Cellular provides cost-effective addition to satellite SCADA system

  • March 06, 2011
  • ProSoft Technology, Inc.
  • Case Study

By Adrienne Lutovsky, ProSoft Technology - March, 2011 Once named the oil capital of the world, Tulsa, Oklahoma rests near the foothills of the Southern Ozark Mountains. Winding among these wooded hills and across the open wheatlands toward Medford, Oklahoma more than one hundred miles away, lays a Liquefied petroleum gas (LPG) pipeline belonging to a midstream oil company. The organization handles over 3 million barrels per day of crude oil, refined products and LPG through an extensive network of pipelines throughout the Midwest. Nationwide, pipeline operational data is monitored in real-time from the company’s office control center in Texas. For security, safety, and real-time accessibility, all critical data is transmitted via satellite to the SCADA control center. To improve line integrity, the engineering team responsible for this one hundred mile LPG pipeline wanted to increase monitoring for some non-critical data points at 12 PLCs along the length of the pipeline. The crux: how to do so when their standardized satellite solution would be cost-prohibitive for these non-critical, low data transfer locations. Without additional monitoring points, they were left with visibility at only three points on the pipeline. In the event of a leak, discovery requires an operator to physically drive the entire length of the pipeline between point A and point B to locate the leak, which in this case could be anywhere along a 20, 30 or 40 mile stretch of pipeline. From a line integrity standpoint, having nothing in between these points meant less resolution as to what was happening on the pipeline, and though leaks are rare, when they occur it’s essential to find and isolate them quickly; for the safety of personnel, collateral, and the environment. With the plethora of wireless products now available, the engineering team began investigating alternatives to satellite for these non-critical locations. “When I was first approached about this opportunity, I immediately thought of ProSoft,” comments Brian White from Rexel Distribution. “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.” Solution Originally, 900 MHz industrial radios were considered for these stations, because of their long-range capabilities and ability to penetrate foliage. Because of the dramatically different landscape, however, a site survey concluded that of these twelve locations, three lacked the required line-of-sight. To bring these sites onto the network, towers would have to be built, which would have brought the cost of implementation close to a hundred thousand dollars, rendering yet another solution infeasible. Luckily, every site had cell service. “Cellular technology is fantastic for real-time network access to industrial devices around the world,” explains Jim Weikert, Wireless Product Marketing Manager at ProSoft Technology. “This application highlights the ease with which devices in remote areas can be made accessible at an affordable price.” The company went with cellular GSM (or Global System for Mobile Communications) serial modems on an AT&T contract. Doing so, they were able to bring the site cost down from a potential $200 monthly satellite fee at each of twelve locations, to $50 per month, and with very minimal hardware costs. Implementation Challenges Within three weeks from the time the order was placed, the radios were onsite. Installation was a challenge for the company only in that they had never worked with cellular. When they began the setup process, ProSoft Technology’s technician engineer, Dan Blome, walked them through the process and with 15 minutes of setup per device, had the radios talking. Results The cellular radios are scattered along that length of the pipeline, monitoring line pressure and valve statuses along the way. Each radio is wired to a PLC via serial Modbus, gathering information from their remote locations. A thirteenth cellular radio is connected to the satellite network, relaying data from all twelve points back to the control center in Texas. By adding these data points to the network, the company was able to minimize risk while keeping the application safe and operational. In fact, using cellular has enabled them to pinpoint line pressures to 5 mile intervals versus 40, so should pressure drop off between two of these points, they can quickly isolate leaks with as little impact as possible. The Future Since this initial project, the company has begun two other similar projects. The first involves five cellular radios along a crude oil pipeline that runs from terminal-to-refinery. The second is an identical application involving two cellular radios.

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