Effects of high temperature creep on magnetic properties of steels [pipeline inspection]

An investigation was performed into detection of creep damage in the welded area of high-pressure, high-temperature steam pipelines. The measurements involved the use of a portable magnetic inspection device called the Magnescope. Results indicated a decline in the coercivity and remanence in creep-damaged pipes, probably due to segregation of impurities occurring during creep. The orientation of the inspection head with respect to the weld line affects the ability to detect creep damage. Measurements taken parallel to the weld line showed greater differences in the coercivity and remanence between the damaged and undamaged specimens. Measurements taken perpendicular to the weld line did not show large differences