Equivalent Area Factor of Tangential Projection Method for Description of Pipeline Corrosion

Taking the corrosion of production fluid pipelines, water injection pipelines and external oil pipelines in oil well as research object, the relationships between corrosion depth, length, width, corrosion morphology and corrosion tangential projection area of nearly 100 pipelines were statistically analyzed. According to the characteristics of corrosion depth, length, width and corrosion morphology, four methods for the classification of corrosion morphology as well as the range of values and calculation methods of various corrosion tangential projection area factors were proposed. Combined with the critical value of 3.5 mm of corrosion depth, 40 mm of corrosion length and four types of corrosion morphology, a new and more accurate method for the value of equivalent area factor was given. The results calculated by ASMEB 31G-1991 and ASME B31G-2009 using the new equivalent area factor were superior to those using fixed area factor in terms of the sum of the residual square and the error distribution stability. It was shown that the adaptability and accuracy of the newly proposed pipeline corrosion tangential projection equivalent area factor were better than the specified values of ASME B31G-1991 and ASME B31G-2009.