TAP SCREW GRAB Russian patent published in 1999 - IPC

FIELD: oil and gas production industry and geological prospecting activities. SUBSTANCE: device is intended for catching by internal surface of pipe string terminating atop with sleeve or lock and extracting pipe string out of oil or gas wells. Tap screw grab has hollow body with tapered head-piece provided with external grabbing thread. It is connected by its sleeve head with drilling pipes and is lowered into well. Hollow shank with tail-piece of tapered shape is located in hollow body and is connected with it by threaded joint. Installed in radial passages of body are extending dies with their end-face part having lateral serrations. Body and shank are secured by shear pins. Sleeve head is located on shank. Application of aforesaid embodiment of tap screw grab improves reliability of catching and holding of gripped pipe string. EFFECT: higher efficiency. 3 dwg