Preventive Maintenance Program Research Articles

Avaliação dos serviços de radiodiagnóstico convencional de dois hospitais da rede pública estadual de Rio Branco, Acre

OBJETIVO: O objetivo principal deste trabalho foi avaliar os serviços de radiodiagnóstico médico de dois hospitais públicos que fazem uso de equipamentos de raios X na cidade de Rio Branco, Acre. MATERIAIS E MÉTODOS: Foram realizadas entrevistas, medições e observações diretas, usando como referência a legislação brasileira em vigor, com especial ênfase à Portaria SVS/MS nº 453 de 1998, que estabelece as diretrizes básicas de proteção radiológica em radiodiagnóstico médico e odontológico. RESULTADOS: Os dados obtidos indicaram a ocorrência de elevado número de itens em desacordo com a legislação consultada em ambos os serviços radiológicos dos hospitais pesquisados, especialmente equipamentos funcionando de forma parcial e o descumprimento de alguns protocolos de segurança. CONCLUSÃO: As infrações técnicas ou operacionais foram, basicamente, em decorrência do desconhecimento sobre a legislação, a ausência de programa de manutenção preventiva dos equipamentos e da falta de investimentos em treinamentos e/ou cursos de atualização profissional. A melhoria dos serviços de radiodiagnóstico médico das instituições investigadas requer, portanto, uma série de modificações, que vão de simples às mais complexas.

Scheduling United States Coast Guard helicopter deployment and maintenance at Clearwater Air Station, Florida

To mitigate the effects of a corrosive operating environment, the Coast Guard has planned an extensive preventative maintenance program for its Sikorsky HH60J helicopters based on helicopter flight time. We construct a mixed integer linear program that schedules the weeks during which each helicopter undergoes maintenance, as well as the weeks during which a helicopter conducts operations either at Clearwater Air Station, Florida or at one of two deployment sites. The schedules must consider different maintenance types, maintenance capacity and various operational requirements, e.g., the number of helicopters simultaneously patrolling a deployment site. Using data from the operations at Clearwater, we generate optimal schedules on a Unix workstation with modest computing power in less than 3 min. Planners have been using our mixed integer linear program since January, 2005 for scheduling guidance.

La calidad de los servicios de radiología en cinco países latinoamericanos

To determine the correlation between certain quality indicators for imaging services and the accurate interpretation of radiological exams for four frequent complaints: breast lumps, gastrointestinal discomfort, back pain, and symptoms of tuberculosis. Twenty-six radiology services in Argentina, Bolivia, Colombia, Cuba, and Mexico were assessed. The mammography and conventional radiographic/fluoroscopic equipment used in selected services were evaluated utilizing common protocols, data sheets, testing instruments, phantoms, and calibrated dosimetry systems. The studies were performed in medium-complexity facilities. Informed consent was obtained from all patients studied, and the confidentiality of results was guaranteed. The following parameters were documented: type of facility (public vs. private); population covered; patient workload; radiological and image-processing equipment and supplies; education and training of professional and technical staff; quality assurance and preventive maintenance programs, and adherence to radiation safety standards. The performance of x-ray units, image receptors and processors; darkroom and image viewing conditions; patient doses and image quality, were determined using standardized parameters in all cases. Independent panels of radiologists, recognized as experts by the local radiological society, assessed the quality of the clinical images obtained and performed a radiological interpretation for each patient using the same films and clinical history available to the institution's imaging physicians. The agreement between the panel of expert's reports and those of local radiologists was taken as an indicator of the radiological diagnostic accuracy. Analyses were carried out of 366 mammograms, 343 radiological procedures for gastrointestinal complaints, 319 X-rays of the spinal column, and 157 chest radiographs. The agreement between the radiological interpretation of the panel of experts and of the local physician ranged from 70% to 100%, except in the case of spinal column films in Cuba (57.8%) and of mammograms in Mexico (33.3%), which the panel of experts found to be among those having the poorest quality. There was a significant positive correlation between the accuracy of the radiological interpretation and the quality of the radiological images. Image quality showed a positive correlation with the technicians' level of education and training. Studies performed in services that had automatic film processors and that complied with the indicators established for screen-film contact yielded better images and a higher proportion of studies with concordant results. More than 50% of the viewboxes did not satisfy the quality criteria for luminance and homogeneity. A good quality image is critical to achieving an accurate diagnosis. Emphasis should be placed on the continuing education of radiology technicians and on the acquisition and maintenance of adequate equipment and accessories, especially viewboxes, intensifying screens, and automatic film processors, given the impact they have on image quality.

