getting started with condition monitoring for only $2000
TRANSCRIPT
GETTING STARTED WITH CONDITION
MONITORING FOR ONLY $2,000? Ray Beebe
(Bitten by the CM bug in 1964!)
CM IS POWERFUL
Can be costly to do properly with depth
Cost can deter smaller companies (or even big
over-thrifty ones!)
BUT, much can be done for low cost
All depends on the mode of degradation…..
CASE 1: DEGRADATION OF “INVISIBLE”
DAMPER
Situation: duct, with hot gas
1000degC
CM – view damper around
bend and assess condition:
Will it last until next repair
opportunity?
Cost of viewing tool: $10?
CASE 2: LINER EROSION
Coal mill casing liners erode in varying
pattern of grooves
Changeout is needed, but wear rate
varies, so routine change may mean
changeout is too early.
Simple CM – straightedge and rule to
get depth of deepest valley.
Plot vs service time
Cost nil
(Note: must carefully spell out in Job
Card how measurement is taken.
Previous method showed liners
apparently “growing”)
CASE 3: FAN EXCESSIVE VIBRATION
Fan handling
hot damp dirty
gas.
High vibration
hot, also
high when cold!
Much
investigation
looking for
complex cause
– and then……
LOOSENESS OF BEARING ASSEMBLY
Vibration
difference on
concrete
shows loose
bolts
CASE 4: FAN UNBALANCE DUE TO DEPOSITION
Moist dust sticks unevenly on fan blades
Unbalance results
Overall vibration goes up!
Manual readings and trending cost little, BUT define and mark
test points……
CASE 4: CONTINUED
Moist dust sticks unevenly on fan blades
Unbalance results
Overall vibration goes up!
Manual readings and trending cost little……
Solution: balancing the fan is expedient, or clean it
Re-design to eliminate cause: not practicable here
Overall vibes are OK if this is the only problem encountered
CASE 5: PUMP NEAR RESONANCE High vibration – so high that outlet valve
wobbled shut!
Stiffening easy to try - and it worked!
(Worth a try. If NBG, then further
investigation needed)
ISO GUIDELINES – EXPERIENCE HELPS
OK
NOT OK
VIBRATION OVERALL
– MANY INSTRUMENTS
AVAILABLE
TRY EBAY! E.G. $300 S/H
Ack: P Todd
VIBRATION OVERALL- THE WEDGY
Make triangle of card, vertical side 2.5mm (i.e. 2500µm),
horizontal side 25mm.
Carefully mark 10 even graduations on base
0 1 2 3 4 5 6 7 8 9 10
Amplitude
Fix on machine with short side in direction of vibration.
Persistence of vision shows double image: cross-over point
shows vibration amplitude.
For high vibration of crude machines!
TURBINE SUPERVISORY INSTRUMENTATION
On bearing in line
with the centreline?
Does that matter?
CASE 6: CASING DISTORTION - 350MW TURBINE
GENERATOR
HP
P LP BGenerator
Journal bearings
Couplings
LP AHP-IP
CASE 6: WHAT TSI RECORDS SHOWED
CASING DISTORTED, PULLED ROTORS OUT OF
LINE Unit was below half
full load, but cooling
water flow was not
reduced, despite ops
instructions.
Pressure
too low-
casing
distorted
If ops
rules
had
been
kept…
CASE 7: BUT, WHAT IS TSI
MEASURING?
Air gap
to actual
bearing
TSI: NON-CONTACT DISPLACEMENT
BETTER THAN SHAFT RIDERS OR
BEARING CAP
OVERALL + BEARING CONDITION
Velocity
Frequencies around rotation order:
Overall machine condition
Unbalance, temporary and permanent
Looseness
Misalignment
Acceleration and ultrasonics
Higher frequencies:
Rolling element bearing condition
CASE 8: RE BRG
Acceleration level trend showed
bearing degrading
Acceleration spectrum
showing bearing
frequencies
Selected Spot
Ack: P Todd
Ultrasonics
TEMPERATURE INDICATION
Thermography, yes – use iPhone adpator?
Spot temperature indicator may be enough: cheap
Temperature sensitive paint
CASE 9: GOT A DCS? STEAM TURBINE INTERNAL
DAMAGE:
INFO FOR “FREE”
Main steam strainer blockage
Blockage in blading
CASE 10: DCS FOR MAJOR PUMPS
Boiler Feed Pump 7000kW
3 × 50%: run all three
combinations: if two sets show
low, the most worn pump is the
one common to both
OR, TAKE DATA FROM HISTORIAN
Head
…then follow
procedure for
optimisation (see
Ray’s book and
papers)
WEAR PARTICLE ANALYSIS
Lube sampling pump: oil samples for both on-site
and lab CM
CM & DEFECT ELIMINATION
Understand defect levels in CM parameters
Record experience- what was found vs what was predicted
Understand key defect causes when a CM parameter changes
Take immediate action to eliminate or slow
Use defect understanding to improve the quality of repair tasks
Use baseline measurements on equipment start-ups
Post overhaul CM checks
Understand defect and causes through equipment post mortems.
Design out where justified!
IMPROVING CONDITION MONITORING
SYSTEMS
Better use of simple equipment inspections & simple
CM techniques
More use of Defect Elimination (Get proactive)
Greater involvement of non-CM specialists
Increase efficiency of CM data analysis
Better prognosis
Simple methods often enough
VITAL: define clearly how measurements are taken, stored, action outcome.
More complex machines deserve more complex approach
Email me for papers on
case studies
Happy monitoring!