Two Minute Tips  

Alignment Check vs. Alignment

Stan Riddle | Technical Trainer, Acoem USA

Alignment Check vs. Alignment

One question that arises regularly in training is about doing alignment checks. Is it okay to just check the alignment? Of course it is. As a matter of fact, many industries have dedicated crews to specifically do alignment checks. The major difference is no equipment is moved, just measured. We lockout, remove guards, install the laser, measure and record the data.

There a few reasons for alignment checks.

  • To verify and document the alignment.
  • To help troubleshoot and diagnose other issues, root cause analysis, or elimination of possibility.
  • If abnormal vibration readings point toward misalignment.

A “hot” alignment check is to verify the thermal growth targets (offsets) used for the “cold” alignment. There are related safety and time issues related to performing hot alignment checks which need to be addressed. You need to quickly lockout and measure the machine position before cooling begins. For instance, a reciprocating compressor manufacturer recommends getting hot alignment readings within 30 minutes of equipment shutdown. Our tools can help with that.

Even when we are going to perform an alignment on a piece of equipment, it is a good practice to record a pre-alignment measurement to document or maybe explain any possible issues later. Data is good. Once misalignment is discovered or verified, it should be corrected: if not immediately, then scheduled very soon after to eliminate the detrimental effects on the machine.

Be sure to follow the COMPLETE procedure of precision shaft alignment from the beginning. I recommend against quick shim adjustments or moves. If I am doing the job, I will remove and discard the shims and begin cleaning, etc.

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5 years ago

When carry out alignment must I always include thermal growth,

About the Author

Stan Riddle Technical Trainer, Acoem USA

Stan Riddle joined Acoem USA 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.