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Analysis

Automatic Leak Detection System

Wed, 01/25/2012 - 14:03

Environmental, safety and economic issues have created a consistent need for eective leak detection solutions, one of which is LeakNet. “We chose LeakNet because it uses conventional instruments for the oil industry,” says Gustavo Pastrana Ángeles, Director General of SITEPP. “In leak detection, you have fibre optic, ultrasonic, and software solutions that understand how the pipeline works and if something is wrong, they can assume where the leak is. But the LeakNet technology is very simple. A pressure detector and flow meter on each side of a pipeline are set up to detect potential leaks. The technology limit as tested here in Mexico is 120km, which is very long. It’s a very simple principle and the technology is patented.”

LeakNet provides automatic leak detection in both flowing and static conditions, and can be used for gas, liquid and multiphase pipelines and storage tanks. It incorporates two leak detection methods into one o-the-shelf package: Pressure Point Analysis (PPA) and MassPack.

PPA detects leaks from holes as small as 1.6mm, and leak rates of less than 0.1% of flow, using data taken from a single measurement point. Additional points improve performance, but are not necessary for the technique to work. Based on research into the behaviour of energy and momentum balance on a pipeline before and after a leak occurs, PPA works by analysing pressure and velocity measurements.

MassPack is a mass balance system that incorporates dynamic correction for changes in line pack. The flow through a protected segment of a pipeline is monitored, and once per minute the mass flow error is computed and accumulated. When the accumulated error indicates fluid is being lost, an alert is sent to the pipeline operator. The system works on the principle that pressure changes aect the quantity of fluid packed into the line. Pressure at each end of the protected segment of the pipeline is monitored and used to compute what changes in pressure have occurred between the beginning and end of the segment. Both MassPack and PPA can be used individually for leak detection, but deliver more accurate results when applied in tandem.

Each LeakNet system incorporates an intelligent alarm processor called SmartPoint. This system allows companies to build alarm systems according to their needs, from fast and fail-safe alarm schemes to conservative, false-alarmfree schemes. Taking data from both MassPack and PPA systems, the SmartPoint alarm system is set up to alert the operator once a certain number of conditions have been reached.

As Pastrana Ángeles explains, “LeakNet is the most-used positioning system in the world. It’s working for every American company in the oil industry and it’s what the US government chooses for the strategic reserves, the Air Force and for very tough industries. It has been on the market for more than 35 years and it’s a very ecient, proven, and simple technology.” The only issue in Mexico, continues Pastrana Ángeles, is finding a cost-ecient communications system to connect the leak detection system to real-time monitoring stations.