An expert-based approach to production performance analysis of oil and gas facilities considering time-independent Arctic operating conditions

-The availability and throughput of offshore oil and gas plants operating in the Arctic are adversely influenced by the harsh environmental conditions. One of the major challenges in quantifying such effects is lack of adequate life data. The data collected in normal-climate regions cannot effectively reflect the negative effects of harsh Arctic operating conditions on the reliability, availability, and maintainability (RAM) performance of the facilities. Expert opinions, however, can modify such data. In an analogy with proportional hazard models, this paper develops an expert-based availability model to analyse the performance of the plants operating in the Arctic, while accounting for the uncertainties associated with expert judgements. The presented model takes into account waiting downtimes and those related to extended active repair times, as well as the impacts of operating conditions on components’ reliability. The model is illustrated by analysing the availability and throughput of the power generation unit of an offshore platform operating in the Western Barents Sea

Resilience of a transportation network: Importance of vulnerable nodes

Transportation Infrastructure is one of key critical infrastructures which are crucial for a wellfunctioning modern society. This study proposes a resilience-oriented framework for analyzing and ultimately mitigating risk and improving resilience for land transportation networks with a focus on vulnerable nodes. The framework uses network theory and considers the concept of independent pathways, network topology, redundancies in the network, reliability of roads, importance of hub nodes and vulnerable nodes. A network score is developed based on the aforementioned criterion of the network which will be used for comparing different failure scenarios under extreme weather events hazard type. The focus of this paper is the importance of vulnerable nodes, and it tries to highlight that throughout the paper. A numerical example has been utilized to illustrate the use of this framework

Road Transportation Challenges in the Arctic

Despite all efforts to mitigate global warming, its rate and magnitude are still rising where transportation is considered to be an important contributor. In the Arctic regions however, unstable weather conditions, strong seasonal variations, and long harsh winters result in additional challenges to transportation in different ways such as those related to environment, human health, safety, and economy. This study deals with challenges related to road transportation in the Arctic regions. With this aim in mind, firstly the effects of weather-related factors, including precipitation, temperature and wind on road transportation are presented. Then, to investigate challenges, a causal analysis utilizing the approach of fault tree analysis (FTA) is conducted in which the related impacts are classified into three categories: environment, health/safety and economy. Accordingly, the critical causes are discussed and mitigating measures are addressed. It is suggested that the holistic review presented in the paper will be useful in identifying the most sustainable ways to decrease negative effects from road transportation in the Arctic.publishedVersio

Observed and unobserved heterogeneity in failure data analysis

In reality, failure data are often collected under diffract operational conditions (covariates), leading to heterogeneity among the data. Heterogeneity can be classified as observed and unobserved heterogeneity. Un-observed heterogeneity is the effect of unknown, unrecorded, or missing covariates. In most reliability studies, the effect of unobserved covariates is neglected. This may lead to inaccurate reliability modeling, and consequently, wrong operation and maintenance decisions. There is a lack of a systematic approach to model the unobserved covariate in reliability analysis. This paper aims to present a framework for reliability analysis in the presence of unobserved and observed covariates. Here, the unobserved covariates will be analyzed using frailty models. A case study will illustrate the application of the framework

Improvement of system availability using reliability and maintainability analysis

System reliability, maintainability and availability have assumed great significance in recent years due to a competitive environment and overall operating and production costs. Performance of equipment depends on reliability and availability of the equipment used, operating environment, maintenance efficiency, operation process and technical expertise of operators, etc. When the reliability and availability of system are low, efforts are needed to improve them by reducing the failure rate or increasing the repair rate for each component or subsystem. The aim of this research study is to analyse operating reliability and availability for a system with periodically inspected and maintained components subjected to some maintenance strategy and find some importance measures that show the criticality of the components or subsystems. This analysis has helped to identify the critical and sensitive subsystems or components of the system that need more attention for improvement. In this research study we suggest a methodology for improving the availability of a repairable system. In the methodology, the concept of importance measures must be used to prioritize the components or subsystems for availability improvement processes. Availability importance measures show the criticality of each component based on different points of view such as availability, repair rate, and failure rate of each component. The reliability and availability of repairable systems can be improved by applying appropriate maintenance strategies; therefore a model is developed for selecting the most suitable maintenance strategies on based of analysis of reliability and maintainability characteristic of the operating system. The empirical data of two crushing plants at the Jajarm bauxite mine of Iran are used as a case study for reliability and availability analysis. The study shows that the reliability and maintainability analysis is very useful for deciding maintenance intervals, planning and organizing maintenance. The results show that availability and reliability importance measures can be used as a guideline for managing the efforts for reliability and availability improvement of a system.Godkänd; 2005; 20061211 (haneit

