Pipeline integrity, safety and environmental concerns are of prime importance in the Canadian natural gas industry. Millions of cubic feet of gas are transported all over the country on a daily basis. Maintenance of this vast pipeline network is an important responsibility of transmission companies. Aging pipes, shifting terrain, difficult river crossings.... all contribute to possible leaks in the system.
Terramatic Technology Inc. (TTI) has developed an integrated GPS/FID gas detection system known as TTI - AirTrac™ (Gehue, 1995) for use in airborne gas detection (AGD) (herein as AGD unit) along pipeline right-of-ways. The Flame Ionization Detector (FID), which has traditionally (and successfully for many years) been used to monitor air quality for gas plants and refineries, has been integrated with the Global Positioning System (GPS) via a 486 DX2-50 computer and specialized open architecture data acquisition software.
The purpose of this technology marriage is to be able to continuously monitor air quality during airborne pipeline inspection. Event tagging from visual surveillance is used to determine an explanation of any delta line deviations (DLD). These deviations are an indication of hydrocarbon gasses present in the plume that the aircraft has passed through. The role of the GPS system is to provide mapping information and coordinate data for ground inspections. When possible, if a DLD is detected, a repeat pass through the area is performed in attempts to confirm the original detection. If a second detection is evident then (if conditions permit) a ground inspection is performed using the Terra Gas™ (Gehue, 1995) multi gas detector (MGD) (herein as MGD unit). The GPS receiver and data acquisition software will time and position tag all information for post mission analysis.
If a DLD is unexplained then the anomaly is logged for post mission analysis to see if it is a candidate for a pipeline leak. Additional information collected onroute (we map all potential sites of DLDs such as gas plants, stock yards, sloughs ....) is compared to the DLD location to determine if further onsite inspection is required. If so, the co-ordinates are uploaded into a handheld GPS receiver (i.e., Magellan DLX-10) and a maintenance crew dispatched to the suspect location.
The ground based inspection using a handheld multi gas detector will confirm whether or not a leak exists. If a leak is detected then the maintenance crew can take action as dictated by NOVA Gas Transmission (herein as NOVA).
The test project performed by TTI and NOVA on Sept. 8, 1995 indicated that the integrated data acquisition AGD unit was capable of detecting DLDs and attaching a DGPS coordinate to this suspect location. Additional information from the flight confirmed that the DLDs detected came from sources such as gas plants and stockyards. Field inspection by TTI staff at two locations did not confirm that the existence of the unexplained DLDs. No indication of a gas leak from a NOVA pipeline was detected.
