Safety Risk Analysis Of Truss Crossing Pipeline Under Thermal And Fluid Load

The crossing pipeline structure is the important component of overhead pipeline system.There are different forms of crossing structures,the truss crossing pipeline have been widely used in small and medium crossing projects because of the advantages of simple structure,stability and anti-elasticity.For the safe operation of the overall pipeline,the safety and stability of the crossing pipeline plays an important role.In order to study the safety of truss crossing pipeline,the thesis selected the truss crossing pipeline of a chemical industrial park in South China as the research object.According to the situation of the truss crossing pipeline in the process of operation,the ANSYS finite element model was established systematically to calculate the distribution of stress,displacement and shear force.And the safety of truss crossing pipeline was judged by checking the parameters.The feasibility of the finite element method by comparing the calculation results with the test data.Finally,based on the collected data,the risk of truss crossing pipeline was evaluated by fuzzy analytical hierarchy process.The purpose of thesis to explore a set of methods that can evaluate the safety status of the crossing pipeline.The main contents and conclusions of this paper are as follows:(1)The load combination and boundary conditions during simulation were determined by analyzing the load on the truss crossing pipeline in the operation process.The methods and related theories in this paper were introduced,including modal analysis and risk assessment techniques.(2)According to the design parameters of the truss crossing pipeline system,the finite element model with uneven settlement boundary and load combination,which included gravity,temperature and medium flow,was established by ANSYS Parametric Design Language(APDL).The parameter distribution of stress,displacement,axial force,shear force and bending moment of the truss crossing pipeline were obtained through simulation calculation,and the secondary stress of the pipeline was checked to judge the safety of system.The critical settlement value of the column was predicted by simulation calculation.Finally,the modal analysis of the crossing pipeline was carried out to obtain natural frequency and mode shape.The safety of truss crossing pipeline was simulated and verified in a nearly real environment.(3)Conducted on-site measurement on the truss crossing pipeline system,studied the effect of pipeline wall thickness,column settlement,pipeline stress and vibration on system safety.And the feasibility of the calculation method was verified by comparing the measured data and the simulation results(4)Based on the data collected by the research,the risk factor set of trussed crossing pipeline was established.The weight of each risk factor and risk level of the truss crossing pipeline were determined by fuzzy analytic hierarchy process.And the corresponding measures were put forward for the risk factors with high weight.