Abstract

Nondestructive magnetic testing indicates that the fatigue life of coiled tubing may be successfully estimated. Grade QT-800 coiled tubing (1 1/4-in. OD with a 0.087-in. wall) was fatigued in bending to 25%, 50%, 75% and 90% of its predetermined fatigue life. Variations in the tubing's magnetic properties were then determined with Magnescope and Magneprobe instruments. The results were then compared to an unfatigued sample. The results show that changes in magnetic hysteresis and Barkhausen measurements occur because of fatigue damage, and these changes can be correlated with fatigue life of the coiled tubing.

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Keywords:
fatigue damage, qt-800 fatigue lifetime, amplitude, barkhausen measurement, specimen, magnetic parameter, ferromagnetic material, artificial intelligence, coercivity, barkhausen activity
Subjects:
Information Management and Systems
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1998. Society of Petroleum Engineers
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