Corrosion is the number one problem of the world especially when we talk about manufacturing industries. In this article we will be talking about what exactly corrosion is and what are the best possible ways for prevention of corrosion.
What Is Corrosion?
Corrosion is deterioration or wearing out of a material caused by interactions with environmental surroundings. It is a natural process, which requires three factors: moisture, a metal body, and an oxidizing agent which is also called a electron acceptor. The concept of corrosion is that this process makes the unstable metal surface into its more stable form, which will be its oxide, hydroxide, or sulfide. An absolutely common form of corrosion is rusting of iron.
Corrosion may cause a variety of negative effects on any metal and that is why we need multiple methods for prevention of corrosion. When any metal object goes through corrosion, they become very unsafe which may lead to many accidents, such as structure collapses. Even the minor corrosion requires full time repairs and maintenance throughout. In fact, an amount of approx 2.2 trillion USD is spent worldwide just for the maintenance and repair of corrosion.
While it is very evident that all metals corrode, it is calculated that 25-30% of corrosion could be prevented using methods mentioned below.
How to manage the Prevention of Corrosion?
Prevention of corrosion can be performed by selecting the right method mentioned below
- Metal Type
- Protective Coating
- Environmental Measures
- Sacrificial Coatings
- Corrosion Inhibitors
- Design Modification
So let’s talk about these methods in a bit of a detail
One of the simplest ways to have prevention of corrosion is to use a corrosion resistant metal which doesn’t get affected by the factors mentioned above. These metals are majorly alloys such as aluminum or stainless steel. Depending on their application, these metals may or may not be used to reduce the any other need for additional corrosion protection method.
Second on the list comes the method which is most commonly used. The application of a paint coating is a wonderful and very cost-effective way of preventing corrosion of any metal. Paint coatings generally acts as a barrier between the metal, moisture and the oxidizing agent to prevent the transfer of electrochemical charge from the corrosive bodies to the metal underneath.
Another way is to apply a powder coating. In this process, a layer of dry powder is applied to the clean the metal surface which is under supervision. The metal is then put under heat which then fuses the powder into a smooth unbroken permanent layer. A lot of different powder coatings can be used, including acrylic, polyester, epoxy, nylon, and urethane.
How to Check Environmental Measures of Corrosion ?
Number three on the list is one of the least used methods as it is quite expensive. So let’s get it straight corrosion is always caused by a chemical reaction between the metal and gases in the environment. By finding out and taking measures to amend or control the environment Corrosion, controlling these unwanted reactions is possible. This can be very simple like reducing seawater or exposure to rain, or more complex type of measures, such as controlling the amounts of elements in the air like sulfur, chlorine, or oxygen in the surrounding environment.
Sacrificial coating means that coating the effected metal with an additional metal layer type that is more likely to oxidize faster; hence it is called “sacrificial coating.”
There are just two main techniques in order to achieve sacrificial coating: cathodic protection and anodic protection.
One of the most common example of cathodic protection of the metal is the coating of iron alloy steel with zinc metal, this process is called galvanization. As zinc is a more active or reactive metal than steel, the moment it starts to corrode it oxides which block the corrosion of the steel hence give us a perfect example of prevention of corrosion. This method is also called cathodic protection because it works by putting the metal steel on the cathode side of an electrochemical cell. Cathodic protection is mainly used for steel pipelines which carry fuel or water, offshore oil platforms, ship hulls, and water heater tanks
The general concept of anodic protection is coating the iron alloy steel with a less active or reactive metal, such as tin. Tin will not corrode for sure, so the steel metal should be protected as long as the tin coating is in the right place. This method is called anodic protection because in this case the steel is on the anode side of an electrochemical cell.
Anodic protection is often used in order to make carbon steel storage tanks used for storing sulfuric acid and 50% caustic soda. In such environments cathodic protection is not a right choice due to extremely high current requirements. In such cases Anode Protection is the best way manage prevention of corrosion
Corrosion inhibitors are fourth in the list yet are second least method used. What happens in this process is that the chemicals are made to react with the metal or all the surrounding gases in order to suppress the electrochemical reactions and activities leading to corrosion. They usually work by being applied on the metal surface where they form a invisible protective layer. Inhibitors can be used as a permanent solution or as a over protective coating using a technique called dispersion. Corrosion inhibitors are usually applied through a process called passivation.
Passivation is a procees in which a light coat of a protective material or substance, such as metal oxide are used to create a protective layer over the metal which then acts like a barrier against corrosion. The creation of this layer is affected by many factors such as environmental pH, temperature, and surrounding chemical compositions. One of the most common examples of passivation is the Statue of Liberty, in which a blue & green patina coating has formed which actually protects the copper metal underneath. Corrosion inhibitors are majorly used in petroleum refining, chemical production, and water treatment works. It is a wonderful method of prevention of metal
Design modification is a process which can help reduce the possibility of corrosion and improve the durability of any existing anti-corrosive coatings. It is often done in the initial phase of setup as it involves a lot of cost Ideally these designs would avoid trapping dust and water, encourage movement of air, and avoid open crevices in order to make sure none of the factors combine together to initiate the process of corrosion.
In the end we would like to vote for either protective coatings or sacrificial coating as the resolves are purpose of prevention of corrosion and are extremely cost effective. But if you are just initiating the setup and want to design fresh then design modification should be your obvious choice.
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