Useful Predictive Maintenance

Technologies for Converting Facilities

Predictive Maintenance or PdM is defined as efforts

that are designed to detect the onset of a means of

degradation with the goal of correcting the

degradation prior to significant deterioration of the

equipment or component.

Simplified, it is to find the problems and correct

them before something catastrophically fails, and

removes a facility, machine or production line from

effective operation.

The diagnostic capabilities of Predictive

Maintenance Technologies have increased in recent

years, largely due to new sensor advancements. I

have been in the Preventive/Predictive

maintenance business for almost 30 years. The

innovation and enhancement of PdM/Reliability

practices has truly been a continual improvement

process.

Any truly effective PdM effort utilizes Vibration

Analysis as the cornerstone of the program.

Vibration Analysis is paramount to such an effort.

The challenges of implementing a successful

facility-wide Vibration Analysis program are

numerous.

Cost vs. perceived benefit

Lack of understanding of the technology

It is not a go/no go technology, and requires

a well trained analyst to be effective

Lack of management buy-in

Lack of training if attempted in-house

Maintenance resists being proactive and

remains in a comfort zone of fighting fires

And the list continues. But let’s forgo Vibration

Analysis and discuss some of the PdM

technologies, and diagnostic tools that could be of

extreme value to your facility.

Those technologies are:

1.Infrared Thermography

2.Ultrasonic Scans

3.Oil Analysis

Infrared Thermography

Infrared (IR) Thermography is the process of

generating visual images that represent variations

in IR radiance of surfaces of objects. This IR

radiance of the object is proportional to its existing

temperature. This is accomplished with an

Infrared Imager (camera).

The principal value of this type of inspection deals

with In-Plant Electrical Systems and components.

Electrical problems are known to be a fire hazard

and many Facility Insurance providers demand

proof of IR electrical testing scans or give a

discount for providing such evidence.

IR scans are successful in identifying problems

with electrical, mechanical, even flat roof issues.

Infrared Thermography Case Studies

This picture shows a fuse block with three 100 amp

600 volt fuses. To the naked eye all seems fine.

The Infared Thermography Scan tells a completely

different story. The top clamp on the third fuse

was very loose with a temperature of almost 300

degrees! Fire hazard? Failure waiting to happen?

Probably both.

This is a disconnect for an industrial fan. The fan

was temporarily idled, locked out and a qualified

Electrician repaired the clip. Afterwards this same

scan had temperature readings that were no

greater than 98 degrees.

This is a photo of a motor and pump combination

in a manufacturing facility. Again to the naked eye

there does not seem to be a problem. It is very

doubtful that a Mechanic or an Electrician walking

by on a PM would suspect a problem.

However the IR scan shows that the motor was

running at an elevated temperature of over 200

degrees. This temperature is detrimental to the

insulation, the iron, the windings and the grease in

the bearings.

The motor was shutdown and a redundant pump

that was put into service. During the motor rebuild

the motor repair shop said that the motor had

been “pumped full of grease”. The added value

here was that the plants lubrication program was

amended to assure that this did not happen again.

Ultrasonic Inspections

Ultrasonic or ultrasounds are sound waves that

have a frequency of greater than 20 kHz. These

frequencies are not perceived by the human ear.

Non-contact Ultrasonic Detectors are utilized in

PdM to detect airborne ultrasound. Contact probes

are used for diagnostics with bearings, steam

traps, etc.

Ultrasonic detectors are useful in identifying

problems in:

Compressed gas (air) leaks

Compressed fluid leaks

Vacuum leaks

Steam trap failures

Bearing condition monitoring

Electrical arcing/tracking or corona testing

Let’s focus on Compressed Air leaks, as this is the

proverbial low-hanging fruit in most facilities.

Compressors that generate compressed air for a

facility’s demand are inherently expensive to own

and expensive to operate. They are a major source

of the Electricity costs associated with operating

the facility. If there are leaks in the compressed air

system, the compressor is operating, degrading,

and utilizing electricity while providing no value to

the facility. The leaking air is simply a source of

cost to the facility, both immediately and in the

future. I have never heard of a single compressed

air leak survey that resulted in finding zero air

leaks. On the contrary a typical survey will identify

dozens of sources of leaks and at times that

number is greater than one hundred. Some

facilities are acutely aware of this and have their

compressed air system surveyed several times a

year.

Compressed Air Leak Case Studies

A manufacturing Plant in the southeast had two

compressors at the site. Both compressors were

continually operating. Plant management had

assumed that there was then a need for a third

compressor and had budgeted capital dollars to

install a third unit. Previous to the purchase and

installation of the third compressor, a Compressed

Air Leak Survey was performed in the plant. This

survey identified 107 air leaks that were tagged for

repair.

