In response to an unexplained pressure drop in a municipal water system, NWE conducted a subsea ROV inspection of a 24-inch transmission pipeline. The aim was to detect leak points, verify the condition of previous repairs, and provide actionable recommendations to restore operational reliability.
Project Execution
The inspection was carried out with a Blueye Pioneer ROV equipped with HD video and high-intensity lighting, enabling effective assessment in low-visibility conditions.
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Initial surveys focused on a previously repaired nearshore branch, confirmed intact with no leakage detected.
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The ROV then advanced further along the submerged section, where detailed inspection of pipeline joints, coatings, and surrounding environment was performed.
Key Findings
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Critical defect identified: a 2-inch diameter hole on the pipe wall with pressurized water visibly escaping.
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No leakage at the previously repaired nearshore branch.
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Environmental hazards: sharp and angular rocks in direct contact with the line, posing risks of coating abrasion and long-term mechanical stress.
HSE Compliance
The entire operation was conducted under a dedicated HSE plan.
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Risk assessments were tailored to strong currents and low visibility.
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Safe launch and recovery protocols were implemented.
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The project was executed without incidents and with full compliance to international standards.
Conclusion & Recommendations
The inspection confirmed that the critical 2-inch breach was the main source of pressure loss. NWE recommended:
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Immediate underwater repair using a pressure-rated clamp or epoxy sleeve.
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Installation of protective measures such as concrete mattresses or rock shielding.
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Implementation of a regular ROV monitoring program supported by flow/pressure sensors.
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Conducting a hydro-environmental risk assessment to address current velocity, sediment movement, and flood risks.
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Development of a long-term rehabilitation and asset management plan.
Closing line:
This project highlights NWE’s expertise in providing rapid, evidence-based subsea diagnostics, ensuring safe and reliable water supply even in challenging conditions.
