Opening in or adjacent to welds

In a construction workshop, it's possible for an opening to fall on a weld line. In such a case, it's important to follow the guidelines set out in the ASME BPVC, Pressure Vessel Specification and Design Practice.

So, what should we do in this case?

• When dealing with longitudinal welded seams on adjacent shell segments, they should be separated by at least 3-5 times the wall thickness of the thicker plate, but not less than 100 mm.
• ?Furthermore, according to “ASME Sec VIII Div.1 Subsection B Part UW, UW-9 DESIGN OF WELDED JOINTS”:

Except when the longitudinal joints are radiographed 4 in. (100 mm) on each side of each circumferential welded intersection, vessels made up of two or more courses shall have the centers of the welded longitudinal joints of adjacent courses staggered or separated by a distance of at least five times the thickness of the thicker plate.

In simpler terms, vessels made up of two or more courses should have the centers of the welded longitudinal joints of adjacent courses staggered or separated by a distance of at least five times the thickness of the thicker plate.

• When an opening falls on the weld line, it must be addressed according to “ASME Sec VIII Div.1 Subsection B Part UW, UW-14 (b) OPENINGS IN OR ADJACENT TO WELDS”:

Single openings meeting the requirements given in UG-36(c)(3) may be located in head‐to‐shell or Category B or C butt-welded joints, provided the weld meets the radiographic requirements in UW-51 for a length equal to three times the diameter of the opening with the center of the hole at midlength. Defects that are completely removed in cutting the hole shall not be considered in judging the acceptability of the weld.

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In conclusion, while efforts are made to avoid having openings fall on the weld line, if such a situation occurs, the radiographic testing requirements should be observed at a length of three times the diameter of the opening.

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