The high-temperature pipeline has a diameter of 1.2 meters; the medium flowing through it is flue gas at around 450 degrees Celsius, and its length is approximately 80 meters. How can thermal stress be reduced?
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Our company has a flue gas pipeline with a diameter of 1.2 meters; the temperature of the flue gas flowing through it ranges from 450 to 400°. The pipeline is disconnected each time it is started up or shut down due to thermal expansion and contraction. How do experts suggest solving this issue? Space constraints prevent the addition of door-type bends.
Since space does not allow for natural compensation, considering the use of expansion joints is an option.
An expansion joint can be added. If it is a boiler flue, it can be cut directly, 1-2 CM removed, and then tied up with glass fiber cloth.
It is advisable to do some calculations for high-temperature flues; for a length of 80 meters, one expansion joint may not be sufficient, given the high temperatures involved.
For metal bellows expansion joints, I’m not sure whether it’s an 80-meter straight section or if there are any elbows in the middle. When there are elbows, special attention must be paid to the force on the blind flange of the expansion joint; to determine this force, concrete thrust blocks need to be designed. Alternatively, a curved pipe can be used for balancing, to prevent the expansion joint from being torn apart due to excessive force from the blind flange after ventilation. In any case, when adding expansion joints, it is essential to pay attention to the force on the blind flanges. Depending on the actual piping layout, choose between hinge-type, universal hinge type, large tie rod type, etc.
There are two 90° bends in the middle; if it is cut in half and covered with heat-resistant fabric, and there are no sliding devices under the pipe, will it not be able to expand or contract? It has been cut open for testing. Let’s see when work resumes. Thank you
The force applied is extremely high; it has been rewelded multiple times and has broken apart several times
It has been cut already; I’ll check it when work resumes next time to see if it works! Thank you
Installing expansion joints is the proper way; don’t resort to improper methods!