Abstract: A method of pretreating the connecting elements of a gas-tight sleeve-type pipe connection which includes a tight metal seat and abutting joint shoulders. The connection is effected by screwing threaded pipe ends into a sleeve having threaded portions. The pipes are of high-alloy steel and the connecting elements are of austenitic steels with chromium and nickel contents of greater than 20% by weight and molybdenum contents of greater than 2.5% by weight, as well as austenitic materials with nickel contents of greater than 50% and chromium and molybdenum contents of greater than 10% by weight. The connecting elements of the sleeve are coated with a metal layer. The method includes cleaning the connecting elements and subsequently applying as a lubricant on the connecting elements a metal-free, ceramic-based paste whose principal components are silicates, titanium oxide, and zinc sulfide as solid components, as well as vegetable oils and white oils.

Abstract: Method for pretreating the connecting elements of a gas-tight pipe connection of the type including an internally threaded coupling for being screwed to externally threaded spigots at pipe ends to be joined, a metallic sealing seat, and an abutment shoulder. Only the coupling, on its innerside, is provided with a covering while leaving the spigots bare. After cleaning threaded and sealing regions of the connecting elements but before screwing together such connecting elements, a lubricant is applied to the cleaned threaded and sealing regions.