Journal of Quality Engineering and Management

Abstract In this research, a Multi-Objective model for reliability-centered preventive maintenance planning for a production system with parallel series components is developed. In this model, maintenance costs and cost of failures; including the cost of lost production, due to system shutdown are considered. In this way, this model plans preventive maintenance operations with the aim of increasing the system reliability level, with the lowest total cost. A binary nonlinear program is developed and a numerical example is solved for it and the results are discussed. To solve the proposed model, the Augmented Epsilon Constraint Method (AUGMECON) by GAMS software is used and the results are discussed. The results show the effect of preventive service planning on system failure rate and reliability. The proposed approach can be used to plan maintenance of industrial systems by considering the reliability related costs
 
 
 

Abstract This research provides a solution for modeling the availability of Feed Water System (FWS) of Heat Recovery Steam Generator (HRSG) in MAPNA Boiler and Equipment Engineering and Manufacturing Company with the aim of determining the system equipment suppliers in such a way that the total cost in the construction and operation of the system is minimized. The Feed Water System is one of the most sensitive parts of boilers; because its failure causes the boiler to stop and incurs irreparable costs to the system. The system may be in three capacities: full capacity, half load, and stop, each of which may impose costs on the system. For modeling, possible states are first written for the system and then the system configuration is plotted using the reliability block diagram and P&ID. Then the results of modeling with Markov chain method are placed in a mathematical optimization model. After solving the model, the optimal strategy in selecting equipment suppliers will be determined. 

Abstract The use of Heat Recovery Steam Generators (HRSGs) in combined cycle power plants dramatically increases the efficiency of power generation. One of the most important parts of HRSG is Feed Water System (FWS). This paper describes the process of selecting the optimal configuration for the FWS of Heat Recovery Steam Generator, which has been done in MAPNA Boiler and Equipment Engineering and Manufacturing Company. First, the important equipment of the FWS is identified and is demonstrated by the reliability block diagram. Then the failure rate of each equipment is estimated using the documents of the International Atomic Energy Agency, the OREDA handbook and the IEEE 500 standard, and the system reliability is calculated in the Excel software environment. Finally, the results were analyzed and based on that, the optimal configuration of the FWS is determined. The proposed approach can also be used to design the reliability-based design of other industrial systems. 
 
 

Abstract Redundancy allocation is one of the important approaches to increase reliability used by system designers. In this approach, to improve the reliability of the system, components or subsets (components) are considered in the system, which in case of failure of sensitive components of the system are quickly replaced and intermittently stop the operation of the system.
It is prevented. In this research, the problem of redundancy allocation for a system with one component with defined constraints and considering the cost of lost production is presented. In this article, the goal is to minimize the total cost of the system, which considers two strategies: cold plug-in and inventory. Cold plug-in refers to a situation where the surplus component is not normally under load and the probability of failure before replacing the damaged component is independent of system performance time. The decision variable in this study is the values ​​of the number of redundancy components and the stock of spare components in stock. The difference between the two is that the plug-in component quickly and without delay replaces the defective component in the system, and its presence does not stop during the maintenance of the main component. The mathematical planning model has been developed to achieve the objectives of the problem as a nonlinear complex problem. An example for the system is also given and solved by GAMS optimization software. Finally, the results of solving the model are discussed.