A Data Acquisition System For Three-axis High Definition Pipeline Inspection Tool

Pipelines are large capacity, safe and convenient, their safety is the important guarantee for a stable oil supply. The technology of magnetic flux leakage inspection is the most widely used and most sophisticated technology for pipe defect detection, The sensors number and dimensions of traditional pipeline detector are not enough, the defects were often easily missed and the assessment errors were large, those reduced the reliability of pipeline integrity evaluation results.This paper described the basic principles of the three dimensional magnetic flux leakage technology, combined with the application of the finite element method for obtaining the simulation of the leakage magnetic field, analyzed correspondence between the three dimensional signal of magnetic flux leakage and the characteristic parameters of defects, and analyzed the influence of the running speed of internal detector and the height between sensor and pipeline, these work laid a good foundation for the system design.As the definition and dimension of traditional pipeline inspection tool was not enough, this paper designed Main probes, IDOD probes and a data Initial processing unit, the Main probe contain several Hell sensors placed in three dimensions for the feature parameters inspection of flaw, while used a coil as a IDOD probe to find out whether the flaw is inside or outside of the pipeline, the voltage signals were A/D transformed by MPU after added and amplified, the data of magnetic flux leakage inspection were transmitted to subsequent processing unit which is FPGA and storage unit which is PC104 through SPI bus which is a rapid, parallel transmission path.The system increased the density of the Hall sensor, the detection dimension and the sampling frequency, the low-power, high-speed parallel design make the system a high definition magnetic flux leakage data collection, Results showed that the system improved the definition of magnetic flux leakage inspection, testing average error was not large. The experiments proved the feasibility of the system.