Precision Laser Cleaning (PLC), engaged by a long-standing customer, was asked to assess the feasibility of removing paint from key internal areas of a spiral casing without turbine disassembly during a scheduled outage. The goal was to prepare the surface for Non-Destructive Testing (NDT) and subsequent repairs. This project highlights PLC’s innovative approach to surface preparation, delivering effective results while eliminating the need for turbine disassembly.
The Challenges
Traditional abrasive blasting methods for spiral casing paint removal typically require extensive disassembly of the turbine and rotor to provide access and mitigate the risk of dust and debris entering highly sensitive, low-tolerance components. While PLC had previously executed successful spiral casing cleaning projects, performing the work without disassembly was a first for both PLC and the customer.
Key challenges included:
Confined Space & Limited Access: Minimal clearance at the trailing edge of Stay Vanes, with tight gaps between guide vanes, presented significant access limitations.
Dust Control: The in-situ nature of the project increased the risk of dust and debris entering critical areas, including labyrinth seals, necessitating stringent dust mitigation strategies.
Equipment Access: All personnel and equipment had to be mobilised through limited manhole access points.
Time Constraints: The project had to adhere to strict outage schedules to minimise turbine downtime and ensure timely reactivation.
First-Time Execution: This was the first time PLC and the asset owner had undertaken such an in-situ cleaning project. Extensive planning and close collaboration were required to ensure project feasibility and success.
The Solution
PLC developed a tailored methodology to address the unique project requirements and overcome the identified challenges:
Deployment of Multiple Laser Systems: Netalux Jango 1000W Systems – Utilised for bulk paint removal from the Stay Vanes. These systems were positioned outside the spiral casing, with a 50m umbilical allowing precision access to internal areas. Netalux Needle 300W Systems – Mobilised internally through manhole access points for detailed cleaning of hard-to-reach trailing edges. The compact design and exclusive rotatable head on all Netalux Laser systems were critical to reaching these restricted areas.
Advanced Dust Control Measures: Industrial HEPA extraction systems, equipped with inline particulate and charcoal filters, were deployed to capture all paint fumes and dust directly at the source. This prevented contamination of sensitive areas and eliminated the need for post-cleaning site cleanup.
Specialised Team and Continuous Operation: A team of five highly trained operators worked in shifts using multiple laser systems, completing the project ahead of schedule.
Precision Surface Preparation: The pulsed laser technology selectively removed the paint layer without affecting the underlying metal substrate. This not only preserved the original surface profile but also enhanced the visibility of cracks and defects, significantly improving the accuracy of subsequent inspections.
The Outcomes
PLC’s innovative approach delivered exceptional results, providing tangible benefits:
Complete and Thorough Paint Removal: All paint was successfully removed as per the project scope, including hard-to-access trailing edges of the Stay Vanes. This was achieved without turbine disassembly.
Effective Dust Control: No dust or debris entered sensitive areas, including labyrinth seals. Direct inline dust and fume extraction eliminated the need for additional site cleanup, allowing immediate progression to the next phase of the outage.
Surface Preservation and Defect Detection: The non-abrasive laser cleaning process exposed the original blasted profile, maintaining substrate integrity. The enhanced visibility of defects and cracks facilitated more accurate and efficient inspections.
Significant Time and Cost Savings: By performing the work in situ over one week, PLC dramatically reduced turbine downtime. Traditional methods requiring full disassembly could extend outages by multiple months to a year.
Safe and Incident-Free Execution: The project was completed without any safety incidents, reinforcing PLC’s commitment to health and safety in challenging industrial environments.