When rotating equipment fails, it is quite common to perform a root cause failure analysis (RCFA).  The RCFA, unfortunately, is not done properly, as it only captures the first level of what failed and what likely caused the failure.    A true RCFA will look at several levels of failures and why an event occurred.  The key question in this case is, “Why did something happen?”.

A bearing failed because there was particulate in the system.  Particulate got into the system because the filter was bypassed.  The filter was bypassed because it plugs too often and maintenance does not have time to replace it.  It plugs too often because the filter is not sized properly for the system.  The bearing ultimately failed not because of particulate, but rather the filter is not right.

A properly done RCFA should be applied for process control and instrumentation.  Process control always starts with a measurement.  The measurement can be a good place to start an RCFA as it can provide valuable insight into what is happening in a process.  Similar to the example above, it should be investigated what caused the failure and trace it back to the true root cause.

A pressure instrument failed because the sensor was damaged.  The sensor was damaged because it was struck by a bolt head from the mixer blade.  The mixer blade bolt broke due to flutter in the process.  Flutter in a mixer is caused by an improperly sized hub.  The instrument failed due to a poor mixer design.

More often that not, an RCFA is not performed for any kind of process equipment.  Time and resources must be dedicated for this activity.  The only way to improve reliability within a process plant is to understand what is happening and develop strategies to improve it.

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