Energy Risk Engineering Insights

In the natural gas distribution industry, underground leaks can be devastating. Or they can be harmless. The industry has techniques to detect underground gas leaks and when someone smells gas, everyone knows that the leak must be found before harm comes.

Fire main leaks can seem harmless. The problem comes when the leak causes the compacted soil beneath the pipe to erode away, leaving cavernous voids in some cases. The unsupported pipe may stay suspended for years before it’s needed for full flow or a water hammer occurs, like in the delay of a secondary fire pump starting. So just when we need the fire main the most is when it’s likely to fail. When a fire main fails, the consequences are not just an uncontrolled fire. The massive amounts of fire water will cause a large hole to develop which if near a process structure could cause collapse.

So the leak is the pre-cursor and we can determine if the collapse danger is present by looking for voids. A leak with no voids could be prioritized lower than one with a large void. Lower priority leaks should be resurveyed periodically until repaired.

The following is an AI refined proposal for a protocol to survey industrial facility fire mains for leaks.

Triggers for Leak Investigation:

1. Jockey Pump Cycle Times:
   • Monitor variations in jockey pump cycle times.
   • Deviations from established norms could indicate potential leaks.
   • If the jockey pump runs continuously, a bigger jockey pump is not the answer.
2. Flow Rate Anomalies:
   • Regularly measure and analyze flow rates in the fire mains.
   • Unexplained drops or fluctuations may signify leaks.
3. Pressure Fluctuations:
   • Track pressure changes within the fire mains.
   • Sudden drops or spikes may indicate a leak or compromised integrity.
4. Visual Inspection:
   • Periodic visual inspections of exposed sections for signs of corrosion, moisture, or discoloration.
   • Look for water surfacing near a fire main, especially a hydrant or PIV.

Using Ultrasonic Listening Equipment for Leak Detection:

1. Equipment Setup:
   • Deploy ultrasonic listening devices strategically along the fire mains.
   • Ensure proper calibration and sensitivity adjustments.
2. Data Collection:
   • Regularly conduct systematic scans using the ultrasonic equipment.
   • Record and analyze sound patterns for anomalies.
3. Identifying Leaks:
   • Anomalies such as hissing or turbulent flow sounds may indicate leaks.
   • Correlate findings with trigger events for targeted investigation.
4. Localization:
   • Use multiple sensors to triangulate the location of detected leaks.
   • Pinpointing exact locations enhances precision in repairs.

Ground Penetrating Radar for Voids Assessment:

1. Equipment Calibration:
   • Calibrate the ground-penetrating radar for the specific soil conditions.
   • Adjust frequency and power settings accordingly.
2. Void Detection:
   • Conduct systematic scans along the fire mains.
   • Interpret radar reflections to identify potential voids or air gaps.
3. Prioritization Criteria:
   • Prioritize voids based on proximity to critical infrastructure.
   • Consider void size and potential impact on fire main integrity.
4. Integration with Ultrasonic Data:
   • Overlay void data onto ultrasonic leak detection results.
   • Correlate void presence with potential leak sources.

Further Investigation Prioritization:

1. Risk Assessment:
   • Evaluate the overall risk posed by each identified void or leak.
   • Consider consequences, probability, and criticality.
2. Critical Infrastructure Proximity:
   • Give priority to voids or leaks near critical equipment or densely populated areas.
   • Minimize potential impact on operations and safety.
3. Quantitative Analysis:
   • Use quantitative data from both ultrasonic and radar assessments.
   • Develop a scoring system for prioritizing repairs.