PTQ Q2 2026 Issue

can effectively ‘freeze’ the remaining substrate integrity, preventing further acid attack without significantly altering base material properties. Moreover, this mechanical bond - ing-based application can proceed quickly during plant turnaround conditions, with typical application rates suffi - cient to enable large-area coverage within tight turnaround windows (see Figure 3 ). HVTS claddings have demonstrated service lives of 10-15- plus years in aggressive industrial service environments. This means that adoption now can delay or avoid full-vessel replacement or recurring weld-overlay maintenance, provid - ing significant lifecycle cost savings. In many case studies, these claddings have delivered 30-50% cost reductions compared to weld overlay, factoring in material cost, labour, PWHT, and shutdown duration. It therefore offers a high return on investment (ROI), lower total cost of ownership (TCO), and significantly reduced risk of unplanned shut - downs, aligning with the facility’s maintenance philosophy. Project execution methodology In one application, an HVTS system utilised controlled shield - ing to minimise oxidation during deposition, enabling dense, low porosity deposition at high particle velocity (see Figure 4 ). This high velocity ensures strong substrate bonding, a critical advantage over lower velocity arc spray methods. Cladding thickness was applied to a nominal thickness consistent with industry practice for HVTS acid service applications, sufficient to provide long-term corrosion pro - tection while maintaining metallurgical integrity. While maintaining an application schedule, cladding was applied using a continuous shift strategy over a short exe- cution window, with multiple passes used to achieve the required corrosion allowance (see Figure 5 ). The HVTS scope was integrated into the scheduled turn- around window without affecting critical path activities. No PWHT, bake-out, or extended downtime was needed, enabling re-commissioning on schedule. Detailed docu - mentation and cladding thickness maps were handed over to the maintenance/integrity team for future monitoring under RBI. Initial performance Structural integrity was maintained with HVTS cladding

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Figure 1 Thermal cycle

Technical justification The HVTS variant deployed was based on high-nobility, nickel-based CRAs, like those used in established HVTS ser- vices globally, and selected for their superior resistance to organic acids, chlorides, CO₂, and acidic condensate attack. Such CRAs are well understood in refinery, chemical, and petrochemical service for aggressive acid- and chlo - ride-laden environments. The asset owner conducted extensive internal prequalification testing of IGS HVTS alloys, with the selected material demonstrating very high resistance to localised corrosion, consistent with upper-tier nickel-based CRA performance (see Table 2 ). IGS HVTS cladding was tested in severe sour service environments (NACE TM0284), in a high-pressure hydro - gen atmosphere, and under thermal cycling at different temperatures (see Figure 1 ) by The Welding Institute (TWI). TWI has also performed an adhesion study exposing HVTS alloys to NACE TM0284/ASTMG146 thermal cycle in a wet H₂S environment (see Figure 2 ). IGS HVTS coupons were prepared for mock-up qualifi - cation testing to simulate representative field conditions. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to evaluate cladding integrity and compositional uniformity. Since HVTS is mechanically bonded rather than fusion- welded, the process avoids heat-affected zones (HAZ), distortion, and thermal stress in the substrate. The result is a dense, impermeable, corrosion-resistant lining that

Coating disbonding

200μm 25.00 kV

100μm 25.00 kV

Figure 2 TSC samples exposed to NACE TM0284/ASTM G146 sour service conditions and thermal cycling. Left: Conventional high-Mo nickel-based CRA overlay showing deg - radation. Right: HVTS cladding showing intact bond and microstructural stability

Figure 3 HVTS sprayed onto a process vessel shell

PTQ Q2 2026