Ultrasonic Applications For Condition Monitoring
A simple, effective multi-purpose tool
What are Ultrasonic signals: Frequency Greater Than 20,000 Hz
Bearing defect (4,000 Hz periodic)
Under-lubricated bearing (30,000 Hz random)
‘A’ abo above ve middle middle ‘C’ ‘C’ (440 Hz)
Subsonic
Steam trap (40,000 Hz)
Ultrasonic Range Ultrasonic Ultrasonic
Sonic
20,000 Hz
Sound Analysis Converts Inaudible Signals into Audible Ones
Bearing defect (4,000 Hz periodic)
Under-lubricated bearing (30,000 Hz random)
‘A’ above middle ‘C’ (440 Hz)
Subsonic
Steam trap (40,000 Hz)
Ultrasonic Range Ultrasonic Ultrasonic
Sonic
20,000 Hz
Where Can You Apply Ultrasonics? Steam Traps Valves and Piping
Compressed Air
Greas Lubrica Contr
Control Valves
Motor/ Pump
Boiler Tubes
Bearing and
Typical Sound Analysis Tools
1) Airborne Probe 3) Magnet Mount
Scanning for Hot Spots
Scan area quickly
Listen for obvious leaks
Findings based on relative sound levels Note: typical applies to Airborne probe only Airborne Probe
Calibrated Measurement
Calibrated measurement Sound level indicates severity of leak or fault Trendable readings
Magnet Mo Probe
Contact Probe
Temperature Readings
Optional with some ultrasonic units Correlate Sound and Temperature readings for improved diagnostics: – Bearings and other mechanical defects – Valves – Steam traps
Trend Temperature and Sound levels
Why Use Sound Analysis?
Primary Health Monitoring technique for: – Valves, steam traps, grease lubrication – Simple to use and understand – Very high return on investment
Excellent ‘second opinion’ for: – Machinery Health Monitoring – Electrical equipment scanning
Correlate Sound Analysis With Other Technologies Application Bearing Faults
Thermography
Vibration
X
X
Lubrication
X
Valves
X
Steamtraps
X
Partial Discharge
X
Load Tap Changers
X
Oil
Application: Bearing Defects
Quick, easy test
Establish baseline
“Clicking” sound indicates bearing damage Trend sound level to track developing faults Bearing fault (4 KHz)
Note: Trending only possible if using a calibrated ultrasonic device)
Application: Lubrication Monitoring
75% of bearing failure is lubrication related*
Damage occurs from both : – Under-lubrication (Premature bearing failure, contamination, etc.)
and – Over-lubrication (Ball skidding, grease overflow, seal damage, etc.)
Application: Lubrication Monitoring
“Waterfall” sound indicative of under lubrication Use sonic analysis to check suitability of lubrication Sound amplitude of 20 dB or greater is significant (if using a calibrated ultrasonic device)
Under lubricated bearing (30 KHz)
Baseline or Optimum 0 dB
Alert
10 dB
Critical Alarm
Re-grease
20 dB
30 dB
Application: Re - -greasing g reasing Re-greasing
Monitor sound level while applying grease
Greas
Sound level drops when grease rea bearing (30 KHz)
Application: Detecting Valve Failure
Failure Modes: – Partially open or leaking – Sounds like rushing water
Failure can result in: – Contamination – Loss of product – Damage to valves and downstream equipment
Defective Valve (40 KHz)
Application: Monitoring Control Valves
Contact measurement to monitor flow rate Airborne measurement to monitor stem packing leaks 70 60
Defective Valve
50 B d e 40 g a r 30 e v A 20
Monitoring boiler spray valves
(average level)
10 0 1
2
3
4
Control Valve #
5
6
Application: Steam Traps
Sound created from turbulent fluid flow and valve/float impact Failed trap leads to significant losses in steam systems A blowing trap (1/4” orifice, 125 lb. steam) results in steam loss of $6,300 per year
Ou
Inlet
Under lubricated bearing (40 KHz)
Application: Air Leaks
Primary loss of energy in plants today. Generates airborne turbulence in the 40 kHz frequency range. A 1/8” air leak in a 100 psi system results in a yearly loss of $2,100 .005” orifice, 5 psi leak
Air Leak (40 KHz)
Application: Gas Leaks
Natural gas leak
Safety hazard
83 dB amplitude, approx. $28,000 per year
Natural Gas Leak (40 KHz)
Electrical Corona and Discharge
Corona caused by: – Insulation breakdown – Improper connections
Generates high frequency waves
“Buzzing” or “Crackling” sound
Confirm with IR Thermography
e g a t l o V h g i H
e g a t l o V h g i H
e g a t l o V h g i H
Corona from Faulty Connection (>40 KHz)
Application: Switchyard Monitoring
Sources of corona: – Arcing in transmission lines – Partial discharge in transformers
Electrical Corona (>40 KHz)
Application: Load Tap Changers
Responsible for nearly half of all failures in Substations and Switchyards Scan for Nitrogen Leaks
. Corona on Load Tap Changer (>40 KHz)
Confirm Fault with IR Thermography
Inspection of load tap changers requires multiple technologies – Scan with Ultrasonics – Confirm with IR and test for dissolved gas IR scan of Load Tap Changer
Application Driven Measurement
Embedded Knowledge
Application specific:
Application: Steam Trap
Step 1: Select Application
– Pre-configured tests – What type of measurements to make
Steam Trap Inlet
– Where to make them
Steam Trap Outlet
Step 2: Measure inlet, sound and temperature
Step 3: Measure outlet, sound and temperature
Route - -Based Based Sound Monitoring Route-Based
“Electronic clipchart” to record measurements
Store and trend data
Calculate savings
Benefits of Sound Analysis
Primary Health Monitoring technique for: – Valves, steam traps, grease lubrication – Simple to use and understand – Very high return on investment
Excellent ‘second opinion’ for: – Machinery Health Monitoring – Electrical equipment scanning
