Abstract: Gas leakage accidents are accompanied by a number of risk threats such as explosion and poisoning which brings about economic losses and casualty losses. In this paper, Ansys/Bow-Tie are adopted to establish diffusion model and analytical calculation model to analyze gas leakage qualitatively and quantitatively. The study indicates that in the qualitative variation, the gas diffusion rate increases exponentially in large modular in the leakage area and the diffusion rate is extremely fast. In the quantitative variation, the main risk of gas leakage comes from insufficient inspection and lack of timely overhaul with the highest probability of 0.039 and 0.046 respectively. It can be helpful for risk control to install toxic and hazardous gas instrumentation alarm monitoring group and strengthen the monitoring of large risk issues.

Key words: gas leakage, Ansys model, Bow-Tie model, risk analysis