Ultrasound for coupling inspection?  What?  Yes, ultrasound technology has many pillars for asset management.  The technology is amazing and can be used in a variety of different not so obvious applications.

Fig 1 – Worn out grid coupling


Types of couplings you can inspect with Ultrasound and how

There are many different types of couplings used in the industry for rotating equipment. These can range from short-flex, spacer type, to even Cardan shaft. Some require lubrication and others do not. One proven method to assess coupling conditions is to use an ultrasound analyzer with dynamic capabilities and a flexible airborne sensor and collect data for approximately 5 seconds per coupling. From there, a user can analyze the data using the Ultranalysis2 software to view the dynamic data (time waveform and spectrum).

Some machines may be running misaligned; therefore, the couplings may be loose.  If we had a thermography camera, we could take an image of the heat signature which might show the periodic friction (squeezing of the coupling as it goes through each revolution).  However, more often than not this will not be possible as all equipment must have coupling guards present during operation. Therefore, a flexible ultrasound sensor will be able to pick up that friction being generated by the coupling.

If you are currently not using an ultrasound system to check your couplings, it’s time to start!

Lack of lubrication and worn out grid coupling example:

Time Waveform for Fig 1
Impacts at running speed with harmonics for Fig 1


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by Alex Nino CRL