Jet Fire Analysis of Highly Flammable Hydrocarbons Part I: High Pressure Natural Gas Transportation

Abstract

This study is based on the analysis of predicted jet fire occurrence following the puncture or rupture of a high pressure natural gas pipeline. A case study of high pressure pipeline transporting natural gas at 8.9 MPa (89 bar) with pipeline diameter of 720 mm (0.72 m), and assumed puncture sizes of 0.1 m, 0.2 m and 0.3 m and a full bore rupture (FBR) are considered. The severity of a jet fire is dependent on the puncture size, flame length and its impingement on nearby equipment, accompanied heat fluxes and the distance between flame zone and target (humans/equipment). Research has shown that 6.3 kW/m² is the maximum bearable heat flux recommended for humans, buildings and other facilities. As such it is recommended that a safe distance be maintained between the pipeline facility and humans/equipment based on this bearable heat flux. Applying a modified Chamberlin’s jet fire model, the results obtained from this analysis showed that for puncture sizes of 0.1 m, 0.2 m, 0.3 m and FBR, the minimum safe distances to receive 6.3 kW/m² heat radiations are 38.5 m, 60 m, 79.5 m and 95.5 m respectively. However, a highly busy major road with residential houses is 10 m away from our case study pipeline. Therefore, calculating the heat fluxes based on that distance for puncture sizes of 0.1 m, 0.2 m, 0.3 m and FBR. The results were 104.05 kW/m², 288.91 kW/m², 395.39 kW/m² and 593.09 kW/m² respectively.

Keywords: heat flux, jet fire, natural gas, pipeline, safe distance