Why are used different raw materials for the same type of product?

The selection of the material to be used for the construction of the equipment is fundamental, whether they are installed in an industrial environment, or in an environment with danger of explosion due to the presence of gas.

This selection is a task for the designer of the plant where they must be installed, who knows the process variables and the presence of gas which, in addition to having a specific ignition temperature, has an aggressiveness such as to trigger a possible corrosive process.

For this reason, materials must be chosen not to be affected by such aggression.

For example, if stainless steel with concentrated sulfuric acid gases or vapors is used, it will not be corroded but if the sulfuric acid is in a diluted form at about 70%, the stainless steel will be corroded. In this case, it is necessary to use carbon steel that will not be corroded.

Similarly, if the choice falls on aluminum, it must be protected from corrosion with appropriate passivation before being painted if in the presence of salt fog.

For different reasons, related to the presence of substances such as grisou gas, the congenial material is cast iron or, alternatively, carbon steel.

Read the treaty "The materails suitable for hazardous areas"