Issues with openings in pressure vessels
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This post was last edited by Forgetting = Forgetting on 2018-6-21 at 15:45. “According to GB150.4-10.3.2, for local radiographic or ultrasonic testing: c) For nozzles that meet the requirements of GB150.3-6.1.3 and do not require additional reinforcement, the weld joints within a range of 2 times the diameter of the opening must be subjected to 100% testing.” However, one of the conditions specified in GB150.3-6.1.3 is that the opening must not be located on weld joints of type A or B. “” Question 1: Does this mean that in the actual manufacturing process, if there are weld joints within a range of 2 times the center of the opening, it fails to meet the requirements of 6.1.3, and such an opening needs to be recalculated and reinforced? Question 2: “6.1.4: If the opening is located through or adjacent to a container weld joint, it must be ensured that there are no defects exceeding acceptable limits within a range of 2 times the diameter of the opening.” Does that mean the manufacturing requirements are specified on the assumption that the openings have already been reinforced? Question 3: In the actual manufacturing process, as long as there are no excessive defects in the inner container joint within a range of 2 times the aperture diameter from the center of the opening, does the location of the opening relative to the A/B type welds not matter? Question 4: If non-destructive testing is required, does it necessitate raising the corresponding qualification level? For example, if the original specification requires 20% to meet grade AB, level III, does expanding the scope of inspection result in 100% meeting grade AB, level II?
I believe that: 1. As long as no holes are made in Class A or Class B welds, even if there are weld joints within 2 times the diameter of the hole in the pipe fitting, the requirements of clause 6.1.3 are satisfied； 2. If the opening passes through or is adjacent to the container’s weld joint, the manufacturing requirements after reinforcement should be taken into account ； 3. 100% testing is required, in accordance with the provisions of GB150.4-10.3.2.
Overthinking it – after additional shooting, it is still evaluated according to the qualified standard specified in the specifications.
Based on my understanding of 150: 1. If the holes are located on AB-class welds, additional reinforcement must be considered. 2. Welds within the required adjacent opening area must be inspected; no defects exceeding the specified limits are allowed. As for the qualification level, it is determined according to the requirements of the local testing level.
These requirements must be met even for hole-opening checks; checks are not a panacea, and they cannot replace these requirements!
The problem now is that on the design drawings, the holes are definitely not located on the welds, but in actual manufacturing, due to reasons such as the layout of the manufacturing process, the holes end up being placed on the welds.
If, due to manufacturing reasons, the hole ends up on the weld, it is necessary to contact the design team to issue a modification order, which must be stamped with the design department’s official seal.
I’m struggling with this issue of calculation and flaw detection
There’s no need for hesitation; follow the standard procedures. First, conduct calculations, complete the necessary paperwork, and then proceed with manufacturing
Why does the standard stipulate in clause 6.1.3 that openings must not be located at Class A or Class B weld joints? The question is whether the standard specifies that openings must not be located at joints, or that there must be no Type A or Type B joints within the area of the openings If it is the former, after making the hole, any defects are already removed; as long as there are no defects exceeding the specified limits within the area of the hole, isn’t that in line with the requirements of 6.1.4? According to ASME Section VIII, Part I, restrictions apply allowing them to be located on Class B and Class C butt joints, but the welds at the opening locations must undergo non-destructive testing. The restrictions imposed by ASME seem more reasonable.