Ultrasound Inspection…
Monitoring lube levels in motors and other
cool things you can do with Ultrasound.
Presented by
Paul Klimuc
SDT Ultrasound Solutions
The World Of Ultrasonic Sound
Frequency band of sound
• Infrasound - Audible sound - Ultrasound
Infrasound
Audible sound
20 Hz
Ultrasound
20000 Hz/20 KHz
sound
Definition
• Audible sound (things we can hear)
– 20Hz → 20,000Hz (definition)
– 2,000Hz → 5,000Hz (optimal)
– Below 17,000Hz (reality)
• Ultrasound (things we can’t hear)
– 20,000Hz and above (definition)
Characteristics
• Ultrasound
– High frequency
– Short wavelength
– Lower amplitude
– Directional
– Quickly attenuated
• Sound
– Low frequency
– Long wavelength
– Powerful amplitude
– Multi directional
– Transports well
Why is Ultrasound
Inspection Effective?
• Ultrasound is generated by many things
– Plant machinery (rotating and non-rotating)
– Leaks (pressure and vacuum)
– Electrical faults
– More later…
Steam Traps
MCC Panels
Bearings
Couplings
Valve Leaks
Lubrication
Two Ways to Detect
• Ultrasound moves through any medium
– Gas, Liquid, Solid… Vacuum
• Two modes of detection
Airborne Detection
Structure Borne Detection
Sources of Natural Ultrasonic Noises
• Turbulence
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Leaks in Pressurized Systems
Leaks in Vacuum Systems
Leaks in Hydraulic Systems
Leaks in Steam Systems
• Friction and Impacts
– Wear from Mechanical Parts
• Couplings, gears, bearings
• Electrical Arcing
– Faults in electrical systems
• Arcing, Tracking, Corona Discharge, RTV Interference
How Does it Work?
• Convert ultrasound
to sound
• Maintain
characteristics of
original signal
• Measure for trending
• Capture for analysis
General Applications
• Let’s put it to work
Leak Detection
Pump Cavitation
Bearing Monitoring
Compressor Valves
Lubrication
Heat Exchangers
Electrical Inspection
Hydraulic Systems
Steam Systems
Tightness Control
Leak Detection
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Turbulent flow at leak site
Produces ultrasound with peaks at 40kHz
Directional… easy to pinpoint
Oblivious to plant noise
Is it a trendable defect?
Is it CBM?
Method
• Leak detection
procedure
– Right/Left/Up/Down
– Leak sound increases
sharply
– Adjust sensitivity and
headset volume
– Use focusing tip and
shielding techniques
– Ricochet
Electrical Applications
• Use ultrasound to find electrical faults
– Arcing
– Tracking
– Corona
– Special areas
• Flow
• Loose part monitoring
Electrical Applications
• The list of applications is huge
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Transformers
Switchgear
Relays
Bushings
Transmission lines
Street poles
Junction boxes/circuit breakers
Buss bars
Capacitors
Insulators
High Voltage
• Corona, Tracking and Arcing
– Corona and tracking do not generate heat
– Corona produces a constant burbling sound
– The ability to capture scalable data allows
comparison
– Enviormental issues
Measurement Cycle
• Find it, Fix it, Check it
BEFORE CLEANING
AFTER CLEANING
Electrical Systems
• Two methods of detection
– Contact or airborne
Choose the right sensors
Flexible for ergonomics
Magnetic for consistency
Parabolic for safety
Mechanical Condition
Monitoring
• Rotating and non-rotating equipment
– Bearings
– Gearboxes
– Pumps
– Motors
– Compressors
– Recips
Rotating Equipment
• Nasa Tech Brief Marshall Spaceflight Center
• SDT Recommendation
Valve Body Inspection
• Checking valve for flow
– Upstream and downstream
– Works for any gas or liquid
Steam Trap Inspection
• Steam traps keep your steam system healthy
• Steam traps remove
– Air, Condensate, CO2
• Steam traps fail either stuck open or stuck shut
• Combining temperature measurement with
ultrasound is the industry standard best practice for
steam trap inspection
• It is not difficult to do
You Decide
1
2
3
4
Making the Inspection
Quantitative
• New generation of
ultrasound systems
can record scalable,
comparable time
signals
• Now instead of just
listening we can
compare:
Temperature Measurement
Thermal Inspection
• Upstream and downstream temperature are taken and
compared
T1
T
2
• Can be affected by back pressure
Heat exchangers
• System leakage
– Tube cracks
– Tube sheet
– Shell
– Inlet/Outlet ports
– Steam traps and
steam system
components
Heat exchangers
• Opportunities for ultrasound inspectors
– External tightness inspection
• Joints, fittings, valves, valve stems, inlets, and
connectors
– Shell tightness inspection
• Seal of tube sheet
• Inlet/outlet tightness
– Tube bundle inspection
• Online and offline inspections
Heat exchangers
Ultrasonic detector
Flexible sensor
Extended distance sensor
Parabolic dish (optional for longer distances where
the laser sight is advantageous)
• Magnetic or other contact sensor
• Bisonic transmitter
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Why Ultrasound?
