Using computational fluid dynamics to assess the risks of a gas leak on an offshore structure

A potentially serious risk onboard an offshore structure is a gas leak from a high pressure pipe. Although the majority of these occur at weak spots on the pipes such as a flange joint there is no accurate method of predicting where and when such leaks will occur. The emphasis is therefore on the safe dispersion of the leaked gases in order to prevent hazardous buildup of explosive hydrocarbons and thus to minimize the explosion risks. Computational Fluid Dynamics (CFD) allows for a relatively inexpensive, quick and effective method of pinpointing problem areas related to gas dispersion on an offshore structure. It will be seen that the choice of scenarios modelled for a particular structure as regards to wind characteristics (speed and direction) and leak rate is important. This paper demonstrates what combination of these factors leads to the greatest explosion risk as regards to the spread of hydrocarbons and also to stagnant pockets of gas for a specific design. This allows either the design to be changed before construction in order to minimize the number of stagnant areas; or potential problem areas can be instrumented and monitored more closely in case of a leak. CFD can also be usedmore » to locate the optimum positions for gas detectors that will give the minimum response time when a leak occurs. The safe dispersion of leaked gases in order to prevent hazardous buildup of explosive hydrocarbons and thus to minimize the explosion risks is of importance in the design of offshore structures today. CFD provides an inexpensive and effective method of highlighting potential hazard areas before construction and allows detectors to be located more effectively.« less