getting started with condition monitoring for only $2000

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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!

r.beebe@federation.edu.au

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