Preventive Maintenance: A Look at the Big Picture

Preventive Maintenance: A Look at the Big Picture

Failure reduction in manufacturing systems through the risk management approach and the development of a reactive maintenance model

Maintenance and failure costs of production machines increase the overall operating cost of a manufacturing organisation and will reduce the profit margin. Hence, management is interested in minimising the resources allotted to these non-productive activities. This work includes a case study, wherein the failures of a plastic injection moulding machine are examined. The reactive maintenance model (RMM) is developed in which risk management technique (RMT) is used to analyse the causes of the failures. Corrective measures are taken to avoid failures and a suitable preventive maintenance (PM) programme is followed to keep the machines in working condition. The loss before and after implementing the RMM is compared using Taguchi's loss function. In this paper, the analysis, development of maintenance model, implementation and results of implementation of the model are presented.

Optimal replacement and overhaul decisions with imperfect maintenance and warranty contracts

In this article, we develop a model to help a maintenance decision making situation of a given equipment. We propose a novel model to determine optimal life-cycle duration and intervals between overhauls by minimizing global maintenance costs. We consider a situation where the costumer, which owns the equipment, may negotiate a better warranty contract by offering an improved preventive maintenance program for the equipment. The equipment receives three kind of actions: repairs, overhauls, and replacement. An overhaul represents an imperfect maintenance action, that is, the failure rate is improved but not a point that the equipment is as good as new. Corrective maintenance actions are minimal, in the sense that the failure rate after each repair is the same as before the failure. The proposed strategy surpasses others seen in the literature since it considers at the same time the warranty negotiation situation and the optimal life-cycle duration under imperfect preventive actions. We also propose a simplified approach that facilitates the task of implementing the method in standard solvers.

Software Maintenance: A Must for Energy Management Programs

There are many reasons for implementing a preventive maintenance (PM) program: to lower power consumption, extend the life of equipment, and to maintain or improve tenants' thermal comfort. However, all the efforts to service and improve the performance of the HVAC system may be promoted or hindered by the building automation system (BAS). While the PM program may provide a certain level of assurance that the HVAC system is working at optimal performance, the BAS is the one dictating the load level as well as the duration of operation, thus impacting the entire cost of operation of the facility. For that reason, I suggest including software maintenance as an integrated part of the PM program. This article will discuss the various aspects of software maintenance and its impact on the power consumption of facilities and their operating cost. I will also present a list of critical BAS items to be included in the software maintenance program.

Detection of equipment aging and determination of the efficiency of a corrective measure

Abstract When too many failures occur on a given piece of equipment, the dependability engineer needs to decide whether these failures are attributable to poor initial design or if they are due to a phenomenon of aging. If aging is confirmed, the problem is then to determine the moment at which the process began and what corrective measure (generally, a modification in the design or in the preventive maintenance program) is the best suited to delay the occurrence of the failure. This measure will thus make it possible to extend the lifetime of the equipment. The method is based on the simple hypothesis of a model of step aging and on Bayesian techniques. The principal benefit of this method is the determination of the time at which aging begins (and the related uncertainties), the evolution in the failure rate of the component in its initial state and once modified, and the probability of success of the corrective measure. The IBTV software was developed to implement this methodology.

Development of Preventive Maintenance Decision Trees Based on Cost-Effectiveness Analysis: An Ontario Case Study

Various transportation agencies have begun to consider implementing preventive maintenance (PM) strategies as part of their regular pavement management programs. To determine whether a PM strategy is more cost-effective than a conventional maintenance strategy, various technical and economic analyses were carried out. Currently, most agencies have limited information on the cost-effectiveness (CE) and long-term performance of PM strategies, so it is difficult to determine when and where these treatments should be used. The use of PM treatments based on a CE calculation and analysis is examined, and a decision tree (including treatments and strategies) is developed for each functional pavement class of the Ontario road network. Pavement data from the Ministry of Transportation of Ontario are used to perform a CE calculation for each suggested PM treatment and strategy. On the basis of a comparison and analysis of CE calculation results, guidance is provided on the right treatment, time, and strategy cost level for each functional pavement PM program within the Ontario environment. The results are summarized in the form of a decision tree.

Issues in Integrating Pavement Management and Preventive Maintenance

For years, pavement-management systems (PMSs) have been used in highway agencies to improve the planning efforts associated with pavement-preservation activities, to provide the information needed to support the pavement-preservation decision process, and to compare the long-term impacts of alternative preservation strategies. As such, pavement management is an integral part of an agency's assetmanagement efforts and an important tool for cost-effectively managing the large investment in its transportation infrastructure. PMSs have been used by several agencies to demonstrate the cost-effectiveness of pavement-preservation programs that include the use of preventivemaintenance treatments. By comparing the long-term effects on pavement condition associated with an agency's current practices with a strategy that includes preventive maintenance, the benefits of a preventive-maintenance program can be demonstrated. However, agencies have had limited success expanding the use of their PMSs to support a preventive-maintenance program because most PMSs have not fully integrated preventive-maintenance treatments into the analysis. The importance of integrating preventive-maintenance treatments into a PMS to support a preventive-maintenance program is addressed, and the most common gaps between maintenance efforts and pavement management are discussed. In addition, current approaches used to integrate these programs and the advantages and disadvantages associated with each approach are presented. Finally, recommendations for improving the integration of preventive-maintenance treatments into an agency's PMS are provided.

