Can a butt flange be installed on the expansion bend of the jacket tube?
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Dear experts, we are currently installing a sulfur jacketing pipe, and we found that a pair of butt flanges have been installed at the π-shaped expansion bend of the pipeline. Since sulfur pipes are installed in sections, it is uncommon to see flanges installed at expansion bends on ordinary pipes. Moreover, we could not find any relevant standards regarding this arrangement; we are not sure whether it is reasonable. Please advise us
Such a connection is indeed uncommon, but it does not affect functionality or usability, and there are no regulations prohibiting it. Flange connections are generally minimized in pipelines to reduce sources of leakage. If the serious consequences of medium leakage are not severe, and some pipes require frequent inspection, cleaning, and draining, it is also acceptable to use flange connections
It’s worth checking what medium is being used; if it’s at a low level, there might be fluid accumulation, and flanges should be considered for cleaning purposes
Liquid sulfur is used, and the key element is the heating jacket; moreover, the pipes often need to be purged with nitrogen, which causes vibrations. Installing a pair of flanges at the expansion bends increases the risk of leaks. The problem is that the specifications do not explicitly state that such installations are not allowed, as designers are not very familiar with the actual conditions of use – they focus only on the specifications