Planning Of Maintenance Activities Research Articles

Management of residual life cycle costs for sustainability in middle of life phase

The aim of this work is to propose a decision support system (DSS) to manage product life cycle in the middle of life phase in order to obtain data which may impact on the whole value chain. In particular, a new maintenance approach based on the integration of information gathered from different actors is taken under consideration and the evaluation of residual life cycle costs (LCCs) is used to define and plan maintenance actions. The system enables to create new value by transforming information into knowledge available for all phases of the life cycle improving product and service quality, efficiency and sustainability. The integrated DSS here described goes in the direction of predictive maintenance for machine tools and trucks to reduce the number of unexpected stops and minimise LCCs of the product avoiding component breakdowns.

Levee Performance Assessment Methods Integrated in a GIS to Support Planning Maintenance Actions

In recent years, there have been many failures of flood levees (river embankments) in France following river floods. The levees are mostly old structures for which few records are available. The matter is further complicated by the size of the levee infrastructure—more than 7,500km in total length. The goal of this paper is to provide managers with methods and tools for assessing the performance of levees and to help them plan inspections, maintenance, and repair work. To do so, we developed a geographic information system (GIS) with the intention of incorporating it with the models for assessing levee performance. The first stage in this research is to model the failure mechanisms and identify performance indicators for each mechanism. The second stage is to assess levee performance with respect to each mechanism by aggregating the corresponding indicators. This paper describes the methods used for modeling levee failure and assessing levee performance. It also discusses the operational tools incorporated in the GIS.

Modeling and optimizing a joint inventory control and preventive maintenance strategy for a randomly failing production unit: Analytical and simulation approaches

This paper presents a joint optimal inventory control and preventive maintenance strategy for a randomly failing production unit which supplies an assembly line operating according to a just-in-time configuration. The production unit is submitted to a maintenance action as soon as it reaches a certain age T or at failure; whichever occurs first. In order to palliate perturbations caused by breakdowns and by planned maintenance actions both with random durations, a buffer stock is built up to ensure the supply of the assembly line at a constant rate. A mathematical model is developed to evaluate the average cost per time unit of the proposed strategy. Due to the complexity of the mathematical model and to some approximation assumptions, a second approach based on simulation and experimental design is developed. It allows us to simulate the proposed policy and to generate a second order response surface for easy computation of the optimal values of the decision variables which are the age T at which preventive maintenance must be performed, and the buffer stock level h.

Management of Utah Highway Culverts

More than 47,000 culverts have been installed under the highways of Utah. The Utah Department of Transportation (DOT) maintains these culverts but has no comprehensive system for assessing condition and planning maintenance activities. Utah DOT initiated a study to determine the condition of its culverts by field surveys. The objective was to develop a system of qualitative and quantitative performance measures to assess both the long- and short-term behavior of highway culverts and to support the Utah DOT effort to modify and populate a computerized data-base designed to store culvert inspection data that can be used for statewide culvert asset management. Culvert management practices currently used by Utah DOT and other agencies are described. A total of 272 culvert inspections conducted during this project showed the inventory to be aging but not generally in need of immediate maintenance. The Utah DOT database, developed to track culvert condition, is effective but could be improved. Improvements woul...

Management of Utah Highway Culverts

More than 47,000 culverts have been installed under the highways of Utah. The Utah Department of Transportation (DOT) maintains these culverts but has no comprehensive system for assessing condition and planning maintenance activities. Utah DOT initiated a study to determine the condition of its culverts by field surveys. The objective was to develop a system of qualitative and quantitative performance measures to assess both the long- and short-term behavior of highway culverts and to support the Utah DOT effort to modify and populate a computerized database designed to store culvert inspection data that can be used for statewide culvert asset management. Culvert management practices currently used by Utah DOT and other agencies are described. A total of 272 culvert inspections conducted during this project showed the inventory to be aging but not generally in need of immediate maintenance. The Utah DOT database, developed to track culvert condition, is effective but could be improved. Improvements would streamline both culvert inspections and priority ranking of culvert repairs. The FHWA system for rating culvert maintenance action was adopted, with a new proposed table for rating thermoplastic pipe. Culvert ratings were adjusted with an importance modifier that focused inspection and maintenance activity on critical culverts with higher consequence of failure. Critical culverts should be placed on a regular inspection schedule, whereas other culverts can be inspected during periodic roadway repaving or rehabilitation. Culvert inspection results will be added to the database to provide more insight eventually into culvert service life than is now possible.

Analysis of a production/inventory system with randomly failing production unit submitted to regular preventive maintenance

In this paper we consider a repairable production unit subject to random failures, which supplies input to a subsequent assembly line operating according to a just-in-time configuration. Preventive maintenance actions are regularly performed on the production unit at instants T,2 T,3 T,… The corrective and preventive maintenance actions have random durations. In order to palliate perturbations caused by breakdowns and by planned maintenance actions, a buffer stock is built up to ensure the continuous supply of the assembly line at a constant rate β. To build up this buffer stock, the production unit produces at a rate α+ β. The proposed strategy consists in building up, at the beginning of each preventive maintenance cycle, a buffer stock whose size ` S' covers at least the average consumption during the repair periods following breakdowns within the period of length T. At the instant T when the production unit has to be stopped to undertake the planned preventive maintenance actions, a certain level of buffer stock must still be available in order to avoid stoppage of the subsequent assembly line. A mathematical model has been developed for this strategy. It takes into account the probability distributions associated to lifetime, repair time, preventive maintenance duration, as well as the renewal process associated to the operation–repair cycles of the production unit. The optimum values of the decision variables ` S' and ` T' are obtained by trading off the maintenance cost, the inventory holding cost, and the shortage cost such as their sum is minimum.

