Protect Your Valves: 5 Different Types of Metal Corrosion

Rust is a sign of deterioration. Technically, rust is a type of corrosion caused by a chemical reaction between metal and the environment.

But, corrosion is much more than an unsightly chemical reaction.

It can have expensive and even deadly consequences if it takes hold of industrial structures like bridges, ships, or airplanes. It’s estimated that corrosion carries a global cost of $2.5 trillion US dollars.

Luckily, many forms of corrosion can be prevented. Read on to learn the 5 types of corrosion and how to keep it at bay. 

General Corrosion

This form presents itself as rust. It affects the entire surface of a metal component, so it is sometimes called uniform corrosion. 

This is one of the most common types of corrosion. It’s also very easy to test for and catch, so it’s not as dangerous as other corrosion types.

General corrosion is created by a chemical or electrochemical reaction. When metal reacts with water, it makes the surface oxidize which leads to rust. A preventative coating can stop this form of corrosion.

Galvanic Corrosion

When two different metals are in a corrosive electrolyte like saltwater, it can lead to galvanic corrosion. 

The two metals create a galvanic couple, with the stronger one being positive (cathode) and the weaker one the negative (anode). The weaker metal will corrode faster than the stronger one.

To prevent this form of corrosion, pairing of metals needs to be handled carefully. Galvanic corrosion can be an issue in the shipbuilding industry because of the exposure to saltwater. Specifically designed anodes are often installed to fight this. 

Localized Corrosion

At first, this corrosion attacks a section of a metal component. It’s very similar to cavities caused by tooth decay.

Pitting, crevicing, and filiform are three common forms of localized corrosion. Pitting and crevice corrosion both start with a small hole or crack that gets worse with continued stress on the decayed area. Filiform corrosion happens when water gets underneath coated surfaces.

Localized corrosion is more difficult to detect and fix. But, it can be prevented by using alloys and controlling the environment.

Stress Corrosion Cracking

This corrosion is created by extreme stress or temperature changes. Small cracks can form when metal expands and contracts in extreme temperatures.

This form is difficult to detect, but it can be prevented by using the correct materials for a particular environment.

Intergranular Corrosion 

When alloys are heated and cooled, crystallite grains form inside the structure of the metal. Grain boundaries separate the grains.

If there are impurities at the boundaries, the grain boundaries can corrode. As a result, the alloy can break apart. Intergranular corrosion can lead to weakened metals.

This form of corrosion can be prevented with post-weld heat treatment and by using stainless steel with low carbon.

Prevent These Types of Corrosion with Valves from CPV Manufacturing

No matter your industry, corrosion can lead to equipment failure and heightened costs. Knowing about all types of corrosion can help you prevent it from happening or stop it before it causes serious damage.

If you’re not sure which type of valve or fitting is right for your needs, contact us today. Our expert staff will help you choose the right product.