Is Stainless Steel Chemical Resistant?
A Guide to Chemical and Acid Resistant Steel
Stainless steel is an industry-standard material for a wide range of industries and sectors—but as we discussed in our previous blog on the importance of food grade steel, not all stainless steels are created equal. For pipe fabrication projects in industrial environments that deal with harsh chemicals, such as acids and solvents, the question, “Is your stainless steel chemical resistant?” is an essential one to ask.
When building pipelines and process line flow control infrastructure for chemical plants, you need to know your choice of stainless steel PVF products can stand up to the harsh and aggressive chemicals that will flow through them day in and day out for years or decades. In this blog post, we’ll explore stainless steel’s chemical resistance and why evaluating alloys for chemical compatibility is so crucial for building flow control systems.
The Right Steel for the Right Job: Why Chemical and Acid Resistant Metal Matters
Chemicals, especially acids and other aggressive substances, wreak havoc on standard metal pipelines. The reactions between the chemicals carried through pipelines and the materials comprising pipe walls, valve bodies, fittings, and flanges lead to corrosion which degrades the material, compromises pipeline integrity, and increases the risk of leaks or failures—failures that can expose nearby workers to potentially hazardous substances or even contaminate soil or groundwater.
If your choice of stainless steel alloy isn’t compatible enough with the chemicals passing through it, the product itself can degrade in quality, in addition to degrading the pipeline itself. Overall, risks of catastrophic failures notwithstanding, the wrong choice of stainless steel PVF leads to shorter service lifetimes for your pipeline infrastructure, more frequent and costly maintenance and repairs, and lower product quality.
As you can see, the stakes surrounding the use of chemical and acid resistant metal can be very high. Industrial PVC pipe and tubing, which is generally highly corrosion resistant and nonreactive (not to mention lightweight) is often especially useful in chemical plants and other industrial facilities, but sometimes industrial plastics are not a sufficient replacement for stainless steel.
That is why it’s important to make sure you’re using the right alloy of stainless steel for chemical resistance and compatibility.
Exploring Stainless Steel’s Chemical Resistance
Stainless steel’s resistance to corrosive chemicals can seem miraculous, but it’s no miracle—just chemistry in action. Let’s explore what makes stainless steel so chemical resistant, then explore some of the best chemical and acid proof steel alloys for industry applications.
Why is stainless steel chemical resistant?
What sets stainless steel apart from normal steel—i.e. what puts the “stainless” in “stainless steel”—is chromium. Traditionally, steel is an alloy of iron and carbon. However, adding additional elements into the mix such as chromium changes the steel’s mechanical properties. When the chromium atoms on the surface of a piece of steel meet the oxygen atoms in the air, the chromium and oxygen bond to form a thin, stable layer of chromium oxide.
This layer of chromium oxide is what makes stainless steel a chemical and acid resistant metal. The passive layer prevents acids, bases, salts, and oxidation from affecting the iron in the alloy. Nickel and molybdenum can also lend a hand to create a more chemical and acid proof steel alloy.
Choose the Right Stainless Steel for Its Chemical Resistance
- 304 Stainless Steel: 18% chromium and 8% nickel, this stainless steel offers excellent corrosion and oxidation resistance. It’s well-suited for handling less aggressive substances, which makes it especially useful in pharmaceutical or food and beverage process lines.
- 316 Stainless Steel: With an additional 2-3% molybdenum compared to 304 stainless steel, 316 is a more acid resistant metal that also resists chlorides and pitting from salt exposure. This is a superior option for pipelines that handle aggressive acids as well as saltwater environments.
- 317 Stainless Steel: Further boosting the molybdenum content improves acid and chloride resistance even further, making this stainless steel’s chemical resistance strong enough to tackle aggressive acids at high temperatures.
- 904L Stainless Steel: 20% chromium, 25% nickel, and additions of copper as well as molybdenum make this alloy one of the best options for chemical plants and pipelines in highly corrosive environments, where it boasts a long service life with minimal maintenance needs compared to other acid proof steels.
American Stainless: The US Southeast’s Trusted Source for Chemical and Acid Resistant Steel
Depending on what materials your pipelines transport and their operating environment, the right choice of stainless steel PVF products can mean life or death for your projects. With so many different types of steel alloys to choose from, though, choosing the appropriate stainless steel for its chemical compatibility and resistance isn’t always easy.
American Stainless is here to help you make the best choices for your projects. Whether your pipelines need to withstand frequent cleaning operations, large volumes of salt water, or harsh industrial chemicals under high temperatures and pressures, we have the vast and diverse inventory—and extensive expertise in PVF applications in your industry—to guide your project to success.
Contact us today to get started.