Regarding the cold adjustment of variable springs

When the support and hanger is initially installed, because the pipeline is not completely installed, there may be deviations after the pipeline tightness test and insulation are completed, such as the support hanging in the air, the pipe on top of the support deforming the top of the pipe, etc. Therefore, it is necessary to check and make adjustments before starting the test run. The spring fixing pins are all naturally pulled out at the end. Once they are pulled out in advance, considering the above process, there may be some situations that cause the force on the spring to be greater than its range, damaging the spring. In addition, if it can be pulled out naturally, it means that the positioning pin plays a protective role. The spring is not subject to additional force and can be used normally. If it cannot be pulled out naturally, it means that the positioning pin is damaged. It is necessary to consider whether the spring is also damaged.

But all the positioning pins should be pulled out naturally, which is ideal. In actual circumstances, the front and rear spring turnbuckle bolts or nuts need to be adjusted before they can be pulled out.

If it cannot be pulled out naturally, it proves that the stent is stressed in advance.

If the springs on a pipeline are naturally drawn out, they will not be stressed.； Who is responsible for the force on the pipeline?

The internal structure of the spring can be understood as a "card" shape, and the fixing pin is the horizontal line in the middle. Before the fixing pin is pulled out, it only relies on the "upper" shape to bear force, which can be understood as a rigid bracket. After the fixing pin is pulled out, the force is applied by the spring. It's not terrible if the spring itself is stressed in advance. What's terrible is that the force that can deform the fixed pin may exceed the stiffness limit of the spring itself and damage the spring.