Decision Making for Safety Assessment of Mobile Mooring System

Abstract Floating structures use mooring system for station keeping in any water depths. Mooring system is a vital component for the safety of floating structures. Mooring accidents can cause serious injury or damage to the vessel, and hence it is necessary to establish a systematic risk-based decision making for safety assessment of mobile mooring system. This study uses the mobile mooring system of a semi submersible pipe laying barge as a case study. The aim of this study is to develop a Methodology for Investigation of Critical Hazards (MIVTA), which is carried out by the development of preliminary risk analysis using HAZOP (Hazard and Operability), to generate the root causes using FTA (Fault Tree Analysis) and to construct the sequence of the consequences using ETA (Event Tree Analysis). HAZOP is a systematic examination of a system helpful to identify and evaluate the risks related to accidents/incidents in mooring system. FTA is a deductive method useful to generate the potential causes of mooring system failure into undesired events. ETA is an inductive method helpful to define all possible outcomes of accidental events. This study conducts risk-based decision making coupled with the knowledge of the experts of mooring system to identify the root causes, to evaluate the frequency of failure and to classify their class of consequences. This study provides a systematic methodology guideline for the risk-based decision making useful to identify the risk of accidents occurring in offshore platforms. Keywords: Assessment; fault; hazard; safety; tree