The component importance measure is an index of how much or how little an individual component contributes to the overall system reliability. It is useful to obtain the reliability importance measure or value of each component in the system prior to investing resources toward improving specific components. This is done to determine where to focus resources in order to achieve the most benefit from the improvement effort. The reliability importance measure of a component can be determined based on the failure characteristics of the component and its corresponding position in the system.
Once the reliability of a system has been determined, engineers are often faced with the task of identifying the least reliable components in the system in order to improve the design. For example, in a series system, the least reliable component has the biggest effect on the system reliability. If the reliability of the system needs to be improved, then efforts should first be concentrated on improving the reliability of the component that has the largest effect on reliability. (The cost of improving reliability is not considered in this article. However, this can be done using more complex algorithms available in ReliaSoft’s BlockSim software.) In simple systems such as a series system, it is easy to identify the weak components. However, this becomes more difficult in more complex systems. Therefore, a mathematical approach is needed to provide the means of identifying and quantifying the importance of each component in the system.
Calculating Reliability Importance
The reliability importance, I, of component i in a system of n components is given by:
Equation 1
where,
Rs(t) is the system reliability, and
Ri(t) is the component reliability.
The value of the reliability importance given by this equation depends both on the reliability of a component and its corresponding position in the system.
Static Reliability Importance
Consider a series system of three components, with reliabilities of 0.7, 0.8, and 0.9 at a given time, t. Using Eqn. (1), the reliability importance in terms of a value for each component can be obtained. The reliability importance values for these components can be calculated using ReliaSoft’s BlockSim. By using the BlockSim plot option and selecting a Static Reliability Importance plot, the graph in Figure 1 can be obtained.
Figure 1: Static Reliability Importance Plot
The values shown for each component were obtained using Eqn. (1). The reliability equation for this series system is given by:
Taking the partial derivative of Eqn. (2) with respect to R1 yields:
Thus the reliability importance of Component 1 is 0.72. The reliability importance values for Components 2 and 3 are obtained in a similar manner.
Time-Dependent Reliability Importance
The reliability importance of a component can be calculated at a specific point in time or over a range of time. In the previous example, time-dependency was not considered. However, as demonstrated in Eqn. (1), the reliability importance of a component is a function of time. Another way to look at it is to generate a plot of Reliability Importance vs. Time. With this plot, the reliability importance of the component as a result of the behavior of its entire failure distribution can be observed rather than the importance relating to just one point on the distribution. For example, Figure 2 illustrates the reliability importance vs. time for a four-component system. In this figure, it can be seen that at 400 hours, Component 4 has a higher reliability importance than Component 1 and at 1200 hours this is reversed. Therefore, the measure will vary depending on the time of interest to the analyst.
Figure 2: Reliability Importance vs. Time
Application to a Complex System
Consider the system shown in Figure 3. All components have the same reliability of 90% at a given time. The equation for system reliability obtained from BlockSim is given by Eqn. (3).
Figure 3: System Reliability Block Diagram and Reliability Importance Plot
Using Eqn. (1), the reliability importance was calculated and the results were plotted in Figure 3. Although the components are identical, their reliability importance is different. This is due to their unique positions within the system. When calculating the reliability importance of a component, its failure properties as well as its system properties are considered.
Over the past twenty years, building information modeling (BIM) has been steadily securing itself as an essential tool in the architecture, engineering, and construction fields. Its advanced 3D capabilities are used in just about every design and construction phase. However, with new developments in real-time data collection, the advantages of BIM can extend beyond the completion of a facility.When applied to facility management, BIM opens the door to better asset management, improved safety, and optimized maintenance strategies that ensure that a building performs at its best 100 percent of the time.
Over the past twenty years, building information modeling (BIM) has been steadily securing itself as an essential tool in the architecture, engineering, and construction fields. Its advanced 3D capabilities are used in just about every design and construction phase. However, with new developments in real-time data collection, the advantages of BIM can extend beyond the completion of a facility.When applied to facility management, BIM opens the door to better asset management, improved safety, and optimized maintenance strategies that ensure that a building performs at its best 100 percent of the time.
