July 2014, Vol. 241, No. 7
Features
Wireless I/O Communication Solutions For Hazardous Environments
In 2010, an incident in San Bruno, CA brought national attention to the oil and gas industry when a natural gas pipeline exploded in a residential neighborhood, leveling homes and claiming several lives. The resulting shockwave from the explosion was equivalent to a 1.1 magnitude earthquake.
After a thorough investigation, it was determined that the cause was a failure in the pipeline from defective welds and increased gas pressure to meet growing energy needs. This is just one example of the potential damage that can occur when our critical infrastructure fails.
Disastrous incidents are not limited to the oil and gas industry. For example, a transformer malfunction in the electric power industry can cause catastrophic damage. In 2012, a transformer explosion after Superstorm Sandy caused major blackouts in Manhattan. Additionally, water main breaks in the water/wastewater industry often create massive sinkholes in highways and neighborhood streets around the country.
While not every catastrophe is preventable, utilities and governments alike have worked to make regulations and find solutions that will minimize risks and prevent damage should there be a fault or act of God that weakens our critical infrastructure. For example, as a result of the San Bruno incident, California has tightened pipeline safety regulations, including requirements for pressure monitoring.
While a single solution cannot eliminate faulty infrastructure, technology companies have worked for years to provide communication solutions that effectively monitor, control and offer data that will indicate when something is not functioning properly. With real-time notification and a fast response by organizations, there is a greater chance for the issue to be mitigated before it causes damage that could potentially risk lives.
There are a number of technology options in the marketplace for the oil and gas industry in particular, that offer communication solutions for both exploration/production and midstream pipeline monitoring. The oil and gas industry is unusual because of the consistently present explosive gases that often create a hazardous environment. There are technologies designed and certified to perform in such conditions.
C1D1 Certification
It is common for technology installed along the pipeline, at the wellhead and production facilities, to require a Class 1 Division 1 (C1D1) UL listing. This type of certification will ensure the technology can operate in hazardous environments and will not cause an increased risk of fire or damage. According to Underwriters Laboratories, the key criteria for obtaining a C1D1 certification include:
Intrinsically safe apparatus: The apparatus must be intrinsically safe, meaning that the device must be secure enough in hazardous environments that it will not contribute to the ignition of a hazardous atmosphere.
• Intrinsically safe circuit: All circuits should be deemed incapable of becoming ignited by any spark or thermal effect under specific testing conditions.
• Intrinsically safe system: Each piece of a system and interconnecting cables used in hazardous (classified) locations must be intrinsically safe.
• Explosion-proof apparatus: The apparatus is enclosed in a case that will uphold in the explosion of a specified gas or vapor that may occur, and, likewise, will prevent the ignition of a specified gas or vapor surrounding the enclosure by sparks, flashes or explosion of the gas or vapor within. It must operate at a temperature that will not cause the surrounding flammable atmosphere to ignite.
• Purged and pressurized: The process of (1) purging – supplying an enclosure with a protective gas at a sufficient flow and positive pressure to reduce the concentration of any flammable gas or vapor initially present to an acceptable level; and (2) pressurization – supplying an enclosure with a protective gas with or without continuous flow at sufficient pressure to prevent the entrance of a flammable gas or vapor, a combustible dust, or an ignitable fiber.
Options
Some technology providers offer a C1D1 certified solution for monitoring in hazardous environments comprised of sensors and a hardwire cable to transmit data. While this is a reliable solution, it can be difficult, sometimes impossible, to run cable to a hazardous spot along the pipeline that is remotely located. In installations in which the sensors need to be deployed miles away from the nearest data hub, the expense of trenching and installing a wired solution could be astronomical. Oil and gas operators will likely want to consider all options in the market place before selecting a sensor and hardwire solution. An additional option is C1D1 certified wireless input/output (I/O) technology.
Wireless I/O
Wireless I/O is a mechanism by which analog, discrete and other raw signals are transmitted via radio to and from a central processing device, such as a distributive control system (DCS), programmable logic controller (PLC), or other remote terminal unit (RTU). I/O is designed for remote process automation, process optimization and condition-based monitoring. Wireless I/O solutions can combine remote measurement, remote control and instant data communications with wireless networks.
By integrating wireless I/O into small field networks, medium plant operations or large supervisory control and data acquisition (SCADA) systems, operators can receive wireless sensor measurements, physical control and communications between remote controllers from a single device. The most common deployments use Modbus, or similar poll/response type data protocols to read and write I/O values.
