The Research On The Motion Characteristics Of The Internal Geometry Inspection Tools For Newly-constructed Pipeline Acceptance Check

It may cause damages to oil and gas pipelines in the construction process;these injuries are concave or roundness changes.As time goes by,such defects will increase.These will lead to pipeline exploded or other serious accidents during the pipeline in service.Therefore,acceptance check for the newly-constructed pipelines is particularly important.The tools used for the geometry and deformation detection of new pipeline called newly-constructed pipelines internal geometry inspection tools.There is no available environmental condition for intelligent inspection before the pipeline put into use.In practice,People often use compressor as the driving source.It usually use no-backpressure mode in the pipeline inspection so as to reduce energy consumption.This article studies the use of air compressors in field applications and various factors which affect the stable operation of the inspection tools in the no-backpressure condition.It aims to provide a theoretical basis and technical guidance for internal inspection tools design and the use of air compressors.The thesis builds a structural model which describes the working principle of the inspection tools,and analysis the sealing device which is the critical parts of the tools.On these bases,a motion model is established.The two main factors that affecting the stable operation of the tools are the driving force of gas and the friction of cup.The differential equation of motion is derived.Characteristic curves of velocity are obtained through numerical simulation,and the effect of each factor on the motion of detector was determined.The numerical simulation is carried out using MATLAB,combined with Runge-Kutta-Fehlbrg method.The model of the seal cup is built to analyze the influence of the support force and friction.On this basis,deep cone cup is designed for the inspection tools.The theoretical model is proved to be feasible in the industrial application.According to the basic equations of fluid dynamics and kinematics model of the tools,the driving pressure and gas injection is derived.As a result,it effectively controls the speed of inspection tools in the pipeline,reduce the detection process energy consumption,improve the detection accuracy and reduce the damage to the pipeline.