اندازه گيري ضخامت باقيمانده جدار لوله ها در هنگام كار به روش پرتونگاري گاما

On-Line Thickness Measurement in Pipes by Gamma Radiography

Corrosion in the pipes and remaining wall thickness measurements are the major concern in the piping service lifetime. Ultrasonic is the most common tool in measuring the wall thickness of the pipes. Although the test is relatively simple and fast, but this method is a local point determining method which requires removal of insulation and local surface preparation. Radiography methods (tangential and density evaluation) are other techniques for thickness loss evaluation. In this investigation, the thickness profile of pipes, with 270 mm in diameter and 7.4-28.5 mm in thickness was determined by the radiograph density measurements and the use of an lr-192 gamma source. Some formulas were derived and suggested in this respect by considering the optical density of radiographs in different thicknesses and exposures. It was concluded that thickness loss of 10, 20 and 50 percent of wall thickness, corrosion area and corrosion type in insulated and non-insulated gas carrying pipes can be detected by this method. Area of corrosion zone and corrosion type can also be shown in this technique.