Material Matters: 316 Stainless Steel
Known for its durability, clean aesthetic, non-reactivity and corrosion resistance, stainless steel can be found in everything from pots and pans to aerospace equipment. In general terms, stainless steel is a type of iron alloy that uses a minimum of 10.5% chromium in its composition—the chromium is what makes stainless steel “stainless” by creating a passive layer of oxidation that protects against further oxidation and essentially makes the steel rust-proof. Other elements, such as nickel, molybdenum, titanium, aluminum, niobium and copper, are sometimes added to the alloy to enhance corrosion-resistance in various environments—there are over 100 different grades of stainless steel with varying properties based on the specific metals used in the alloy.
“Austenitic” stainless steels are the most common and contain 16% to 26% chromium and up to 35% nickel—this category usually has the highest corrosion resistance of all stainless steels. The most widely used type is called “304,” which is typically found in the aircraft, dairy and food-processing industries, as well as in architectural applications where aesthetics are prioritized. 304 stainless steel is well-known for its versatility, corrosion-resistance, heat-resistance and high-formability. Its only weakness is salt—pitting and minor erosion can occur in or around salt water.
At Eureka, we wanted to create the world’s finest cold water therapy tubs, so we chose 316 stainless steel for the interior of our cold plunge tub. 316 is a more expensive austenitic alloy that surpasses the industry standard of 304. Its composition is similar to 304 but includes 2% molybdenum in the alloy, which not only provides additional strength and heat resistance, but also brings substantial improvements in salt water and chloride resistance. For this reason, 316 stainless is the preferred option for marine and surgical applications, and for cold plunge tubs designed to last a lifetime. Additionally we use 11 ga, or 1/8″ thick 316 stainless, which provides an unparalleled level of durability and structural weight, and gives the Eureka cold water therapy tub a luxurious and substantial feel.