Quantitative fire risk assessment of gas pipeline leakage

HE Jing, College of urban construction and safety engineering, Nanjing university of technology, Nanjing 210000, C hina;
Abstract: O nce gas pipeline breaks, compressed gas rapidly expand. The
electrostatic discharge spark energy can ignite the gas, causing a large range of gas combustion and explosion, and leading to catastrophic losses. Due to the characteristics of natural gas are flammable and explosive, there exist explosion, fire risk, casualties and damage in transport, storage and using process. In addition, if leakage continues long time, it can cause long-term harm because of continuous gas supplying. The factors contributing to gas pipeline leakage most are third party damage, corrosion, design and incorrect operation.
In this paper, the accident consequences of gas pipeline leakage and quantitative risk assessment method of gas pipeline leakage consequence are analyzed. Gas pipeline leakage patterns mainly include pipeline completely rupture leakage, big hole leakage and the middle hole leakage. Disaster patterns mainly include flash fire and vapor cloud explosion. In order to achieve quantitative fire risk assessment of gas pipeline leakage, flash fire model, vapor cloud explosion model and thermal radiation damage criterion are analyzed. F irstly, the gas leakage quantity is estimated. Then, the incident thermal radiation intensity, damage range and damage area are got by using flash fire model, vapor cloud explosion model and the thermal radiation damage criterion respectively.
Combined with an example of gas pipeline, damage ranges of different disaster patterns are estimated according to different gas pipeline leakage pattern. At the same time the damage degree is assessed.

 Under the same leakage pattern, the damage ranges varies with different disaster patterns. When the flash fire caused by pipeline completely rupture leakage occurs, people will 100% die in 1min and 1% die in 10s within 244m range. In

contrastï¼?when the vapor cloud explosion caused by pipeline completely rupture
leakage occurs, people will 100% die in 1min and 1% die in 10s within 60m range. When the range extend to 107m, people will 100% die in 1min and seriously injured in 10s. When the range extend to 176m, people will 1% die in 1min and first-degree burn within 10s.

 Under the same disaster patterns, the damage ranges varies with different leakage patterns. When the flash fire caused by pipeline completely rupture leakage occurs, people will 100% die in 1min and 1% die in 10s within 244m range. In

contrastï¼?when the flash fire caused by the middle hole leakage occurs, people will
100% die in 1min and 1% die in 10s within 90m range.
The quantitative risk assessment method for hazard evaluation of natural gas pipeline accident can be applied in estimating the gas leakage consequences. Through comparing the accident consequences of gas pipeline leakage, this paper provides some reliable scientific references for gas pipeline management departments of operation, construction and others.
Keywords: gas pipeline; leakage; flash fire; vapor cloud explosion;
quantitative risk assessment