Mechanical pipe joint capable of withstanding repeatedly varied internal fluid pressure

Abstract From the Canadian patent

A metal tubing joint to connect lengths of pipe is made either by forcibly drawing a ductile sleeve over ends of pipe in telescopingly engaged overlapped relation the sleeve being plastic-, ally strained and enlarged permanently in diameter by from 1% to 7% by the drawing operation, or by forcibly drawing an enlarged end of another pipe over the pipe end to plastically strain the enlarged end further by at least 1%, and the heat developed in distending the metal and in frictional work during rubbing contact is controlled so that the members, when cooled to ambient temperature have relative, diameters at their engaged surfaces such that the remanent circumferential tensile stress is the wall …