Variable-diameter structure design of MFL inline detector for oil and gas pipelines

Abstract

In order to meet the requirements of long-distance oil and gas pipelines with variable diameters of 610-762 mm for inline detection, a Magnetic Flux Leakage(MFL) inline detector applicable to such oil and gas pipelines was developed.In the new design, a folded cup was used for the sealing section, the floating structure was applied for the magnetic circuit and probes, and probes were arranged in two rows in a staggered way. Thus, the deformability of the detector was improved and the overall mechanical structure was optimized. In addition, the performance of the detector was tested through the magnetization capability test, straight pipe traction test and air tightness test. According to the test results, the magnetic circuit can meet the magnetization requirements of pipeline detection in a wall thickness of 10-20 mm, and the folded cup,with good sealing performance, can provide the detector with the required driving force. Besides, the floating effect of the magnetic circuit and probes is good for pipelines with different diameters, so that the detector could fit well with the pipeline wall to meet the detection requirements. In general, this structure of detector realizes the function of diameter variation during MFL inline detection, and plays a positive role in promoting the localization of intelligent inline detectors for oil and gas pipelines with variable diameters.

Keywords

• oil and gas pipelines
• variable diameters
• inline detector
• structure
• magnetic flux leakage(mfl)