expansion joint
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The expansion joints installed for natural gas pipelines in the residential building seem to be of poor quality; does installing them in this way pose any problems?
The fixing bolts should be loosened to allow the expansion joint to expand and contract freely
1. Natural gas is a medium at normal temperature, so the axial expansion of the pipes that needs to be compensated for is not significant; only a small amount of lateral displacement needs to be compensated for. 2. As can be seen from the diagram, the upper and lower pipes are not aligned axially, and the expansion joints compensate for this small amount of lateral displacement; there are also no obvious signs of axial instability. 3. The expansion joints have three shipping bolts, which should be removed after the pipes are put into operation. It is also possible to loosen the nuts on these bolts, allowing the expansion joints to expand and contract freely as well as to undergo appropriate lateral movement. The nut on the diagram should also be loosened a bit more
How can one be so professional and skilled?
The flange surfaces are of different sizes; could this pose a risk?
The flange surfaces are of different sizes; could this pose a risk?
The only drawback is that after installation, it is necessary to prevent the internal nut of the compensator from loosening; this is done to avoid damage caused by excessive stretching due to overpressure, so it needs to be secured at its maximum limit. Loosening the inner nut prevents the minimum span variation of the compensator; this degree of loosening should be set based on the maximum and minimum span variations required by the compensator. (For reference)
The expansion joint does not match the pipeline, the pipe diameters are different, and the fixing screws are not loosened, so it fails to function.
Firstly, an expansion joint is what it is meant to be: it can cushion excessive stress on pipelines and prevent damage, provided that its four fixing bolts are loosened to allow it to move freely in order to function properly. If none of the bolts are loosened, the yield will be much lower
The friends above have covered it quite comprehensively. First, the positioning bolts need to be loosened, and care must be taken to ensure that the amount of expansion and contraction does not exceed the specified limits； Rather, the flange is clearly not of the same grade; it is of a lower grade than the pipe flange.