Regarding the openings in the straight sections of the head
Thread Content
I need to make a hole in the straight edge section of the head; the hole is 25 mm in diameter. The dish-shaped head has a diameter of about 2 meters – should the length of the straight edge section be increased to 35 mm?
Why must holes be made in the straight sections of the head? Change the design of the holes and the connecting pipes to avoid those straight sections of the head.
If it is a pressure vessel, holes must be made in the straight edges. Although GB150-2011 does not specify this explicitly, it is recommended to follow the requirement of using a hole diameter that is three times the thickness of the plate, with a minimum size of 100 MM; therefore, 35 MM is definitely not sufficient. If it’s a pressure vessel at normal pressure, then it doesn’t matter.
It is not recommended to locate it at the straight edge of the head; if the length of that straight edge is too large, it is better to place it at an appropriate position on the cylinder body.
If it is necessary to make an opening in the straight edge section of the disc-shaped head (with a straight edge length of 35 mm), this is also possible, but the following measures must be taken: 1. The fillet welds at the opening must be fully penetrated, and magnetic particle testing should be conducted on both the inner and outer surfaces of the welds； 2. Welds within a range of at least 100 mm around the opening, and not less than 3 times the thickness of the head wall, must undergo 100% flaw detection ； 3. Perform heat treatment to eliminate welding stress and head processing stress.
The straight sections of the butterfly head are still this long:o
I completely agree with the person on floor 8. It is best to avoid welds; modifying the structure can reduce the workload for workers, improve production efficiency, and save costs.