One of the top questions I get in my process safety circles is…
Do we have to pressure test/leak test piping that has been opened/modified before we re-introduce the HHC/EHS to the piping?
I turn to one of my favorite sources for RAGAGEPs, NFPA, and one of the best NFPA codes is NFPA 58, which I use as my baseline RAGEGAP for all my flammable liquified pressurized gases.
Now, I do take issue with using Hazardous Material as the “leak testing media,” something I was raised to call “farmer’s test,” as this is how they test their NH3 connections when using NH3 as fertilizer. But if NFPA will allow it, then I may not like it, but I can’t say it’s “not to code.”
6.17 Testing New or Modified Piping Systems.
6.17.1 Piping Systems.
6.17.1.1 After installation or modification, piping systems (including hose) shall be proven free of leaks at not less than the normal operating pressure.
6.17.1.2 LP-Gas shall be permitted to be used as the test medium.
In the 2014 edition, separate code requirements were added to distinguish between a one-time pressure test and the leak check that is required following any interruption in service.
A pressure test, as defined in 3.3.66, is a test of the gastight integrity of the piping system conducted only after initial installation or modification. This is very similar to the pressure test required by NFPA 54. However, note that NFPA 58 specifically allows LP-Gas to be used as the test medium, while NFPA 54 requires air, nitrogen, carbon dioxide, or an inert gas to be used. In addition, piping under the scope of NFPA 54 must be tested to at least 1.5 times the normal operating pressure but not less than 125 psig (862 kPag), whereas the piping in NFPA 58 is only required to be leak tested at normal operating pressure. Where an installer chooses to meet the test conditions of NFPA 54, one test could be conducted on the entire piping system. Otherwise, separate pressure tests must be conducted: one on the piping upstream of the final stage regulator covered by NFPA 58, and one on the downstream piping covered by NFPA 54.