Misalignment in rotating equipment is one of the leading causes of failures throughout the industry. It breaks down machines and often costs your company thousands upon thousands of dollars in repair expenses and unplanned downtime. Imagine if you could combine two technologies you may already be using to prevent some of these failures. Ultrasound testing and precision laser alignment will make your maintenance department more proactive than ever before. For example, we all know couplings can be misaligned, and couplings can be loose. Infrared training tells us that a misaligned coupling generates heat. This heat is generated by the periodic friction caused by the coupling being squeezed with each revolution. Remember, friction we can hear. Therefore, a misaligned coupling will generate a periodic ultrasound signal like the one shown in Figure 1.

Figure 1

If you are already using ultrasound and laser shaft alignment, you are already there.  All you have to do is add the coupling data point to your current ultrasound routes. This simple step combined with some trending will tell you when you need to check and correct the misalignment on the pieces of equipment along the route. Furthermore, a loose coupling will generate an ultrasound signal caused by the fretting of the coupling halves rattling. This fretting will be harsher and less periodic in nature than misalignment (see Figure 2).

Figure 2

Once the imminent failure is being detected, we can address it with a realignment of the machines using an Easy-Laser laser alignment system like the XT770. It is easy to use and it will provide the user with a detailed PDF alignment report for documentation and accountability.

Ultrasound Coupling Inspection with Flexible Sensor

For more information on Ultrasound coupling, refer back to our blog, “Airborne Ultrasound Keeps Flexible Couplings Reliable” as shown above featuring our SDT340 Ultrasound Solution.


This blog was inspired by Uptime Magazine’s article, “There’s Something in the Air”, July 2009, pp. 48-53, written by Thomas J Murphy with SDT Ultrasound Solutions.

Download our 5-Step Shaft Alignment Procedure which provides a simple and effective procedure for shaft alignment of rotating equipment.

As an additional resource, we recommend watching, “Utilizing Ultrasound for Reliable Coupling” a presentation by Robert Dent with SDT Ultrasound Solutions

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, by Carlos Bienes CRL