Regarding the issue of the fixed pipe rack crossbeam being bent under pressure
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The pipeline installation is now complete, but during pressure testing, the crossbeams of the pipe support frames were bent as a result of external forces. Experts are requested to analyze the reasons for this issue and suggest solutions. The pipeline has expansion joints of DN500 size; no restraints are in place. The crossbeams are made of 20-series channel steel, with an operating pressure of 0.8 MPa and a test pressure equal to 1.5 times the operating pressure, That is, 1.2 MPa. My own analysis suggests that the force exerted by the blind flanges is the cause of this problem
If there is an expansion joint, it should be the expansion joint that gets damaged first. The fixed supports at both ends of the expansion joint are there to absorb the displacement of the pipe between those two fixed supports. If the crossbeam of the fixed support bends during the pressure testing process, there are two possible explanations. One is that the setup of the fixed support is inappropriate – it is too close to the expansion joint, as a result of which the expansion joint is unable to absorb excessive amounts of displacement. The pressure applied during testing acts on the blind flange, and the counterforce generated by this flange causes the fixed support to deform. Additionally, there may be issues with the quality of the expansion joints, which fail to provide protection.
Following, learning*. Pipeline stress is a very important aspect in pipeline installation design, and it deserves sufficient attention.
The cross-section of the beam is too small; increase the size of the beam or replace the expansion joint with a larger one.
The reason is a problem with the design of the fixed bracket. The load-bearing capacity of the fixed support should be greater than the sum of the internal pressure thrust generated by the expansion joint (equivalent to the blind flange force), the elastic force resulting from displacement, and frictional forces.