Thermowells for Large Size Pipe

The piping specifications for a refinery or petrochemical plant will often give the allowable sizes permitted for screwed pipe branch connections. For usual piping services, the 2,000-pound or 3,000-pound F.S.S.E. fitting will be specified. 

Thermowell requirements differ from the screwed pipe branch connection in that the threaded thermowell must be removed occasionally for inspection, especially during plant shutdown, and then replaced. This will require perfect pipe threads for the thermowell connections. Good threads can be assured if the 3/4-inch, 1-inch or 1-1/4-inch F.S.S.E. type fitting rated at 6,000 pounds such as a thread adapter, elbow adapter or pipe coupling is welded in the process piping or equipment. 

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