Improvements in or relating to safety releasing drill strings, safety releasing joints for use in drill strings, and method of forming a tool string for deep well drilling

摘要

539,951. Rod and tube joints. STEVENS, A. H. (Byron Jackson Co.). April 1, 1940, No. 5841. [Class 99 (i)] A drill string for deep wells having screw-threaded joints includes a premature-release joint in which the threads 9 are of greater pitch than in the normal joints at 11, 19 and in which abutting shoulders 13, 17 have one or more hardened antifriction washers clamped between them. The shoulders 13, 17 have less area than the shoulders 12 of the normal joints.