Equifactor® Troubleshooting and FMEA
For those of you that have met me, you know that I am a huge fan of proactive improvement processes. Why wait until something bad happens to fix your issues? Wouldn’t it be nice if we could fix problems before we have an incident that actually hurts someone, or damages our equipment? I’ve spoken numerous times about using TapRooT® proactively for HSEQ problems, but I wanted to give you a tool to help you with your proactive equipment troubleshooting.
Design and process engineers are usually familiar with Failure Modes and Effects Analysis, or FMEA. This is a generic tool that can be used to look at a piece of equipment or a process, identify what can go wrong, and determine more stringent controls should be put in place to prevent that failure. There are actually quite a few ways to do this, but most FMEA’s are all based on a fairly standard format. For this discussion, I’m going to focus on equipment failures. Generally, the system walks you through several distinct steps:
- Identify the piece of equipment you wish to analyze.
- Look at all realistic potential failure modes that can occur with that equipment.
- Assign a Severity, Occurrence, and Detectability score to each failure
- Multiply these scores together to calculate a Risk Priority Number (RPN).
- Determine the controls that are currently in place to prevent this issue.
- Decide if additional controls are required, based on the RPN.
Now, looking at these steps, it occurs to me that many of these steps are somewhat subjective. For example on a scale of 1-10, what is the Severity of the failure? Most companies have put a matrix in place to help quantify these numbers and make it easier to come up with consistent results. This guidance is really important if you want to have any kind of meaningful, systematic way of determining that RPN. While not perfect, these matrices do a pretty good job of keeping everyone focused and getting consistent answers.
However, the one step that is still VERY subjective is step #2. Somehow, you need to come up with a list of all the potential failure modes that your piece of equipment can experience. This is the very basis of the entire analysis, and it is probably the most difficult. Imagine telling your maintenance manager or design engineer, “Tell me all the ways this compressor can fail.” While I’m sure your team is pretty sharp, this is a daunting task. Ideally, they will need to list every possible failure mode to ensure we don’t miss anything. Imagine how many “unknown unknowns” are floating around in our FMEA’s!
Wouldn’t it be nice if there were some compendium of possible failures that we could use to initially populate our FMEA list? This is where I would recommend pulling up your Equifactor® tables. Take a look at (for example) the Centrifugal Compressor troubleshooting tables. Just in this category alone, we have nearly 50 possible failure modes, spread across 7 symptoms. Imagine if you could start your FMEA with all of these items. You’d be well on your way to conducting a detailed FMEA on your centrifugal compressors, with the ability to add a few more failure modes that may be unique to your situation.
We normally think about Equifactor® as a reactive troubleshooting tool. While it excels in that mode, try using the Equifactor® tables more proactively. Use those tables as the baseline for your FMEA, and limit the number of unknown issues that may be lurking in your equipment.