Threaded joint for well casing and tubing
US4384737A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 25, 1980 |
| Grant date | May 24, 1983 |
| Priority date | — |
| Expiry date | Apr 25, 2000 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B17/042
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A threaded joint for well casings and tubings includes a coupling or integral socket into which pipe sections are threaded. The coupling or socket includes an inner, unthreaded portion and an outer portion having threads on its inner surface. The pipe sections include an end having a threaded portion and an unthreaded nose portion at the outer end of the threaded portion. The nose portion terminates with an annular surface and includes a plurality of convex surfaces of revolution extending circumferentially of the nose portion, all of which surfaces are adapted to engage the unthreaded portion of the coupling or socket to establish a fluid-tight seal. The thread construction is a modified buttress type with relatively flat crests and roots. An interference fit occurs between thread portions not likely to be damaged during handling, and clearance between other thread portions permits the joint connection to be made with reduced friction and with reduced concern for machining tolerances. To increase effective wall thickness and overall strength of the joint, the threads are truncated to vanishing points. Hoop stresses are made low and relatively uniform throughout the entire range of…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.