Chemcote Specialty Coatings is the Australian applicator and distributor of Chemco International’s protective coatings. In 2015, they were contacted by representatives of a nearby steel production plant searching for a solution to issues with high temperatures and chemicals, which had taken a toll on many conventional coatings at their facility.
The coking coal transport wagons carry 1,000 °C [1,832.0 °F] coke to the quenching station, where 80 °C [176.0 °F] water is used to quench the coke used for export and local use,” explained Greg Bladowski, national manager for Chemcote. “The regular thermocycling of the coking process puts an extreme strain on protective coatings.”
Chemcote had worked with the steel plant for about 20 years in other departments, where they provided corrosion-resistant solutions mainly for immersion areas. “But this area where the hot coke is quenched during coal production was one where we hadn’t worked previously,” Bladowski said.
Major structural steel repairs were being carried out every two years or sooner in this area due to the aggressive nature of this environment, which exceeded the limitations of many traditional coating and lining systems. Thus, Chemcote’s expertise as both a coatings applicator and its relationship to the manufacturer made them a particularly strong candidate for this client. “Engineers had tried and tested many different coatings with varied results,” said Bladowski, who led a crew of two supervisors and six technicians and applicators on the first assignment.
Beating the Heat
Before Bladowski and his crew could begin their work, an initial priority was selecting the appropriate coating system for the extreme conditions. They also needed a coating technology low in volatile organic compounds (VOCs), given strict local environmental laws. Ultimately, they chose a two-coat system consisting of Chemco International’s Epo-chem RE 500P primer and Epo-chem RW 500 topcoat.
According to the manufacturer, the RE 500P is described as a 100-percent solids, zero-VOC, solvent-free epoxy, which works as a rust-tolerant primer for areas needing resistance to high temperatures and aggressive chemicals. Meanwhile, the RW 500 is a solvent-free, glass-flake-filled epoxy Novolac coating designed to be used in tandem with the RE 500P primer. Both coatings are applicable in levels up to 90-percent humidity, which was a major help on the coking coal wagon job, given the quenching process at the facility.
“It’s an ideal tank lining system, specifically designed for the aggressive combination of high temperature and chemical environments in immersed conditions,” Bladowski said. The primer is applied in one coat at approximately 100 microns (3.9 mils) dry film thickness (DFT), while the topcoat goes down at an average of 250 microns (9.8 mils) DFT. The two-part coatings include a resin and hardener, which are mixed at the application site.
For this client, both the surface preparation and coatings application phases each required two distinct strategies. The most efficient route to prepare the steel surface was via blasting, which the Chemcote crew did whenever possible to meet the NACE No. 2/Society for Protective Coatings (SSPC) Surface Preparation (SP) 10: Near-White Metal Blast Cleaning standards. They used abrasive blasting equipment and hoses from Australian manufacturer ABSS, along with blast hoods from Clemco as personal protective equipment (PPE).
However, in most cases, blasting could only be done on new steel fabrications, which Chemcote handled off-site in its shop. “Abrasive blasting is not always possible at the site, due to the time-critical schedules that we need to work to,” Bladowski said. “This is mostly while we’re working alongside other trades, boiler makers, fitters, and project managers.”
Thus, the crew developed a second preparation technique. For the larger, new fabrications it could handle at the shop, abrasive blasting was the choice. But for repairs of existing infrastructure at the site, they used hand tools such as a scabbler, needle gun, and Montipower’s Bristle Blaster to thoroughly remove all signs of corrosion. To access higher areas, the crew used scaffolding supplied by the client, along with harnesses with retractable lines as additional PPE. Generally, this type of on-site work was considered “spot repairs,” since it could be handled in a tight timeframe of four to eight days, including weekend work. This was to avoid costly plant outages and ensure that all equipment quickly returned to service.
Once the surface on a given asset was prepared, the crew would also use two distinct methods to apply the coatings. If in the workshop, they used an airless spray pump in even vertical and horizontal passes to seal the surface. But for on-site repairs, application was performed using hand tools such as brushes and rollers to coat just the critical areas. This, of course, allowed equipment to be returned to service faster. Hand trowels were used to fill pits.
The technical properties of the coatings themselves were also critical in enabling such flexibility. "The RE 500P is solvent free, which is always useful when working in tight areas on site and alongside other tradespeople during shutdowns," Bladowski said. "It was also selected for its property of strong adhesion to less than ideally prepared surfaces, as we were required to do in the spot repairs."
A PosiTector 6000 coating thickness gage from DeFelsko was used to verify appropriate thickness levels for the system, with the topcoat in the client’s desired gray color.
The big question, of course, was how the new system would hold up over a longer time period when exposed to the aggressive industrial environment at the steel production plant. So even when the crew completed its first job for the client in 2015, which was conducted at the site, the client and contractor weren’t completely sure as to the ultimate success of the project. But Chemcote regularly returned to the site to inspect their work in the months following, and they found they had identified the proper solutions.
“Most [prior] linings were breaking down and failing within a short period of time, between two and eight weeks of service,” Bladowski said. “After 12 months, our coating was still in good condition. They were happy with the longevity of our solutions in their waterboxes, condensers, and turbines. From there, the asset owner tasked us with coating the new fabrication of frames, which make up the walls of the structure.”
The Chemcote crew completed that second job in 2016, using the same two coatings and identical surface preparation methods, as appropriate. Since that job involved a new frame structure, they were able to do more work in the shop, which meant using more powerful resources such as blasting equipment and the airless spray pump. And once the success of the initial job was replicated, the crew suddenly found itself with a long-term client partnership!
“We are now regularly engaged to provide repairs on all crucial areas as they arise in service,” Bladowski said of Chemcote’s relationship with the client in 2019. “We also coat all new fabrications as they are replaced on the structure, to ensure that the lifecycle is extended and to minimize [maintenance] costs.”
Larger items, such as new fabrications, are planned well in advance and handled off-site due to the amount of work required. And for the smaller spot repairs, the crew has developed a relationship and routine that works for itself and the client. “We expect the freshly coated components to provide the most superior coating system used on the steel structure to date,” Bladowski said. “This saves the client a lot of money and reduces a lot of equipment downtime.”
With steely resolve but a flexible approach, this contractor beat the heat and formed a new partnership that continues to pay off after all these years.