Critical Machines? It Depends on Who You Ask

I recently taught alignment training at a gas compression site.  These were sharp technicians, and they keep these large gas compressors in excellent shape.  We went out to check alignment between the engine and compressor.  It was great just as I expected, because compressing gas is their only product.

So I asked if they had anything else they would like to check alignment on.  Their answer, “Well, we do have an lube oil pump underneath.  I guess we could check it.”

The result – not so good!  Gross misalignment.  High vibration.  A coupling insert that looked like a large dog’s chew toy!

The difference – their perspective.  A facility’s critical machines are usually considered those that are important for production.  But the machines that service those machines are also critical.

In their case, if the lube oil pump fails, for something as simple as a sheared coupling insert, they are down until it can be replaced.  Not to mention that proper alignment of the shafts would reduce coupling wear.

Every maintenance shop should create a criticality list, and give it some thought.  In my history in reliability, I prioritized machines like this.


  1. Someone die or be injured?
  2. Production stop, and people be sent home?
  3. Repair/replacement take a long time?
  4. Repair/replacement be expensive?
  5. Cause problems for other machinery/processes?

We’d love to hear how you prioritize your machines!

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1 Comment

  1. Jack Metcalf on July 26, 2017 at 7:39 pm

    Safety, quality, cost, and delivery…in that order with cost and delivery interchangeable subject to change based on circumstances.

    Also…based on likelihood and consequences in the following category

    Production critical
    Critical – Infrastructure
    Moderate Criticality
    Low Criticality
    Run to Fail

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