Iran [Summary country report on coordinated research project on development of protocols for corrosion and deposit evaluation in large diameter pipes by radiography]

Full text: Corrosion evaluation and remaining wall thickness is a major concern in piping inspection in the inspection programs in the country. The radiographic method has been used for qualitative evaluation in the past years. This CRP provided a new attempt for developing the standard procedure and precise measurement including the deposit in insulated and non insulated pipes. During the period of the project, required calibration blocks were fabricated for 6 inch and 10 inch pipes as was planned in the first RCM. Ir-192 and 300 kV X-ray machine was used for the experiments. More than 250 films were produced by Tangential and Double Wall Techniques and parameters and limitations were carefully studied and results plotted on the Excel sheets provided for this purpose. Precise quality control measures were applied in all process of exposures and film processing for accuracy and repeatability of the tests. Results show that these techniques can be successfully applied in evaluation of remaining wall thickness, corrosion and deposit with no significant effect of insulation on the results. It was noticed that relatively higher values of densities give better result in increasing sensitivity of measurements. Proposed values suggested for standard procedure preparation. For sake of comparison of the outcomes, Co-60 was also used for thickness evaluation. Some real experiments were performed in the selected industrial complexes to verify the accuracy of the procedures. (author)