Data Identification Method And Application Research Of Magnetic Flux Leakage Detection Of Submarine Pipeline Defects

At present, the submarine pipeline length has more than 5000 km, corrosion and ageing, such as to endanger the safety of submarine pipeline operation factors is becoming more and more serious. In submarine pipeline inspection mainly rely on foreign technical service, which not only hinder the submarine pipeline defects found in time, but also to a certain extent, to our country the distribution of marine resources and development strategy of related work secret brought hidden trouble, through the study of defect magnetic flux leakage form effective identification technology and the method will significantly improve submarine pipeline safe operation ability, not only it has the remarkable social benefit, economic benefit, but also more important safety benefits and environmental benefits.On the basis of comprehensive analysis of characteristics of submarine pipeline structure, through the detection principle and the method of comparative analysis, in view of the defect data identification and analysis of the magnetic flux leakage testing, magnetic flux leakage testing data preprocessing and rendering, defect data automatic analysis and recognition, the test and application research, the formation of submarine pipeline defect magnetic flux leakage testing data identification methods, for the pipeline within the BZ 34-1 submarine pipeline inspection application, effectively identify the internal and external corrosion defects and reasonably determine the failure stress, improve the ability of submarine pipeline safe operation, the paper studies the following main research results were obtained.(1) In a reasonable analysis of submarine pipeline structure characteristics, properties, and defect characteristics, the magnetic flux leakage detection technology is choosed to detect the submarine pipeline defec. Based on the magnetic flux leakage signals of the most obvious weld position, the effective mileage correction methods and model is put forward. At the same time, combined with filtering algorithm and eliminating method, data reorganization, compensation algorithm and the corresponding process is also discussed in the paper.(2) By using curve, reliefs views and color view generation technology visualization method, submarine pipeline defects are analyzed and the application process, based on expansion of Canny operator, morphology and corrosion, determine the magnetic flux leakage testing data, identification method, through the defect of the ANSYS finite element identification, accurate detection to the entire pipe fixed parts and more than 90%, this meet the signal-to-noise ratio of the defect signals.(3) Within 0.4～3 m/s speed range, research and development of magnetic flux leakage inside the detector is conducted by the various test, defect detection result meets the requirements. In view of the operating company CNOOC Bohai south BZ 34 No.1 pipeline, application research and development of 8 inches inside the submarine pipeline magnetic flux leakage detector and T.D. Williamson, the magnetic flux leakage detector test results in the comparison, both in the number of defects and defect distribution, type of defect recognition has a good consistency, can be used in the submarine pipeline defect magnetic flux leakage testing.(4) The BZ 34-1 submarine pipeline has 3030 defects, according to ASME B31G specification, calculate and determine the defect of the five different types of ERF values and the corresponding failure stress, its value is between 2.73 MPa to 3.08 MPa, so the pipeline operation pressure should be limited under 3.08 MPa.