Study Of The Deformation Calculation,Strain Measurement And Health Monitoring System Of Long Distance Transportation Pipeline

Pipeline is one of the important means for oil and gas transportation. Because of low cost, high efficiency and safety, pipeline transportation is getting more and more attention in China and a pipeline system for oil and gas transportation has been basically formed all over the country. Chinese territory is vast and topography is complicated. For a long pipe, geological hazards, such as the ground collapse, would induce the pipe’s deformation seriously which adversely affect the oil and gas transportation. It is even possible to cause the pipe fracture and as a consequence, the resource would be wasted, the natural environment would be harmed and people’s life would be threatened. Therefore, it is important to study and monitor the pipeline’s deformation. In this dissertation, deformation of the long distance pipeline is calculated based on strains, strain transfer of fiber Bragg grating sensor is studied and a health monitoring system is established. The main work and achievements are as follows:(1) The pipe deformation is chosen as the parameter for pipe safety assessment. The pipe is simplified as a beam. Based on quasi-distributed strains measured at different points at the pipe and with use of the large deflection theory and the spline function of numerical treatment, a so-called deformation quasi-distributed calculation method is proposed to calculate the deformation the pipe’s axis. This method is simple and applicable in engineering especially when the actual loadings on the pipe can not be accurately determined.(2) The feasibility of the proposed deformation quasi-distributed calculation method is verified numerically and experimentally.(3) Parameters involved in the calculation of pipe deformation are investigated numerically for their influences on the calculation accuracy. Based on the results, some suggestions are given for the choice of these parameters when applying the proposed deformation quasi-distributed calculation method in engineering.(4) Measurement principles and the application scope of fiber Bragg grating are analyzed and its accuracy is studied experimentally by comparing with strain gauge method. For the grip-packaged fiber Bragg grating strain sensor fixed on the pipe by welding or pasting, relationship between the strain measured with the fiber Bragg grating sensor and the actual structural strain is deduced to raise the strain measurement accuracy of the long distance pipeline.(5) Safety assessment criteria based on pipe deformation are studied and the pipe deformation of3%the diameter is chosen in this dissertation as the one for pipe safety assessment and the evaluation criterion of deformation.(6) A health monitoring system with application software for long distance pipeline deformation is developed based on the proposed deformation quasi-distributed calculation method and the use of the fiber Bragg grating sensor as the measuring means. With the system, the pipe deformation could be monitored in real-time and warnings could be sent out before pipe accident.