Applying Condition

Based Monitoring

Approach in Facility

Management Services by

Ismail Yusof

CONTENTS

Maintenance Strategies

Condition Based Maintenance (CBM)

Condition Based Maintenance Cycle

Spectrum of CBM

Detection Method in CBM

Mortality of Machinery & Bathtub

Type of CBM

IR/VA/OA/PQA/US

Benefits

The Challenges

MAINTENANCE

STRATEGIES

Maintenance

Reactive

Maintenance

Unplanned

Preventive

Maintenance

Planned

Condition Based

Maintenance

Condition Based

Condition Based

Maintenance

A predictive approach can be applied to any equipment problem if,

A physical parameter like vibration, temperature,

pressure, voltage, current, or resistance can be measured.

An engineering limit for the measured physical parameter must be, established so a problem can be detected during routine monitoring.

The limit should be low enough to detect the problem before excessive damage occurs. Correcting of the root problem is the key to most predictive efforts.

Condition Based

Maintenance Cycle

yes

Analyze Problem

Open Corrective

Work Order

Corrective

Maintenance (Schedule)

Condition Based or Periodic

Monitoring

no

Spectrum of CBM

With CBM technology, a vast number of

equipment failures can be predicted.

Vibration measurement on rotating equipment

& InfraRed Thermography is probably the best

known of current CBM applications, but other

categories of industrial equipment also benefit

from a CBM approach.

Detection Method in CBM

Spectrum of CBM

Equipment

Category

Equipment

Types

Failure Mode Failure Cause Detection

Method

Rotating Machinery Pumps, Motors,

Compressors, Blowers

Premature Bearing

Loss

Excessive Force Vibration and Lube

Analysis

Lubrication Failure Over, Under,

or Improper Lube; Heat

and Moisture

Spectrographic &

Ferrographic Analysis

Electrical Equipment Motors, Cable,

Starters, Transformers

Insulation Failure Heat, Moisture Time I Resistance

Tests, IR Scans and

Oil Analysis

Corona Discharge Moisture Splice

Methods

Ultrasound

Heat Transfer

Equipment

Exchangers,

Condensers

Fouling Sediment I Material

Buildup

Heat Transfer

Calculations

Containment and

Transfer Equipment

Tanks, Piping,

Reactors

Corrosion Chemical Attack Corrosion Meters,

Thickness Checks

Stress cracks Metal Fatigue Acoustic Emission

The mortality of machinery

There is a definite pattern of life spans. In practice, this pattern manifests itself when a collection of machinery is subjected to rigorous operation. The plot of typical life spans is shown in the so-called bathtub curve.

There is a rather high incidence of early failures, called infant mortalities. Most equipment that survives infancy will continue to perform with few failures occurring. In time, however, the failures begin to increase until the last of the group succumbs.

Bathtub Curve

Machine

Failures

Machine Life - Years

Random Failures

Normal Aging

Infant Mortalities

Type of Condition Based

Maintenance

o Infra Red Thermography

o Vibration Analysis

o Oil Analysis

o Power Quality Analysis

o Ultrasound

InfraRed Thermography (IR)

Infrared thermography, thermal imaging, thermographic imaging, or thermal video, is a type of infrared imaging science. Thermographic cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900–14,000 nanometers or 0.9–14 µm) and produce images of that radiation, called thermograms.

Since infrared radiation is emitted by all objects near room temperature, according to the black body radiation law, thermography makes it possible to "see" one's environment with or without visible illumination.

The amount of radiation emitted by an object increases with temperature, therefore thermography allows one to see variations in temperature. When viewed by thermographic camera, warm objects stand out well against cooler backgrounds; humans and other warm-blooded animals become easily visible against the environment, day or night. As a result, thermography's extensive use can historically be ascribed to the military, security services and Condition Based Maintenance.

Sample of IR Images

Sample of IR Images

33.3°C

151.5°C

40

60

80

100

120

140

SP01

AR01

AR02

LI01

LI02

SP02

50

100

150

Line Min Max Cursorli01 37.6°C 125.9°C -li02 36.2°C 58.9°C -li03 - - -

°C IR01

Infrared Image Photo

Thermal Profile

VIBRATION ANALYSIS (VA)

Vibration refers to mechanical oscillations about an equilibrium point.

The oscillations may be periodic such as the motion of a pendulum or

random such as the movement of a tire on a gravel road

Rotating machinery has a characteristic vibration pattern depending on

the location the vibration data is collected. Characteristic vibrations are

produced at different frequencies for similar equipment.

Any change to these vibration patterns will indicate the nature and

severity of a defect such as misalignment of shafts, bearings and footing

etc. In vibration analyses a transducer converts mechanical motion

(vibration) to electrical signals.

These electrical signals are then plotted on amplitude versus frequency

plots, which then is analyzed to predict the source of vibration.

Defining VA Limits

Many engineered limits have already been established for equipment by manufacturers, professional societies and industrial groups.

Vibration Institute, a not-for-profit professional organization, and other organizations have established levels of equipment health as a function of vibration velocity based on experiments.

A simplification of this equipment health data for ‘Rotating machinery ratings.‘ This table is useful for categorizing vibration levels on most industrial equipment operating between 600 rpm and 3600 rpm.

Vibration Limits

Rotating Machinery Ratings

Rating Vibration Level Necessary

Action

Good Less than .15 ips Continue to trend

Fair .15 ips to .30 ips Continue to trend

Poor .30 ips & above Analyze & Correct

Using Ultrasound & Vibration

In the past, ultrasound and vibration technologies

have been used independently to monitor ball

bearings in plant equipment.

However, it is becoming more common to use

ultrasonic inspection interfaced with vibration

analysis to support CBM maintenance programs for

periodic inspection of critical bearings to monitor

wear and predict failure.

Using Ultrasound & Vibration

Oil Analysis

Oil analysis (OA) is the sampling and laboratory analysis of a lubricant's properties, suspended contaminants, and wear debris.

OA is performed during routine preventive maintenance to provide meaningful and accurate information on lubricant and machine condition. By tracking oil analysis sample results over the life of a particular machine, trends can be established which can help eliminate costly repairs.

The study of wear in an machinery is called tribology. Tribologists often perform or interpret oil analysis data. The sample sent to Accredited Lab for analysis.

Oil Analysis

OA can be divided into three categories:

Analysis of oil properties including those of the

base oil and its additives.

Analysis of contaminants.

Analysis of wear debris from machinery.

Oil Analysis

Comparing the OA results of new and

used oil, a tribologist can determine when

an oil must be replaced.

Careful analysis might even allow the oil to

be "sweetened" to its original additive

levels by either adding fresh oil or

replenishing additives that were depleted.

BENEFITS OF APPLYING

CONDITION BASED

MAINTENANCE

Increase Your Profitability by:

• Reducing capital costs.

• Reducing maintenance costs.

• Reducing energy costs.

Reduces the risk of:

• Costly business interruption.

• Fire/ life safety.

• Code violations.

The Challenges Ahead !!!!

First and most important of all, the initial cost of CBM is high. It requires improved instrumentation of the equipment. Often the cost of sufficient instruments can be quite large, especially on equipment that is already installed.

Next introducing CBM will invoke a major change in how maintenance is performed, and potentially to the whole maintenance organization in a company. Organizational changes are in general very difficult.

The technical side of it is not always as simple. Even if some types of equipment can easily be observed by measuring simple values as vibration (displacement or acceleration), temperature or pressure, it is not trivial to turn this measured data into actionable knowledge about health of the equipment.

Also Limited Maintenance/resources budgets (insufficient manpower, tools, training and skilled staff).

Lastly Obsolete systems & equipment.