The external surface of this decomposition boiler being exposed to chemical fumes comprising of sulphur, ammonia along with moisture and high temperatures has lead to corrosion over this aluminized equipment. Owing to these working conditions the metal surface has tremendously corroded, although it has been covered up with the aluminized paint system. Underneath corrosion with heavy metal loss is observed over the surface.
Preliminary arrangement to access the complete surface of this huge equipment was made by erecting a tailor-made scaffolding system with safety requirements. First round of blast cleaning was carried out to remove the loose rust flakes and old paint from the surface. Surface was scrubbed thoroughly to foaming using cleaning agents and water washed using a high pressure water jet cleaning. This was performed to neutralize the surface and make it free from the entrapped electrolytic chemical molecules.
In order not to expose the prepared surface to the continuously liberated chemical fumes of this process plant, the boiler was wrapped up all over by using a tarpaulin to minimize the effect of chemical impregnation. The neutralized surface was thoroughly blast cleaned again using copper slag abrasive medium to SA3 surface profile to an average surface roughness of 100+ microns to near white metal finish ensuring the surface is also free from adsorbed contaminants.
Over the prepared surface, ProCoat coating was applied using synthetic rollers and tynex brushes to the recommended thickness levels not exposing the surface for longer times to the expelled chemicals and prevailing humid environmental conditions. Intermittent checks were made using Elcometer WFT gauge to ensure the desired thickness of coating as per the requirements.
On completion of coating works the cured coating surface was checked for Dry Film Thickness using the Elcometer DFT Gauge & examined with Holiday Spark Tester to ensure tough coating integrity. This decomposition boiler is being protected convincingly from the adverse corrosion affect caused due to the electrolytic chemicals since year 2013.