Categories: Shaft Alignment,Machinery Maintenance

Critical Machines? It Depends on Who You Ask

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By on July 20, 2017

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!

About the Author

Stan Riddle joined VibrAlign in 2008. He has over 35 years experience in aligning industrial machinery. Stan received his AAS Degree in Machinist Technology from Surry Community College in Dobson, NC, and also holds a diploma in Industrial Systems Technology from Forsyth Technical Community College in Winston-Salem, NC, where he was also an instructor in the program.

Stan began his maintenance career working as a machinist and millwright for companies such as Weyerhaeuser, R.J. Reynolds, and Tyco Electronics. He also has over 25 years experience in Predictive Technologies, such as vibration analysis, thermography, oil analysis, and ultrasonic inspection. He is a certified Level III Vibration Analyst with the Vibration Institute, and is a Past Chairman and Board Member of the Piedmont Chapter.

Stan and his wife live in Yadkinville, NC.

One response to “Critical Machines? It Depends on Who You Ask”

  1. Jack Metcalf says:

    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