Slip assembly
US4940118A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 31, 1988 |
| Grant date | Jul 10, 1990 |
| Priority date | — |
| Expiry date | Oct 31, 2008 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B19/10
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
An hydraulically operated slip assembly useful to grip pipe being run into or pulled from a well. This assembly has upper and lower plates, each having a passage for pipe. Wedges, carrying unique slip systems are positioned around the passages between the plates and are slidably mounted for guided radial movement inwardly to grip pipe and outwardly to ungrip pipe as moved by an hydraulic cylinder pivotally mounted aside on the lower plate. The unique slip systems automatically increase grip on pipe on up or down movement of gripped pipe caused by up or down loads on the pipe. Forces resulting from increased pipe grip develop frictional forces within the slip assembly, which effectively prevent outward movement of the wedges after inadvertent or on purpose operation of the cylinder to ungrip the pipe. The pipe must be returned to near the neutral position where the slip systems are not automatically gripping pipe tighter before the cylinder can move the slip systems outwardly to ungrip pipe.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.