SUS304 Versus SUS316L For Processing Tanks

The Difference Is Molybdenum

316L contains molybdenum, which greatly improves resistance to chlorides and acids. That single addition is what separates a tank that survives a salty or acidic product from one that develops pitting. The L means low carbon, which reduces the risk of corrosion at and beside weld seams.

Where 304 Is Enough

Milk, water, beer and most neutral products in a plant with controlled cleaning chemistry are well served by 304. It is cheaper, widely available and easier to fabricate, and most storage and blending vessels in a dairy are built from it.

Where 316L Earns Its Price

Salty products, acidic juices such as citrus and tomato, brines, and any process where chloride-bearing cleaning agents are used. It is also the sensible choice for the parts of a vessel that stay wet, even where the shell is 304.

Mixing Grades In One Vessel

It is normal and economical to build a vessel with a 316L product-contact layer and a 304 jacket or outer shell. Specify which surfaces are which, because a quotation that just says stainless steel can mean either.

Finish Matters As Much As Grade

A polished internal finish is what makes a tank cleanable. A correctly specified 304 tank with a good internal finish will outperform a 316L tank with rough welds and dead legs that never get properly cleaned.