Box-and-pin joint (tool joint) – a coupling element of drilling pipes for making-up a column (string). Box-and-pin joint consists of nipple (pin) and coupling (box) fixed at the end of drilling pipe. The joint is connected with the pipe via conical thread or by welding – in the last case the joint elements are usually called connecting ends – a nipple end and a spigot end. Screwed tool joints are usually assembled with the pipes via hot/hot procedure (the elements of the joint are heated up to 400–450 °С). Drilling pipes are screwed together via pipe joint consisting of coarse pitch conical thread and shoulder bearing faces (coupling face and nipple shoulder) assuring air tightness and quick assembly-disassembly. To decrease alternate stresses in the threaded joint stabilizing bands on the pipe and bores on the joint are used.