Low pressure vessel hydro test
Low pressure vessel hydro test
(OP)
Is there a code which states that pressure vessel with design pressure of 15 psig needs to be hydro tested at minimum of 50 psig.
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
Low pressure vessel hydro test
|
RE: Low pressure vessel hydro test
RE: Low pressure vessel hydro test
But what if the vessel is designed for 16 psig, would it have to be hydro-tested to anything greater than 1.3 times i.e. 50 psig
RE: Low pressure vessel hydro test
RE: Low pressure vessel hydro test
RE: Low pressure vessel hydro test
RE: Low pressure vessel hydro test
There are many applications where an end user specifies 15 psi (or less) so that he does not go through the expense of registration, AI inspection and future in-service inspections. He may still want some additional mechanical integrity and designs for a higher pressure. To support this additional integrity he specifies a higher test pressure.
RE: Low pressure vessel hydro test
Too much emphasis is placed on hydrostatic testing of in-service components to assure a false sense of security that by going to higher test pressures you have additional mechanical integrity. Also, more importantly, the effect of elevated service temperature is not included with hydrostatic testing.
RE: Low pressure vessel hydro test
RE: Low pressure vessel hydro test
RE: Low pressure vessel hydro test
Calculated thickness: 0.2"
Corrosion allowance: 0.2"
Since we can't get 0.4" thickness we round up to 0.5"
Test pressure = 0.5/0.2 x 15 x 1.3 = 49 or 50 psig
It could be even higher if the design temp was high since the stress ratio would be greater than 1.0.
RE: Low pressure vessel hydro test
That is fine to agree with one another, with the example provided I see your line of reasoning for wanting to increase the test pressure for new vessel construction. However, in my world, this approach is not necessary and would not provide any benefit in assuring further design integrity beyond what the design margins in the code inherently provide, and certainly would not increase the ability to find leaks from gross defects. A 1.5X DP hydrostatic test is plenty of pressure to find leaks.
For in-service vessels, hydrostatic testing of aged equipment must be done with extreme caution, and in some cases I would not recommend it. If anything, this could result in serious problems related to service-exposed materials because they may actually have reduced fracture toughness. Any future benefit of attempting to use a higher pressure hydrostatic test goes away as soon as the material is placed into service.
RE: Low pressure vessel hydro test
Shop stress during test = 0.2/0.5 x 1.3 = 52%
Operating stress (corroded) = 0.2/0.3 = 67%
This is a very undesirable situation and thats why we always insist on new and cold testing.