Non-Destructive Evaluation of Corrosion on Insulated Pipe using Double Wall Radiographic Technique

Abstract

The research explored the Double Wall Radiographic inspection technique using Ir-192 for evaluating deposits and corrosion attacks across the inner and outer walls of an insulated steel pipe .The experiment was performed on a designed test piece to simulate corrosion attacks and deposits on industrial pipes. From the relationship curve drawn between the radiographic film density and the thickness of the pipe, the attenuation coefficient of the insulating material was negligible compared to the concrete deposit. The Double Wall Technique (DWT) had a maximum underestimation of 1.3% of the corroded surface area of the pipe and was within an accuracy of ± 0.29. This tolerance limit is 5% less than the wall thickness of the pipe. From the results obtained, effective corrosion monitoring of insulated pipes can reliably be executed by the DWT without the costly removal of insulation material.

Keywords: Double Wall Radiography, Corrosion, Insulated Pipe, Ir-192, Attenuation Coefficient.