I have written a lot about leak testing and pressure testing our piping systems and those articles all mention using the “bubble test” method. Now lets talk about the actual requirements of this test method.
ASME B31.3, 345.8 Sensitive Leak Test refers us to ASME BPVC, Section V, Article 10, Mandatory Appendix I, for how this leak testing method is to be performed and documented. In this mandatory appendix, we will find the specifics that will produce our WRITTEN PROCEDURE for this safety-critical task.
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ASME B31.3, 345.8.2 Method The test shall be the Bubble Test – Direct Pressure Technique in accordance with ASME BPVC, Section V, Article 10, Mandatory Appendix I or another leak test method that has a demonstrated sensitivity not less than 10-3 std mL/s under test conditions. When the Bubble Test – Direct Pressure Technique is used (a) the test pressure shall be at least the lesser of 105kPa (15 psi) or 25% of the design pressure. (b) the pressure shall be gradually increased until a gage pressure equal to the lesser of one-half the test pressure or 170 kPa (25 psi) is attained, at which time a preliminary check shall be made. Then the pressure shall be gradually increased in steps until the test pressure is reached, the pressure being held long enough at each step to equalize piping strains. |