To begin there is not a visible difference between the two, both are polished or grained the exact same way, you can’t tell just by looking at it. That is
Sanitary Stainless Steel Tubing
why we generally send a material test report (MTR) of the actual material to validate it as being 304 or 316 as requested.
From a chemical or scientific standpoint the answer would be that 304 stainless steel contains 18% chromium and 8% nickel while 316 contains 16% chromium, 10% nickel and 2% molybdenum. The molybdenum is added to help resist corrosion.
Type 304, with its chromium-nickel content and low carbon, is the most versatile and commonly used of the austenitic stainless steels. Type 304 proves to be resistant to oxidation, corrosion, and durability. Type 304 stainless provides ease of fabrication and cleaning, prevention of product contamination and offers a variety of finishes. Type 304 stainless steel is used in enclosures, storage tanks, pressure vessels and tubing or piping.
Type 316 stainless steel is an austenitic chromium-nickel stainless and heat-resisting steel with superior corrosion resistance as measured up to other chromium-nickel steels when exposed to many types of chemical corrodents.
Given that Type 316 stainless steel alloy contains molybdenum it has a considerable more resistance to chemical attack than 304. Type 316 is durable, easy-to-fabricate, clean, weld and finish. It is considerably more resistant to solutions of sulfuric acid, chlorides, bromides, iodides and fatty acids at high temperature. Stainless steels containing molybdenum are required in the manufacture of certain pharmaceuticals in order to avoid excessive metallic contamination.
Holland Applied Technologies inventory of sanitary fittings and tubing includes both Type 304 and Type 316 Stainless Steel in a wide range of sizes and polish specifications. Both Materials meet 3A and FDA requirements. We also carry fittings and tubing that meet ASME BPE standards.
In summary the end result is that Type 316 stainless steel costs a little more but you could save a whole lot on the back end. Something worth keeping in mind when you’re planning your next project.
Holland Applied Technologies