Research On Flexible Pipeline Pig For Oil And Gas Pipelin

Oil and gas pipeline caliper pig is an important equipment to ensure the safe operation of pipeline.Because the traditional Caliper pig with gauging plate can not detect deformations at different positions in the pipeline,and the gauging plate can not be reused,a flexible caliper pig is designed in this paper.The aluminum gauging plate is replaced with hyperelastic polyurethane material,and a strain gauge is placed in the polyurethane layer to prepare a flexible caliper sensor.Based on the strain effect,the flexible detection and quantification of the pipeline deformation can be realized by measuring the strain change of the flexible caliper sensor when it encounters resistance.In this paper,the principle is verified and its geometric parameters are optimized by finite element simulation,and the accuracy of the flexible caliper sensor is tested.The main research work is as follows:(1)The detection principle of flexible caliper pig is proposed,the basic structure is designed,the mechanical model of the process of flexible gauging plate crossing the depression is established,and the corresponding relationship between strain and displacement is preliminarily obtained.Taking polyurethane gauging plate as the research object,ABAQUS finite element simulation software is used to simulate its operation in the concave pipeline.The placement position of the strain gauge was calibrated from the three aspects of placement surface,longitudinal distribution and lateral distribution.The influence of the three parameters of thickness,number of petals and polyurethane material hardness on the stress-strain distribution of the flexible gauging plate was discussed.(2)The simulation model of flexible caliper sensor is constructed to analyze the strain output characteristics when tensile and compression deformation are produced.At the same time,in order to improve the detection sensitivity of flexible caliper sensor,the built-in relationship between strain gauge and different thickness of flexible caliper disk is studied.The three factors and three level test training database is established.The strain output characteristics of the flexible caliper sensor are predicted by BP neural network,and the genetic algorithm is used to find the optimal parameters of the flexible caliper sensor,which provides a basis for the structural design of the flexible caliper sensor.(3)In order to evaluate the technical parameters such as the detection accuracy and measuring range of the flexible caliper,the exercise test bench of the flexible caliper sensor is designed and built.The static accuracy test of the flexible caliper sensor is carried out,and the voltage displacement fitting curve of the flexible caliper sensor is obtained;Through the dynamic accuracy test,the whole process of the flexible caliper sensor crossing the defect is analyzed,and the influence of different moving speeds and different defect length-to-height ratios on the detection accuracy is discussed.Finally,through experiments,the influence of different flexible caliper sensor geometric parameters on the strain output is further analyzed.