Hydrotest on flanged vessel 2

[SDRME]

I have recently designed some vessels with body flanges. In fact, each vessel can be divided into some parts. The question is that “Is it allowed to perform hydrotest on each section separately (using blind flanges) and then assemble the whole system or the whole system shall be tested at once?“

 

[jamesl]

UG-99 requires a hydrotest on a COMPLETED vessel. So you cannot test a vessel in sections.

There is a code interpretation VIII-1-01-04 on separate testing of vessel body and upper head.

 

[SDRME]

Great!!!
Thanks...

 

[SnTMan]

SDRME, if the vessel is field assembled, it may be hydrotested by the (stampholding) assembling entity. See U-2(h).

Regards,

Mike

 

[SDRME]

I think we shall assemble the vessel and hydrotest it on the workshop. Then we shall disassemble it and transfer it in separate sections to site (it is not possible to transfer the whole vessel) and then reassemble it there. I think it is not needed to perform the hydrotest in site again. Am I right?

 

[SnTMan]

SDRME, my guess is, somebody will want it.

Regards,

Mike

 

[kennyc71]

Nothing like proving the final "service" gasket seals.

You could offer something less than 1.3X design as a final proof. The AI could sign off on a service pressure test rather than a full hydro.

Either way, good luck!

 

[gr2vessels]

The code requires only one hydro test, in the workshop or on site. It is up to the Client to request additional hydro test (and pay additional, associated costs). If the Client specification does not address this test issue, then your minimum duty is to assemble the equipment and perform the hydrotest as per the code requirements. Remember, the equipment in service will have the sections unbolted many times, for service and cleaning, then re-assembled and operated without re-hydro testing.
The reason is that the hydrotest is for checking the pressure retaining components, not the gaskets, bolts and other removable components.
Cheers,
gr2vessels

 

[zelgar]

I think a lot of you suggesting not performing a pressure test at site are asking for problems. The process of disassembling and reassembling the tank may have caused some changes in the tank. Also, enviromental factors may be different from the workshop and the tank farm (e.g., thermal differences).

Part of the reason for doing the pressure test is to verify that the tank doesn't contain any leaks. I doubt that you'd get any repeat business if you installed a tank that leaked the first time your customers put product into it.

 

[gr2vessels]

zelgar,
The object of the post was a pressure vessel designed with a girth flange, not a storage tank. The BPVC is different from the API tanks standard. A pressure vessel is hydrotested for integrity purposes, not for gasket leaking.