Meisam Doust mohammadi - PhD Candidate، Department of Civil Engineering،Arak Branch, Islamic Azad University،Arak,، Iran.
SeyedMohammad Mirhosseini - Assistant Professor, Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran
Seye Hamid Lajevardi - Assistant Professor, Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran
Ehsanollah Zeighami - Assistant Professor, Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran

Two points need to be taken into consideration regarding buildings built around gas transmission pipelines in Iran, first, the density of the buildings and second, the distance from the axis of the pipeline. These values ​​are determined by standard tables IGS-C-SF-۰۱۵. Nevertheless, determining the two mentioned factors is not enough to determine the risk level of threats caused by gas pipelines explosion. The best way to calculate the risk level that threatens buildings around pipelines is by using computer calculations such as PHAST software to estimate the consequences of accidents and analyze the results based on natural accidents. However, it is worth mentioning that the PHAST software also cannot calculate the effects of soil in the explosion of burial pipes. Hence, the simulation by PHAST for an explosion-exposed gas pipeline can be a basis for other evaluations. After determining the appropriate consequence modelling, the effectiveness of using equipment that can reduce the explosion‘s consequences is also investigated. In this paper, after logical modelling for the real explosion, the effectiveness of a standard protective device in gas pipelines called Line Break Valve (LBV) for reducing the explosion’s consequences is measured. At first, the probability of the LBV functioning at the time of the explosion is checked. Subsequently, by the diagram, the consequences of the accident for two modes of operation and non-operation of the LBV system are displayed and compared with each other. Ultimately, for the simulated mode, it is observed that the correct operation of the LBV system could reduce the accident consequences by more than ۶۰%.

Pipelines, gas, PHAST, Automatic valve, Line Break Valve (LBV), Consequence