Optimization Technology Of Pressure Test For The Long Distance & Hilly Pipeline In Mountain Area

Pressure test is the premise of effective and safe pipe commissioning, which is the key technologies to construct high-quality pipeline. Pipelines in the mountain areas and tunnels with high drop become critical during the pressure testing. So, the study on the long distance & big drop pipeline pressure test in mountain area has significant engineering value.The main contents and achievements are summarized as follows:(1)The relative theories about pressure of the strength test and standup pressure time is introduced. Then, the functions are induced, which is specialized in calculating the highest test pressure during the pressure testing for straight pipe and elbow. And this mathematical model is established for water and gas pressure test, which provides theoretical basis for optimize of test pressure and standup pressure time of hilly pipelines.(2)The theoretical equations of maximum height difference are built up basing on the code and circumferential stress control methods, aiming to optimize the divisions of the pipelines during pressure test. Meanwhile, the elbow of hilly pipeline is the critical part during the pressure test for the stress concentration. So, the 3D FEM of the elbow part is set up to get the pipeline stresses distribution and the location of the critical part during pressure test, verifying the correctness of theoretical modal.(3)Shell-Spring of Pipe-Soil coupling model and solid element of FEM model are used to analyze the highest test pressure of hilly pipelines which laying at mountainous area and inside tunnels according to second West-to-East Gas Pipeline project and Sichuan-to-East Gas Transmission Project. Parameters that influence test pressure such as wall-thickness and bending radius also investigate to optimize test pressure of hilly pipeline. Engineering estimation formulae of hilly pipeline test pressure is deduced according to project example topographic features.(4)According to mechanical model of standup pressure time, the influences of gas content and conduit volume are analyzed. It shows that the standup pressure time has a proportional relationship with gas content and conduit volume, and provides theoretical basis for optimize of standup pressure time of second West-to-East Gas Pipeline project and Sichuan-to-East Gas Transmission Project in some contract section.(5)The optimization scheme on Sichuan-to-East Gas Transmission Project in some tunnels section is made, considering optimal selection of water feeding mode and pressure test equipment. It affords an important guiding in the pressure test of hilly and large-diameter pipeline.