Original Article Proc IMechE Part M: J Engineering for the Maritime Environment 1–18 Ó IMechE 2021 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/14750902211043423 journals.sagepub.com/home/pim Safety performance assessment of a marine dual fuel engine by integrating failure mode, effects and criticality analysis with simulation tools Sokratis Stoumpos, Victor Bolbot , Gerasimos Theotokatos and Evangelos Boulougouris Abstract Marine Dual Fuel engines have been proved an attractive solution to improve the shipping industry sustainability and environmental footprint. Compared to the conventional diesel engines, the use of additional components to accommo- date the natural gas feeding is associated with several safety implications. To ensure the engine safe operation, appropri- ate engine control and safety systems are of vital importance, whilst potential safety implications due to sensors and actuators faults or failures must be considered. This study aims at investigating the safety issues of a marine dual fuel (DF) engine considering critical operating scenarios, which are identified by employing a Failure Mode, Effects and Criticality Analysis. An existing verified digital twin (DT) of the investigated DF engine, capable of predicting the engine response at steady state and transient conditions with sufficient accuracy is employed to simulate the engine operation for the identified scenarios. Thesimulated scenarios results analysis is used to support the risk priority number assess- ment and identify the potential safety implications by considering the manufacturer alarm limits. Appropriate measures are recommended for the investigated DF engine safety performance improvement. This study demonstrates a metho- dology integrating existing safety methods with state-of-the-art simulation tools for facilitating and enhancing the safety assessment process of marine DF engines considering both steady state conditions and transient operation with main focus on switching operating modes. Keywords Safety analysis, marine dual fuel (DF) engines, digital twins, simulation, FMECA, actuators and sensors faults/failures Date received: 18 June 2021; accepted: 14 August 2021 Introduction Background The maritime industry is a significant contributor to the global greenhouse gas emissions accounting for 3.524% of the worldwide carbon dioxide (CO 2 ) emissions. 1 To mitigate the air pollution impact of the maritime industry, a series of regulations for non-greenhouse gaseous emis- sions including nitrogen oxides (NO x ) and sulphur oxides (SO x ), as well as greenhouse gas emissions have been enforced by the International Maritime Organisation (IMO), 2 the European Union (EU) 3 and the United States Environmental Protection Agency (EPA). 4 Responding to the imposed regulatory framework, the use of marine dual fuel (DF) engines are considered as an attractive solution, 5–8 as they can achieve high output whilst combining fuel flexibility, low emissions, high efficiency and reliability. These engines can typi- cally operate at either the gas or diesel modes, as well as the shared fuel mode, where both gas and diesel fuels can be used in defined percentages. The marine DF engines typically run under steady state conditions using the same fuel type, although relatively slight power demand fluctuations may occur due to vessel weather conditions changes. Switching to a different mode needs to be implemented either when the vessel Maritime Safety Research Centre, Department of Naval Architecture, Ocean and Marine Engineering, University of Strathclyde, Glasgow, UK Corresponding author: Gerasimos Theotokatos, Maritime Safety Research Centre, Department of Naval Architecture, Ocean and Marine Engineering, University of Strathclyde, 100 Montrose Street, Glasgow G4 0LZ, UK. Email: gerasimos.theotokatos@strath.ac.uk