Composite wrap system combats corrosion in industrial tank repair

A global blue-chip nickel mine in Australia required a solution for repairing and preventing corrosion of its stainless steel ammonium sulphate feed tank, and industrial maintenance company Rezitech (Melbourne, Australia) was able to provide a full turnkey solution in the form of an industrial composite wrap system.

The mine refines granulated nickel matte from its smelter into premium-grade nickel powder and briquettes containing 99.8% nickel. Nickel powder is further processed into nickel sulphate at a refinery in Australia.

Nickel sulphate is an essential ingredient in the lithium-ion batteries that drive electric vehicles (EV). It could be argued that the increase in sales of EVs is one of the biggest climate wins of 2023. Indeed, according to the 2023 Report from Climate Action Tracker, of the 42 sectors which need to achieve net-zero status by 2050, the only sector which is on track is the share of EVs in light-duty vehicle sales. Considering how road transport currently accounts for 11% of global greenhouse gas emissions, EVs play a vital role in reducing these emissions.

As such, the polymeric technology required to repair and improve assets within the EV industry equally plays a vital role in supporting the transition to net zero. By repairing damaged assets instead of decommissioning and sending them to landfill, this significantly reduces the climate impact that would otherwise be incurred in this process.

The mine’s stainless steel ammonium sulphate feed tank, measuring 2 meters tall from ground level and 9.5 meters in diameter, was suffering from corrosion under insulation and chloride-induced stress corrosion cracking. The company required a solution that would not only restore the integrity on the substrate, but also protect the asset against future corrosion damage. Not only this, but as the tank operates at elevated temperatures of approximately 70°C and processes highly corrosive media, the repair solution would need to be able to withstand these harsh conditions.

Having already worked for more than five years with Rezitech, an authorized distributor of Belzona (Harrogate, U.K.) coatings and composites, the mine contacted Rezitech again for advice and a system recommendation. Following an inspection by Heath Westell, sales engineer at Rezitech, the composite wrap system, Belzona SuperWrap II, was specified.

“This composite wrap system is comprised of a fluid-grade epoxy resin system, a bespoke hybrid reinforcement sheet, based on fiberglass and carbon fiber, as well as a release film to compact and consolidate the application,” Heath explains. “The system is specially formulated to restore the strength of holed, weakened and corroded pipe and tank walls, making it the ideal solution for protecting the asset against corrosion under insulation for the long term. In addition, thanks to the cold-curing properties of the composite wrap system, this mitigates the need for hot work, making it a reliable alternative to welding.”

To perform this procedure, first, all traces of oil and grease contamination were removed using a suitable Rezitech degreaser. Next, the surfaces were grit-blasted to provide a surface cleanliness compliant with ISO 8501-1 SA 2½ (ASNZ 1627.4 class 2.5) with a minimum 75-micron (3- millimeter) rough angular profile. Once the surface was prepared, the dry glass/carbon fiber Belzona 9381 reinforcement sheet was measured out and then wetted out on-site with the Belzona epoxy resin system. The resin was then systematically applied to the areas to be repaired. Following this, the Belzona reinforcement sheets were then applied to the tank in three layers, and the compression film added to the top of the application area. Finally, using a roller, the Belzona SuperWrap II composite wrap system was spread, rolled and compressed to the surface of the tank. The system was then left to cure for approximately 8 hours.

The Belzona composite wrap solution enabled the customer to bypass the need to replace the corroded asset, and instead prolonged the lifespan of the asset for years to come. Thus, this enabled the customer to make significant savings in both time and money. In addition, given the important role EVs play in reducing global carbon emissions, it could be argued that polymeric technology also plays a fundamental role in supporting this transition by safeguarding the integrity of key assets within this industry.