For the most part, we can describe in fairly exacting detail the functional components of a strong reliability program. Moreover, we are confident that implementing these reliability practices will yield results that benefit virtually every aspect of our business and provide distinct competitive advantage. However, we seldom see these reliability practices and results in an operating plant. This is what I call the Reliability Paradox.
For the most part, we can describe in fairly exacting detail the functional components of a strong reliability program. Moreover, we are confident that implementing these reliability practices will yield results that benefit virtually every aspect of our business and provide distinct competitive advantage. However, we seldom see these reliability practices and results in an operating plant. This is what I call the Reliability Paradox.
Yes, I think that most maintenance organizations are overstaffed, not necessary with their own staff, but they use more total maintenance hours than necessary. Total maintenance hours include your own internal hours, overtime hours, and contractor hours. As an example a newsprint mill or a linerboard mill making 600,000 tons recycled paper per year on two machines is very good at less than 0.3 total maintenance hours per ton while most operations we have been working with are using about 0.5 total maintenance hours per ton.
Yes, I think that most maintenance organizations are overstaffed, not necessary with their own staff, but they use more total maintenance hours than necessary. Total maintenance hours include your own internal hours, overtime hours, and contractor hours. As an example a newsprint mill or a linerboard mill making 600,000 tons recycled paper per year on two machines is very good at less than 0.3 total maintenance hours per ton while most operations we have been working with are using about 0.5 total maintenance hours per ton.
Contrary to what most people think, paint plays a significant part in constructing and maintaining structures. Commercial and industrial painting is a complex process that involves protecting the substrate from environmental factors, enhancing its aesthetic appeal, and ensuring longevity. If you're working on commercial or industrial projects, choosing the right paint is absolutely crucial for achieving the results you want. Two of the most popular paint options are oil and latex, each with its unique properties.
Contrary to what most people think, paint plays a significant part in constructing and maintaining structures. Commercial and industrial painting is a complex process that involves protecting the substrate from environmental factors, enhancing its aesthetic appeal, and ensuring longevity. If you're working on commercial or industrial projects, choosing the right paint is absolutely crucial for achieving the results you want. Two of the most popular paint options are oil and latex, each with its unique properties.
The industrial maintenance sector is experiencing a significant shift with the integration of the Internet of Things (IoT) and the advent of Industry 4.0. These innovations are fundamentally altering the way maintenance teams function, introducing a new era of efficiency, predictive maintenance, and real-time data utilisation. IoT technology is central to this transformation, enabling teams to access and analyse data in real time. This advancement shifts maintenance from a reactive to a proactive and predictive model, significantly reducing downtime and extending equipment life.
The industrial maintenance sector is experiencing a significant shift with the integration of the Internet of Things (IoT) and the advent of Industry 4.0. These innovations are fundamentally altering the way maintenance teams function, introducing a new era of efficiency, predictive maintenance, and real-time data utilisation. IoT technology is central to this transformation, enabling teams to access and analyse data in real time. This advancement shifts maintenance from a reactive to a proactive and predictive model, significantly reducing downtime and extending equipment life.
“Serialized” spare parts are repairable components, usually expensive and complex, where each individual item needs to be tracked and recorded to ensure reliability. Serialized components are often in contact with the process and require refurbishing several times over their life span. The example I’ll use here are covered rolls used on a paper machine.
“Serialized” spare parts are repairable components, usually expensive and complex, where each individual item needs to be tracked and recorded to ensure reliability. Serialized components are often in contact with the process and require refurbishing several times over their life span. The example I’ll use here are covered rolls used on a paper machine.
Lack of investment in maintenance could potentially have costly consequences. Besides safety risks, defects in power stations often result in cost-intensive remediation measures and temporary loss of power production. The ideal maintenance strategy is about applying the right measures at the right times. However, there are no silver bullets for power station maintenance.
Lack of investment in maintenance could potentially have costly consequences. Besides safety risks, defects in power stations often result in cost-intensive remediation measures and temporary loss of power production. The ideal maintenance strategy is about applying the right measures at the right times. However, there are no silver bullets for power station maintenance.
