Jacketed Vessel Pressure Test 1

[Svk-Mn]

Hello,

I have a fully covered jacketed vessel. That means the jacket is fully covering the inner vessel, including heads at both ends.

Inner Vessel internal working pressure is 1.2 Mpag @ 40C.
Jacket internal working pressure(Inner vessel external pressure) is 0.3 Mpag @ 40C.

I want to know how the Hydrostatic Pressure Testing is performed?

-Each side must be tested separately or simultaneously?
-The client didn't mention the test pressure, so I must decide what shall be the test pressure.

 

[IdanPV]

See UG-99(e) and Interpretation BC-79-603.

 

[r6155]

1) I suggest pressure test before installing the jacket.
2) Install the jacket and pressure test
3) Pressure test the inner pressure vessel.

Pressure test as per UG-99

Regards

 

[Svk-Mn]

IdanPV,

What is Interpretation BC-79-603?

 

[IdanPV]

You will need to connect to the ASME Interpretations Database:

https://cstools.asme.org/Interpretation/SearchInterpretation.cfm

Under "Record #:" type BC-79-603.

 

[Svk-Mn]

r6155, the both vessels are already installed. The manufacturing procedure is such that we couldn't test them before installation. (See attached pic.)

1. We first manufactured the inner vessel(36inch) with 3 and 2 inch nozzle openings
2. We then inserted it inside the 40inch jacket and closed the both ends of jacket
3. And then we installed the nozzles(3 and 2inch) and inserted the 24inch vertical pipe on 40inch jacket
4. At the end we installed the 3 and 2inch pipes flanges

With this procedure, there is no chance you could test them before installation.

My question is, Do we test them simultaneously with design pressure x 1.3? Or we test them separately?

Please help!

 

[gr2vessels]

Hi Svk-Mn, testing separate shell side and jacket side makes sense;- the shell will be first internally tested and then external tested when hydrotest the jacket. The 0.3 x 1.3MPag jacket hydrostatic pressure is actually equivalent to 3x1.3 full vacuum pressure on the shell side. Testing simultaneously you test the shell for differential pressure only.
Cheers,
gr2vessels

 

[LittleInch]

Has the inner vessel been designed to handle 3 bar external pressure when inside is atmospheric pressure, or is it also designed for 4 bar external pressure allowing for a vacuum inside the vessel?
If not you need to have the inner vessel at the same pressure or a little bit higher than the test pressure of the jacket to avoid vessel collapse.

so you need to choose the worst case.

For me this is inner vessel with no jacket pressure and jacket pressure +1 bar with inner vessel open to atmosphere ( if that has been confirmed as allowable - see above).

Then do a leak test for both at MAWP in case there is some weird combination of stresses which peak when both are at pressure.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[r6155]

@ Svk-Mn
if your calculation is for each chamber, as you say, then the hydrostatic pressure test should be done separately. See UG-99.

Regards

 

[LittleInch]

They look very small pipes in and out compared to the volume of the inner vessel. And your jacket in your sketch has no nozzles at all? Just kind of curious.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Svk-Mn]

Thank you guys for your help.

LittleInch, no there are still nozzles connected to both vessels, just for simplification I didn't draw them in the pic.