Assessment of Hillside Coal Waste Embankment Failures Using Qualitative Analysis

Qualitative assessment provides a sound process for defining specific aspects of risk associated with potentially unstable slopes. Field observations, experience, field data, and back analysis from eleven past slope failures have been used to identify common and significant factors associated with the potential failure of coal waste embankments located in southwest Virginia. A database containing information about site location, characteristics, and conditions has been developed using Office of Surface Mining program narratives and engineering reports. It was observed that the pattern of failure was almost identical at each site and driven by the same phenomena. Degradation of the spoil material, accelerated by poor drainage conditions and periods of increased precipitation, lead to a decrease in interparticle strength and failure along a “lubricated,” or highly weathered, surface. The development of a rating system for the identification of potentially unstable coal waste embankments, based on the factors and characteristics reviewed here, will eventually lead to the implementation of a preventive maintenance program. Preventative maintenance will most likely need to include monitoring of the area, installation of a proper drainage system, and revegetation.

Applying Pavement Preservation Concepts to Low-Volume Roads

As the challenges associated with managing a low-volume road network increase, agencies have realized the benefits associated with the use of pavement management tools for the road network. One of the benefits of the use of these tools is the ability to illustrate quickly and effectively the impacts of various pavement preservation strategies (such as worst-first repair) on overall network conditions. As a result, agencies are in a better position to communicate the needs of the road network to individuals responsible for the allocation of funds. In some cases, agencies have successfully lobbied for additional funds to support their road management efforts. The benefit of pavement management tools in supporting the preservation of the low-volume road network is illustrated by their use in evaluating the long-term impact of various funding strategies, the cost-effectiveness of pavement preventive maintenance programs, and various cost analyses that can be used to enhance road system management. Information from a variety of transportation agencies is used for this illustration. For instance, a summary is presented of the use of pavement management information to compare a worst-first repair strategy with a strategy that includes pavement preservation techniques. Examples are provided of the types of presentations that can be given to top management to illustrate these effects. In addition, the cost-effectiveness of pavement preservation programs is illustrated by showing the reduction in life-cycle costs and the overall benefits provided to the agency through the implementation of preventive maintenance programs.

Pavement Management Perspective on Integrating Preventive Maintenance into a Pavement Management System

Many transportation agencies use pavement preservation programs to manage their pavement assets cost-effectively. One important aspect of pavement preservation is the use of preventive maintenance treatments to improve the functional condition of the network and retard the overall rate of deterioration. Because preventive maintenance treatments are less expensive than resurfacing or reconstruction projects, a preventive maintenance program can provide a cost-effective means of meeting pavement performance goals. Pavement management systems support pavement preservation strategies in important ways. They assist in identifying and prioritizing preventive maintenance needs, justifying funding levels, and evaluating the long-term impacts of various preservation strategies. To date, many agencies have operated preventive maintenance activities in isolation from pavement management programs. However, many potential benefits can be gained from the closer integration of these two activities. A transportation agency that wishes to integrate preventive maintenance and pavement management might be required to make several changes. Specific technical areas in which changes might be needed include condition surveys and condition index calculations, pavement performance models, treatment rules, and program development. In addition, several institutional issues must be addressed to successfully integrate the two programs. Examples from state highway agencies illustrate possible solutions.

Construction Equipment Management Practices of Major Contractors in Saudi Arabia

Construction equipment constitutes a major resource for a contractor. This paper presents the results of a survey performed to unfold the practices followed by contractors in Saudi Arabia in managing their construction equipment. It was possible to find that contractors in Saudi Arabia follow practices similar to those followed by top contractors in the USA. They were found to identify needs, evaluate alternative proposals quantitatively and qualitatively, and make decisions to acquire equipment. During its useful life, contractors maintain accurate records and subject equipment to preventive and scheduled maintenance programs. The contractors also use several economic analysis techniques to determine the economic life, pricing, rate of returns, accounting, etc. of equipment. This information and other parameters are used in equipment replacement evaluation. Finally, the contractors standardize equipment on equipment brand or on the family engine.