Subsequent to the repair of the tagged leaks the

two existing compressors were capable of handling

the needs of the plant with capacity to spare, and

only one compressor was operating for much of

the day. Calculated at $.05/kilowatt/hour to

operate the compressors, and the fact that the

plant operated 24 hours a day it is estimated that

the Energy savings were over $70,000.00. That

savings is in addition to the fact that they did not

have to spend the capital dollars to buy and install

another compressor (and, the additional unit would

have cost more in electricity, not less).

This is a real example, it may be an extreme

example. Let’s look at an opposing example.

Let’s assume that all the air leaks in your facility

combined equate to an opening of 1/4”. That’s all

of the cracked tubing, all of the loose fittings, all of

the threaded connections that are leaking-by, etc.

Let’s also say for this example that the facility only

operates 8 hours a day 5 days a week.

That 1/4” total air loss would result in $2,000.00 in

Energy savings per year.

If the plant is operating 24/7 the estimated

savings would be $ 8,000.00 annually.

So, is this “Low hanging fruit”? No machinery to

replace, no energized components to work on, just

some fittings, sealing, tubing replacement, etc.

Outsourced Compressed Air Surveys typically cost

$1200-$1500.

Does your facility own an Ultrasonic Inspection

Meter? Maybe it could be better utilized. Maybe the

users could be better trained in how use the tool.

Oil Analysis

Oil Analysis analysis is one of the oldest PdM

technologies that is still used today. It dates back

to just after World War II and was first utilized by

the railroad industry to monitor the health of diesel

engines in locomotives.

Oil analysis is used to determine three basic

machine conditions relating to the machine’s

lubrication or lubrication system. The first

condition is that of the oil, that is, will its current

condition lubricate as per design. This is

determined by the viscosity of the oil. The second

is assessing the lubrication mechanism itself. Have

the physical boundaries of the lubricant been

compromised or contaminated. Water is the main

culprit, but other contaminates could be intrusive

depending on the operating environment. The third

is the condition of the machine itself. By analyzing

wear particles present in the lubricant, machine

wear can be evaluated and quantified.

Oil analysis is most often an outsourced function.

Oil Analysis Labs typically provide oil sample

bottles and labels with mailing instructions that the

plant utilizes to gather and ship the oil samples.

Oil analysis is performed on machines an

components such as:

Oil lubricated motor/pump/fan bearings

Antifriction (sleeve) bearings

Oil lubricated Ball Bearings

Oil Lubricated Roller Bearings

Gearboxes

Hydraulics

Any system where the condition of the oil is

directly related to decreased equipment wear,

longer lubricate life, or improved equipment

reliability

Oil analysis is another potential for a good return

on the investment. Oil samples are typically

analyzed for $30 to $100 per sample depending on

the level of analysis required. Most facilities are

effectively supported with the lower end of this

analysis range.

The costs are high when equipment and

components fail. Equipment replacement cost,

labor cost, the lead time in acquiring replacements

and downtime associated with a bearing or

gearbox failure can be tremendous. A single failure

prevented by an oil analysis program could easily

pay for the programmatic cost of performing Oil

Analysis for several years.

Oil Analysis Case Histories

Oil Analysis was performed on a large electric

motor with antifriction or sleeve bearings. The

analysis showed that wear particles as large as 30

microns were suspended in the oil sample. The

bearings were flushed and new oil was added.

Also, a new set of bearings were acquired due to

the oil sample. Several weeks later the motor was

scheduled for downtime. The existing bearings

were rolled out and damage was noted. The new

bearings in-hand were installed and the plant

averted a shutdown due to a bearing failure.

W ear

C ontam ination C hem istr y

E xtr em e

B ad

Mar ginal

Fair

G ood

IM02-1750 - IM02 1750 H P Motor

02W - IM02 W estB ear ing 1750hp Mtr

S am ple Date: 06-N OV -07

E stim ated total water content 0.0000%

In S olution N /A +E m ulsified 0%

+Fr ee 0% = 100%

An oil lubricated Cooling Tower gearbox was found

to have a breakdown in the lubricating properties

of the oil as well as being contaminated with

water. Further inspection of the gearbox reveled a

damaged seal that was allowing the intrusion of

water. The seal was replaced and the gearbox was

spared an untimely failure as the water would have

continued to invade if the oil analysis had not lead

to the mechanical inspection of the gearbox.

W ear

C ontam ination C hem istr y

E xtr em e

B ad

Mar ginal

Fair

G ood

C ool Tw r #2 - C ooling Tower #2

C T2 - C ooling Tower #2

S am ple D ate: 08-D E C -03

In Conclusion

I began this discussion with useful. Maybe cost-

effective or of-value might be better descriptions

for this discussion, but the fact is that some

Predictive Maintenance applications may be

difficult to quantify in regards to the return on your

investment. Vibration Analysis, being the

foundation of Equipment Reliability Based

Technology is certainly useful and of value.

However it is but one of several tools to help keep

plants from unscheduled downtime as well as in

capturing cost savings.

J. Scott Glover

126 Periwinkle Lane

Mooresville, NC 28117

800-732-2890 toll-free

704-528-3628 fax

scott@theADVANCEDteam.com