Stainless and carbon steels are both excellent options for a range of uses; however, deciding which steel type you need may be tough to know. Understanding the basics of what steel is and how it is used will help you better determine which fits your project needs most appropriately.

What Is Steel?

Steel is an alloy. An alloy is two or more metal types that are blended together to make a different, distinctive metal. Iron and at a minimum one other metal type combine to make steel, so depending on the different properties the alloy has determines the type of steel you have. Two of the most common metal types found in industrial piping systems are carbon steel and stainless steel, and each of these alloys have different grades that determine special characteristics of the same classified metal type.

Carbon Steel

Carbon steel is an iron and carbon alloy. It may or may not have a few other materials such as manganese in its makeup. With little other materials in its composition, it is known as a “low” alloy and is categorized in three levels based on the amount of carbon and manganese in its composition. The levels are Low-carbon steel, Medium-carbon steel and High-carbon steel. Overall, carbon steel is known for its:

1. Strength
2. Ability to withstand very high temperatures
3. Durability
4. Wear resistance
5. Overall lower cost profile than other alloys

It is also environmentally friendly because of its recyclability, but it is susceptible to rust.

Stainless Steel

Stainless steel is a type of alloy defined by the addition of chromium and other metals including nickel. Chromium provides a protective layer that doesn’t allow oxygen to react with the metals iron content, thereby making the metal corrosion resistant. In fact, the most significant characteristic of stainless steel is that is doesn’t rust or corrode. Like carbon steel, stainless steel is available in various level types. Duplex is one such type and is a composition frequently found in the petrochemical industry.

Considerations

If you are deciding between stainless steel and carbon steel for your project(s), consider the following:

What material is going through your pipes?

Is it a corrosive fluid, like chemicals or salt water? If so, a 304 (the most common) or 316 grade of stainless steel may be the material you will want to work with; however, check the properties of the material you are working with to see what it reacts with first.

What temperature will your alloy be exposed to?

Carbon steel is known for its heat resistance capability and is good for things like steam or gases. However, in low to extreme cold temperatures, aluminum, titanium or nickel-based materials may be better options.

What's the budget?

Carbon steel is typically the least expensive steel found in piping systems, but stainless steel is a close second in terms of cost analysis. Therefore, you can likely choose between carbon and stainless steel without substantial cost considerations.

Does appearance matter?

Stainless steel usually has a shine to it and holds up when exposed to weather and other elements. Carbon steel is darker and has a matte finish look. This may also start to corrode if exposed, deteriorating the steels appearance.