Emergency Fired Heater Inspection Reveals Critical Coil Thinning After Rupture Incident
31 July 2025
When a rupture on a Stabiliser Tower Reboiler triggered a fire at a major Eastern Mediterranean refinery, the consequences were immediate and severe. While no personnel were injured, the damage to equipment and infrastructure was considerable, highlighting the urgent need for a thorough inspection of the affected fired heater unit.
Rapid Response to a Critical Incident
Cokebusters was called in within days to assess the condition of the heater’s remaining coil passes using our advanced in-line ultrasonic inspection technology. The ruptured coil, temporarily patched to prevent water leakage, was excluded from the scope. However, the remaining five passes underwent full inspection using our MK5 Smart Pig – a tool designed specifically for high-resolution data capture in fired heater environments.
Advanced Inspection Technology in Action
The MK5 Intelligent Pig offers significant advantages over traditional inspection methods. Its compact titanium design enables navigation through challenging coil geometries, while its array of 5 MHz ultrasonic transducers provides detailed measurements of wall thickness and internal diameter along the full coil length. The enhanced circumferential resolution – double that of its predecessor – ensures a higher probability of detecting localised wall loss, which is often missed during manual spot-checks.
All inspection data was processed through Cokebusters’ proprietary analysis platform, with expert technicians guiding every stage from on-site setup to final defect mapping and reporting.
Findings: Critical Wall Thinning Detected
The inspection revealed significant wall loss across multiple coil passes. Passes 3 and 5 showed the most severe degradation, with minimum wall thickness readings dropping to just 2.11mm – nearly 70% below the nominal specification of 7.10mm. Several instances of localised thinning were identified within individual tubes, particularly in Tube 9 of Pass 5, which exhibited six to seven discrete areas of severe internal corrosion.
Graphical plots and 3D visualisations of wall thickness data highlighted the clustered nature of this thinning, demonstrating how spot-check inspections might have easily overlooked these critical defects.
This internal diameter graph supports the conclusion that the metal loss was predominantly internal.
Key Learnings for Asset Integrity Management
This case underscores a vital lesson: scheduled in-line inspection is essential for fired heaters, particularly for units that have been revamped or have seen prolonged service without recent assessments. Traditional handheld UT methods, while valuable, often rely on selective sampling and can miss isolated yet critical defects.
By contrast, in-line ultrasonic inspection captures continuous data across the entire tube surface, offering detailed visualisation of corrosion patterns and facilitating more informed integrity decisions.
Although the ruptured coil pass could not be inspected, the findings from the remaining passes revealed that the failure was not an isolated incident but indicative of broader degradation. This insight enabled the client to take immediate action and plan for future inspections across similar assets.
This 3D visualisation of wall thickness data across the radiant section of Pass 3 highlights not only the extent of metal loss, but the clustered nature of the thinning, reinforcing the importance of full-coverage inspection in capturing localised corrosion activity that might otherwise be overlooked.
Proactive Inspection Prevents Unplanned Shutdowns
For many years our company slogan was ‘Around the Clock, Around the World!’ and to this day we make every effort to respond to be available to our clients 24/7 in case of emergency. Our ability to mobilise rapidly and deliver high-resolution data in complex coil geometries proved crucial in this emergency scenario.
This case reinforces the value of in-line inspection not only as a reactive diagnostic tool post-failure, but also as an essential proactive strategy for maintaining asset integrity and preventing costly unplanned outages.
Ensure your fired heaters aren’t hiding critical defects
Contact Cokebusters today to schedule an inspection and gain full visibility of your asset’s integrity, before small issues turn into costly failures.
Environmental Policy