Threaded and coupled connection for improved fatigue resistance
US6609735B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 21, 1999 |
| Grant date | Aug 26, 2003 |
| Priority date | — |
| Expiry date | Jul 21, 2019 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B17/085
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
Threaded and coupled pipe connections are provided with a number of design features that increase resistance of the connection to fatigue failure from cyclical side loading. The features acting alone or in combination include the provision of a pin thread that is formed along a single taper and that vanishes at the surface of the pipe. The coupling engages the pin such that the threaded area of the coupling engages all of the pin threads and extends beyond the vanish point of the pin threads at the optimum coupling makeup position. The threads of the coupling and pipe may engage along both the stab and load flanks to distribute the side loading. The external surface of the coupling may be tapered from the center toward each coupling end to reduce the stiffness ratio of the connection, and the ends or faces of the coupling may be reduced in radial thickness to prevent coupling splitting. The coupling length may be extended to exceed standard coupling lengths to provide the additional threaded area and/or taper areas and/or reduced stiffness ratios.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.