Financial pressures, combined with increasing safety and
environmental requirements, have resulted in a significant
increase in the need for valve-position monitoring in
industrial plants. However, the potential cost involved in
putting a monitoring system in place means that larger numbers
of valves remain unmonitored.
Keeping a large population of unmonitored valves has several
implications. For example, a manual valve may be incorrectly
left open, closed or partially open. Since most manual valves
are not monitored, those events can go undetected for a
significant time, causing considerable operational losses,
along with environmental and safety risks.
A major restriction when installing automation systems is
the need to use wires to connect sensors and actuators. Wiring
an automation system in a modern plant is time-consuming and
costly [e.g., due to the cost of cables, cable trays, cabinets,
and associated input/output (I/O) points and installation],
leaves a considerable footprint and adds significantly to
Due to wiring cost, only one third of the automated valves
have limit switches (only the solenoid is wired), leaving two
thirds of these automated valves without any position
The valve industry has reacted to this need by developing
wireless technological solutions to help plants increase the
number of monitored valves, avoiding the financial burden.
According to recent research, wireless technology can triple monitoring
instrumentation in a typical plant.
This technology can be applied to both manual and automated
rotary or linear valves, and it provides real-time information
about a valves status directly into the control system,
increasing safety and yield. In addition, it can provide the
valves operational signature, enabling cost-effective
predictive maintenance. Finally, in new construction, it can reduce material
costs, simplify engineering and installation, reduce
commissioning and startup costs and help in space-constrained
The increasing need to monitor valves
The need to remotely monitor valves in a wide range of plant
applications is driven by several key factors: facilities must operate efficiently,
and they must adhere to industry and regulatory standards for
safety and the environment.
There is mounting evidence of the cost of incidents and
accidents. Of all major incidents and accidents in the refining and petrochemical industry, about 30%
result in injury or loss of life, and over 60% result in
regulatory fines and production downtime. In addition, while
the occupational safety incidents in these two industries
declined by 90% between 1993 and 2005, the level is still
considerable because, on average, plants in these industries
will have one incident for every 500,000 work hours. The
material cost of each incident in the same period has risen by
50%. The average cost of each incident is about $12/1,000
barrels (bbl) of refining production.1
Plant management is increasingly seeking a higher awareness
of plant conditions to improve efficiency and safety. In
addition, plants must adhere to a growing body of safety and
regulatory requirements that often increase the need for
monitoring. At the same time, an important trend in the
industry is to extend the intervals between planned shutdowns
to increase productivity.
Lack of valve monitoring alone is not the reason for all of
the safety, efficiency and environmental issues mentioned
above; those incidents happen for a number of reasons other
than lack of valve monitoring. However, the understanding of
valve status needed to support these objectives can only be
achieved through real-time monitoring.
Monitored vs. unmonitored valves
Despite the ability of monitoring systems to address many of
these valves efficiency, safety and regulatory issues,
installation of valve monitoring technology is limited.
Industry research indicates that as many as 70%85% of
valves in plants are not monitored.
As Fig. 1 suggests, the range of automation
of valves varies largely from one plant to another. Manual
valves can make up between 10% and 55% of the valve population
of a plant, and practically all of them will have no
monitoring. Among automated valves, typically two thirds will
also have no monitoring. In total, that leaves as many as
70%85% of valves without monitoring capabilities.
1. In a typical industrial
most valves are not monitored. Image
courtesy of Westlock Controls.
Implications of unmonitored valves
One of the main implications of having a large number of
unmonitored valves has to do with safety. Less monitoring means
less information about valve positions in both manual and
automated systems, which increases uncertainty and risk.
Without remote monitoring, many plants must physically inspect
valves to ascertain their statuses. This sends personnel into
potentially dangerous environments or limits inspection.
Lack of monitoring also affects efficiency and performance
in plants. The adage, You cannot improve what you cannot
measure, applies almost perfectly to this situation.
Valves precisely control the flow of media in process plants.
Lack of information from a large percentage of these valves can
lead to a bad batch and significantly limit plant engineers in
their efforts to control and improve efficiency.
There are also environmental implications. If an outflow
valve that should be closed is accidentally left open, media
can leak to the environment without notice or until another
part of the control system discovers the error.
As previously mentioned, plant operators can face situations
where the valve is incorrectly opened, closed or left partially
open. These events can cause considerable operational losses,
impose high costs and pose environmental and safety risks.
