Distance between takeover opening and longitudinal seam ring seam
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According to ASME: what is the minimum distance between an opening and a longitudinal or circumferential seam for a DN250. pipe? I checked UW14, and it seems to not meet the requirements of UG36(C)(3), right? So I don’t know what to do. Seeking advice from experts
This post was last edited by cxf4587 on 2011-8-30 at 11:47. Based on my personal understanding, I hope it can help resolve this question. First of all, the original poster should understand the difference between ASME’s calculations for reinforcing openings and those outlined in GB150, even though both methods involve using equal-area reinforcement. Because according to ASME standards, any opening that meets the requirements for reinforcement design can be located at a welded joint; in the case of Class A joints, the welding joint factor E1 is taken into account in the calculations for reinforcement due to such openings. For small openings that do not require reinforcement calculations (no joint factor is applied, hence no calculation is done), the standards do not allow them to be located at Class A joints. When such openings are located near Class A joints or at Class B or Class C butt joints, RT inspection should be carried out within a radius of 3d. (i.e., UW14) The hole with a diameter of DN250 in the original design does not fall under the category of small openings UG36(C)(3); therefore, it can be located on the weld seam, as the welding joint factor E1 has already been taken into account in the calculations. Any type of opening that is designed for reinforcement in accordance with this ASME code may be located at a welded joint. GB150 is different. The above is my personal understanding of the ASME standards, for reference only.
Senior Lu: I agree too, haha
That’s absolutely correct; there’s no mistake in that. Holes that do not require reinforcement shall not be made in Class A welds, whereas holes that meet the reinforcement requirements can be made in any type of weld.
Reply to 5# xxyinhe: Could you please explain in more detail? What are the differences between GB150 and ASM, and how does GB150 make provisions?
It can be placed on the weld; if not on the weld, the minimum distance is 13 mm
If, in the reinforcement calculations for a DN250 fitting, the welding joint coefficient E1 for the shell is set to 1, then when the opening is located on a weld, whether there is also no need to add additional non-destructive testing requirements for Class A, B, or C welds in such cases.