Non-Destructive Evaluation Of Corrosion On Insulated Pipe Using Tangential Radiographic Technique

CATEGORY: NON DESTRUCTIVE TESTING
International Journal Of Scientific & Technology Research Volume 2, Issue 6, June 2013
Non-Destructive Evaluation Of Corrosion On Insulated Pipe Using Tangential Radiographic Technique
Alexander Boateng, Dr. K.A. Danso, Dr. C.P.K. Dagadu
austinite10@yahoo.com
Nuclear Application Centre (NAC), National Nuclear Research Institute (NNRI), Ghana Atomic Energy Commission (GAEC).
Graduate School of Nuclear and Allied Sciences, University of Ghana-Legon.
Abstract:
Tangential Radiographic Technique (TRT) principle was explored for evaluating deposits and corrosion attacks across the inner and outer walls of an insulated steel pipe using Iridium-192.The research was performed on a designed test piece to simulate corrosion attacks and deposits on industrial pipes. Pitting corrosion measurements based on TRT were more sophisticated, and therefore magnification factor and correction were used to establish the estimated pit depth on the film. 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 TRT method overestimated the degree of penetrated corrosion attack in the tangential position in the neighbourhood of 9% and was within an accuracy of ± 0.37 mm. 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 TRT without the costly removal of insulation material.
This research seeks to explore the Tangential Radiographic Technique (TRT)using Ir-192 for evaluation of corrosion attack across the inner and outer walls of insulated steel pipes (mild steel) with diameter greater than 150 mm, a vital need for many industrial installations.
It is only periodic inspection for the integrity of pipes and equipment can mitigate the risk in connection with failures associated with corrosion activities. It is therefore imperative to evaluate inner wall corrosion and deposit in large diameter pipes by radiography to address the challenges confronting processing industries.
Free Full Text Source: http://www.ijstr.org/final-print/june2013/Non-destructive-Evaluation-Of-Corrosion-On-Insulated-Pipe-Using-Tangential-Radiographic-Technique.pdf