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Report: Ultrasound Inspections on Press Washers

SDT was tasked with measuring the press washers at a major paper processing plant in Europe.  

​First Press Wash dBuV
(RMS)​
dBuV
(Crest Value)​
Second Press WashdBuV
(RMS)​
dBuV
(Crest Value)​
Opposite Side Hydraulic Motor bearing 1​ -2.4​ 23​Bearing 1​-7​16.8​
bearing 2​4​31.3​Bearing 2​-6.8​18.5​
Engine Side Hydraulic Motorbearing 3​18.1​42.6​Bearing 3​17.7​43.1​
bearing 4​18.9​42.6​Bearing 4​3.6​31.2​

Ultrasound measurements were taken on 2 press washers, the first rotated at 6 rpm and the second rotated at 7 rpm. 

The first press washer had a recorded value if -6.8dBuV, while the second press washer's recorded value was 4 dBuV.  The difference between the two press washers is 10.8 dBuV, which show signs of early bearing degradation in the second press washer.  It is important to keep a close eye on this bearing and plan for its inevitable replacement.

The time wav forms of the two wash presses are shown below.

​First Press Washer - Measurement -6.8dBuV - Y axis rescaled

Second Press Washer - Measurement 4.dBuV

The difference in signals can be viewed on the time wave spectrum. On the 7 rpm press washer you can see a solid blue area which is the ultrasonic signature of the rolling and the blue lines are the impacts of the hydraulic motor.

The spectrum for the 6 revs/min press represents a bearing that is degrading.

First Press Washer - Y axis Original Scaling

Second Press Washer - Bearing Degradation

This events showed anomalies on the rolling bearings of the two press washers. The washer that rotated at 6 revs/min had a measurement of 10.8 dBuV higher than the other washer indicating degredation. It is important to monitor this bearing closely.

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