Pipeline leak incidents have serious consequences:
- Threat to human safety
- Damage to the environment
- Damage to property
- Damage to reputation
- Financial loss through fines and clean-up costs
Even an arguably small release could cause a devastating effect on the local area, particularly if the product enters the water system. An example of this is the 2014 leak from China’s biggest oil company, China National Petroleum Corporation. The contamination affected 2.4 million people after entering the water supply¹.
The U.S. Department of Transportation’s 2012 Leak Detection Study² reports that between 2010 and 2012 the maximum volume for a ‘release incident’ reached 843,444 gallons for hazardous liquids, 614,257 MSCF for natural gas transmission lines, and 25,555 MSCF for natural gas distribution lines.
With the risk of fatality, serious environmental damage and clean-up costs, it is important that pipeline operators have a leak detection system they can rely on.
To provide maximum support to pipeline operating companies, a leak detection system should:
- Detect leaks quickly
- Locate leaks accurately
- Issue minimal false alarms
- Be easy to retro-fit
- Work effectively under all operating conditions and
- Use sensors with high reliability and low maintenance
When selecting a pipeline leak detection system, operators may choose from a number of systems using different physical principles. Although initially a bewildering task, the particular pipeline topology and performance requirements may dramatically reduce the number of systems that can be applied. With leak detection systems there are trade-offs between many of the characteristics. Atmos recognizes that one size does not fit all. As a result Atmos provides multiple leak detection products to suit every pipeline, which in some instances can be implemented together. Combining systems means that the operator is getting the best features from each, making a faster, more accurate and reliable leak detection system.
Atmos Leak and Theft Detection Suite includes:
Atmos Pipe employs Atmos’ unique statistical volume balance method to provide an extremely reliable leak detection system that can detect both onset and existing leaks.
Atmos Pipe has the ability to identify operational changes in the pipeline and can detect leaks during transient operations. Data validation algorithms and filtering techniques are employed to improve data quality. Flow measurement errors are also learned to assist in the provision of reliable and sensitive leak detection.
Atmos Wave detects the rarefaction wave caused by a leak in a pipeline. When a leak occurs, a rarefaction wave travels in both directions along a pipeline. Using fast response pressure meters Atmos Wave filters the pressure signals to find those with the frequency and magnitude of a leak. The time at which the pressure signal reaches each pressure meter is used to determine the location of the leak extremely accurately.
Atmos’ newest leak detection system uses elements from both volume balance and rarefaction wave methods. The sophisticated system uses a multi-element model to reduce uncertainty and improve performance. This provides accurate leak detection and location in a significantly faster time.
Atmos Tightness Monitor is a statistical tightness monitoring system used to test for leaks in airport hydrants. It uses sequential probability ratio test (SPRT) to detect changes in the overall pressure.
SPRT analyzes the pressure variation over a high pressure and then a lower pressure to confirm the tightness of a test section. The system does not require temperature sensors for leak confirmation.
Atmos SIM RTTM (Real Time Transient Model) leak detection continuously calculates the volume balance. This volume balance is obtained by calculating the total flow into the system minus the total flow out of the system corrected by the inventory changes calculated by Atmos SIM. The volume balance is statistically analyzed by the sequential probability ratio test (SPRT), which calculates the ratio of leak probability over no-leak probability. This ratio is then tested against certain threshold values to provide leak warnings/alarms. The combination of RTTM with the statistical analysis is also referred to as E-RTTM (Extended Real Time Transient Model).
Atmos SIM also monitors the discrepancies between measured and calculated pressures and flows. These discrepancies are processed by the sequential probability ratio test in order to generate reliable leak alarms.
1 China water contamination affects 2.4m after oil leak. BBC News.
2 U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration. Leak Detection Study – DTPH56-11-D-000001 Final Report. Page 32.