Issues with openings in the roof of storage tanks
Thread Content
We have two small, custom-made tanks with a capacity of 800 cubic meters on site. The reinforcement plates with holes in the tank’s top plate overlap partially with the welds. After checking the relevant standards, I found that they specify requirements only regarding the distance between openings in the tank walls; does this mean there are no requirements regarding the distance between openings in the top plate and the welds? After all, the distance from the welds located at the center of the tank to the top plate is very small, and in many cases this distance does not meet the specified requirements.
Non-destructive testing should be carried out on both ends of the welds where opening interference occurs; efforts should be made to avoid these welds through the proper arrangement of the layout
The storage tank is relatively small, and the design drawings divide the tank’s roof into many sections; there are also numerous holes in the tank, so it simply cannot meet the requirements regarding the distance between openings and welds.
It’s best to avoid it; the key is the size of the opening.
The stress conditions on the tank walls and the tank roof are different; for the tank roof, external pressure stability is a key consideration, and the requirements regarding openings in the tank walls are stricter than those for the tank roof.
It should be driven to the weld, and non-destructive testing shall be carried out as specified.
The hole is not located on the weld; the reinforcement ring created after drilling will cover part of the weld
Does that mean the covered welds don’t need to be RT-tested? ? It’s too troublesome to do RT on the tank top
The opening is very small and is used to fit the level gauge guide tube.
Treat in accordance with the requirements of 10.3.2 b) in GB/T150.4.