What To Know About Different Kinds of Corrosion

Many of the metals in pipework and other applications are sturdy and long lasting, but they have one kryptonite: corrosion.

Corrosion can wreak havoc on metals and deteriorate them beyond repair. Fortunately, early identification and treatment of corrosion can keep it at bay. Here’s what to know about different kinds of corrosion.

What’s Corrosion?

Corrosion is what happens when a metal reacts chemically with its surrounding environment. It’s the environment’s attempt to break down metals into a chemically stable form, like oxide or sulfide. As a metal corrodes, it gradually deteriorates.

There are multiple different kinds of corrosion, which can break down into two main categories: uniform and localized corrosion.

Uniform Corrosion

Uniform corrosion is the most common form of corrosion. It occurs when the chemical reaction deteriorates the entire surface of the metal, or deteriorates it “uniformly”.

Localized Corrosion

Localized corrosion occurs when the chemical reaction deteriorates the surface of the metal unevenly. This means that one or more areas of the metal experience the effects of corrosion, but other areas remain unaffected.

There are several forms of localized corrosion. Crevice, filiform, and pitting corrosion are the three most common subtypes.

Crevice

You can commonly find this form of corrosion under clamps, gaskets, and other immobile parts where there are low oxygen and acidic conditions that are favorable to corrosion.

Filiform

Filiform corrosion is a form of corrosion that affects painted or coated surfaces. When the protective layer on top of the metal suffers damage, water sneaks past and comes into contact with the metal underneath. This causes the layer beneath the paint or coat to corrode.

Pitting

Pitting corrosion is a form of corrosion that causes holes to form in the metal. It happens when a metal loses some, but not all, of its protective coating. This small area becomes anodic and begins to slowly corrode.