Evaluation method for concave and scratch combined defect of mountain pipeline

The invention provides an evaluation method for concave and scratch combined defects of a mountain pipeline. The method comprises the following steps: A, determining parameters required to be measured for the sunken scratches of the pipe section and the outer diameter of the pipeline; b, the scratch depth and the pipeline wall thickness in evaluation are determined; c, judging whether a related calculation formula is true or not, if yes, performing a step D, and otherwise, performing unqualified evaluation; d, axial stress is determined, and the minimum yield strength is corrected through the mountain safety correction factor; e, the ratio of the scratch depth to the wall thickness and the ratio of the sunken depth to the pipeline diameter are determined, whether the pipeline serves under the alternating stress condition or not is judged, if not, the step F is carried out, and if not, evaluation is unqualified; and F, the MAWP of the pipeline is determined, if the MAWP is larger than or equal to the current d