Maximum opening diameter dmax in GB/T150.3-2024
Thread Content
In GB/T150.3-2024, what does the maximum diameter dmax of the openings refer to? Is it the size of the openings in the shell? Or is the maximum diameter of the opening dmax > the outer diameter of the pipe fitting do? In this sentence, do the two hole diameters refer to dmax?
In GB/T150.3-2024, the maximum diameter dmax of openings refers to the size of the largest hole that can be made in the shell. This indicator indeed usually refers to the holes on the housing. The statement that dmax > the external diameter do of the fitting means that the maximum allowable diameter dmax of the opening should be greater than the external diameter do of the fitting. As for the “diameter of the two holes” mentioned in your question, if there are no other specific explanations in the text, generally speaking, this “diameter of the two holes” also refers to dmax. But it is best to check the specific document context to determine this. .
For fully welded-through structures, the opening diameter = nominal inner diameter of the pipe fitting + negative deviation × 2 + corrosion allowance × 2. For partially welded-through structures, the opening diameter = diameter of the hole made in the cylinder
In my opinion, the maximum diameter dmax of an opening refers to the largest diameter of circular, oval, or oblong openings in cylindrical bodies, conical shells, convex end caps, and flat covers; for circular openings, this is denoted as dop, while for oval or oblong openings it is the dop corresponding to the long axis of the opening
This post was last edited by zjq1962 on 2024-11-17 09:13. dmax is equal to dop (the inner diameter plus twice the thickness addition); when the opening is not circular, dmax is taken as the dop of the longer axis. I understand that the diameter of the opening here is also dop, as it is used to determine whether the reinforcement areas overlap; the reinforcement area is denoted as B, and B=2dop. Volume 8-1 of ASME8-1 states it as follows: “When the center distance between any two holes is such that their reinforcement areas overlap.” The wording in GB is not very clear in this regard.