On the heat treatment of pressure vessels
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The medium is ammonia water; after the overall heat treatment, it was found that the open-ended pipe and the cylinder had not been fully welded together, so re-welding was required. Is overall heat treatment after welding necessary in this case?
In all cases, flaw detection is carried out first followed by heat treatment – how could your process end up like this? Welding is generally not allowed after heat treatment.
Yes, I’m in charge of inspection; during the on-site inspection, it was found that there was incomplete welding
I am in charge of supervision and inspection; the on-site inspectors are too lax, and a notice has been issued accordingly
This post was last edited by Lantian on 2017-1-5 at 12:29. The manufacturing capabilities of this company are really poor; how did it get such a certification? Are you still here helping them fool people? Aren’t you responsible if something goes wrong?
It is necessary to carry out heat treatment again. One is the requirement of technical conditions, and the other is that the material is prone to stress corrosion cracking in ammonia solution; therefore, the stress must be reduced to the lowest level possible.
Don’t label people harshly. . It’s impossible to watch every weld. . Moreover, incomplete penetration at the root of the welds connecting to the cylinder is a common phenomenon. Especially in the case of small pipe diameters. . Double-sided welding must be required. For those that cannot be inspected visually internally, RT sampling is conducted.
This should be repaired by digging, not by rewelding; it’s the same as carrying out repairs in that way. . If heat treatment is really necessary, then perform localized heat treatment. . If the depth does not reach a certain level, it is not necessarily necessary to carry out re-heat treatment per GB150.4 7.4
This is what you mean by the common phenomenon in China – no one is responsible or serious.
Deceiving people is definitely not an option; otherwise, a notice of decision wouldn’t be issued. It’s just my approach to handling this issue, as well as what needs to be avoided in the future
In my opinion, the regulators should definitely criticize them; it’s not always necessary to carry out full heat treatment after weld repairs – it depends on the size and depth of the repair, and there should be regulations regarding this in the factory.