Inspection issues of butt welds on the nozzles of pressure vessels with DN250 and below
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If the equipment requires 100% flaw detection, then in accordance with GB/T150.4-2011, section 10.4 on surface inspection, requirement h states that: h) For containers that require full radiographic or ultrasonic testing, the nominal diameter DN…
For Class AB local flaw detection of equipment, unless otherwise specified in the drawings, can the Class AB seams of fittings smaller than DN250 be exempted from non-destructive testing?
Is there any provision in the standard you mentioned?
I didn’t understand any of it; the original poster, please give an example.
It seems the original poster didn’t understand it themselves
GB150 stipulates that for sizes smaller than DN250, the provisions in the drawings shall apply; if the drawings do not specify anything additional, then no testing is required. Once, for a task that required the provision of drawings, the supervisor was quite strict and asked us to contact the design institute to obtain the necessary documents. We did as requested, and the design institute responded accordingly.
How is it that the drawings don’t specify this? Each set of drawings specifies the inspection requirements for types A and B, and small pipe joints fall under category B (this is important).
Is this specified in the drawings? So is the takeover and high-diameter flange welding classified as Category B?
If you think it’s easy to shoot, then go ahead and shoot; no one will refuse to help you. Even if you do shoot, it will still be counted within the 20% limit – no problem at all.
Doesn’t this diagram require standards to be met for both categories A and B, while no requirements apply to categories C and D? Do you mean that without using fittings with a DN of less than 250 mm, it’s not possible to achieve a 20% ratio? If it really can’t be achieved, you should consider whether this counts as a pressure vessel.