Torque hold system and method
US4938109A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 10, 1989 |
| Grant date | Jul 3, 1990 |
| Priority date | — |
| Expiry date | Apr 10, 2009 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B19/166
- WIPO fieldCivil engineering
- WIPO sectorOther fields
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.