Date post: | 15-May-2015 |
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A Practical Guide to Maximizing Machine Uptime
Every day, maintenance professionals across the world face the challenge of pushing
maximum machine potential while at the same time, keeping repairs at a minimum – a
challenge that is difficult to accomplish. Thankfully, there is a solution that opens the
door to reliability – predictive maintenance technology.
very day, maintenance professionals across the world face the challenge to maintain maximum
machine uptime while reducing costly downtime – a challenge that is difficult to accomplish.
Predictive maintenance programs can accomplish this predicament with low investment
requirements. Predictive maintenance services help determine the condition of in-service
equipment in order to predict when maintenance should be performed. This approach offers
savings over routine maintenance since tasks are only performed when needed. The main value
of predictive maintenance is to allow the convenience of scheduling corrective maintenance
ahead of time. Additionally, this allows one to prevent unexpected equipment failures. Benefits
may include:
Increased equipment lifetime
Increased plant safety
Optimized spare parts handling
Lower maintenance costs
Reduced machinery downtime
Increased production
There are three types of machinery maintenance:
1. Reactive
2. Preventative
3. Predictive
Reactive maintenance is really no maintenance at all – run your equipment until you experience
a total failure. The problem with this technique is that failures are often untimely and more
expensive to deal with. Not to mention, some failures can result in a complete disaster to your
business. That’s where preventative maintenance comes in.
Preventative maintenance involves periodic disassembly, full inspection and replacement of
worn parts to prevent a future disaster from occurring. By doing so, you’ll experience a lower
frequency in breakdown repairs and shutdowns. Furthermore, this leads into predictive
maintenance which involves the trending and analysis of a machine’s current condition to
detect and identify developing problems before experiencing equipment failure.
Predictive programs help get the maximum performance out of a machine before end of life. By
monitoring and diagnosing problems ahead of time, you can significantly increase the life and
productivity of your equipment before a catastrophic failure may occur.
E
The ultimate goal of predictive maintenance is to perform maintenance
at a scheduled point in time when the maintenance activity is most
cost-effective; prior to performance loss. The “predictive” component
derives from the goal of predicting the future trend of the equipment’s
condition. In order to achieve maximum productivity and minimize
disruption of normal operations, predictive maintenance inspections
are performed while equipment is in use.
An integral part of predictive maintenance is analysis and reporting. It’s
important to be able to track equipment performance factors to fully
utilize predictive maintenance for what it’s worth.
Predictive Maintenance Technologies
To evaluate equipment condition, predictive maintenance utilizes non-
destructive testing technologies such as:
Infrared Thermography
Oil Analysis
Vibration Analysis
Dry-ice Blasting
Motor Circuit Testing
Infrared Thermography
Infrared monitoring and analysis can be used from low-speed equipment to high-speed
equipment, and can be effective for spotting both electrical and mechanical failures.
Oftentimes, infrared has been said to be the most cost-effective technology available. Infrared
technology can be defined as the process of generating visual images that represent variations
of IR radiance of surfaces of objects. IR radiation falls outside that of visible light and therefore,
it’s invisible to the naked eye. However, an IR camera or similar device allows us to escape the
visible light spectrum and view an object based on temperature. Why is this important? Similar
to other predictive maintenance technologies, IR attempts to detect the presence of stressors
or conditions that will decrease the life of your equipment.
Predictive Maintenance
Services Offered through
ACT/Whelco:
Turnkey services
Vibration Analysis
Motor Circuit Testing
Online Analyzer
Laser Alignment
Coupling Inspections
Belt Tensioning
Field Balancing
Cryogenic Dry Ice
Cleaning
On-sit Winding
Analysis
DC Brush
Maintenance
Oil Sampling
Infrared
Thermography
On-site
Installation/Removal
Bearing Replacement-
Sleeve and Rolling
Elements
For example, rotating equipment problems are normally the result of frictional changes that
can be detected in the thermal profile. The following list contains just a few of the possible
:
Transmission lines
Splices
Shoes/end bells
Inductive heating
problems
Insulators
Cracked or
damaged/tracking
Distribution lines/systems
Splices
Line clamps
Disconnects
Oil switches/breakers
Capacitors
Pole-mounted
transformers
Lightning arrestors
Imbalances
Substations
Disconnects, cutouts, air
switches
Oil-illed switches/breakers
(external and internal
faults)
Capacitors
Transformers
Internal problems
Bushings
Oil levels
Cooling tubes
Lightning arrestors
Bus connections
Generator Facilities
Generator
Bearings
Brushes
Windings
Coolant/oil lines: blockage
Motors
Connections
Winding/cooling patterns
Motor Control Center
Imbalances
In-Plant Electrical Systems
Switchgear
Bus
Cable trays
Batteries and charging
circuits
Power/Lighting
distribution panels
The following list provides a few examples:
Steam Systems
Environmental
Boilers
Water discharge patterns
Refractory
Air discharge patterns
Tubes
Motors and rotating
equipment
Traps
Bearings
Valves
Mechanical failure
Lines
Improper lubrication
Heaters and furnaces
Coupling and alignment
problems
Refractory inspections
Electrical connections on
motors
Tube restrictions
Air cooling of motors
Fluids
Vessel levels
Pipeline blockages
Oil Analysis
One of the oldest predictive maintenance technologies still used today is that of oil analysis. Oil
analysis is used to define three basic machine conditions related to the lubrication system:
1. The condition of the oil – test the viscosity, acidity, etc.
2. The condition of the lubrication system – test for water content, silicon, or other
contaminants
3. The condition of the machine itself – analyze wear particles existing in the lubricant
Taking samples from your active, low-pressure line ahead of any filtration devices is a good way
to indicate the condition of the oil, lubrication system and machine. For consistent results and
accurate trending, be sure to take samples from the same place in the system each and every
time. A full analysis will help determine the condition of the lubricant, excessive wearing of oil-
wetted parts and the presence of contamination.