A major study in the offshore oil and gas industry showed
that almost 50% of valve incidents resulting in leakage to the
environment were attributed to
operational issues (not to valve defects or
malfunctioning), and almost 30% of these operational issues
were the direct result of a valve simply being left open or
wrongly opened without notice.2
Restrictions for monitoring-system installation
In valve-intense applications, monitoring has historically
been achieved with wired systems. These systems facilitate
monitoring but present many challenges that restrict the extent
to which they can be deployed. The challenges are inherent to
wired systems and include such fundamentals as the cost of
installation and constraints on design and expansion.
Design limitations are presented by many factors, including
weight, the number of installed devices and the complexity of
the system. Costs are driven by installation of an
infrastructure of wires, cable trays, cabinets and I/Os. For a
typical industrial installation, this may total
$2,000$5,000 per valve.
Automated valve-monitoring systems are generally more
expensive due to the need for wiring both sensors and
actuators. Due to wiring cost constraints, two thirds of
automated valves will have only a solenoid without position
feedback. More significantly, for every automated on/off valve,
there will be another 34 manually operated valves in the
Using conventional wiring to monitor valves has a huge cost associated
with connecting I/O points in the control system, distributed
control system (DCS), supervisory control and data acquisition
(SCADA) system or programmable logic controller (PLC)
2. Wired monitoring has a complex
infrastructure. Image courtesy of Westlock
Long cable runs, full cable trays and marshalling cabinets are
common problems with these applications. The labor-intensive
layouts and the difficulty in maintaining and modifying the
system constrains engineering and installation options.
A wired system can increase maintenance requirements in
industrial or severe service applications. Wires can wear and
break, and connections can shake loose. These systems require
knowledgeable personnel to ensure reliability and performance, which
can involve training and/or certifications.
Manufacturer response to wireless valve monitoring
Wireless technology is the industrys response to the
increased need for remote valve monitoring in manual and
automated applications. In contrast to wired systems, wireless
valve monitoring uses radio signals and a networked system of
field monitoring devices. The technology is integrated with
DCS, PLC and SCADA systems to provide real-time information on
valve status, along with flow, temperature and density
conditions with wireless transmitters (Fig.
3. Wireless systems greatly simplify
the monitoring infrastructure. Image
of Westlock Controls.
Wireless technology varies among
manufacturers; however, a typical manual valve system consists
of a wireless device at the valve, a wireless router, and a
gateway connected to the plant networks maintenance and
operations functions. Automation adds a return leg, with
DCS/PLC controllers and solenoid wiring back to the valve. Integration with the plant network
is facilitated with open protocols such as object linking and
embedding for process control (OPC), Modbus remote terminal
unit/transmission control protocol (RTU/TCP), and
Battery-powered monitoring devices used in the field are
typically configured with a mesh network topology, which
ensures full redundancy and avoids any single point of failure.
Within a network, data is routed using the most expedient
Wireless remote-monitoring systems address many of the
challenges inherent in wired systems. Chief among these is a
significant reduction in cost, which provides a more affordable
valve-monitoring system that can be applied to a larger
population of valves and a greater percentage of plant
Wireless valve monitoring can reduce the cost per valve vs.
that of a wired system by 25%60%, depending on factors
such as the application, area, classification and distances.
The cables and routing (cost of attachment) that can sometimes
account for 50% of the installation budget for a wired system
are eliminated with wireless monitoring. The difference can
account for thousands (and even hundreds of thousands) of
dollars in installation costs over conventional wired systems.
Lower installation costs mean that monitoring can be
economically extended to a larger, more complete valve
population, providing the information needed to improve
efficiency and reduce risk.
Health and safety risks are reduced because fewer personnel
are required in the field to determine valve status, thereby
limiting exposure to hazardous situations. Also, reducing and
eliminating the labor-intensive process of physically
monitoring valves eases workload and frees personnel for other
Monitoring devices are easily deployed as needed, with no
practical limits to the number of valves that can be monitored.
Deployment is also enhanced by a much smaller footprint, which
helps overcome space obstacles and routing issues.
Reliability and security standards
are key advantages of wireless monitoring technology. Wireless
systems have an inherent reliability based on multiple paths of
communication. If a device fails or a path is blocked, another
route is used to ensure that valve data reaches the control
system. Devices based on industry standards have greater than
99% data-transfer reliability.
Wireless security advantages include encryption to prevent
reading of intercepted data. Each message must also be
authenticated, which requires that the origination and
receiving devices recognize each othera function that is
built into the devices.
