Hydrocarbon Processing Copying and distributing are prohibited without permission of the publisher
Email a friend
  • Please enter a maximum of 5 recipients. Use ; to separate more than one email address.



Use wireless valve-monitoring technology to your advantage

07.01.2013  |  Sequeira, T.,  Pentair Valves & Controls, Houston, Texas

Keywords: [wireless] [valve] [refining] [monitoring]

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 weight.

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 feedback.

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 valve’s status directly into the control system, increasing safety and yield. In addition, it can provide the valve’s 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 situations.

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.

 
  Fig. 1. In a typical industrial installation,
  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 3–4 manually operated valves in the plant.

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) (Fig. 2).

 
  Fig. 2. Wired monitoring has a complex
  infrastructure. Image courtesy of Westlock Controls.

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 industry’s 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).

 
  Fig. 3. Wireless systems greatly simplify
  the monitoring infrastructure. Image courtesy
  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 network’s 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 Profibus.

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 path.

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 operations.

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 tasks.

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 other—a 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 considerations.

These real-world constraints include the free space in a plant’s 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 technology.

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 Shell’s 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 Shell’s 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 more popular.

Takeaway

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

ACKNOWLEDGMENTS

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 the industry.

LITERATURE CITED

1 Bennett, G., “Reducing Major Accident Potential: Lessons from the Refining Industry,” DNV Energy.
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, 2003.
3 Hale, S., “Online Valve Monitoring Helps Shell Achieve Goals at the Ormen Lange Gas Plant in Norway,” Score Atlanta Inc.

The author

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.  


 



Have your say
  • All comments are subject to editorial review.
    All fields are compulsory.

Related articles

FEATURED EVENTS





Sign-up for the Free Daily HP Enewsletter!

Boxscore Database

A searchable database of project activity in the global hydrocarbon processing industry

Poll

As low oil prices make naphtha cracking margins in Europe and Asia more competitive, are investments in new, ethane-based petrochemicals capacity in the US and Middle East becoming less attractive?


15%

64%

21%




View previous results

Popular Searches

Please read our Term and Conditions and Privacy Policy before using the site. All material subject to strictly enforced copyright laws.
© 2015 Hydrocarbon Processing. © 2015 Gulf Publishing Company.