Coiled tubing with improved fatigue resistance and method of manufacture
AssigneeQuality Tubing, Inc.
InventorsDavid L. Daniel, William D. Van Arnam, III, Danny J. Dennis, Kevin J. Elliot, Clayton D. Hargis
Life of this patent
Estimating the term…
Abstract
New methods of manufacturing coiled tubing result in increased useful life of the coiled tubing string by creating an enhanced strip-to-strip weld zone having load bearing and/or fatigue resistance properties substantially equal to or greater than the load bearing and/or fatigue resistance properties of the strip base material. The enhanced weld zone is transition into the nominal tubing to reduce stress concentration.
Claims20
A method of manufacturing a length of coiled tubing comprising:
- providing a first length of strip material having a nominal thickness and a first end;
- providing a second length of strip material having a nominal thickness substantially the same as the nominal thickness of the first length of strip material, and having a second end;
- providing an area of increased material thickness extending longitudinally away from each strip end for a predetermined distance;
- forming a weld along the first and second ends, thereby joining the first and second strips together to create a new length of strip material;
- and
- forming the new length of strip material into tubing.
Coiled tubing formed from a plurality of lengths of flat strip material welded together, comprising:
- the tubing having a nominal wall thickness along its length;
- an enhanced strip weld area having a wall thickness that is at least 103 percent of the nominal tubing wall thickness and a longitudinal length away from the weld of at least twice the enhanced wall thickness;
- and
- first and second transitions between the enhanced weld area and the unenhanced coiled tubing.
Dependencies are inferred from the claim text.