# Accident Risk Analysis of Gas Tankers in Maritime Transport Using an Integrated Fuzzy Approach
## 4 Findings
### Interaction Analysis Between Risks Identified by the FTA
R3 (Corrosion and leakage in tank or piping systems) and R7 (Hose or manifold damage during loading/unloading) represent potential risk factors associated with damage to storage and operational equipment. These risks are connected by an 'OR' gate, as either can contribute to R11 (Large gas leakage due to accident) by causing equipment failure or system malfunction during operations. R16 (Failure of cargo tank pressure control systems) is a risk indicating the failure of pressure control mechanisms, while R20 (Impact on cargo and ship operations due to cyber-attacks) is a risk arising from the increasing reliance on automation and digitalisation in ship management systems, which may expose security vulnerabilities. R20 is a risk that affects R16 and is linked to R16 by an AND gate, representing potential risks that contribute to triggering risk R11 (Large gas leakage due to accident). Risk R2 (Gas leakage following collision or grounding) is a risk that may occur during the voyage or manoeuvring of the ship and results from potential contributing factors. Risk R8 (Risk of collision/crash during harbour or berthing) is particularly relevant for ships manoeuvring in narrow areas in ports. These risks are linked by an 'OR' gate as they cause the risks R2 and R8. Risk R19 (Inadequate post-accident contingency plans) reflects this inadequacy and is linked as an influencing risk by an AND gate to risks R2 and R8, which together represent potential risks contributing to the triggering of risk R11 (Large gas leakage due to accident). \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Risk Code** & **Risk Description** & **Contributes to** & **Gate Type** \\ \hline R3 & Corrosion and leakage in tank or pipe systems & R1: Gas leakage during cargo handling & OR \\ R7 & Hose or manifold damage during loading/unloading & R1: Gas leakage during cargo handling & OR \\ R5 & Non-compliance with safety procedures & R1: Gas leakage during cargo handling & OR \\ R17 & Incorrect valve or pump operation due to human error & R1: Gas leakage during cargo handling & OR \\ R1 & Gas leakage during cargo handling & R9: Toxic gas release & AND \\ R18 & Failure to comply with international regulations & R9: Toxic gas release & AND \\ R15 & Technical failure in fire extinguishing systems & R4: Fire/explosion & AND \\ R19 & Inadequate post-accident crisis management & R4 and R9 & AND \\ R14 & Incomplete emergency procedures & R4 and R11 & AND \\ R6 & Pressure increase due to seawater temperature & R11: Large gas leakage & OR \\ R13 & Extreme weather conditions & R11: Large gas leakage & OR \\ R16 & Failure of cargo tank pressure control systems & R11: Large gas leakage & OR \\ R20 & Cyberattack on cargo/ship operations & R16 (therefore affects R11) & AND \\ R2 & Gas leakage after collision/grounding & R11: Large gas leakage & OR \\ R8 & Collision/crash during harbour or mooring & R11: Large gas leakage & OR \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Fault tree risk relationships and logic gates. R11 (Large gas leakage due to accident) represents the risk of a significant release of gas following an accident, while R14 (Incomplete or inadequate emergency procedures) represents the risk arising from such procedures during potential emergencies. As R14 is a risk that influences R11, it is linked to R11 by an AND gate and grouped together as the final level of risks that will cause a gas leakage accident. At the top of the diagram, gas fire/explosion and gas leakage are linked by an AND gate as two significant events, emerging as the main causes of the critical event, the gas tanker accident and its environmental impact. The gas tanker accident and its environmental impact are the most significant events because they result in serious damage to the ship, the port, and the environment, irrespective of the specific event. Regardless of the cause of the major incident, the outcome will be devastating and result in significant economic loss.