Is it okay to have a weld skirt after a hydrostatic test?
Thread Content
Today, I went to the container factory to inspect the equipment and noticed a problem: we have a tower-type vessel with a skirt structure. The transition section cylinders in the skirt have already been welded to the lower head; what remains is only the lower part of the skirt cylinders and the base ring (which has already been prefabricated as a single unit). This portion has not been welded to the transition section of the vessel’s skirt or to the parts above it. According to the technical specifications, this portion does not require heat treatment. Yet the manufacturer still carried out a horizontal hydrostatic test on the equipment. Is it acceptable to do this? The manufacturer said there are other products as well; considering factors such as the site and equipment, a hydrostatic test was carried out first. The drawings also permit horizontal hydrostatic testing, and the parts that have not been welded are non-pressure components, so it has no impact on the tower, and there is no problem with doing this. I would like to ask if this approach is appropriate? Is it a violation of regulations or standards?
”After the pressure vessel is manufactured, it should undergo a pressure test. “ This is the exact wording from the Solid Content Regulations...
Equipment that does not require heat treatment is acceptable.
No problem; in some designs, it is not desired for the skirt cylinder to undergo heat treatment, so it is proposed to weld the skirt cylinder to the transition section after heat treatment. It doesn’t matter whether the pressure test is carried out on a vessel with a skirt or without one; after all, the testing is not done in an upright position. It is sufficient to ensure the tolerances during the assembly of the skirt cylinder and the transition section.
It’s fine if there is a transition section; if not, neither heat treatment nor anything else is allowed!
The connection welds between non-compressed components and pressure vessels are considered part of the pressure vessel itself. So the skirt base mentioned by the original poster should not be governed by the code. The manufacturer should not have violated the tolerance specifications.
Yes, a hydrostatic test is used to verify strength and sealing performance; whether or not a skirt is welded has no impact on the strength and sealing performance of the container shell
Even for equipment that requires heat treatment, there is no problem; a transition section has already been welded in for heat treatment, and it is more reasonable to weld the lower skirt portion after the heat treatment.
”It’s fine if there is a transition section; if not, neither heat treatment nor anything else is allowed! “——I agree with your view