What are the requirements regarding the distance of openings in pressure vessels from longitudinal and circumferential seams?
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I couldn’t find any requirements in the standards regarding the distance between the openings and the longitudinal and circumferential seams. Could everyone please give me some guidance? It would be great if I could also be provided with the source of these regulations. Thank you.
It is specified in Article 6.1.4 of GB150.3-2111 for welding joints near openings
The second floor is correct. To add, openings that do not require reinforcement, or in other words, those for which no additional reinforcement is needed, must not be located at Class A or Class B joints (as specified in 6.1.3)
This is mainly because the holes weaken the shell; it is generally believed that beyond a range of 2 times the diameter of the hole, the weakening is minimal and can be ignored. Therefore, to avoid insufficient strength due to the weakening caused by the holes within a range of 2 times the hole diameter, longitudinal ring seams are not recommended in this area. If such seams are unavoidable, 100% non-destructive radiographic testing at grade II, or ultrasonic testing at an equivalent grade, should be carried out to ensure that the strength at the welds is not lower than that of the steel plate.
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It is generally not less than 50 mm and not less than 3 times the wall thickness.
It is difficult to avoid the main welds when providing openings in some containers, especially circumferential welds; this must be taken into account during the design calculations, for example in the case of tray towers.
Thank you very much for your answer. I would like to ask: in which standard are there clear requirements specifying that 100% radiographic testing is required for the range of two times the hole diameter, with a pass grade of Class II? Thank you
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