Revamps 2026 Issue

These results indicate that the alloy cladding maintained its integrity under operating conditions over the inspection period. In contrast to previous coating systems, which exhib- ited degradation at each inspection cycle, the HVTS applica- tion demonstrated consistent performance over time. Robust barrier This case demonstrates that coating performance in corro- sive environments is strongly influenced by coating density, adhesion strength, and resistance to permeation. While conventional thermal spray coatings may provide adequate protection in less demanding environments, their perfor- mance can be limited in systems where: • Process fluids promote aggressive corrosion mechanisms. • Coating defects allow ingress of corrosive species. • Repeated thermal or operational cycling affects adhesion. In this application, HVTS provided a more robust barrier due to its dense microstructure and higher bond strength, reducing the likelihood of coating failure mechanisms observed previously. It is noted that the selected approach was appropriate because structural repair was not required. In cases where wall thickness has fallen below allowable limits, alterna- tive methods such as WOL may be necessary to restore mechanical integrity. Case study 2: Alloy cladding across refinery assets A major Japanese petroleum company operating multiple refinery sites experienced persistent corrosion-related challenges across a range of critical process equipment. Routine inspections identified coating degradation, local - ised pitting corrosion, and recurring maintenance require- ments in several units. Previous thermal spray coatings had been applied in var- ious locations. However, these systems did not consistently provide sufficient resistance to corrosion, particularly in environments involving hydrocarbons, H₂S, ammonia, and elevated temperatures (see Figure 5 ). Given the diversity of equipment, operating conditions, and degradation mechanisms, a site-wide evaluation was

Figure 4 HVTS inspection in 2025 (good condition)

conducted to identify appropriate mitigation strategies for each asset. Technical challenges The project encompassed multiple assets across three refinery sites, presenting several technical challenges: • Variation in operating conditions, including temperatures up to approximately 370°C and pressures exceeding 8 MPa. • Exposure to aggressive process environments, includ- ing hydrocarbons, H₂S-containing streams, ammonia, and mixed-phase fluids. • Presence of existing coating failures and localised pitting corrosion. • Complex internal geometries and restricted access in vessels, columns, and heat exchangers. • Requirement to execute work within defined turnaround schedules. These factors required a flexible and engineering-led approach to repair and corrosion mitigation. Engineering approach Rather than applying a single solution uniformly, an asset-specific approach was adopted. For each compo - nent, the following factors were evaluated:

Figure 5 Condition of several vessels before HVTS application

Revamps 2026