B31.3, Category M, Sensitive Test
B31.3, Category M, Sensitive Test
(OP)
I'm in mining consulting business where there are not many Category M fluids. We use B31.3 for piping design.
Per ASME B31.3, para. M345 Testing, a sensitive leak test shall be included in the required leak test.
My understanding is : a normal hydrostatic test is required (1.5x design pressure) and a air and bubble test is also requried (para. 345.8, 1.25x design pressure or 15psi+ design pressure, whichever is less).
I specified the requirements in the line list for the previous projects but myself did never supervised the tests on site. When I talked about those tests lately with the commissioning engineers, none of them remembered they did the bubble test and telling me that was overkill. We all agreed that the Category M was specified correctly for those fluids.
How do you think?
Per ASME B31.3, para. M345 Testing, a sensitive leak test shall be included in the required leak test.
My understanding is : a normal hydrostatic test is required (1.5x design pressure) and a air and bubble test is also requried (para. 345.8, 1.25x design pressure or 15psi+ design pressure, whichever is less).
I specified the requirements in the line list for the previous projects but myself did never supervised the tests on site. When I talked about those tests lately with the commissioning engineers, none of them remembered they did the bubble test and telling me that was overkill. We all agreed that the Category M was specified correctly for those fluids.
How do you think?





RE: B31.3, Category M, Sensitive Test
RE: B31.3, Category M, Sensitive Test
The search function included in this discussion board is a truly useful utility.
thread124-105766
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thread378-23594
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thread378-79125
Regards, John
RE: B31.3, Category M, Sensitive Test
For a piping system that has been classified as Category M fluid service, is both a hydro test (or pneumatic test) AND a sensitive leak test required?
I read all the threads listed and didn't see this addressed. ASME B31.3 interpretation 20-48 says that both a sensitive leak test and a hydrostatic/pneumatic test are required, but this doesn't make sense to me especially if you are doing the sensitive leak test first and then following it up with pneumatic test.
Is this double test the committee's intention or am I and bulkhandling reading this incorrectly? (Apologies as this probably belongs in the ASME Issues forum.)
RE: B31.3, Category M, Sensitive Test
Wouldn't the sensitive leak test be done at a lower pressure? So, the hydrostatic test is done to make sure that the tank will not suffer a gross failure if it is overpressurized and the leak test is done to make sure there aren't any small leaks of the Class M fluid.
And if there is an official ASME Interpretation, then that is the official ASME answer.
Patricia Lougheed
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RE: B31.3, Category M, Sensitive Test
150% of the design pressure for hydrostatic leak test
110% of the design pressure for pneumatic leak test
25% of the design pressure for a sensitive leak test (or 15 psi whichever is lower)
The hydro and sensitive state specifically "at least", but the pneumatic states "shall be". But I would assume that you could test at a pressure higher than that.
So if you ran a pneumatic test at 110% of the design pressure I would think that would cover both. Here is the link to the interpretation (it is 20-48 and it is on page 49 of the PDF):
ht
RE: B31.3, Category M, Sensitive Test
The subject of doing pneumatic versus hydrostatic has been addressed several times on Eng-Tips. You might want to look at them. There are concerns about personnel safety associated with them.
Personally, I'd do the gross failure first and the sensitive leak test second; especially if you are using a fairly expensive gas for the sensitive leak test. Also, if you decide to do only one test, don't be surprised if your local jurisdiction tells you to do the second one anyways.
Patricia Lougheed
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Want to post an image? Look at the FAQ's in forum559: SolidWorks 3D CAD products
RE: B31.3, Category M, Sensitive Test
RE: B31.3, Category M, Sensitive Test
RE: B31.3, Category M, Sensitive Test
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/