Hot steam having continuous wet temperature around 100° C mixed with various casting chemicals is making it to be extremely corrosive by forming Hydro Fluoric Acid on Steam Fan casing surface. Suspended particles in the steam flowing at a high speed, also causing abrasion over the surface. Cyclic affect of chemical & abrasion attack on casing surface is leading to punctures in short periods, i.e. within 3 months of operations.
After disengaging the equipment from it’s operation, team ProCoat has carried out the surface preparation & coating application works. Initially the surface was blast cleaned thoroughly and checked for presence of contaminations. On identifying the presence of chemicals, relevant removal methods were carried out ensuring the surface is free from adsorbed contaminants. Blast cleaning was repeated again to attain the surface roughness of an average 100+ microns to Sa 3 Swedish Standards which was measured using the Elcometer Profile Gauge corresponding to near white metal finish which was examined using the shade card.
Over the prepared surface, ProCoat coating was applied using spatulas & synthetic rollers in order to deposit the material all over the surface uniformly. Two different coatings systems were incorporated for this application, an high end ProCoat Coating system was applied on the internal surface which not only provides resistance to corrosion but also the endurance to the accumulation of chemicals by the extreme smooth surface that the coating attains upon curing. The external surface was coated using ProCoat’s chemical resistant coating system to offer the best protection the metal surface from falling prey to the working environmental conditions.
Throughout the coating application works, the various quality checks were carried out in order to ensure flawlessness. Deposition of coating was examined using WFT Elcometer Gauge to ensure the thickness levels meet the desired recommendation, upon curing the coating thickness was verified using DFT Elcometer Gauge. Holiday Spark Testing was performed on either side of the casing to identify coating application errors and ensure rigid coating integrity.
The images on the right hand side corresponds to another steam fan casing that was coated using ProCoat Coating Systems which was examined to check after an operating period of 6 months. The observation has brought forward the intact characteristic of the coating offering required protection to the casing surface from the prevailing corrosive conditions.