DESIGN CURVE FOR ATYPICAL STAINLESS STEEL CORRUGATED FIREWALL SUBJECTED TO BLAST LOADING

摘要

Since the Piper Alpha tragedy in July 1988 in which a hydrocarbon release caused the complete loss of an offshore platform, the Health and Safety Executive (HSE) of the United Kingdom requires safety cases to be carried out at various stages of the working life of an offshore installation. The study must normally show some attempt at predicting failure pressures of vital structural systems and the integrity of a temporary refuge during a blast and fire scenario. This paper presents results from large scale tests carried out at a test site in the North of England by BG Technology on stainless steel (316) corrugated firewalls which were representative of actual members on existing platforms in order to establish safe containment pressures of such systems in light of the Piper Alpha tragedy and as part of an ongoing safety study. An explicit non-linear finite element package, accounting for plasticity large deflections and the dynamics of the structural system has been used to both validate numerical models and to carry out sensitivity studies to establish variations in response of both local parameters such as plastic strain and global deflections to variations in mesh density, pressure time histories and span. It was found that care is required in establishing a suitable mesh density at high ductility values associated with the extreme loading conditions produced by a hydrocarbon explosion. The experimental and numerical results are finally presented as a simple design curve giving safe containment pressures for a shallow corrugation firewall adopting a flexible angle support with a varying span.