Probabilistic method for planning of maintenance activities of substation components

This paper suggests a probabilistic method for the calculation of operation cost throughout a planning period and availability evaluation of substation components, in connection with planned maintenance activities. This method is conceived to provide lower operation cost, consisting of failure repair cost and maintenance cost, and higher availability of substation components. The method identifies minor and major failures. It is assumed that each component has two independent, competing failure modes: wear-out failure mode, modelled by a two-parameter Weibull distribution, and a chance failure mode, characterized by an exponential distribution. The application of the method suggested is demonstrated for a 145 kV air-blast circuit-breaker. By applying the method, influence of condition monitoring systems application on operation cost is evaluated. Also, because of comparison, expected operation cost in case of time-based maintenance performing is calculated.

Maintaining Equity in Surface Irrigation Network Affected by Silt Deposition

Planning maintenance activities in surface irrigation systems is essential for optimal use of the annual credits. In many countries, the equity of the water distribution is largely affected by sediment deposition but budgets do not allow the performance of all the necessary maintenance works and priorities must be defined by the irrigation agencies. A methodology based on numerical modeling is developed and illustrated on a secondary network in South Pakistan. Improvements on the current desilting procedure are proposed, but it is shown as well that the system could be designed differently in order to preserve the equity longer.

Can we make maintenance decisions on risk analysis results?

For several branches of industry, an increasingly competitive environment has raised important questions concerning maintenance in plant systems. For example, the 1996 deregulation in Sweden’s electricity sector has resulted in increased competition among the country’s power producers. To survive the competition, suppliers have to reduce maintenance costs, i.e. handle maintenance more efficiently. Risk analysis is one tool decision makers can use to help them prioritise as they plan maintenance actions. There are a number of different approaches to risk analysis. As the results of an analysis must form a reliable basis for decision making, it is important to consider whether the quality of the results will vary significantly with the risk analysis approach chosen. This paper presents a comparative study based on three independent risk analyses performed on a specific hydro‐power plant. The comparison and evaluation of the analyses reveal major differences in performance and results, along with various factors that affect the quality of the analyses. The study establishes the importance of a well‐planned requirement specification and the need to analyse and interpret risk analysis results, before making maintenance decisions.

Validation of the Eurofighter Typhoon structural health and usage monitoringsystem

The structural health monitoring (SHM) system being developed forthe Eurofighter Typhoon is resident on each aircraft and is integrated withinexisting aircraft and ground-based systems. The system will enable theoperators to accurately monitor fatigue life consumption, usage informationand significant structural events, thereby safeguarding the structuralintegrity of the aircraft. The information obtained can be used to planmaintenance actions effectively, and to manage the fleet fatigue lifeproactively (Hunt S R and Hebden I G, Eurofighter 2000 structural healthand usage monitoring: an integrated approach 2nd Joint NASA/FAA/DoD Conf.on Aging Aircraft (Williamsburg, VA, August 31-September 3 1998)).This paper gives an overview of the philosophy and techniques involved in thevalidation of the Eurofighter SHM system, together with some preliminaryresults.

TPM: PLANNED AND AUTONOMOUS MAINTENANCE: BRIDGING THE GAP BETWEEN PRACTICE AND RESEARCH

Competitive pressures and changing production management paradigms have, in recent years, increased the importance of reliable and consistent production equipment. Initially, the Japanese, and now others, have espoused the virtues of a management philosophy known as total productive maintenance (TPM). We are interested in the maintenance‐investment decisions for TPM. This paper (1) describes the basic elements of TPM programs, (2) categorizes the relevant research literature using a practitioner's framework for autonomous and planned maintenance activities, and (3) identifies the current gaps between practitioner needs and academic research in the area of TPM and offers suggestions to close the gaps.

Using a hydro-dynamic flow model to plan maintenance activities and improve irrigation water distribution: application to the Fordwah distributary in Punjab, Pakistan

In secondary canals in Pakistan‘s Punjab, the waterdistribution depends on the hydraulic characteristicsof channels, cross-structures and tertiary outlets.Maintenance of channels and structures plays a crucialrole in upholding equitable distribution of water tothe tertiary units. In the past, maintenance has beenundertaken by irrigation managers based on experienceand observations. In the present study a hydro-dynamicmodel (SIC – Simulation of Irrigation Canals) is usedto assess a priori the impact of maintenance measureson water distribution. Maintenance measures can thusbe selected that remove existing bottlenecks in thewater distribution in the most cost-effective way. The methodology is applied to a secondary canal insouth-east Punjab. The simulation results show thatthe main cause of present inequity in waterdistribution are deviations in dimensions of tertiaryoutlets, which, if restored, would make the mosteffective contribution to improve the waterdistribution. Maintenance of the channel is necessaryif its capacity diminishes.

Examination of issues related to the development and implementation of real-time operational safety monitoring tools in the nuclear power industry

In recent years, risk and reliability techniques have been increasingly used to optimize deterministic requirements and to improve the operational safety of nuclear power stations. This paper discusses the historical development and current status of implementation of real-time operational safety monitoring tools in the nuclear power industry worldwide. A safety monitor is defined as a PC-based risk management tool, based on a plant specific PSA, which can be used to manage plant safety during the day-to-day operation of a nuclear power plant by planning maintenance activities and providing advisory information to plant operational staff in order to avoid high risk plant configurations. As this technique has only been applied in a few plants worldwide, the technology is still evolving and there are several technical and implementation-related issues which still need to be resolved. This paper attempts to summarize all such issues and describe how they have been addressed in several different applications of this technology around the world.