Unless the pipelines are shut down immediately the damage could be catastrophic. Recent history is littered with examples such as the mechanical puncture of the US LPG/NGL pipeline that spilled 130,168 gallons of product. This resulted in the death of a member of the public, and injury to another. This event and many other incidents convinced the industry of the need for reliable rupture detection systems.
The 2012 DOT pipeline leak detection study states that if detection and shutdown is not acted on as soon as a rupture occurs, the consequences can escalate (1).
Leaks and ruptures should not be considered a single class of pipeline failure because they are not. When a pipeline ruptures, the volume of escaped fluid can be unavoidably large even if detection, response, and containment are performed very quickly.
A rupture alarm should not be treated like a leak alarm - any rupture alarm should trigger immediate shutdown of the pipeline. In contrast, because conventional leak detection systems search for very small leaks as well as ruptures, inherent uncertainties such as instrument error and hydraulic anomalies may cause a false alarm. Then the operator must take some time to confirm a leak alarm before shutting down the pipeline.
The leak size that can be classed as a rupture, and the time to detect that rupture depend on the individual pipeline. API RC 1175 states that what constitutes a rupture is determined on a pipeline by pipeline basis (2).
Slack conditions within the pipeline will likely increase the minimum size of the rupture that can be detected, and also may increase the detection time. Slack conditions must not decrease the reliability of a rupture detector. The promise must always be zero false alarms.
Robust rupture detection is not easy given challenges such as the diversity of pipelines, and the need to detect and alarm the rupture quickly, even when a pipeline is already shutting down automatically. The reference in API RC 1175 to address pipeline rupture detection in company leak detection programs means that companies who have not already done so will need to review their rupture detection methods in the near future. Fortunately, a robust system, inexpensive system is now available that can detect ruptures with 100% reliability, and issues no false rupture alarms.
Read about Atmos Rupture Detector here
1. SHAW D., ET AL. Leak Detection Study – DTPH56-11-D-000001. U.S. Department of Transportation, Pipeline and Hazardous Materials Safety Administration, Final Report, n. 12-173, December 2012.
2. American Petroleum Institute. (December 2015) Recommended Practice 1175, (First Edition), Washington, DC: Author