| At present,multi-channel high-resolution caliper pipe inspection gauge(pig)is widely used to measure pipeline deformation and diameter reductions such as dents and ovalities.CoMParing with the foreign caliper technology,the domestic product is left behind.China has not developed a multi-channel caliper pig independently until 2012.Consequently,it results in the lack of theoretical research on the caliper pig.Based on the above background,this dissertation is mainly to study the key technologies of multi-channel caliper pig,including:(1)A multi-channel caliper pig which is used in 14.7 inches gas pipeline and a data processing software are developed.It can be used to detect pipeline fedect,deformation and so on.Through experiment method,its performances are tested to ensure it meets basic detection requirements.Furthermore,some design principles and theries about caliper pig are proposed in the designing process,which provide theoretical basis for china caliper pig development to some extent.(2)Through analyzing the process of the detection arm of caliper pig sweeping across the convex and concave defect,“bouncing model” and “contraction model” are proposed.Through analyzing the models,it shows that the running speed,spring reload,spring stiffness and the shape of defect have an important influence for the detection precision.(3)An inspection system are built to study the detection precision of detection arm.Through experiment method,it studies the realtion between the running speed,spring reload,spring stiffness and defect shape and the detection precision of the detection arm.Through analyzing the experiment result,the following conclusion can be obtained.With the increasing of the running speed of the detection arm,its bouncing height will increase,so the radial and axial detection precision will decrease.With the increasing of the spring reload or spring stiffness of the detection arm decrease,its bouncing height will increase,so the radial and axial detection precision will decrease.For the defect,the precision decreases as the defect curvature grows.In addition,the experiment result prove the correctness and accuracy of the “bouncing model” and “contraction model”.(4)Through building recognition model of caliper pig detection data,the offset error between caliper pig center line and the center line of the pipeline is corrected and it improves the detection precision of caliper pig.In addition,the characteristics of the decteion arms sweeping across the defect,weld,pipeline tee and pipeline bend are studied and the recognition algorithm of these pipe features are proposed,which provides a theoretical basis for the study of caliper pig data processing.The results of this paper may be helpful for the development and theoretical studies of domestic caliper pig in the future. |
