The Signs of Failure: Advanced vibration-monitoring technologies protect critical assets
Written by Dan Nower
Rotating equipment seldom fails without notice, so breakdowns can
usually be predicted and avoided by watching for signs of failure.
Vibration monitoring, followed by machine diagnostics, is an effective
way to track the health of production machinery in order to adhere to
best maintenance practices, extend equipment longevity and avoid
unplanned downtime.
More
than ever, it is important to have access to reliable information about
the operating condition of critical production equipment, not just a
“trip” signal that comes only after internal damage has already
occurred. Machinery shutdown protection is only part of a complete
monitoring strategy to guard against events with little or no apparent
warning. The right monitoring equipment, trained personnel and software
package are needed to sense and identify the signs of failure long
before a key compressor, turbine, gearbox, pump, coupling or air
induction fan fails “unexpectedly.” In any economy, timely maintenance
is far better than catastrophic failure and the costly repairs that
follow.
Even so, studies indicate that more than 50 percent of industrial
maintenance man-hours is spent fixing equipment after a failure has
occurred, whereas less than 18 percent of the time is spent determining
when equipment might fail and acting accordingly. The numbers will
improve only when maintenance departments establish the monitoring of
machine health as a key mission.
Advanced in-the-field vibration analysis as well as online and wireless
vibration monitoring can be integrated with process control systems to
nurture the health of the rotating machinery that is essential to high
reliability production.
Route-Based Monitoring
The traditional method of collecting vibration data from rotating
machinery has not changed appreciably in more than 25 years. A
technician, with a hand-held data collector that can be attached to
predetermined points on a machine or connected to permanently installed
sensors, follows an expeditious route through the plant to obtain
detailed vibration information on different rotating assets. This data
is later uploaded to a computer software package for analysis and
comparison with earlier measurements taken on the same machine.
Industry leading data collection equipment (such as Emerson’s CSI 2130
Machinery Health Analyzer) accurately identifies the earliest signs of
bearing and gear wear, along with many other potential machine faults,
and provides an indication of severity while the technician is still at
the machine. Real-time decisions can be made on whether to collect more
detailed data or move on to the next machine.
Online Monitoring
In every process plant, certain rotating machinery must perform
continuously to maintain a high level of production, and some critical
situations can be averted only if a stream of data regarding the
real-time condition of that equipment is available. To assure a flow of
information regarding the health of a whole range of gas turbines,
steam turbines, generators, compressors, fans, motors, pumps and the
like, recently developed online monitoring systems represent technology
well beyond route-based monitors that provide only snapshots of an
operation. Essential equipment can be monitored for changing vibration
patterns and rising temperatures - sure signs of impending trouble.
Data received directly from a machine are presented in a variety of
plots that depict exactly what is occurring. Maintenance engineers and
machine specialists are given real-time information for use in
analyzing changes in the machine’s operation.
These signals enable analysts to pinpoint the location, nature and even
the severity of developing problems. The information from these
automated monitoring systems enables plant personnel to predict with
greater accuracy when a machine will need maintenance to prevent
damage, avert unscheduled downtime and avoid lost production. Machinery
health management software categorizes the significance of each machine
in a production environment, focusing greater attention on those
machines that would likely shut down all or a major section of the
plant if they fail. Online monitoring assures that the condition of
these machines is being assessed continuously.
For example, the CSI 6500 Machinery Health Monitor is designed for
process automation and protecting new installations and upgrade
projects, combining prediction and protection in a single chassis.
Fully compliant with API 670, this online monitor delivers real-time
information needed for immediate decision-making. As well, the AMS
Suite: Machinery Health Manager predictive maintenance software
captures vibration data continuously from a range of plant equipment,
processing it and displaying the results graphically to give machinery
analysts a better understanding of what is going on inside a machine.
This combination of machine health and process status/health gives
operators much greater ability to recognize and manage controllable
scenarios in order to avoid problems that might otherwise lead to
degraded machine health. Such controllable events represent the best
opportunity for plant personnel to optimize processes and performance
and make a positive contribution to return on investment.
Wireless Monitoring
One of the newest technologies to be adapted for vibration monitoring,
wireless communication eliminates “blind spots”: areas that have been
either technically or economically unreachable with conventional
wiring. Wireless has the potential to improve communications with a
wide range of assets, including field instruments, valves and safety
showers. Wireless vibration monitors are also adaptable to many types
of rotary equipment that are critical to the process. These devices
provide convenient access to information that was formerly not
available but may be essential to the overall performance and safety of
each process unit.
The IEC62591 (WirelessHART) standard is based on a self-organizing mesh
network in which transmissions defy the “canyons of metal” that define
most large process industry plants. With this technology, each wireless
device is a transceiver, so a direct, line-of-sight connection between
an instrument and the data gateway is not required. In the event one
transmission path is blocked, the network automatically directs the
signal to an adjacent device, which relays it to the gateway, ensuring
transmission reliability and data integrity.
With a wireless vibration transmitter (such as Emerson’s CSI 9420),
vibration data from essential equipment can be transmitted
simultaneously to control room operators and machinery health
monitoring application, assuring that the right kind of data gets to
the right person at the right time. This information can be used
initiate predictive maintenance to prevent an unexpected failure
leading to an expensive unplanned shutdown of part or all of a
facility. Many times potentially disastrous conditions can be resolved
before they are even recognized as problems in the control room.
Efficiently operated plants utilize every means of monitoring to obtain
early indications of failing equipment so appropriate action can be
taken. A system incorporating protection monitoring, prediction
monitoring, performance monitoring, and integration with process
control is the most effective way to achieve a complete maintenance
solution.
Tracking the health of production machinery in this way is a best
practice, leading to extended equipment longevity and avoidance of
downtime.
Dan Nower is with Emerson Process Management. For more information, visit www.emersonprocess.com.
More
than ever, it is important to have access to reliable information about
the operating condition of critical production equipment, not just a
“trip” signal that comes only after internal damage has already
occurred. Machinery shutdown protection is only part of a complete
monitoring strategy to guard against events with little or no apparent
warning. The right monitoring equipment, trained personnel and software
package are needed to sense and identify the signs of failure long
before a key compressor, turbine, gearbox, pump, coupling or air
induction fan fails “unexpectedly.” In any economy, timely maintenance
is far better than catastrophic failure and the costly repairs that
follow.
