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Title: SUBMARINE PIPELINE AUTOMATIC-REPAIR SYSTEM - AN APPROACH TO THE MISSION-AVAILABILITY ASSESSMENT
Author: CAPUTO, G; IANNELLA, C; DELUCA, F; UGUCCIONI, G
Abstract: This paper presents the methodology followed to evaluate mission availability of a remotely controlled submarine system designed to repair damaged pipelines laying in deep waters. The goal of the analysis has been to identify the technical and operational solutions, with respect mainly to the Logistic Support System design, to guarantee operational availability thereby minimizing delays. To this purpose, the FMEA and Fault Tree analysis technique for reliability assessment of each subsystems have been supplemented by a Event Tree Analysis performed through a computer package (ADMIRA). All sequences of failure and/or success for the whole system have been analyzed during the whole operation steps. This analysis has allowed an estimate of the delay for each possible system state. The analysis performed has shown that the Event Tree approach is a very adequate tool to handle situations where failures occurrence and dependencies among different events have to be taken into account. Of course this problem could be handled as well with conventional methods as FTA, though it would require complex and skilled manipulations of the many "trees". The FMEA/FTA method has been limited to specific analysis of subsystems whose states are considered independent from other subsystems states, thou obtaining failure probabilities that are inserted at the appropriate nodes of a decision tree. The inductive reasoning has permitted to follow system behaviour and to identify all possible output states. Such representation of the system permits: to evaluate the probability distribution of each state in which the global mission has been subdivided; to evaluate the probability-consequence curves for a number of parameters of interest (time delay, costs, ecc.), by associating a value representing the parameter itself to each state. In this study such parameter has been the time delay, so deriving a delay distribution for each module operation. Such delay distribution as well as meteorological statistics data correlated to the area of operation have been used to perform a Monte Carlo simulation. This allowed an assessment of the distribution of mission duration as a function of the area of operation, the type of support vessel used and the logistic support system chosen both at ground level and on board. The whole analysis has led to improved design, operator skills and training as well as support system definition.
Source: PROCEEDINGS ANNUAL RELIABILITY AND MAINTAINABILITY SYMPOSIUM
Publication Year: 1992
Volume:
Issue nr: SYM
Pages: 126 - 130
Science Code: Engineering, Multidisciplinary; Engineering, Industrial
Tags: MISSION AVAILABILITY; EVENT SEQUENCE ANALYSIS; MONTE-CARLO SIMULATION; LOGISTIC SUPPORT
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