New magnetic techniques for inspection and metal-loss assessment of oil pipelines

Superconducting quantum interference device (SQUID) magnetometer has been u sed to detect metal-loss on the outside surface of small diameter pipes cov ered with thermal insulation at lift-offs up to 40 mm. In addition, an inve rsion method based on a finite element model was developed to recover of th e metal-loss three-dimensional shape from fields obtained with high sensiti vity Hall sensors due to metal-loss in both wall surfaces of a large diamet er pipe. (C) 2001 Elsevier Science B.V. All rights reserved.