The research on the risk management based on Web GIS is being considered to improve safety management of oil pipeline.An information management system for oil pipeline based on Web GIS has been established.According to the collected practical pipeline data and ananalytic hierarchy process(AHP),the latent risk of oil pipeline was quantified based on the modified Muhlbauer W K method,the risk grading of oil pipeline was devised and daily maintenance was emphasized.The orientation system of leakage in the oil pipeline was devised based on negative pressure,and the best emergency rescue paths was decided based on improved Dijkstra arithmetic.Finally,it was demonstrated with examples that this system of the risk management and emergency response based on Web GIS is more veracious and easier to apply.

The safety management was among the most important management work for oil and gas pipelines． As an alternative，the risk grading division based on WebGIS was being considered to improve safety management．An information
management system for oil and gas pipeline based on WebGIS had been established using ArcGIS Server as the developing system of WebGIS，SQL Server as the database to store pipeline data and ArcSDE as the GIS Server．According to the practical pipeline situations，the expert grading method on risk assessment of oil and gas pipeline set by Muhlbauer W K was modified．
An analytic hierarchy process （AHP） was introduced to comprehensively evaluate the expert grading method，and a kind of categorization method for the risk of oil and gas pipelines was proposed．Finally，it was demonstrated with examples that this improved categorization method based on WebGIS is more intuitive and easier to apply．

 

For gas pipeline, simulating the working condition was necessary in order to work safely and economically and manage rationally. Some gas pressure was up to 10 MPa in the pipeline, in which the result by equation for ideal gas has the greater error. L-E-E equation was applied to solve the physical parameters such as the compression factor, practice gas density, specific heat, adiabatic index, entropy, enthalpy and so on. And the program was compiled to calculate the properties. The calculate results show that L-E-E equation is much accurate and can be applied widely in the practice.

Analysis of samples taken from the cracking area of the multilayered urea reactors verified the existence of stress corrosion cracking (SCC) cracks. The influence factors of SCC in multilayered urea reactors were investigated. The results show that the leak detection steam may condense in the interlayer clearances, which would cause alkaline medium concentration at the heavy weld. It was the initiation and propagation of micro-cracks under alkaline environment and local high stress concentrations that lead to the SCC of heavy girth weld urea of the multilayered reactors. The results can give beneficial directions to avoid SCC of layers and catastrophic ruptures of multilayered urea reactors.