IGS was invited to apply HVTS cladding to mitigate gas turbine corrosion caused by high-temperatures. The high efficiency, air-cooled gas turbine is installed at an electricity, water and gas authority facility in the Middle East.
High temperature gas turbine corrosion on unprotected casing surfaces causes wear and plugging. Protecting turbine components with high nobility cladding protects them from HT corrosion. This turbine’s upper and lower half OTS and CDC suffered base metal spalling challenges with a total affected area of more than 26m2 .
The initial condition of the turbine components was acceptable. Pitting was discovered on the upper half OTS after clean blasting. Minor pencil grinding was required for the upper half OTS substrate to comply with IGS’ surface acceptance criteria. No additional grinding was required on the upper half CDC and lower half OTS and CDC as the initial blasting application by IGS was sufficient surface preparation for HVTS application.
In compliance with the IGS Hexavalent Chromium Exposure Control Plan, the company utilized radial fans with ClearStream filtration systems containing a HEPA filter in the upper half and lower half enclosures that provided adequate ventilation. IGS installed and used special hexavalent contamination booths and protocols throughout the project execution to reduce the risk of external contamination within the work area.
IGS vacuumed and removed all hazardous material into drums for disposals. Used filters were placed in 6 hazmat filter bag modules and stored in the same location as the barrels containing the hazardous waste. Hexavalent Chromium measurements were taken at the ducting outlet of the upper half and lower half enclosure.
The High Velocity Thermal Spray (HVTS) process included true high velocity application using IGS’s proprietary Metalspray 3000 Low Stress equipment. This cutting-edge technology allowed IGS to apply cladding with much greater density and decreased permeability, while keeping internal cladding stresses low.
IGS achieved the smallest possible thermal spray particle sizes and applied them in as dense a pattern as possible. This type of application increases the distance of pathways leading from the surface of the thermal spray to the substrate beneath. Permeation levels were virtually eliminated and erosion resistance increased.
The project was executed successfully without any major issues or concerns. The gas turbine is now protected from oxidation, significantly reducing any future recurring maintenance costs.
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