مطالعه و استفاده از تعمیر و نگهداری بر اساس قابلیت اطمینان با توجه به تعمیر و نگهداری رادیکال

Radical Maintenance (RM) takes the root causes of failures as executive objects to make maintenance decisions. A Root Cause Analysis (RCA) is carried out on the function failure of equipment to perform RM and to create a maintenance plan using the combined methods of Failure Mode, Effects and Criticality Analysis (FMECA), and Fault Tree Analysis (FTA). Evaluation criteria and matrixes of criticality are used to evaluate the criticality level of failure modes. Moreover, Minimum Cut Sets (MCS) and importance calculation are applied to analyze the fault tree quantitatively. Based on our research, the concept and the analysis process of Reliability-centered Maintenance (RCM) considering RM are proposed and then applied to an actual engineering project in the petrochemical industry. The results of the application are presented through a maintenance strategy based on the project analysis by establishing the evaluation criteria and matrixes of criticality for petrochemical rotating machines and a fault tree of compressor vibrations. The direct causes of the induction of vibration faults in rotating machinery are classified according to the fault mechanism and frequency domain features in this paper. The research shows that using RM in the traditional RCM can help assign maintenance resources rationally and improve the quality of maintenance strategies.

Reliability-centered Maintenance (RCM) analyzes the functions and failures of a system and identifies the consequences of these failures to implement preventive measures using a standardized logical resolution procedure (Moubray, 1997). Traditional RCM focuses on the function failures of a system. It determines a maintenance plan by considering failure probability statistics and consequences; the analysis does not involve in-depth research to identify the failure mechanism and the real causes of function failures. Radical Maintenance (RM), on the other hand, considers the fundamental factors that cause failures and investigates the elements affecting the reliability and safety of a system and equipment. In this article, Failure Mode, Effects and Criticality Analysis (FMECA), and Fault Tree Analysis (FTA) were used to implement RCA on a system failure to perform RM, which was then combined with RCM analysis to improve the quality of maintenance strategies. The proposed theory and analysis procedure of RCM considering RM were applied to an ethylene plant in China. An ethylene refrigerant compressor was taken as a demonstration model, and its failure modes were studied to conduct CA and establish a fault tree.

Compared with routine maintenance, RM takes failure root causes as the implemental objects. The actual conditions of equipment operation are adjusted through various monitoring and detection techniques to correct and eliminate the basic factors that cause failures, such as materials, equipment, the environment, and management, among others. This is conducted to discover and solve failures effectively and reduce the recurrence of similar failures. In addition, RCA can be carried out smoothly by combining FMECA and FTA for failures, thus strengthening the combination of RM with traditional RCM. The establishment of evaluation criteria and matrixes of criticality for petrochemical rotating machines allows for equitable distribution of service resources. The root causes of failures can then be obtained effectively through the foundation of a fault tree. The maintenance strategies considering RM contain service plans for almost all basic factors that may induce function failure. Of these, some maintenance scenarios may be found in the conventional strategies based on the operator’s experience. However, these maintenance works were often ignored in the ordinal operation, because there was no specific RCA process to make operators clearly understand the relationship between failures and root causes. The factors, which should be improved first to reduce the probability of the failure effectively, can be determined through the comparison of probability importance and criticality importance. In this paper, the direct causes that induce vibration faults in rotating machinery were classified according to the fault mechanism involved. Furthermore, the faults were differentiated based on their characteristics in the frequency domain. With knowledge of the dominant frequency of faults, the possible main causes were approximately determined, and some causes were excluded. The specific project analysis in this paper shows that applying RM in the traditional RCM improves the quality of the maintenance strategy and enhances the practicability and purpose of RCM.