Limitations of wireless valve monitoring
Wireless systems have limits that should be considered when
examining any application. Most of these boundaries are related
to the distances and topologies, which may vary depending on
the protocol used. Care should be taken in choosing the most
appropriate wireless technology to address these
These real-world constraints include the free space in a
plants layout and in obstructions that can block
communications. Weather can also be a limiting factor. Rain,
ice and snow all affect transmission error rates.
Area classification can also limit the use of wireless
technology. These restricted areas may include hazardous and
corrosive environments, as well as remote, unmanned platforms.
Some limitations may be due to incorrect perceptions. For
example, even though batteries can last up to eight years,
there is a persistent concern about unexpected failure.
The next wave of valve monitoring
Complete understanding of what is happening within the
facility is a key point of the future industrial facility.
Incremental sensors are the foundation for collaborative
applications and advanced process management.
Companies will increase the use of risk analysis to
determine how much monitoring is required. Risk is defined as a
function of the likelihood that an event will happen and the
consequence or cost if it happens. This will drive an increase
in monitoring and, therefore, the use of wireless
An increase is also expected in wireless valve monitoring
driven by companies trying to automate their processes and
reduce labor. Some companies that currently operate remote
plants (such as Shells Ormen Lange gas plant in Norway)
are setting goals of operating and maintaining the plants with
as few people as possible. To accomplish this, online
condition-monitoring systems are employed to monitor virtually
everything that moves in the plant, including pumps,
compressors and valves (especially emergency shutdown valves).
In Shells case, the goal is that 70% of the maintenance
budget and spending should be based on the result of condition
monitoring, as opposed to reactive maintenance.3
In looking toward the future, it is important to understand
when and why wireless monitoring technology is being used. The
most common use is basic monitoring, where wireless is used to
cut cable and other infrastructure costs. Diagnostics is the
second reason, and it is becoming more popular as the
importance of valve performance is understood. Control is the
third reason; the technology can be used to control valve
positions, as well as for monitoring and diagnosis.
However, the acceptance of wireless technology for control
is limited due to safety, security and power concerns. There is
a limit to the amount of power available at the valve to move a
solenoid. The industry has developed ultra-low-power solenoid
technology to control the valve position, but this technology
is not available for 100% duty cycle.
Open standards are gaining share and are likely to dominate
in the future, allowing a single wireless and asset-management
solution for instrumentation, actuators and positioners.
Another technology that cannot be ruled out is WiFi. As
companies extend their WiFi networks, and as suppliers add WiFi
capabilities to their actuators, this technology may become
The demand for valve-position monitoring in industrial
plants is driven by the need for greater efficiency and
increasing safety and environmental requirements, although
traditional wired monitoring systems are expensive to install,
maintain and expand. The result is that relatively few facilities benefit from the
advantages of monitoring. Only 10% of possible monitoring
instrumentation may actually be installed.
Wireless systems transmit data over the air, eliminating the
costs and constraints of wired systems that have limited the
use of valve monitoring. By extending monitoring to a much
larger valve population, these systems set the stage for
significant efficiency improvements and new capabilities in
safety and environmental stewardship. These
factors are fueling a growing interest in wireless systems and
a general need to better understand the technology and how it
can be applied. HP
The author thanks Leo Minervini, Marcelo Dultra and Michael
Latolf of Westlock Controls for their contributions, and
Pentair management for its support and permission to present
this examination of the state of wireless valve monitoring in
1 Bennett, G., Reducing Major Accident
Potential: Lessons from the Refining Industry, DNV
2 Peters, J., Assessment of valve failures in
the offshore oil and gas sector, National Engineering
Laboratory, TUV NEL Ltd. on behalf of the Offshore Division of
Health and Safety Executive, UK Offshore Oil and Gas Industry,
3 Hale, S., Online Valve Monitoring Helps
Shell Achieve Goals at the Ormen Lange Gas Plant in
Norway, Score Atlanta Inc.
Tito Sequeira is the global marketing
manager for midstream and downstream at Pentair Valves & Controls. He is
responsible for the strategy and marketing mix required
to serve these global markets. Mr. Sequeira has
experience in product management as well as in industry
marketing for the power, refining, LNG, pipeline and
petrochemical segments. He
has provided strategic leadership to pursue business
opportunities in these industries for leading valve and
control manufacturers. Mr. Sequeira holds a BS degree
in industrial engineering from the Monterrey Institute
of Technology in Mexico and an
MBA degree from Yale University. He has six years of
experience in the valve industry.