Abstract: A slip die with a substantially smooth pipe contact surface is employed in a conventional slip assembly as a primary mechanism for gripping pipe. A second conventional slip assembly with conventional dies having penetrating die teeth on their contact surfaces is employed as a secondary gripping mechanism to automatically grip the pipe in the event the primary mechanism loses its grip. The smooth slip elements are constructed of a malleable material which tends to conform to surface irregularities on the outer surface of the pipe to increase the gripping force on the pipe. In the method, the pipe is initially gripped by the primary slip mechanism before the secondary mechanism is actuated to contact the pipe. The slips are set by downward pipe forces acting on the dies so that the die teeth of the secondary mechanism do not grip the pipe unless the primary slip mechanism fails.

Abstract: Hydraulic tongs, used to screw oilfield tubulars together, are equipped with torque control means which enable the tongs to rotate the tubulars and then gradually apply torque until a preselected torque value is reached, hold the torque at this value a desired period of time and then release the torque. In one form of the invention, a tong control restricts the power of the tong motor to enable low torque rotation while limiting the maximum torque which can be produced by the tong motor. A hydraulic cylinder placed in the tongs' restraining line is controlled to shorten, hold or extend the line. When the line is shortened, the tongs are pulled in a direction which increases the torque to a value above the maximum torque produced by the tong motor. The system allows heavy, powerful tongs to be used to accurately apply and hold a wide variety of selected torque values.