Local hydrotest of circumferential seam
Local hydrotest of circumferential seam
(OP)
Hello,
Sometimes I think I get a lot of unusual requests from clients, maybe it's normal.
So here's my latest. We are working on a carbon steel vessel that is ~14ft in diameter and ~40ft tall. Internally this vessel is extremely complicated, and is also refractory lined. Speaking with the refractory lining company, they really want to be able to refractory line the bulk of the vessel prior to the installation of the internals so they have room to work. Add to that, the internals do not fit through any of the manways, and the refractory can't get wet.
What they would prefer to have us do is as follows:
1) Fabricate the complete pressure boundary
2) Hydrotest the complete pressure boundary
3) Cut one of the 14ft diameter circumferential seams
4) Refractory line each half of the vessel, leaving a section un-lined where the vessel will need to be rejoined.
5) Install all internals in each half of the vessel.
6) Close up the vessel and re-weld the circ seam.
7) Weld in an internal chamber to enclose the circ seam
8) Perform a local hydrotest on only the rewelded circ seam, using the internal chamber from step 7 to keep the rest of the internals dry.
9) Cut away the internal chamber, and refractory line the exposed cirm seam.
With this procedure, all of the joints in each half of the vessel are tested in step 2, then the final circ weld is tested in step 8.
I've heard of local hydrotests being performed for nozzles, but have never heard of it for an entire circ seam. I know that I need to propose this to our local AI, but before I go there I was hoping any of you could provide any experiences you've had with local hydrotests. Does this sound reasonable?
Our only other option would be to perform a pneumatic air test, which our shop tries to avoid like the plague due to safety concerns.
Cheers,
Marty
Sometimes I think I get a lot of unusual requests from clients, maybe it's normal.
So here's my latest. We are working on a carbon steel vessel that is ~14ft in diameter and ~40ft tall. Internally this vessel is extremely complicated, and is also refractory lined. Speaking with the refractory lining company, they really want to be able to refractory line the bulk of the vessel prior to the installation of the internals so they have room to work. Add to that, the internals do not fit through any of the manways, and the refractory can't get wet.
What they would prefer to have us do is as follows:
1) Fabricate the complete pressure boundary
2) Hydrotest the complete pressure boundary
3) Cut one of the 14ft diameter circumferential seams
4) Refractory line each half of the vessel, leaving a section un-lined where the vessel will need to be rejoined.
5) Install all internals in each half of the vessel.
6) Close up the vessel and re-weld the circ seam.
7) Weld in an internal chamber to enclose the circ seam
8) Perform a local hydrotest on only the rewelded circ seam, using the internal chamber from step 7 to keep the rest of the internals dry.
9) Cut away the internal chamber, and refractory line the exposed cirm seam.
With this procedure, all of the joints in each half of the vessel are tested in step 2, then the final circ weld is tested in step 8.
I've heard of local hydrotests being performed for nozzles, but have never heard of it for an entire circ seam. I know that I need to propose this to our local AI, but before I go there I was hoping any of you could provide any experiences you've had with local hydrotests. Does this sound reasonable?
Our only other option would be to perform a pneumatic air test, which our shop tries to avoid like the plague due to safety concerns.
Cheers,
Marty





RE: Local hydrotest of circumferential seam
RE: Local hydrotest of circumferential seam
I hadn't thought of that. I read through the applicable sections of NBIC, and it states that the vessel should be tested in the same way as the original vessel testing, however this can be waived if it is impractical and if the inspector and owner agree. At the least we could perform 100% RT + MT.
That could very well be a path forward! It would look a little funny delivering a brand-new piece of equipment with a repair nameplate, but it could work.
The fact that this is a circumferential seam and not a longitudinal seam makes me a lot more comfortable going with just NDE.
Can't hurt to ask the AI, thanks for the idea.
Cheers,
Marty
RE: Local hydrotest of circumferential seam
1. Carber's Weld Test Service...
http://www.carber.com/services/weld-test.html
http://www.carber.com/documents/Weld_Test_Brochure...
2. Body flanges