Development Of Eddy Current Sensor For Geometrical Deformation Inspection Of Oil And Gas Pipeline

Oil and gas transported in pipelines are flammable and explosive.Regular pipeline inspection is important to avoid the loss of person and property.The method of contact detection used in the existing equipment can't detect expansion of the pipeline.Through the study of oil and gas pipeline deformation detection methods,the method of eddy current is firstly applied to long-distance oil and gas pipeline inspection.In this paper,the model of eddy current testing equipment is built based on the characteristics of oil and gas pipelines.Eddy current sensors cover the whole pipe wall though double staggered umbrella frame structure.Through the study of the three eddy current sensor detection method and the pipeline inspection environment,the method of constant frequency and amplitude modulation using transceiver detection coil can achieve pipeline expansion.A block diagram of the eddy current sensor is built based on the detected requirements.The outer diameter of the sensor can be increased to improve the measurement range of the linear range of the sensor.The axial thickness and the outer diameter of the coil can be decreased to improve the sensitivity of the sensor.Output curves of the eddy current coil are non-linear at both ends while it is linear in the central.Eddy current sensor can work in the linear range to have a better linearity by adjusting the eddy current sensor transmitting circuit operating point.The output signal of the coil is processed by the signal processing circuit to reduce the influence of the external interference signals.The output signal is turned into a DC voltage output by the phase-sensitive detection circuit.The circuit can make the output signal easy to store and reduce the influence of other sensors.The noise immunity of the eddy current sensor is improved by the signal processing.According to the detection model,the eddy current sensor and test platform is developed.The static and dynamic performances of a single sensor and a plurality of sensors are tested to verify the feasibility of detecting pipeline expansion by eddy current sensors.It is verified that the eddy current sensor can achieve 40mm range and±0.5mm detection accuracy through the eddy current sensor test.Eddy current sensor developed in this thesis can achieve dynamic and multi-channel inspection of pipeline expansion.It laid the foundation for testing equipment manufacturing and industrial applications.