Criteria for single openings and multiple openings in the stress reinforcement calculation per GB/T150
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This post was last edited by zjq1962 on 2025-3-8 at 13:12. In GB/T150.3, sections 8.3.1 and 8.4.1 specify that, whether there is a single opening or multiple openings, the determination is based on the sum of the diameters of the two openings. What affects the opening reinforcement between the two holes is the range of reinforcement. The reinforcement range B = max(2dop, dop + 2δn + δnt); when 2δn + δnt > dop, the reinforcement range is greater than twice the diameter of the opening. Using the standard judgment method will result in a situation where, even if the distance between the centers of the two holes is greater than the sum of their diameters, their reinforcement areas still overlap. Therefore, to determine whether there is a single opening or multiple openings, the criterion should be whether the reinforcement areas overlap, rather than the sum of the opening diameters. Figures 8.3 and 8-4 provided in the standard are correct; what is indicated is the range of reinforcement. Referencing ASME Code Section 8-1, Volume UG-42(a), also uses the reinforcement area as the basis for determination.
In the GB/T150.3 standard, when calculating reinforcement for openings, it is indeed necessary to determine whether it is a single opening or multiple openings based on whether the reinforcement areas overlap, rather than simply relying on the sum of the diameters of the two openings. In practical applications, attention should be paid to the calculation of the reinforcement area B, and the issue of opening reinforcement should be handled properly based on whether there is overlap. The description in the standards regarding the sum of the diameters of individual openings may lead to misunderstandings; it is more reasonable to determine this by considering the overlap of the reinforcement areas. .
Clause 8.3.1a of GB/T150.3-2024 specifies the applicable conditions for individual openings: “...”； The housing has 3 or more openings, and the distance between the centers of any two openings (for curved surfaces, the distance is calculated in terms of arc length) is not less than twice the sum of the diameters of those two openings. The following figure illustrates the issue using an opening in a spherical tank plate as an example: For instance, the distance between the embedded manhole and the center of a certain opening is 905; yet 2*(diameter of the manhole + diameter of the opening) > 905. Although the effective reinforcement area B values for these two elements do not overlap, rule 8.3.1a still does not permit reinforcement based on a single opening. In SW6, no method for computable joint reinforcement is also seen in the embedded takeover. So, in my personal view, this clause is ambiguous
That makes sense; just do two calculations directly and calculate them both for him