Seeking advice on container flange design issues
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I’m learning about U-shaped heat exchangers and have run into some problems; I would appreciate some guidance from those who are more experienced. The design pressure for the DN400 tube side is 6.8, and for the shell side it is 1.2. The original design was modified by using DN400 PN6.4 standard flanges, with 4 additional bolts added. In actual testing, the standard DN400 PN6.4 flange was modified; no additional bolts were needed, and compliance was achieved by simply adjusting the h value. What considerations led to the increase in the bolt area? Leave a surplus?
Increasing the area of the bolts is intended to enhance the strength and stability of the flange connection, facilitating a tight fit between the tube side and the shell side and preventing leaks and safety incidents. At the same time, adding bolts can also improve the sealing performance of the flange connection, ensuring the proper operation of the equipment. Generally, a certain margin is taken into account during design to meet the requirements for the long-term stable operation of the equipment. Therefore, when increasing the bolt area, factors such as the actual usage of the equipment and subsequent maintenance also need to be taken into consideration. .
This post was last edited by wanlirn on 2023-6-13 at 10:51. The area of the bolt is related to the internal pressure and the material of the gasket; it is certainly also related to the material of the bolt itself. Increasing the number of bolts allows for a better calculation of the allowable stress compared to increasing H, which helps reduce costs. In the example above, the area of the partition groove is 0, meaning there is no partition, while in the example below there is a partition, and the gasket at that location also needs to be taken into account when calculating the tightening force of the flange bolts
The number of bolts has increased from 24 to 28, and the total torque Mo has also increased; it’s a bit hard to understand this new situation.
Take a look; there might be an issue with the calculations. When using standard flanges as usual and then checking with SW6, it generally doesn’t work, let alone when the nominal pressure exceeds that of standard flanges
It can also be calculated based on the dimensions shown in the diagram; however, the value of Ab/Am is too low, at less than 2.5%. I asked the designer today, and the design department specifies that a margin of at least 10% should be reserved for custom flange bolts, so 4 additional bolts were added.
Hello, original poster. Why did you enter 9 as the effective thickness g0 of the small end of the neck? As far as I understand, the effective thickness of the small end of the neck is δ1 according to the standards, right?
Hello, expert. Why is the value 9 entered for the effective thickness g0 of the small end of the neck? Is the effective thickness of the small end of the neck, as I understand it, equivalent to δ1 according to the standards? It should be 16, right? G1 should be δ2=26 according to the standard, right?
OP, did you enter 406 for the inner diameter with a 3mm corrosion allowance taken into account?
Increasing the bolts definitely increases the compressive force, and of course this affects the strength of the flange