Application of Reliability Centered Maintenance Techniques to a Dynamically Positioned Vessel using Failure Mode Effect and Analysis – a Case Study

Published in: IIRE Journal of Maritime Research and Development Vol. 2 Issue 1 May 2018

Author: Mr. U. S. Kalghatgi

Date of Publication: May 2018

Reliability Centered Maintenance (RCM) is a systematic approach to ensure that a system maintains its functional capability through optimum maintenance activities. One of the key step in implementing RCM is to carry out Failure Mode Effect Analysis (FMEA). FMEA is an engineering technique used to define, identify and eliminate known and/or potential failures. FMEA is a proactive method to analyze possible failures before the failure has occurred. Such failures cause interruption in the operation of the vessels, leading to cost implications, besides loosing precious time in restoring the system. The consequences of such failures could be disastrous too. FMEA is a study of any system’s functioning and anticipating probable failures and then taking suitable corrective actions to prevent them from occurring.

Dynamic positioning (DP) is a system to automatically maintain a vessel's position and heading by using its own propellers and thrusters. Position reference sensors, wind sensors, motion sensors and gyro compasses, provide information pertaining to the vessel's position and environmental forces affecting its position. It enables operations at sea where it is difficult to moor or anchor the vessel. Some of the common applications of the DP systems are ships and semi-submersible mobile offshore drilling units (MODU), oceanographic research vessels and cruise ships. These vessels are usually engaged in critical operations, where position keeping of the vessel remains a key function of the DP System.

The aim of FMEA study was to identify the single point failures in any system in the vessel which would lead to loss of position keeping of the vessel. The causes and effects of any such failures were analysed and possible corrective actions recommended in the FMEA report.

The vessel, for which the FMEA was carried out, is fitted with diesel driven main propellers and electrically driven tunnel and bow thrusters. The findings of FMEA were used to identify functional failures and plot P-F curves using failure rate data from OREDA. This was used to structure the RCM framework to develop a maintenance plan that will provide an acceptable level of operability, with an acceptable level of risk, in an efficient and cost effective manner. In the end, Cost-benefit analysis was carried out to determine which systems would benefit from RCM and which were better off with traditional maintenance practices.