The issue of reinforcement width in perforated reinforcement
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Actually, it’s not recent; I’ve had doubts about this for a long time, but I kept forgetting to ask everyone. The details of the question are as follows: In GB150, there is a formula for determining the reinforcement width, which involves selecting the larger of two values. In practical design applications, for heat exchanger tube boxes, it is generally done by calculating based on the actual width of the short sections (when the width of the short sections is less than the value specified in GB150’s formula). In all other cases, no other considerations are taken into account; the calculations are carried out using GB150’s formula. Here comes the question: First, is there an issue with the way we handle the heat exchanger tube box stubs – is it correct or conservative? ； Second: If the above treatment method is correct, then in the case of a fixed-tube-sheet heat exchanger with an opening in the shell side that is located very close to the tube sheet, should the reinforcement width also be reduced?
After the calculation is done, the designer needs to perform further verification manually, as the software is not yet advanced enough for this purpose; especially when the diameter of the tube sheet is smaller than the width of the reinforcement openings provided above it. This input is available in the PVlite software, but not in our country’s SW; therefore, the designer should make an estimate first and then verify it by checking the calculation documents.
In my opinion, the reinforcement width must meet the requirements of the reinforced structure with openings; the length should not be reduced due to welding or manufacturing issues.
PV Desktop can be modified. Even SW no longer has any special status these days, as there are no such things as certification certificates anymore; all computing software is treated equally, and it is up to the people involved in the design to make the final decisions. So you mean you agree, then what about the second scenario?
Yes, if interpreted literally according to GB150, there is no need to take other factors into consideration. However, the opening model specified in GB150 features small openings on a large flat surface, and edge stresses do not affect the calculations for strengthening such openings. In the current situation, the basic assumption model does not meet these conditions, which is not appropriate, unless it is assumed that the values remain within safe limits.
The screenshot is as follows, PV Desktop
This is Sinopec’s calculation software, which has this option; you just need to enter the actual dimensions. The same principle applies to the pipes that are closer to the tube sheet.
This post was last edited by zjq1962 on 2018-10-17 at 12:41. When entering the reinforcement parameters for the SW6 software, there is a field for the reinforcement range, which refers to the width of the reinforcement; if this value is not entered, the program will use the standard reinforcement range instead.
It’s a bit off-topic; I hope someone with a theoretical background can answer the topic of this post: lol
1. It is fine to directly enter the length of the tube box segment within the reinforcement range, as the program will automatically determine which reinforcement width to use; however, it is important to note whether the connections on the segment are located in the middle of the segment 2. The openings on the shell side are located close to the tube sheet; I believe the issue of reinforcement width should also be considered.