I want to pressure test my compressor tank which I assume is in good condition. I have a plumbers' pressure testing hand pump and will fill the tank with water before adding pressure. What would the recommended testing pressure be? I presume I need to exceed the maximum working pressure. I want to confirm it is safe to use. This is for my own personal use. Thanks.
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Jelly_Sheffield
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If this is just for your own use, the standard test used in the ASME code and (parts of) the EN standards is:
"Not less than 1.1 and not more than 1.3 times the maximum working pressure".
In commercial use, you need a "suitably qualified and experienced person" to prepare a "written scheme of examination", then follow the recommendations set out in that scheme of evaluation.
"Not less than 1.1 and not more than 1.3 times the maximum working pressure".
In commercial use, you need a "suitably qualified and experienced person" to prepare a "written scheme of examination", then follow the recommendations set out in that scheme of evaluation.
Agreed, but I want to test it for peace of mind. The compressor came to me in bits (some missing) and I'd like it tested. I also have another much older unit I'd like to test.
Perfect! Many thanks.
Agroshield
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A visual examination of the inside with an endoscope camera and a good light would be advisable. The pressure test might hold, but seeing inside could inform you concerning how far into the future that would remain true.
addjunkie
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Having done a lot of pressure and leak testing do not do it with out a safety valve fitted in your test set up. Hydro testing is the safest, but once liquid filled the pressure comes up very quickly.
Jelly_Sheffield
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This is a good point.
Rust pitting (localised patches of rust with a diameter ≤ the shell thickness) in particular is a warning sign to pay attention to, not super common in carbon steel vessels, but comparatively unpredictable, and can cause particularly spectacular failures.
If you identify significant pitting it's probably worth consulting a professional to assess the shell integrity.
Jelly_Sheffield
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Actually this probably bears explaining why there's a maximum hydro-test pressure reccomended.
If you exceed the design pressure enough to stress some part of the shell to or beyond its yield point, then the whole thing is permanently, irreversibly weakened...
and, unless you have the design documents, it is difficult to determine how much pressure would be required to do that, but it can be reasonably assumed that a standards compliant vessel is intended to withstand the test pressure for that standard.
In all likelihood the pressure required to cause damage is a lot higher than 1.3× the MWP but best not to take chances.
I will use a hand pump that pumps just a few ml on each stroke. I don't think there's much chance of me going over pressure by accident. I've seen videos of people using high pressure jet washers... Well that's an entirely different matter!
I'll have a look at the tank later. It may be possible to remove an end bung (if it has one).
I'll have a look at the tank later. It may be possible to remove an end bung (if it has one).
addjunkie
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Its a while since Ive read the ASME or API standards, but if my memory serves me correctly a manufactured vessel or piping section would be hydro tested to 150% of working pressure. Once assembled would then be leak tested to 110% of the MAWP, or 95% of the Safety valve set point.
If they are going to leak its normally on a welded seem, unless you have some severe localised corrosion due to a defect in an internal coating for example.
If they are going to leak its normally on a welded seem, unless you have some severe localised corrosion due to a defect in an internal coating for example.
Is that a good camera or a cheapie import? I'm guessing it is the former.
JOEPRO
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Why would you guess that?
Wait for the update... Washing it out now....
Reasonably clear and decent depth of field
