Condition Monitoring Methodology Research Articles

Development of a fouling monitor for safety-related heat exchangers

Periodic safety reviews (PSRs) are performed to verify and/or improve the safety of operating nuclear power plants. When the PSR of Gori Units 3/4 in South Korea was performed, a few safety-related heat exchangers were pointed out as components in need of an ageing management program. This study shares the motivation with the necessity of the ageing management program. We developed a condition monitoring methodology for identifying one of the ageing mechanisms in the safety-related heat exchangers and named it the fouling monitor. The fouling monitor is composed of (1) the model for determining the test fouling resistance and the projected design fouling resistance at a test condition, and (2) the monitoring and detection of their deviation. The mathematical model for determining the projected design fouling resistance at a test condition needs to be considered carefully because the heat exchanger, and particularly in this study, the letdown heat exchanger, is normally tested under operating conditions that differ considerably from the design conditions. This need was met by developing independent physical and empirical correction methods of which consistency is cross-checked. Either or both correction method(s) convert the design fouling resistance into a projected fouling resistance, which is finally comparable with the test fouling resistance. The monitoring and detection method tracks the deviation of the test fouling resistance and the projected fouling resistance. Considering the stochastic characteristics of fouling phenomena, we adopted the sequential probability ratio test to determine appropriate scheduling for cost- and safety-optimized maintenance of the heat exchanger.

System and methodology for vibration analysis and condition monitoring

A system and methodology for continuous condition monitoring of rotating equipment. Employ adaptive signal processing techniques to determine the RPM of a rotating machine from time-based vibration data. RPM is determined based upon the input of a digitized time-based sample sequence of vibration data acquired directly from a vibration transducer for on-line real-time measurement of the machine RPM. Once RPM is determined, online vibration analysis for a given RPM or set of RPMs may be performed. The present invention extracts characteristic vibration features from vibration data and uses these extracted values to provide condition detection and diagnoses of machine faults.

Condition monitoring of first mode of metal transfer in friction stir welding by image processing techniques

This paper discusses a method for online condition monitoring of the friction stir welding (FSW) process using image processing techniques. Many FSW experiments are carried out at different process parameters and images of the first mode of the weld zone are captured. They are subsequently digitally processed and analysed using MATLAB to study the variations in the quality of weld, subjected to various conditions such as pin failure, and pin depth. This facilitates development of a methodology for online condition monitoring.

Meeting the challenges related to material issues in chemical industries

Reliable performance and profitability are two important requirements for any chemical industry. In order to achieve high level of reliability and excellent performance, several issues related to design, materials selection, fabrication, quality assurance, transport, storage, inputs from condition monitoring, failure analysis etc. have to be adequately addressed and implemented. Technology related to nondestructive testing and monitoring of the plant is also essential for precise identification of defect sites and to take appropriate remedial decision regarding repair, replacement or modification of process conditions. The interdisciplinary holistic approach enhances the life of critical engineering components in chemical plants. Further, understanding the failure modes of the components through the analysis of failed components throws light on the choice of appropriate preventive measures to be taken well in advance, to have a control over the overall health of the plant. The failure analysis also leads to better design modification and condition monitoring methodologies, for the next generation components and plants. At the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, a unique combination of the expertise in design, materials selection, fabrication, NDT development, condition monitoring, life prediction and failure analysis exists to obtain desired results for achieving high levels of reliability and performance assessment of critical engineering components in chemical industries. Case studies related to design, materials selection and fabrication aspects of critical components in nuclear fuel reprocessing plants, NDT development and condition monitoring of various components of nuclear power plants, and important failure investigations on critical engineering components in chemical and allied industries are discussed in this paper. Future directions are identified and planned approaches are briefly described

Monitoring automatic machines

In the context of full automation of manufacturing processes, it is important to develop predictive maintenance methodologies in every industrial field. This paper presents experimental tests carried out on some components of high-performance automatic machines. The aim is to assess and compare the effectiveness and reliability of different condition monitoring methodologies based on vibration analysis. A methodology based on recovery of the acceleration pattern of the final actuator of the mechanism under consideration seems to be particularly promising. It allows the working conditions to be judged, directly comparing the recovered output member acceleration with the functional requirements which, for this kind of mechanism, are mainly relative to the motion law. A lumped parameter model of the same mechanism is presented and its application for diagnostic purposes is shown.