As I work on calculating MTBF for a range of equipment using CMMS data, I am encountering challenges in determining what constitutes a failure. While sifting through the data, I have come across instances where pumps were intentionally stopped to address issues like seal cooler cleaning and lube oil leaks in order to prevent major malfunctions. Should these instances be considered as failures? I am seeking insights from fellow forum members on how they define failure in similar analyses. Your input is greatly appreciated.
When any undesirable condition leads to the initiation of corrective or emergency maintenance work orders at a production facility, it is classified as a failure. To calculate the Mean Time Between Failures (MTBF), use the formula: MTBF = Time / Number of Emergency or Corrective Work Orders. For instance, track all emergency or corrective work orders for a specific production area or asset group within your plant. Even minor failures should be documented through work orders. If, for example, 45 emergency or corrective work orders were issued in a month (equaling 720 hours), then the MTBF would be 720 / 45 = 16 hours. Analyze this data on a monthly or daily basis to monitor the health of your assets. For a scenario where 3 emergency work orders were issued in a day (24 hours), the MTBF would be 24 / 3 = 8 hours. Utilize these calculations to improve your MTBF tracking. Best regards, Mohammad.
Thank you for your post. Let's discuss the situation from a different perspective. When dealing with emergency work orders that require 24-hour attention, the Mean Time Between Failures (MTBF) can be calculated as 24/3 = 8 hours. Have you encountered actual downtime during these emergency situations, despite having work orders in place? Emergency work orders often help prevent minor issues from becoming major problems, but should they be considered failures of the equipment/system/plant? Evaluating the ratio of emergency work orders to mission time can help determine the Maintenance Intervention ratio, rather than attributing failures to your equipment/system/plant. I hope you see things the same way!
It appears that you have found the answer to your own question. Your post has helped me confirm a particular fact. We recently discovered that an operator was eating food from the production line at a specific spot without surveillance cameras. The act of opening a barrier door at that spot inadvertently deactivated a switch, which in turn caused the fans in the neighboring freezer to shut off. As a result, the temperature of the food product rose significantly. This led to the false accusation that the freezer was causing the production line to stall multiple times a day. Thanks to the data from our computerized maintenance management system (CMMS), we were able to pinpoint the issue and identify the responsible party. It's estimated that the actions of this lead operator, who enjoyed free snacks in the morning, cost the company over $4 million. Without accurate logging of non-critical incidents, this significant loss would have gone unnoticed.
When an item undergoes maintenance or is taken out of service due to a breakdown, a trip, a condition monitoring or inspection recommendation, it is considered to have failed in service. For example, if your oil cooler is removed from service because of poor performance trends, it can cause a halt in operations for both the cooler and the main equipment. This incident serves as a valuable data point for calculating the Mean Time Between Failures (MTBF) of the cooler. The stoppage also impacts the MTBF calculation of the main equipment. However, only scheduled stoppages based on time or age can be excluded from MTBF calculations. In such instances, the item is still functional, and components may be replaced as a preventive measure well before a failure occurs.
Steve, do you believe that it would be considered a failure to rely on online equipment for condition monitoring and greasing bearings? Vee
Great question! In my experience, defining a failure can be tricky, especially with proactive maintenance tasks like the ones you mentioned. I typically consider a failure as an unplanned event that leads to equipment downtime or loss of functionality. So, if the pumps were intentionally stopped but still operated as intended afterward, I wouldn't classify those as failures. Instead, they would fall under maintenance activities aimed at preserving the equipment’s integrity. It might be helpful to establish a clear criterion for what you define as a failure in your context to ensure consistency in your MTBF calculations.
That's a great question! Defining a failure can definitely be tricky, especially when preventive maintenance comes into play. In my experience, I like to differentiate between unplanned downtime (true failures) and planned maintenance activities. If a pump is intentionally stopped for maintenance to avert a more serious problem, I typically wouldn’t categorize that as a failure. Instead, I would focus on unplanned outages that resulted in operational disruptions. However, it might be worthwhile to track both metrics separately to get a fuller picture of reliability and maintenance needs. What do others think?
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Answer: 1. How should instances where equipment is intentionally stopped for maintenance or preventive measures be classified in MTBF calculations? - In cases where equipment is intentionally stopped for maintenance or preventive actions, it is important to consider whether the stoppage is a planned part of the maintenance schedule or an unplanned event. Planned maintenance activities should not typically be classified as failures for MTBF calculations.
Answer: - When defining a failure in equipment maintenance analysis, it is essential to consider the impact of the event on the equipment's function and performance. Events that lead to downtime, loss of production, or compromised operation should generally be classified as failures.
Answer: - The definition of failure in MTBF calculations can vary among organizations and professionals. Some may include only unexpected breakdowns as failures, while others may also consider planned maintenance activities that impact equipment availability. It is important to establish a consistent definition within your analysis context.
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