Vibration Analysis
Abnormal levels of vibration can cause equipment failure without proper analysis. Vibration, as
defined in the dictionary – “a periodic motion of the particles of an elastic body or medium in
alternately opposite directions from the position of equilibrium when that equilibrium has been
disturbed or the state of being vibrated or in vibratory motion as in oscillation or a quivering or
trembling motion.”
The important factor in this definition is that vibration is motion. As this motion continues to
build up, the level of frequency can change and is undetectable by human touch. In order to
obtain valuable data about equipment vibration, we use vibration detection instruments and
signature analysis software. We use sensors to quantify the magnitude of vibration and convey
them in the following three ways:
1. Displacement
2. Velocity
3. Acceleration
With a good understanding of machine design and operation, we can interpret the information
received from testing to define the machine’s problem. Once the information is retrieved, an
easy-to-follow report is generated for anyone with basic knowledge to read.
Vibration monitoring and analysis can be performed on these types of equipment:
Unbalance
Eccentric rotors
Misalignment
Resonance problems
Mechanical
looseness/weakness
Rotor rub
Sleeve-bearing problems
Rolling element bearing
problems
Flow-induced vibration
problems
Gear problems
Electrical problems
Belt drive problems
Analyzing this equipment to determine the presence of bad vibration is not a simple task.
Properly performed and evaluated tests require highly trained and skilled individuals.
Dry-ice blasting
Dry-ice blasting is a form of abrasive blasting where dry ice is accelerated in a pressurized air
stream and directed at a surface in order
to clean it. Why use dry-ice? Dry-ice
leaves no chemical residue as it
sublimates at room temperature.
Essentially, the sublimation process
absorbs a large portion of heat from the
surface which produces shear stress due
to thermal shock. This is claimed to
improve cleaning as the top layer of dirt is
expected to transfer heat and flake off
very easily.
Dry ice cleaning removes the following:
Paint/varnish
Oil
Grease
Tar
Bitumen
Dirt
Ink
Resin
Adhesives
Wax
Binders and solvents
Silicon/rubber residues
Chewing gum
Graffiti
…And much more
Motor Circuit Testing
If you’re looking for a full analysis of your motor condition, infrared and vibration will not
provide all the answers required to properly diagnose the condition of your motor. Over time,
motor circuit testing techniques have become more and more sophisticated. Motor faults such
as winding short-circuits, improper torque settings, open coils, etc. can be easily evaluated with
professional motor circuit testing. Motor analysis equipment remains fairly expensive and
requires a degree of skill and technique. There are two commonly used tests:
1.) Electrical Surge Comparison
a. One of the primary concerns of motor condition is winding insulation. Surge
comparison testing can be used to properly identify turn-to-turn and phase-to-
phase insulation deterioration. Due to differences in insulation thickness, motor
winding insulation tends to be more susceptible to failure from stress. Surge
comparison testing allows us to quickly identify where the deterioration exists by
applying a high frequency transient surge to the winding and compare the
resulting voltage waveforms. When differences in waveforms exist, this indicates
insulation or coil deterioration.
2.) Motor Current Signature Analysis
a. Another worthwhile tool in motor circuit testing is motor current signature
analysis (MCSA). The benefit of MCSA is that it uses a non-intrusive method for
detecting mechanical and electrical problems. The technology is based on the
idea that a conventional electric
motor driving a mechanical load
acts as a transducer. The motor
senses the mechanical load
variations and then converts them
into an electrical current that
moves along the motor power
cables. These particular currents
are reflective of a machine’s
condition.
Motor Circuit Testing Applications:
Stem packing degradation
Incorrect torque switch
settings
Degraded stem
Worn gear tooth wear
Restricted valve stem
travel
Improper seal installation
Inaccurate shaft alignment
or rotor balancing
Improper bearing or gear
installation
Obstructions in the valve
seat area
Disengagement of the
motor pinion gear
Insulation deterioration
Turn-to-turn shorting
Phase-to-phase shorting
Reversed or open coils
Short circuit
Conclusion
As with most predictive maintenance services, the greatest saving opportunity does not come
from preventing a catastrophic failure, but rather the less tangible cost savings benefits. It’s
important to understand that one, unplanned motor failure can cost more than one year of
predictive maintenance services. Reduced downtimes, increased productivity, ability to
schedule maintenance, decreased inventory cost and decreased overtime are just a few of the
advantages of predictive maintenance services.
ACT is first and foremost a service company. We measure our
business and success every day on three variables: the quality of
our work, our turnaround time, and cost-effective pricing. Our
team takes pride in providing excellent customer service to our
customers. We understand we are only as good as the service
we provide TODAY. When we build a relationship with our
customers, we consider it a partnership. Consider ACT when
looking for a partner to assist with you industrial repair needs.
When your motor or equipment fails, your line goes down and
you are losing money, you need a trusted partner who is
experienced, diverse and able to address your needs on your
schedule. Whether your situation involves critical production
downtime and/or a unique technology or process, Whelco is the
shoulder you can lean on.
For a FREE evaluation and quote on your equipment, contact us via one of the methods
below:
Phone: 888-655-3955
Email: [email protected]
Fax: 419-873-6575