­­Cellular-communication monitoring can improve coverage and reduce cost

A midstream oil and gas company installs cellular-radio technology to boost its monitoring system along a 100-mile oil pipeline near Tulsa, Oklahoma.

Once named the oil capital of the world, Tulsa, Oklahoma, rests near the foothills of the Southern Ozark Mountains. Wending among the wooded hills and across the open wheat lands toward Medford, more than 100 miles away, is a liquefied petroleum gas (LPG) pipeline owned by a midstream oil company based in Houston.

The organization transports more than 3 million barrels per day of crude oil, refined products and LPG through an extensive network of pipelines throughout the Midwest. Its pipeline-operational data is monitored in real-time from the company’s SCADA control center in Houston. As part of its operation, critical data is transmitted via satellite to the control center to ensure security, safety and real-time accessibility.

In 2009, the pipeline operator wanted to improve its pipeline-leak integrity system along a 100-mile LPG pipeline. The driver for improvement was its desire to reduce, as much as possible, any response delay in the event of a leak. The company knew that, although leaks are rare, when they occur it’s essential to locate and isolate them quickly to protect the environment and personnel and to reduce expense.

To that end, management tasked an engineering team to find a way to increase its monitoring capability for some non-critical data points at 12 PLCs along the pipeline’s route.

The challenge

By using ProSoft’s cellular-based Global System for Mobile Communications, an operator was able to pinpoint its line pressures along an LPG pipeline to precise five-mile intervals, versus its previous 40-mile interval.

On this pipeline, any time a leak is detected, a worker is required to personally travel along the length of pipeline between at least two other monitored locations. Due to the spread of the existing monitoring systems, the driver would search for the leak along a 20-, 30- or 40-mile stretch of pipeline. By adding 12 additional data points along the pipeline, however, the company would be able to pinpoint a leak within five miles, dramatically improving its ability to isolate the leak with little impact.

Looking at today’s plethora of commercially available wireless products, the engineering team began investigating monitoring technologies. As part of the study, the company contacted Rexel Distribution, a provider of technology solutions. Brian White, sales representative for Rexel, started looking at options.

“When I was first approached about this opportunity, I immediately thought of ProSoft,” comments White. “With its extensive line of products and services and history of assistance to Rexel in Oklahoma, I felt confident they could provide a viable option for this application.”

ProSoft Technology, based in Bakersfield, California, specializes in communication-linking solutions to bridge various automation products from other suppliers’ controllers, such as those provided by Rockwell Automation Inc. and Schneider Electric SA. These connectivity solutions allow various systems to work together as seamlessly as if they were all manufactured by one supplier. The capability streamlines systems expansions.

As a first step, 900-megahertz industrial radio stations were considered for 12 locations along the line. The 900-megahertz frequency radios are preferred due to their long-range capabilities and ability to penetrate foliage. However, because of the dramatically changing landscape along the route, a site survey led to the conclusion that, of the 12 locations, three lacked the required line-of-sight for optimal electronic communication.

To alleviate the problem and bring the sites into the satellite network, communication towers would have to be built for the three sites. Construction and implementation costs for those were estimated to be about $100,000.

Meanwhile, during the search for alternatives, the engineering team discovered that each station site was in an area that had available cellular-communication service. Mark Ewing, regional area manager for ProSoft, saw an opportunity to use cellular communication as a viable alternative to satellite-radio towers.

“Cellular technology is fantastic for real-time network access to industrial devices around the world,” Jim Weikert, wireless product marketing manager for ProSoft explains. “This application highlights the ease with which devices in remote areas can be made accessible at an affordable price.”

The solution
After careful analyses of several possible systems, the company decided to try ProSoft’s cellular-based Global System for Mobile Communications. The system uses serial modems based on an AT&T contract, though ProSoft offers serial and Ethernet options for both AT&T and Verizon networks. In the U.S., modems can be pre-activated on service plans structured specifically around the needs of industrial users. In this case, the company chose RadioLinx Intelligent Cellular Serial Modem for Global GPRS/GSM (RLXIC-SG).

The RLXIC-SG has a compact form, low power consumption and is Class I Div 2 certified for hazardous locations. Its applications include SCADA for oil, gas, water, wastewater, and electric utility automation, as well as remote equipment monitoring, management and control.

The implementation plan called for 12 cellular radios to be positioned along the length of the pipeline to monitor line pressure and valve status. Each radio was wired to a PLC via a serial Modbus interface to gather and transmit information from each remote location. An additional cellular radio was connected to the satellite network to gather data from all 12 points and relay it back to the control center in Texas. Within three weeks from the time the order was placed, the radios were onsite.

The pipeline operator realized that learning and working with the new system could be problematic because the company did not have prior experience with cellular-based monitoring systems. So, to provide support for the set-up process after installation, ProSoft’s technician engineer, Dan Blome, worked with one of the onsite pipeline engineers through the set-up process. As a result, the radios were up and running communications within 15 minutes of setup per each device.

Conclusion
By adding these 12 additional data-gathering points to its SCADA network, the operator was able to minimize cost while maximizing the safety and operations of the pipeline. In fact, using the cellular system has since enabled the company to pinpoint its line pressures along the LPG pipeline to precise five-mile intervals, versus its previous 40-mile interval.
Going forward, should the pipeline experience drop-off pressure between any two data-gathering points along the system, the company can quickly isolate leaks with as little time and environmental impact as possible.

Also, the cellular-communication system reduced satellite fees to about $50 per month, a significant savings from potentially $200 per month, at each of the 12 discrete locations. The solution minimized hardware costs as well.
Since the initial project, the oil company has undertaken two similar projects. The first involves installing five cellular radios along a terminal-to-refinery oil pipeline. The second is a similar application involving two cellular radios.

Adrienne Lutovsky is a staff writer for ProSoft Technology (www.prosoft-technology.com).