Review of condition assessment of power transformers in service

As transformers age, their internal condition degrades, which increases the risk of failure. To prevent these failures and to maintain transformers in good operating condition is a very important issue for utilities. Traditionally, routine preventative maintenance programs combined with regular testing were used. The change to condition-based maintenance has resulted in the reduction, or even elimination, of routine time-based maintenance. Instead of doing maintenance at a regular interval, maintenance is only carried out if the condition of the equipment requires it. Hence, there is an increasing need for better nonintrusive diagnostic and monitoring tools to assess the internal condition of the transformers. If there is a problem, the transformer can then be repaired or replaced before it fails. An extensive review is given of diagnostic and monitoring tests, and equipment available that assess the condition of power transformers and provide an early warning of potential failure.

Aseismic evaluation for aging degradation of nuclear power plant components

The commercial operation of light water reactor plants in Japan already has a history of nearly 30 years. Since the beginning of the 1990s, studies have been conducted on aging degradation of nuclear power plants in Japan and abroad and, earlier in 1999, the domestic program of plant life management (PLM) was settled on. The program is based on the results of the PLM Study, which started in 1997. The purpose of the study was to develop the preventive maintenance program with an evaluation of aging degradation for maintaining the functions of plant component equipment. Taking account of the need for proper management of aging degradation, meanwhile, the technical evaluation of aseismic capability of aged plants is also considered to be important. Based on this concept, we evaluated the impact of assumed aging degradation on the aseismic capability of the plant facilities and structures covered by the PLM Study. In the aseismic evaluation, aging degradation modes selected in the PLM Study were divided into two categories—the one is including some degradation modes which impact on the aseismic capability of the facilities and structures should be taken into account, the other is including those whose impact might be ignored. Then the aging degradation modes composing the former one were quantitatively evaluated primarily based on the Technical Guidelines for Aseismic Design of Nuclear Power Plants (JEAG-4601) ( NUREG/CR-6241, 1987). The result of the evaluation indicated that no aging degradation mode to be reflected in the maintenance program was extracted from the viewpoint of securing the aseismic capability of the plant components. However, establishment of rational evaluation methods for aging degradation, e.g. aseismic capability evaluation of thinned piping systems, was made a future technical subject.

Developing an effective inspection and preventive maintenance program.

Developing an effective inspection and preventive maintenance program.

Probabilistic safety assessment and reliability based maintenance policies: application to the emergency diesel generators of a nuclear power plant

This study is performed on the four 2.5 MWe emergency diesel generator (EDG) sets of Hydro-Quebec Gentilly-2 Nuclear Power Station. EDGs are safety related systems for the case of the loss of off-site power. This study establishes the basis of an enhanced preventative maintenance and periodic testing program with the objective of improving the long-term reliability and availability of the EDG. It is also the first step to a PSA program based on the real historical data of the system.

Cost-Effective Preventive Maintenance: Case Studies

With most of the highway systems in place, emphasis has shifted from design and construction to preservation and expansion. Unfortunately, the engineering skills, knowledge, and experience required to preserve the systems are significantly different than those required to originally design and build the systems. The experience gained in the initial phase, although important, is not in itself sufficient to preserve the systems. Pavement preservation is defined as the sum of all activities undertaken to provide and maintain serviceable roadways. This includes corrective maintenance and preventive maintenance, as well as minor rehabilitation projects. A cost-effective pavement preservation program requires a systematic and comprehensive engineering management of, and a solution to, pavement network problems. Preventive maintenance (PM) is defined by AASHTO as the “planned strategy of cost-effective treatments to an existing roadway system and its appurtenances that preserves the system, retards future deterioration, and maintains or improves the functional condition of the system (without increasing the structural capacity).” Hence, PM actions must be taken on pavements in relatively good condition. The development and implementation of a cost-effective PM program faces several obstacles: political debate, budget constraints, lack of education, and the existing practice of “worst pavements are first.” Some state highway agencies have overcome these obstacles, and they are harvesting the success of their PM programs. The state of the practice of three agencies—those of Arizona, Montana, and Pennsylvania—is presented and discussed.

Optimizing Pavement Preservation: An Urgent Demand for Every Highway Agency

Preventive maintenance is a tool that has the potential to both improve quality and reduce expenditures for a pavement network. Preventive maintenance is based on the concept that periodic, inexpensive treatments, such as seals, are more economical than infrequent, high-cost procedures, such as reconstruction. The paper presents a step-by-step procedure for selecting the appropriate preventive maintenance treatment for asphalt pavement and evaluating the optimal timing for that treatment under different pavement, traffic, and climatic conditions. The information presented in this paper is a useful tool for highway engineers and superintendents at various governmental levels throughout the world to develop a preventive maintenance program that would maximize the cost-effectiveness of maintenance treatments. Typical examples of pavement distresses are presented showing appropriate treatments that can be used. A model is presented to provide the basis for the analysis of the cost-effectiveness of a pavement preventive maintenance program.