OVERVIEW: The asset owner was looking at extending the life of the condenser tube sheet to prevent galvanic corrosion. We found the water boxes were also experiencing some deterioration. Chemcote were contracted to apply a coating with high insulating properties preventing long term corrosion.
40-60°C, brackish / sea water
8 Year Old – Mild Steel water boxes & Stainless Steel tube sheets
New tubes were installed in the condenser tube sheet made from an exotic Stainless Steel compared to the low grade tube sheet. We were asked to provide a solution with a coating with a high dielectric strength to prevent the galvanic reaction between dissimilar materials.
Tube internals were protected by inserting specially designed plastic caps on Inlet/Outlet and Return side of Water Box. This protected the condenser tube sheet.
A glass flake filled vinyl ester was applied to provide excellent permeation resistance and high dielectric strength.
The entire face was hot washed to remove any lubricants and other potential contaminants before abrasive blasting to ensure surface is clean and the correct surface profile is obtained
RB 300 was applied to tube-sheet face, followed by some other areas considered critical, such as the baffle plates, where the existing coating has failed due to under specification
Carried out high voltage spark test beyond Australian Standards to ensure coating integrity
The extended life of the coating is expected to exceed 20 years in service, the plant owner is requesting Chemcote to assist further with other corrosion related issues with nearby ancillary equipment.