Roderic K. Stanley, Quality Tubing Inc Houston, Texas, USA
Keywords: coiled tubing, ferromagnetic tubes flaws, yield point, NDT methods
ABSTRACT
Coiled steel tubing represents a major advance away from range II and III oil field casing, tubing, drill pipe and line pipe. Lengths of ferromagnetic tubes upto 35, 000 ft have been reported. Coiled drill pipe is becoming more common, while coiled line pipe, originally invented for the PLUTO (pipeline under the ocean) project of World War II, is finding increasing use because of ease of laying. This paper describes the NDT processes employed in manufacture and use of coiled steel tubing. While manufacturing NDT is relatively traditional (radiography for strip welds, and eddy currents for tube inspection) due to the need to follow newly introduced API regulations, the inspection of used coiled tubing, which must be performed to detect both flaws and areas of degradation due to excessive working of the tubing beyond its yield point, presents new challenges. For used coiled tubing, combination NDT methods are employed including eddy current inspection for steel degradation caused by cycling into the well, total flux measurement for wall thickness, laser and eddy current OD measurements, and magnetic flux leakage(MFL) for flaw detection. Some of the authors experiences with the inspection of used coiled tubing are presented.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.full paper not received Publisher:Ashgate Publishing Company
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