METHOD FOR DETECTION OF CRACKS AND METAL LOSS IN METAL STRUCTURES

摘要

Method for detection of cracks and metal loss in metal structures, such as risers, drilling pipes, platform structure or pipelines. Direct current is applied to at mutually distanced first set of contact points. A second set of contact points is arranged between the first set. Voltage response is measured at the second set of contact points during a period of time to provide a set of measurements. This voltage response is compared to a voltage response from a reference with known conditions. The relation between the measurement voltage and the reference voltage is used to calculate deviation values. The deviation values are normalized. Information from the deviation values, normalized deviation values, and analyses of deviation values from the very beginning just after current onset and later on the voltage response, is used to determine geometry, depth, direction of development and location of metal loss and cracks.