Abstract: A process for placing heat-shrinkable polyfluoroolefin polymer sleeves, preferably, FEP resin or PFA resin, over Frasch sulfur well piping and other downhole well piping to protect such piping from corrosion.A heat chamber for heat-shrinking the polyfluoroolefin polymer sleeves onto the piping.

Abstract: A pipe coupling is disclosed for connecting two pipelines of different materials together in a high temperature, corrosive environment which, at the same time, prevents deterioration of the pipelines due to galvanic action. The coupling achieves its purpose by using a relatively rigid insulating material to prevent contact between the pipelines. It also achieves high pullout resistance while maintaining minimum outer dimensions to facilitate its use in all types of wells, such as oil, gas, sulfur, etc.

Abstract: A novel system is disclosed for utilizing, in the mining of subterranean sulfur by the Frasch process, the heat of water that has accumulated underground above at least a portion of the subterranean sulfur deposit from previous mining operations wherein the underground water is brought to the surface, mixed with fresh heated water, and returned underground to melt the subterranean sulfur via a return pipeline which is separate and distinct from the pipeline through which the molten sulfur is brought to the surface. In one embodiment the return pipeline is in the same well casing as the sulfur pipeline, but displaced laterally from it. In a second embodiment, the return pipeline extends through a separate well casing.