Used for drainage, support, filtration, partition and enclosure formation, gratings are employed in many different environments and may be made of a number of different materials. Common metal grate materials that are pre-treated through galvanization include iron, steel and aluminum. Though these grates may be used without galvanization, this protective process improves the working lifespan of a grate in industries such as heating and cooling, refrigeration, architecture, power generation, automotive, walkway construction, marine superstructure, petrochemical processing, sewage treatment and waste management. The materials moving through these grate systems are often highly corrosive to even durable materials such as steel. Zinc galvanization provides an added layer of protection. While this layer, varying in thickness from 1mm to just over 4mm, will eventually corrode, the damage caused by corrosion is significantly slowed. The application of zinc is a relatively simple and cost effective procedure making its use popular for a variety of metal grating fixtures such as grills, grids, grip plates and grates, stair treads and drain grates.
Galvanization is most commonly achieved through a process known as hot-dip galvanizing. Essentially, this involves bathing iron or steel grates or grate components in molten zinc. Zinc is kept liquefied at temperatures near 860 degrees F. The metal articles, first cleaned with a light acid solution, are either dipped or fed into the zinc bath which forms a metallurgical bond with the substrate materials. When exposed to oxygen and carbon dioxide in the atmosphere, the zinc is cured and forms a layer of zinc carbonate that further protects the bars, mesh and sheets of iron, aluminum or steel grates. While traditional hot-dipping is still widely used, two additional techniques are growing in use and popularity. Electro-galvanizing passes an electric current through the zinc compound in order to create a thinner and more tightly bonded coating. The newest development is the environmentally friendly thermal diffusion galvanizing which eliminates the hazardous caustic and acid baths used in traditional methods. Rather than a molten bath, zinc powder is applied to grate components which are then sealed in a drum and processed through a rotary oven. Each technique produces spangle, either uniform or large grain, on the finished grate. Spangle is the appearance of a crystalline structure that gives the formerly shiny metals a dull grey appearance.