Research On Key Technologies Of Pipeline Orientation Measurement Using Spherical Internal Detector

Pipeline is the main way to transport resources such as oil,natural gas and water,and also is the lifeblood of national economy.However,along with using years cumulated,weld cracking,corrosion perforation,deformation and so on will occur in the pipeline,because of the transmission medium,transportation conditions,geographical climate change and man-made destruction and construction.Once the leakage accident occurs,it will cause great losses to industrial production even threat people's lives and property safety.And regular testing is an efficient way to ensure long-term safe operation of the pipeline.The spherical internal detector has advantages such as small size,low power consumption,high detection sensitivity,no jamming,safe and convenient.It shows huge benefits in pipeline damage detection,pipeline orientation and geographic coordinate measurement.In this paper,the design of the spherical internal detector,the inclination of the pipeline and the magnetic shielding model of the pipeline have been studied.The main contents include:The hardware circuit of the spherical internal detector is improved,including optimization of the device and configuration,and adoption of the more efficient and streamlined system architecture.The program is developed for the new hardware circuit,including driver program design and application program design about sensor data interface.The power consumption test,high and low temperature test and field application test of the spherical internal detector verify the improvements of the hardware.The shielding effect of the pipeline in the geomagnetic field is quantitatively studied by using finite element method and the experiment,and compared the two classical pipeline magnetic shielding models.The results show that the variation trend of the magnetic shielding coefficient with the length,wall thickness and relative permeability of the ellipsoid model agrees well with the simulation results,but the numerical values have some deviation with the simulation results;the radial shielding coefficient of the infinite cylindrical cavity model agrees well with the simulation results,but the axial magnetic shielding coefficient doesn't agree with the simulation and experimental results.Therefore,when calculating the magnetic shielding coefficient of oil and gas pipeline,the radial magnetic shielding coefficient can be got from infinite cylindrical cavity magnetic shielding model and finite element simulation,and shouldn't use the ellipsoid model;axial magnetic shielding coefficient can be obtained by using the finite element method.A new method of measuring pipeline inclination was proposed without using pipeline magnetic shield model.It was based on cycloidal motion characteristics of the sensor in spherical internal detector while rolling inside pipelines,uneven radial distributions of magnetic fields inside after pipeline unilaterally magnetized,and the coordinate transformation method.This method was verified by simulation and experiments.Good measurement accuracy can be obtained and maximum relative error is 3.55%.