The ceramic coatings solution offered by local thermal coatings supplier General Thermal Spray has caught the attention of State-owned power utility Eskom, as it is designed specifically to combat erosion or corrosion in coal-fired boilers at power stations.
The coating, applied by airless spray, has been proven to extend the service life of boilers by more than ten years in the US, where it has been in use for over ten years.
General Thermal Spray MD Howard Shaw says the ceramic coatings are under consideration by Eskom for a pilot project at one of its stations.
“Hopefully, when convinced that the coatings work, Eskom will apply the solution to all its stations over time,” he says.
Shaw believes that the new range of ceramic coatings will dramatically extend the life of the boiler tubes and, therefore, reduce maintenance and downtime, which will prevent power outages.
General Thermal Spray is the local distributor for original-equipment manufacturers based in the UK, the US and Europe.
“The equipment that produces the coatings is expensive and South Africa has a relatively small market; therefore, it is not feasible to develop a local production base,” Shaw states.
The coatings are used by a range of industries, including the aerospace, chemicals, crude petroleum, natural gas, pulp and paper, shipping, textile and tobacco industries.
The thermal spray coatings incorporate metal spray, powder spray, arc spray, plasma spray and high-velocity oxy-fuel (HVOF) spray.
“As a result, a relatively thin coating of a specific material can be applied to a low-cost base material to extend the life of the product, while limiting the cost of coating. Many components in today’s industry are allowed to wear only a small amount before they are considered scrap, so it makes sense to use a relatively thin overlay on an inexpensive base material,” Shaw explains.
Most of the coatings are applied quickly at a base component temperature of between 100 ºC and 200 ºC.
Shaw says the coatings are readily accepted by industry, especially the newer HVOF spray, while the carbide coatings contribute to a dramatic increase in component service life.
“We hope that the coatings industry continues to grow, owing to this range, and that engineers are prepared to test the coatings in aggressive environments,” he concludes.