Apparatus for sensing anomalies at the threaded pipe joints of a pipe string using a double telescoping probe

摘要

The combination of a power driven pipe tong and a backup tong is supported upon a hoist mechanism to be positioned vertically with respect to the tool joints of a string of drill pipe. A magnetic eddy current detector is disposed adjacent to the drill pipe and produces a command signal to control the hoist mechanism and stop motion when the tong assembly is in a position at which the tool joint engaging jaws of the power tong and the backup tong are properly engageable with the tool joints.