No metal is immune to corrosion. Bare steel corrosion occurs if it comes in contact with a corrosive element in the atmosphere. Corrosion can be explained as the chemical or electrochemical reaction between a metal and its environment that results in the gradual degradation of that metal and its properties. In steel, corrosion occurs when the protective coating or galvanization of steel gets eroded leaving the bare metal exposed to air and moisture. Besides corrosion, exposure of steel to moisture gives rise to oxidization of the metal, commonly known as rust.
The different kinds of protective coating that are commonly used to protect steel from getting corroded are:
Galvanization
Contemporary steel pipes are used with either an aluminum or zinc alloy as the principal coating material as these have proven to show high resistance to corrosion over long periods of time.
Emulsions
These can either be water-based or oil-based and are the most effective metal coatings against rust buildup in most industrial in-plant setups. However, these coatings need to be reapplied at regular intervals and are primarily used on machinery parts that are frequently exposed to high temperatures.
Powder-based coatings
Powder coating is applied to steel during the manufacturing process. However, to effectively bond chemically to the steel, it requires either heat or pressure (or both) treatment.
Water-based coatings
Water-based coating commonly requires to be reapplied at regular intervals for prolonged protection against corrosion, and it usually does last several years.
Solvent-based coatings
Solvent based coating also requires timely reapplication, generally in the 5 to 10 years’ time frame.
The type of coating to be used depends a great deal on what the end use of the pipe is going to be. For steel pipe suppliers, storing these pipes carefully becomes a great challenge as it is difficult to keep them from coming in contact with the environment. A lot of steel pipe suppliers tend to store fittings made of stainless steel. These types of fittings are the most commonly used alloy steel pipe fittings which offer more resistance to corrosion, stains and rust. Mentioned below are a few more pointers for storing steel pipes and other steel products in a way that prevents their corrosion.
Change the Environment
As stated above, corrosion is caused between metals and the gases and moisture's in the environment. One of the ways of curtailing corrosion is by either removing the metal from such an environment, or modifying the environment to suit the metal, thereby preventing its deterioration. If you stay in a tropical/coastal region, it will serve you well to simply store metal indoors tightly wrapped in plastic or paper covers and use dehumidifiers every once in a while.
Change the Metal
If changing the environment is beyond your control, how about changing the metal! Various alloys have been developed using a combination of metals that make the final product stronger and non-corrosive. Some examples of such alloys are nickel and titanium which are used most commonly. However, care needs to be taking in combining the metals as reactive metal combinations can spell doom for creating alloys.
Look for Vulnerable Surfaces
The condition of the surface of the metal can also either prevent or accelerate the metal corrosion process. Watch out for cracks, crevices or an uneven surface on the steel product as these can easily be caused by their constant or incorrect usage or due to inherent manufacturing flaws. These factors can increase the rate of corrosion in your metal. There are certain things that can be done to decrease the occurrence of such surface conditions. Regular checks, cleaning and coating of metals can help to a great extent.
Sacrificial Coating/ Anodizing
Another way of protecting metals from corrosion is by the process of sacrificial coating, which involves coating a metal surface with another metal that is more likely to be oxidized.
In anodizing, the metal is dipped in a particular solution, and electrochemical conditions are adjusted so that tiny holes appear in the metal's oxide film. This results in the buildup of a thick protective layer around it, which is tough and robust to be corroded.
Inhibiting Corrosion
Certain chemicals can help in preventing corrosion by interrupting the chemical reaction with either the metal’s surface or the moisture and air in the environment. These chemicals are called corrosion inhibitors. These chemicals can be applied on the metal as a protective coating and they work by forming a protective layer or film around it.
To Conclude
Although one cannot completely stop corrosion in steel, with the above mentioned measures one can at least slow the process down to a great extent. These tips will prove to be especially beneficial to steel pipe suppliers who supply/store pipes that are used in transporting water, fuel, gases and chemicals.