An Integrated FTA-FMEA Model for Risk Analysis of Engineering Systems: A Case Study of Subsea Blowout Preventers

Engineering systems such as energy production facilities, aviation systems, maritime vessels, etc. continue to grow in size and complexity. This growth has made the identification, quantification and mitigation of risks associated with the failure of such systems so complicated. To solve this problem, several advanced techniques such as Fault Tree Analysis (FTA), Failure Mode and Effects Analysis (FMEA), Reliability-Block Diagram (RBD), Reliability-Centered Maintenance (RCM), Monte-Carlo Simulation (MCS), Markov Analysis (MA) and Bayesian Networks (BN) have been developed in the literature. In order to improve the strengths and eliminate the drawbacks of classical techniques, some hybrid models have been recently developed. In this paper, an integrated FTA and FMEA model is proposed for risk analysis of safety-critical systems. Minimal cut sets derived from the fault trees are weighted based on Birnbaum’s measure of importance and then the weights are used to revise Risk Priority Numbers (RPNs) obtained from the use of traditional FMEA techniques. The proposed model is applied to a Blowout Preventer (BOP) system operating under erratic and extreme conditions in a subsea oil and gas field. Though those failures caused by kill valves and hydraulic lines remain among the top risks in the BOP system, significant differences are revealed in risk rankings when the results from the hybrid approach are compared with those obtained from the classical risk analysis methods

Applying systems thinking and aligning it to systems engineering

This is a paper on thinking about thinking. Systems engineering is an emerging discipline in the area of defining and solving problems in the manner of (Wymore, 1993). The emerging paradigm for problem solving is “systems thinking”. Both systems engineering and systems thinking have recognized the need to view a system from more than one perspective. This paper proposes a set of perspectives for applying systems thinking in systems engineering and then defines a systems thinking perspective set of views for a system, the use of which will provide one way of aligning systems thinking to systems engineering. The paper then provides an example of applying the set of perspectives to the Royal Air Force Battle of Britain Air Defence System and shows that not only does the set of perspectives provide a way to model the system; it also picked up two potentially fatal flaws in the system. The paper then concludes with some observations on the state of systems engineering from a number of the perspectives

Improving maintenance strategies from experience feedback

A huge amount of rough data is available in companies on past maintenance activities as a result of the implementation of CMMS (Computerized Maintenance Management System). In that context, we focus on an experience feedback system dedicated to maintenance, allowing the capitalization of past interventions by means of a formal knowledge representation language, and the extraction from these interventions of new knowledge for future reuse

Productivity improvement of transmission electron microscopes - A case study

This paper aims to improve the performance of Transmission Electron Microscopes (TEM) used in asbestos detection processes in a business context. Failure Modes and Effects Analysis (FMEA) were studied, identifying the critical failure modes, proposing risk reduction measures and changing maintenance practices based on the Reliability Centered Maintenance strategy. In the elaboration of the FMEA it was evident the lack of data and poor information quality regarding the reliability and maintenance of TEM. These circumstances led to the implementation of training projects to standardize operations and to the development of a software application for data collection and reports generation with relevant performance indicators (Costs, Mean Down Time, Overall Equipment Effectiveness, …) to support operators tasks and decision-making. The approach followed and the tools developed allowed monitoring TEM productivity and maintenance performance. As a result, more informed decisions can be made that will lead to improved performance of TEM.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020

Towards reliability centred maintenance of wind turbines

Reliability centred maintenance applied to a fleet of wind turbines is presented in this paper. The key components and failure modes are identified via analysis of maintenance records. Corrective actions which an operator can take to mitigate such failures are discussed, together with implementation issues. By developing a robust set of RCM tools, wind farm operators can better quantify and minimise operational expenditure of wind farm fleets

Achieved availability importance measure for enhancing reliability-centered maintenance decisions

An effective defense strategy requires aircraft, among other weapons systems, to be available and ready for use when circumstances deem necessary. This article offers a set of importance measures to identify the critical components in a system from their influence on system-achieved availability, a common Department of Defense availability calculation that is a ratio of mean time between maintenance and total system time, including mean maintenance time. With these measures, more effective maintenance plans, including inspection and supply inventory, can focus on those components that more significantly impact achieved availability. A decision-making formulation results from these component importance measures, and an example based on a US Air Force system illustrates the modeling contributions.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Joint maintenance-inventory optimisation of parallel production systems

We model a joint inspection and spare parts inventory policy for maintaining machines in a parallel system, where simultaneous downtime seriously impacts upon production performance and has a significant financial consequence. This dependency between system components means that analysis of realistic maintenance models is intractable. Therefore we use simulation and a numerical optimisation tool to study the cost-optimality of several policies. Inspection maintenance is modelled using the delay-time concept. Critical spare parts replenishment is considered using several variants of a periodic review policy. In particular, our results indicate that the cost-optimal policy is characterised by equal frequencies of inspection and replenishment, and delivery of spare parts that coincides with maintenance intervention. In general, our model provides a framework for studying the interaction of spare parts ordering with maintenance scheduling. The sensitivity analysis that we present offers insights for the effective management of such parallel systems, not only in a paper-making plant, which motivates our modelling development, but also in other manufacturing contexts