(54f) An Analysis of the Gas Pipeline Explosion at Ghislenghien, Belgium

On July 30, 2004 the rupture of a major underground high-pressure natural gas pipeline in Ghislenghien, Belgium resulted in 24 deaths and over 120 injuries. According to local media, a gas leak was reported to fire-fighters at about 08:30, local time, and the explosion occurred around 09:00. The pipeline was buried 6m underground carrying gas at 60 bara from Zeebrugge, on the northern coast of Belgium, to the French frontier.

Aerial pictures of the scene showed burned grass extending several hundred metres on either side of what appeared to be a trench and crater, suggesting that there was a major release of gas before the explosion occurred. Witness statements said collisions and rubbing between the various metal pieces ejected to the summit of the gas column had provided the sparks which ignited the gas. The official inquiry following the incident has since revealed several similar incidents across the globe where an initial leak in the gas pipeline has been followed by rupture and explosion sometime later.

This paper describes a rigorous CFD based mathematical model which presents a pictorial timeline presentation of the processes leading to the catastrophic failure of such pipelines. The model accounts for unsteady state fluid dynamics and heat transfer effects of the fluid escaping through an initial through-wall defect. These are in turn used to show significant cooling of the surrounding pipe-wall to below its ductile-brittle transition temperature. The resulting significant reduction in the fracture toughness coupled with the accompanying thermal and pressure stresses then result in the transition of the initial defect into a running fracture and hence catastrophic pipeline failure.

Significantly, delay in pipeline isolation following its puncture is shown to have a profound effect in circumventing such failures. The study for the first time quantitatively highlights the importance of taking into account the expansion induced cooling effects as a credible failure scenario when undertaking safety assessment of pressurised pipelines.