process possible leakage to pass through the insulation and (see para. F345.4.1). In that case another suitable non- weather sheathing. toxic liquid may be used. If the liquid is flammable,its (d) All joints may be primed and painted prior to flash point shall be at least 49°C (120°F),and consider- leak testing unless a sensitive leak test (para. 345.8) is ation shall be given to the test environment. required. 345.4.2 Test Pressure. Except as provided in (16) 345.3.2 Temporary Supports. Piping designed for para.345.4.3,the hydrostatic test pressure at every point vapor or gas shall be provided with additional tempo- (a) not less than 1.5 times the design pressure. in a metallic piping system shall be as follows: rary supports,if necessary,to support the weight of test liquid. (b) when the design temperature is greater than the test temperature,the minimum test pressure,at the point 345.3.3 Piping With Expansion Joints under consideration, shall be calculated using eq. (24). (a) Unrestrained expansion joints depend on external pT = 1.5 PSIS (24) main anchors to resist pressure thrust forces. Except as limited in para. 345.3.3(c), a piping system containing where unrestrained expansion joints shall be leak tested with- P = internal design gage pressure out any temporary restraints in accordance with PT = minimum test gage pressure para.345 up to 150%of the expansion joint design pres- S = allowable stress at component design tempera- sure. If the required test pressure exceeds 150% of the ture for the prevalent pipe material; see expansion joint design pressure and the main anchors Table A-1 or Table A-IM are not designed to resist the pressure thrust forces at ST = allowable stress at test temperature for the the required test pressure, for that portion of the test prevalent pipe material; see Table A-1 or when the pressure exceeds 150% of the expansion joint Table A-IM design pressure,the expansion joint shall either be tem- porarily removed or temporary restraints shall be added (c) in those cases where the piping system may not to resist the pressure thrust forces. include pipe itself, any other component in the piping (b) Self-restrained metallic bellows expansion joints system, other than pipe-supporting elements and bolt- (i.e.,tied,hinged,pressure balanced,etc.)have restraint ing,maybe used to determine the ST/S ratio based on the hardware designed to resist the pressure thrust forces. applicable allowable stresses obtained from Table A-1 or Except as limited in para. 345.3.3(c), a piping system Table A-IM.In those cases where the piping system may containing self-restrained expansion joints shall be leak be made up of equivalent lengths of more than one tested in accordance with para. 345. A self-restrained material,the ST/S ratio shall be based on the minimum expansion joint previously shop tested by the manufac- calculated ratio of the included materials. turer in accordance with Appendix X may be excluded 345.4.3 Hydrostatic Test of Piping With Vessels as a from the system to be leak tested,except when a sensi- System 3 tive leak test in accordance with para. 345.8 is required. (a) Where the test pressure of piping attached to a Restraint hardware for all types of expansion joints shall vessel is the same as or less than the test pressure for be designed for the pressure thrust forces at the test the vessel, the piping may be tested with the vessel at pressure. the piping test pressure. (c) When a metallic bellows expansion joint is (b) Where the test pressure of the piping exceeds the installed in the piping system subject to a leak test and vessel test pressure,and it is not considered practicable the leak test pressure determined in accordance with to isolate the piping from the vessel,the piping and the para. 345 exceeds the pressure of the test performed by vessel may be tested together at the vessel test pressure, the manufacturer in accordance with Appendix X, the required leak test pressure shall be reduced to the manu- 3 The provisions of para.345.4.3 do not affect the pressure test facturer's test pressure. requirements of any applicable vessel code.