Corrosion is a common occurrence in iron, as well as steel wire, sling and chain that have not been treated for protection against the elements, says corrosion control specialist Galvaspin owner Henning van Wyk.
Regular maintenance checks have to be performed on these materials to ensure corrosion does not occur. It is also better to fix early-stage corrosion before it weakens the material, which is a serious concern for end-users, he notes.
Depending on the application, corrosion could jeopardise the safety, functionality or efficiency of the end product, Van Wyk states.
Corrosion occurs in the presence of moisture – for example, when iron is exposed to moist air and reacts with the oxygen to form rust. The oxide formed through oxidation does not firmly adhere to the surface of iron and that of many other metals. It flakes off easily, causing pitting, he explains.
Extensive pitting eventually causes structural weakness and disintegration of the metal.
Van Wyk adds that the industry realises the importance of preventing corrosion in wire, sling and chain, but end-users need to maintain the material and prevent corrosion, or treat it in the early stages of formation.
He states that hot-dip galvanising can be an effective corrosion protection measure.
Hot-dip galvanising entails the application of a thin zinc coating to metal by immersing the object in a bath primarily consisting of molten zinc. This protects the steel, even if the surface is scratched, Van Wyk explains.
Galvaspin adds that hot-dip galvanising is not a costly process and that it is more cost effective to protect and maintain materials than to replace a weakened area in the material.
Meanwhile, Galvaspin has been contracted by local artist Wehrner Lemmer to protect his latest art piece against corrosion, as it will be displayed outdoors.
“This was an unusual request, as we have never worked on artwork before and it was something on which the team enjoyed working,” Van Wyk tells Engineering News.
Lemmer is known for his earthy Africa-inspired work, but plans to use more colour in his art.
Van Wyk explains that Lemmer wanted a paint finish on the piece.
Galvaspin chose thermal-metal spraying as the best option to allow for the best results in this specific type of coating. The process involves spraying items with a molten metal application that includes a zinc or aluminium alloy.
“We have thermal-metal-sprayed the sculpture to protect it from corrosion; the next process is to spray it with the artist’s colour of choice.”
Further, Galvaspin is currently involved in the ongoing coating of water pipes for the Buffalo City metropolitan municipality, in the Eastern Cape, and for the Colesberg municipality, in the Northern Cape.
Both projects involve the thermal-metal spraying of pipelines, which are used in the movement of water, to prevent corrosion and leaks as well as maintain a consistent supply of water for the areas.