Cold-state displacement of the spring
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For some spring hangers used in c2 calculations, when the vertical displacement of the spring is small under SUS conditions, whether in the positive or negative direction, the assignment method is once again employed to adjust and reduce the displacement under SUS conditions. But some SUS displacements are relatively large; what is the cause of this? Also, what adverse consequences can occur if the displacement in the SUS state is too large.
The intuitive impression is that the spring is too soft~ The reason for this situation might be that the load on the spring was manually set in order to adjust a certain parameter. The adverse consequence is stent instability.
The intuitive impression is that the spring is too soft~ The reason for this situation might be that the load on the spring was manually set in order to adjust a certain parameter. The adverse consequence is stent instability.
This situation generally occurs during thermal zeroing, as well as when the piping system is very flexible and the temperature is high. In this case, the cold-load will be greater than or less than the pipe distribution load, causing the spring to move upward or downward. In fact, such a result mainly makes it difficult to remove the pins from the springs on site. There are mainly two ways to solve this problem: 1) Use cold-zeroing, 2) Adjust the piping compensation scheme by adding appropriate rigid supports.
If the cold-state displacement is too large, could it cause the spring to be crushed?
I have encountered situations where, in order to adjust the torque at the pipe ends, artificial values that are relatively small were assigned; the displacement at low temperature was -11 mm, and at high temperature it was -21 mm. In this way, the overall tilt of the piping system improves the torque on the equipment nozzles. The designers said this is how they have always dealt with the problem of excessive nozzle torque. Is this setting reasonable? And could the spring be crushed under excessive load at the moment the pin is pulled out?
A locked-up condition can occur, which is why secondary adjustment using springs is provided on-site.
Thank you for the answer. Could you please provide a detailed explanation regarding the secondary adjustment of the spring? {:1_90:}
Firstly, the artificial assignment method for specifying the spring load seems to be a good approach in design, as it enables better calculations of the forces acting on the pipe ends. But what I decided personally was not right. On-site adjustment of springs is primarily a means to eliminate the discrepancies between design and actual conditions. The actual load on the spring is mainly adjusted by modifying the heights of the basket screw and the top flange.