Production assurance : concept, implementation and improvement

The dynamic business environment is characterized by short-term and long- term uncertainties in the business processes, combined with a short-term focus on meeting customers' and share-holders' requirements. Therefore, making correct decisions in a dynamic business environ-ment is a major challenge for production plant engineers and managers all over the world. Such a situation necessitates the successful application of tools and engineering solutions to minimize the total business risk and reduce uncertainties through assurance of world-class production plant performance, which can ensure that the right level of production can be ob- tained in order to meet customer demands. To meet these challenges, many approaches such as reliability analysis techniques have proved an effective solution during both design and operation of a production plant, and have been implemented by production engineers and managers. The main focus of reliability is on the process of ensuring a reliable product and/or system as well as reducing system uncer- tainty. However, these are not discussing the issues of production availability which are criti-cal for meeting customer requirements and market demands and may increase risk and uncer-tainties in decision-making. However, production assurance (PA) plays a significant role in supporting the decision-making process by production managers and engineers deal with the above mentioned challenges. The main focus of existing research on the area of PA is on the models and methodologies for data analysis and prediction of future system performance. Fur-thermore, existing models and methodologies supporting PA analysis and management have been primarily developed for the planning phases, specifically for the petroleum sector, but have not yet been sufficiently developed for general use. In many cases, the engineers and managers may face many problems in the process of implementing and executing the PA con-cept. The purpose of this research is to study, analyze and evaluate the application and implementa-tion of Production Assurance Programs (PAP) in production plants, and find some importance measures that show the criticality of the components or subsystems. To fulfill the stated pur- pose, an explorative literature study combined with a case study of a process plant has been performed. Various examples and data from the oil and gas industry are also used to support the thesis. In this study, firstly the concept of production assurance is discussed and Overall Production Assurance Effectiveness (OPaE) is suggested as a developed metrics for measuring the per-formance of a production plant which is considered internal effectiveness of production plant as well as external effectiveness as it considered customer requirement and demand. This thesis present and discusses a methodology that facilitates implementation of PAPs in a production plant. Such a methodology would support production engineers and managers in reducing or eliminating uncertainties and risks in their day to day operation and maintenance decisions. In this research study, some availability importance measures are defined. Thereafter, it a methodology is suggested to improve the production assurance effectiveness through im-provement of reliability, maintainability, and availability of production plant. In the method-ology, the concept of importance measures is used to prioritize the components or subsystems. This analysis of importance measures has helped to identify the critical and sensitive subsys-tems or components that need more attention for improvement. The research study shows that in order to measure the performance of a production plant, the PA provides a more comprehensive measure of a production plant's real performance com-pared to system availability performance as the production assurance provides information about the production plant's delivery capacity, production rate and ability to deliver according to design or customer demands. The study also indicates that availability importance measures can serve as a guideline for developing a strategy for improvement of production assurance.Godkänd; 2007; 20071108 (ysko

Reliability and maintainability analysis of crushing plants in Jajarm bauxite mine of Iran

Reliability is an important consideration in the planning, design and operation of engineering systems. As the size and complexity of mining equipment continue to increase, the implications of equipment failure become ever more critical. An unplanned failure can result in significantly higher repair costs than a planned maintenance or repair. Of even more importance is the loss of production associated with larger equipment failures. One method to mitigate the impact of failures is to improve the reliability of the equipment. Reliability is a performance indicator of overall equipment condition. A first step in reliability improvement is collection and analysis of the appropriate data.This paper presents a case study describing reliability analysis of crushing plants in Jajarm bauxite mine. In this study crushing plants are divided into seven subsystems. Reliability analysis has been done for each subsystem by using failures data. The parameters of some idealized probability distributions, such as Weibull, Exponential, Lognormal distributions, have been estimated by using ReliaSoft's Weibull++ 6 software. An investigation has also been made to determine which of these distributions provide the best fit for characterizing the failure pattern of the two crushing plants and their subsystems. Some aspects of system failure behavior are analyzed briefly for ongoing machine improvement. Reliability of both crushing plants and its subsystems has been estimated at different mission times with their best fit distribution. Analysis of the total downtime, breakdown frequency, reliability, and maintainability characteristics of different subsystems shows that the reliability of crushing plant 1 and crushing plant 2 after 10 hour reduce to about 64% and 35% respectively. The study shows that reliability and maintainability analysis is very useful for deciding maintenance intervals. It is also useful for planning and organizing maintenance.Godkänd; 2005; 20070315 (ysko

Availability alocation through importance measures

Purpose - To define availability importance measures in order to calculate the criticality of each component or subsystem from availability point of view and also to demonstrate the application of such importance measures for achieving optimal resource allocation to arrive at the best possible availability. Design/methodology/approach - In this study the availability importance measures of a component are defined as a partial derivative of the system availability with respect to the component availability, failure rate, and repair rate. Analyses of these measures for a crushing plant are performed and the results are presented. Furthermore, a methodology aimed at improving the availability of a system using the concept of importance measures is identified and demonstrated by use of a numerical example.Findings - The availability importance measure of a component/subsystem is an index which shows how far an individual component contributes to the overall system availability. The research study indicates that the availability importance measures could be applied in developing a strategy for availability improvement. The subsystem/component with the largest value of importance measure has the greatest effect on the system availability. Research limitations/implications -The result of availability improvement strategy is demonstrated using only a hypothetical example.Practical implications - Using of availability importance measures will help managers and engineers to identify weaknesses and indicate modifications which will improve the system availability.Originality/value - This paper presents the concept of availability importance measure for a component/subsystem. It also introduces some availability importance measures based on failure rate, mean time between failures (MTBF), and repair rate/mean time to repair (MTTR) of a component /subsystem. The concept of importance measures are used to prioritize the components or subsystems for the availability improvement process.Validerad; 2007; 20071008 (javbar

Production assurance performance

The concept of Production Assurance increasingly plays an important role to support the decision-making process for the managers and engineers dealing with challenges to meet the varying demand of customers as well as production control. The Production Assurance concept incorporates several other concepts such as availability, reliability, maintainability, supportability, capacity and so on. The aim of this paper is to discuss such concept and its applicability for manufacturing production processes. The other closely related topics to this concept such as throughput capacity, demand capacity and on-stream capacity are also presented.Godkänd; 2007; 20071009 (javbar