J. Marine Sci. Appl. (2016) 15: DOI: 10.1007/s11804-016-1368-4 Enabling a Viable Technique for the Optimization of LNG Carrier Cargo Operations Onakoya Rasheed Alaba 1 , T. C. Nwaoha 2* and M. O. Okwu 3 1. Nigeria LNG Ship Management Limited, PMB 5660, Port Harcourt, Rivers State, Nigeria 2. Department of Marine Engineering, Federal University of Petroleum Resources, P.M.B. 1221, Effurun, Delta State, Nigeria 3. Department of Mechanical Engineering, Federal University of Petroleum Resources, P.M.B. 1221, Effurun, Delta State, Nigeria Abstract: In this study, we optimize the loading and discharging operations of the Liquefied Natural Gas (LNG) carrier. First, we identify the required precautions for LNG carrier cargo operations. Next, we prioritize these precautions using the analytic hierarchy process (AHP) and experts’ judgments, in order to optimize the operational loading and discharging exercises of the LNG carrier, prevent system failure and human error, and reduce the risk of marine accidents. Thus, the objective of our study is to increase the level of safety during cargo operations. Keywords: analytic hierarchy process (AHP), Optimization, LNG carrier cargo, precautions, safety Article ID: 1671-9433(2016)03-0000-00 1 Introduction 1 The use of Liquefied Natural Gas (LNG) as a major energy source has resulted in an increase in the demand for LNG. In recent years, there has been a growing number of LNG carriers transporting LNG to meet global demands. LNG carriers are specialized vessels designed, constructed, and equipped to carry cryogenic LNG stored at a temperature of −162°C at atmospheric pressure (Moon et al., 2009). While the carriers all have similar features, they differ in their tank designs (Nwaoha et al., 2013). These carriers can either have a membrane tank design, a structural prismatic tank design, or a spherical (moss) tank design (Nwaoha et al., 2013). Loading and discharging operations of LNG carrier cargo at LNG terminals is more complex than those of other vessels. The connection of loading arms, pressurizing and purging of the arms, securing the vessel, and checking the safeguard systems must be carried out prior to loading and discharging at the LNG terminal. These operations expose the involved personnel and environment to various high-risk hazards. Knowledge about the LNG carrier cargo-related precautions to be taken during loading and discharging operations can optimize the outcome of LNG carrier cargo operations and identify potential high-risk hazards. Received date: 2016-02-01 Accepted date: 2016-02-28 *Corresponding author Email: nwaoha.thaddeus@fupre.edu.ng thaddeus_cn@yahoo.co.uk © Harbin Engineering University and Springer-Verlag Berlin Heidelberg 2016 Therefore, a viable qualitative and quantitative technique is necessary for this type of research. The analytic hierarchy process (AHP) has been demonstrated to be a useful qualitative and quantitative multi-criteria decision-making technique for application in various fields (Mishra et al. 2015; Socaciu et al. 2016; Singh and Nachtnebel, 2016; Arslan, 2009; Cheng, 1997; Liu and Hai, 2005; Shang and Sueyoshi, 1995; Takamura and Tone, 2003; Wang et al. 2008; Zhang and Cui, 1999; Rocha et al. 2016). Arslan (2009) utilized the AHP technique in a quantitative evaluation of the precautions used on chemical tanker operations. Cheng (1997) adopted the AHP method in combination with the fuzzy logic approach to evaluate a naval factual missile system. Liu and Hai (2005) employed the AHP method in their determination of the voting weighting criteria in the selection of suppliers. Shang and Sueyoshi (1995) used AHP methodology to quantify the elusive benefits associated with a manufacturing company’s cooperative and longterm objectives for a Flexible Manufacturing System (FMS). Takamura and Tone (2003) applied the AHP method to determine the weight criteria in a site evaluation study for relocating the Japanese government from Tokyo. Wang et al., (2008) incorporated the AHP method in determining the weight of criteria for a risk assessment of bridge structures. Zhang and Cui (1999) employed AHP in the development of a project evaluation system to determine a reasonable investment ratio in China. Since the usefulness of AHP has been clearly demonstrated, we selected this method for use in this study. We detail the precautions associated with LNG carrier cargo operations in section 2, and describe the AHP methodology in section 3. In section 4, we apply AHP in the prioritization of the precautions of LNG carrier cargo operations, and in section 5 we draw our conclusions. 2 LNG Carrier cargo operation precautions Negligence with respect to taking necessary precautions during LNG carrier cargo operations can result in adverse consequences. The safety and optimization of the operation must begin with a thorough understanding of the precautions required in order to avoid hazards and system failures. In this study, the necessary precautions to be taken by