Recent developments to evaluate global explosion loading on complex systems

During the engineering phase, a “Design Explosion loads Specification” is often developed by the safety discipline in order to provide the necessary explosion response inputs to other engineering disciplines for each individual item part of a safety critical system. This includes the specific targets, the associated performance criteria and the corresponding design explosion loads. This is an efficient way to manage explosion in design for each individual item composing a safety critical system but when combination of items need to be addressed, for instance global loading on complex items (e.g. modules, critical pipework or packages), this approach may result in an overly conservative design if the maximum explosion loads on each item are summed simultaneously. Indeed each component may experience variability in loading time due to the propagation of blast wave during the explosion event. In the opposite, only considering explosion loads on each individual item successively may be not safe enough. An alternative methodology based on Computational Fluid Dynamics (CFD) FLACS® software simulations is presented in the article in order to get more adequate global blast loads for design verification, in particular taking into account potential shielding effects, group effects of elements. It focuses on the development of dedicated blast load cases for the design in order to address both internal and external explosion events related to complex items such as whole onshore units or offshore modules on floating facilities. This method will be favorably implemented on generic typical systems in order to develop blast loads cases combination rule sets on future projects. This will contribute to enhance blast design approaches and promote opportunities for further optimization.