In some simple installations, wireless I/O is used as direct wire replacement – the wireless communications link emulates wire in an existing application. No changes are required to the system architecture. Rather, wireless links are used to transmit the same data that the physical wire once carried.
In the applications requiring C1D1 certified technology there are I/O solutions that offer two analog inputs, including sensor power and two selectable digital I/O channels at 900 MHz. There is at least one wireless networking and communications provider who offers a solution that is backward compatible with any other radios by the manufacturer, including other Class 1, Division 2 (C1D2) radios.
This flexibility allows for easy integration into an existing solution and opens the door for a variety of options in a new deployment. Because these radios can transmit data more than 60 miles line-of-sight (LOS), they are easily incorporated into remotely located sites that require C1D1 certification. This saves money, time and the headache of trenching for wire placement over long distances.
Some C1D1 wireless data radio solutions also offer an integrated solar power system that eliminates the need for regular battery systems, significantly decreasing trips to remote locations for battery replacement. C1D1 certified wireless I/O radios are versatile and can be used for any application that requires the monitoring of analog values, including pressures, temperatures and tank levels.
Applications
Wireless I/O technologies are used for the monitoring and control of many data points on a common well pad. With increasing liquid production and the drive to consolidate wellheads on a single pad site, six to 10 tanks are common, and some installations having even more. Some wireless I/O providers can transmit tank levels for multiple tanks, allowing for a more cost-effective solution.
Essentially, wireless I/O takes the information from the wellhead or the tank back to the controller. The controller then processes the data and makes decisions which the wireless I/O data radio carries back to the valve or other control point. The valve opens, closes or does nothing, depending on the signal from the radio.
Wireless I/O is recognized as an effective and reliable way to monitor and control plunger lift, gas lift, rod lift and all forms of artificial lift systems. Many producers are now adopting it as an option for free-flowing wells before they need artificial lift and local controllers. Wireless I/O radios have the ability to transmit varying data straight to the SCADA systems at producers’ offices, allowing them to closely monitor casing, tubing and surface pressures. Producers also use the technology to view temperatures, pressures and alarms in the system miles away.
With a C1D1 certification, wireless I/O can also be used directly in hazardous areas where sensors are often hardwired. Every company is ultimately responsible for interpretation of what they consider C1D1 locations and U.S. and international hazardous location regulations vary slightly.
Operators may want to consider a solution that can easily communicate with an existing communication network, giving them the flexibility to use a wireless I/O solution, both for shorter distances, such as a well pad or to longer distances for direct links back to a SCADA network.
In oil and gas production, a C1D1 solution may be required to monitor the oil tanks at production facilities.
As any oil and gas producer knows, wherever there are tanks with oil, there also will be some amount of gas. With the presence of these gasses, it is critical for all of the devices on or around the tanks to prevent the creation of any ignition source. With a C1D1 wireless I/O solution, the operator can ensure the technology will be safe and has passed intensive testing that certifies that fire/explosion hazard is minimal.
While there are many requirements for C1D1 certification in oil and gas production, there can be potentially explosive gas anywhere along pipelines used to transport these hydrocarbons. Anytime an operator is dealing with a hazardous environment along the pipeline, a C1D1 I/O solution can offer safe monitoring, despite dangerous conditions. In these installations, I/O will be beneficial because of the elimination of wires and its ability to transmit reliable data, in real time and over long distances.
Selecting Right Provider
Choosing a wireless communications provider is essential in selecting the best fit technology for a hazardous environment deployment. A reputable technology provider will offer a variety of wireless networking options and will be dedicated to helping an operator find the most suitable option for their needs.
There are wireless providers that go beyond selling a product and offer complementary path study and network design services to ensure that the C1D1 technology easily integrates into the existing communication network. At the end of the day, it is up to the decision-makers to determine which technology is best-suited for them, but they should be sure they are aware of all of the options on the market.
Conclusion
While the causes and damages from pipeline explosions have varied from small contained fires to the devastation of homes and the loss of lives, this remains clear: by monitoring the pipeline with a properly installed communication network, issues can be identified and resolved early. While there is no way to completely eliminate the potential for pipeline catastrophes, taking preventative measures is the best way to reduce the number of incidences and minimize damage.
By using a certified C1D1 wireless I/O solution an operator or producer can receive real-time updates from the pipeline and production facilities that could enable them to act before an incident occurs.
Author: Glenn Longley is a manager at FreeWave Technologies in Boulder, CO. He is working on a master’s degree in business administration from Leeds School of Business, University of Colorado at Boulder and holds a master’s degree in software engineering from Portland (OR) State University.
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