The three dimensional model of the pipe leakage in the open ground was established and the grid refinement was made to aim at the highspeed leak areas. Using CFD commercial software FLUENT 6.3 for gas pipeline leakage process was simulated. The different wind speed, the influence of the initial velocity and leak mouth shapes (round and diamond) under the condition of leak were examined. The numerical simulation results showed that the wind speed had a great influence on jet angle on gas leak. The diffusion range increased with the diffusion height. The initial velocity had a great influence on jet height. The diffusion height increased with the initial velocity increasing. The wider range of hydrogen sulfide leak was circle leak mouth. The simulation results had certain significance for long distance natural gas pipeline leakage diffusion laws awareness and accident prevention.

The heavy oil electric heat pipe tracing twodimensional unsteady model was established to analyze the influence and the laws of heavy oil pipeline safety shutdown time under the thickness of pipe insulation, the number of heating pipes and location parameters. The results show that in the case of a single tube with heat, when the pipe thickness was respectively 60, 70 mm, and 80 mm, corresponding security shutdown time was about 26, 30 h, and 34 h| in the case of double pipes heating, the change of the angle between the two tubes had the smaller impact on the safety shutdown time, and the safety shutdown time was about 36 h.