Different types of corrosion within steel structures

If you are one of the steel structures South Africa companies, it is imperative that you have knowledge about a very important factor called corrosion. If you render your services and erect the steel structure for a client, it will be a bad portrayal of your professionalism if your product rusts or corrodes after even the first rains or adverse weather conditions. Here are some types of corrosion and how to combat them.

The process of corrosion is when the metal reacts with the environment and produces rust that slowly eats away at the metal and would, after years of corrosion, either have to be totally retreated or replaced as a whole. This could lead to large damages to the structure and high costs to rectify the problem. The best way to go about this is to use the best possible pre-treatment upon installation.

With dry corrosion, metals carry a thin oxide layer that forms when it is exposed to the atmosphere. Increases in temperature results in the layer detaching. For this you will have to use a coating that consists of zinc that will increase the thickness of the oxide layer slowly and thereby prevents it from detaching from the surface.

With wet corrosion, metals with lower oxygen supply will be more susceptible in areas with the humidity exceeding 60%. This will also happen in areas where the atmosphere contains salts.

There are many types of actual corrosion that are subdivided into their form of occurrence.

• General or uniform corrosion is where the whole area rusts at once.

• Local corrosion is where only parts of the steel structure rusts at a higher rate than other parts. Local corrosion are then divided into different areas.

• Pitting corrosion is where the effect of the rust has left a mark of permanent damage such as a small piece that has rusted totally away.

• Crevice corrosion is where a certain area is permanently covered by deposits such as trash, causing small cavities in the area.

• Galvanic corrosion is where two different metals that are far from each other in the galvanic series, causing damage in that certain area.

• Intergranular corrosion is a rust that runs along the metal grain boundaries.
  Stress corrosion is where a metal is permanently exposed to different types of stresses which could cause a fracture in the long run.