• Why is Ultrasound an effective technology for
condition based lubrication?
Lubrication Fundamentals
Rubbing between
machine parts causes
wear, temperature
increase, and energy
waste
More… Enough… Too Much!
• How do we know when to stop greasing?
1)
2)
3)
4)
Inner Race
Outer Race
Rolling Element
Cage
Acoustic Lubrication
Regardless of how well a
bearing is lubricated, friction
produces an ultrasonic signal
that can be detected and
trended
Acoustic Lubrication
A well lubricated bearing produces an ultrasonic
signal with lower intensity than a poorly
lubricated bearing
Lubrication
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Before Grease
After Grease
55 dBuV
47 dBuV
Time Based
Condition Based
When to Grease
How Much Grease
Listen Only
Digital Metering
Half Shots
• Why do ultrasonic greasing procedures
recommend using ½ shots of grease over full
shots?
Acoustic Lubrication
Intensidad vrs
vrs Tiempo
Intensity
Time
34
32
30
Intensidad d
Trending the ultrasonic
intensity over time, it
is possible to predict
when new lubricant is
needed, and how
much is the optimum
amount.
28
Data in dBµV
26
24
Línea base histórica
22
Historical base line
20
0
2
4
6
Semanas
Weeks
8
10
12
Grease Tubes Extensions
• What challenges do grease tube extensions
pose for ultrasonic lubrication?
– Grease Tube
– Zirk Fitting
Lubrication
• A picture is worth a thousand words
• What is the value of this picture?
Acoustic Lubrication
Acoustic lubrication require
us to build a base line. When
intensity increases 8dBµV
over the base line, small
amounts of grease is applied
until intensity returns to
historical level
Acoustic Lubrication Audit
Any point in the plant can be
audited for lubrication
performance
Manual or automatic
application devices work
under the same principles
Picture courtesy Moventas
Acoustic Lubrication Audit
Centralized Grease Systems
Check before and after
injection cycles to record
difference in signal intensity
Change means the injector is
working well
Picture courtesy Farval
Monitoring auto lube injectors in
a cement mill with SDT 170MD
Lube Tech Kit
Acoustic Lubrication Audit
Automatic Grease Lubricators
After just a few minutes of
installation take a reading and
for baseline. Every week recheck this value. A max 3
dBµV change is permissible
Picture courtesy Perma Lubrication System Australia
Acoustic Lubrication Audit
Automatic Spray Systems
Air pressure is critical for
system performance.
Use you’re the leak detection
capacity of your ultrasound
detector to check air leaks
®
Picture courtesy Farval Lubrication Systems, Inc
Listen-Only Instruments
• How do I get a baseline from listen-only
acoustic re-greasing tools?
Ultrasonic Data
• What kinds of useful data can an ultrasonic
data collector provide?
Data Collection Points
• Does is matter where the acoustic sensor is
placed?
Multiple Lube Techs
• More than one person greases the same
bearing. How can we be sure we all hear the
same thing?
Slow Speed Bearings Need
• Can Ultrasound be used to inspect slow speed
bearings?
Singapore Flyer
• Ferris Wheel Feng Shui
A
• Spindle bearing
measurements taken one
month after rotational
direction changed (Feng
Shui)
• 37 minutes for one
rotation .0004 RPM
Rotating Machinery
• Slow Speed Condition Monitoring
– Difficult with vibration
• 37 minutes for one rotation .0004 RPM
• Ultrasound does not need 1 minute
Rotating Machinery
• Special Applications – Hoist Bearing
– Doesn’t operate long enough for vibe
– 14 RPM but for 10 or 20 seconds only
– SKF 24160CC
– BPFI expected at 2.88Hz/173CPM
Rotating Machinery
• Inner Race Defect Discovered
– Spalling across the length of the raceway
Hoist Bearing
• The point
– NOT that U/S is better than vibe
– Ultrasound can measure this difficult vibration
measurement in 20-30 seconds
– Structural vibration is taken out of the equation
Thank You
• 1-800-667-5325
• sdthearmore.com
• [email protected]