Corrosion evaluation and wall thickness measurement on large-diameter pipes by tangential radiography using a Co-60 gamma-ray source

摘要

This paper contains some useful parameters which can be applied to the tangential radiography technique to detect and measure the internal and external corrosion attack on large-diameter insulated and non-insulated carbon steel and stainless steel pipes using a Co-60 y-ray source. The tangential radiography technique has been successfully applied to specially designed 8" diam (219mm) and 12" diam (324 mm) steel pipes, having internal and external machined steps of different thicknesses. The application of this technique has given 96% accuracy in the determination of the real thicknesses, for both reference pipes when they were covered with insulation, and 98% accuracy in the determination of the real thicknesses for both reference pipes when they were not insulated.