Explosion risk on offshore and onshore facilities—is there an explosion risk problem or an explosion modelling problem?
Ingar Fossan A and Sverre Nodland AA Lloyd's Register Global Technology Centre
B Lloyd's Register Consulting
The APPEA Journal 55(1) 337-344 https://doi.org/10.1071/AJ14026
Published: 2015
Abstract
Management of the risk related to the loss of containment of flammable fluid is paramount to ensure safe operations at facilities processing or storing flammable fluids. According to best industry practice, an extensive set of safety functions—including measures that reduce the frequency of initiating events (e.g. leaks) and measures that mitigate consequences in case of ignition—are implemented in design to control the risk.
Adopting the risk-based design principles that are commonly enforced in the oil and gas industry, the performance of implemented safety barriers are assessed both qualitatively and quantitatively using different methodologies such as hazard and operability analysis (HAZOP), failure mode and effects analysis (FMEA), and quantitative risk analysis (QRA).
The ultimate outcome from the QRA methodology is used to assess the overall risk level as well as to assess dimensioning accidental loads (DALs) for equipment and structures that will ensure a design that is within the tolerable risk level set for the facility. An accurate assessment of DALs resulting from fires and explosion is crucial to manage both the risk and corresponding cost driving factors. The most critical safety barrier in this regard is to minimise leaks and thereafter to prevent ignition of the dispersed flammable fluid. A fundamental safety design principle is to find ways to avoid the occurrence of incidents rather than implement measures that mitigate consequences.
This peer-reviewed paper demonstrates the significance of modelling the safety functions that are in place to ensure that the initial leak does not ignite by presenting a case example for different layouts of a conventional jacket installation with gas turbines.
It is concluded that the difference between various available ignition models can be more prominent than the uncertainty related to any other model element in the QRA. To uncover potential hazards not reflected by the model and identify optimal control measures, the effect of the ignition model applied should be investigated in detail for installations where the QRA displays a prominent fire and explosion frequency.
Ingar Fossan is Senior Principal Consultant and R&D Manager at Lloyd’s Register (LR) Consulting’s Energy Global Technology Centre (GTC) in Singapore. He has more than 15 years of experience in safety analysis for offshore installations and land-based facilities, and has thorough knowledge of the risk analysis work process; that is, from being a facilitator of HAZIDs to the detailed modelling of risk and reliability. Ingar is a focal point at LR Consulting with respect to detailed fire and explosion risk assessments, and has been the project leader for the development of many in-house risk models. He has been responsible for numerous probabilistic explosion projects, both onshore and offshore worldwide. Ingar has long and varied experience from the performance of numerous flow analyses of fire and explosion loads to gas dispersion and ventilation conditions by the use of advanced CFD tools FLACS and KFX. Ingar joined LR Consulting in 1998, and initiated and developed LR Consulting’s office in Trondheim in 2005–09. |
Sverre Nodland is a Technical Team Leader, and holds a Master’s degree from the University of Stavanger’s Department of Industrial Economics, Risk Management and Planning (2007), with emphasis on offshore technology and technical safety. He also holds a Bachelor of Petroleum Technology from the same university (2005). Sverre gained extensive international experience by working for LR Consulting in Norway (from 2007), Houston, Texas, (from 2009) and Perth (from 2012), where he has been exposed to how methodologies differ within the industry; in particular, how probabilistic explosion risk assessments are conducted. Sverre mainly works with consequence modelling with relation to probabilistic explosion and fire risk, gas dispersion, the outdoor working environment, and general technical safety for both offshore and onshore facilities using CFD. Sverre has written several papers presented in conferences worldwide on his work on explosion risk for offshore facilities. Sverre is presently based in Perth and is the manager for LR Consulting in Australia. |
