Development and Application of Inner Detector in Drilling Riser Auxiliary Lines Based on Magnetic Memory Testing

Drilling riser auxiliary lines are critical components of deep-water floating drilling platform, which mainly consist of choke line, kill line, hydraulic line, boost line, etc. This paper discusses an inner detector in drilling riser auxiliary lines based on metal magnetic memory testing. In contrast to conventional detect methods currently employed, the prominent advantage of the detector is that it can scan the inner wall directly by the pull of a winch, with no need to disassemble the buoyancy modules. This way, the time and cost of testing would be shortened considerably. The detector is designed with two sensor arrays assembled in staggered pattern, and each array consists of six tunnel magnetoresistance probes radially arranged from the canter of the shaft, much like spokes on a wagon wheel, ensuring 100% coverage of the inner wall. The raw data acquired from the front and rear sensor arrays can be aligned automatically by the alignment algorithms of imaging software for further processing. For determination of the detector characteristics, the laboratory test was conducted with 3.5″ tubing that were modified with a series of prefabricated groove and dome-shaped artificial defects. And result shows that it can present the damage sharply. Besides, field test also confirms the design has features of reasonable structure and stable performance.