It is rare; I can not recall ever disputing NFPA in any of their guides/standards/codes. However, section 27.7 of NFPA 30 is worded incorrectly and needs to be called out as it poses significant risks if followed by the letter. Section 27.7 covers the pressure and leak testing of “flammable liquid” piping circuits. Although I am thankful for NFPA including this in NFPA 30, some users who may not know better may place their people or contractors in harm’s way. Here is the issue:
NOTE: This requirement goes back ever since NFPA 30 included this pipe testing requirement
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27.7 Testing of Piping Systems. 27.7.1 Initial Testing. Unless tested in accordance with the applicable sections of ASME B31.1, Power Piping; B31.3, Process Piping; or B31.4, Pipeline Transportation Systems for Liquids and Slurries, all piping shall be tested before being covered, enclosed, or placed in use. 27.7.1.1 Testing shall be done hydrostatically to 150 percent of the maximum anticipated pressure of the system or pneumatically to 110 percent of the maximum anticipated pressure of the system, and the test pressure shall be maintained while a complete visual inspection of all joints and connections is conducted.
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Did you catch it? Was my hint by bolding a few words enough? Here is another hint from ASME B31.3…
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345.5.5 Procedure. The pressure shall be gradually increased until a gage pressure that is the lesser of onehalf the test pressure or 170 kPa (25 psi) is attained, at which time a preliminary check shall be made, including examination of joints in accordance with para. 341.4.1(a). Thereafter, the pressure shall be gradually increased in steps until the test pressure is reached, holding the pressure at each step long enough to equalize piping strains. The PRESSURE SHALL THEN BE REDUCED TO THE DESIGN PRESSURE before examining for leakage in accordance with para. 345.2.2(a). |
The bottom line is that NO ONE should be near the piping while it is being PRESSURE TESTED!!!!
After a successful pressure test, we then LOWER the pressure to the piping’s DESIGN PRESSURE and then we can approach the piping to conduct our LEAK TESTING.
We should never allow our leak test (or visual inspection) to be performed when the piping is either 110% (pneumatic test) or 150% (hydrostatic) of its DESIGN PRESSURE.
At least, that is my professional opinion.