Stainless Steel Mixing Tanks 101: Open-top Mixing Tanks
Producers of liquid products have utilized industrial mixing tanks fabricated from stainless steel alloys for many years. Common variations include simple open top tanks used to mix paints and chemicals, deluxe finish sanitary versions for food or cosmetics production and completely sealed aseptic vessels for the pharmaceutical and biotech industries. The following is a general description of user considerations when selecting or specifying an industrial grade mixing tank. We will save the discussion of sealed aseptic mixing vessels for another post, Stainless Steel Mixing Tanks 102!
The designation as an “industrial grade” tank refers to a simply-constructed single wall vessel utilized at atmospheric pressure. These tanks are most often used for open top mixing using a portable mixer and do not feature polished surfaces. A loose fitting lid is frequently ordered to prevent splashing or to shield the contents from contaminants. A hinge in the lid is often provided to allow a small access area. The tank wall and bottom head are usually 10- to 14-gauge material. Common configurations for tank bottoms include conical, elliptical and sloped. The conical design promotes the most complete drainage to a center located drain. This configuration is popular for liquids that blend easily with other liquids or powders with little risk of unmixed materials accumulating beyond the reach of the mixing impeller. A dished bottom is chosen when it is important for the impeller to most effectively suspend settled materials and provide maximum batch turnover prior to draining. Finally, the sloped bottom design directs the liquid flow to a horizontally mounted drain valve or spigot at the bottom of the tank wall. A formed lip around the perimeter of the top of the tank, pipe legs with mounting flanges and mixer mounting brackets are common features for open top industrial tanks.
Consisting of 18% chromium and 8% nickel, 304 stainless steel is the most widely used stainless steel alloy for general industrial mixing and for food production. It provides good resistance to rust and corrosion and is relatively easy to clean. When increased corrosion resistance is required 316 stainless steel can be specified although at a higher cost. It contains 2% molybdenum in addition to the chromium and nickel which significantly improves its chemical resistance to chlorides, bromides, fatty acids and sulfuric acid.
Our industrial tanks have a 2B mill satin finish and welds are ground and brushed. All of our tanks can be ordered with a deluxe polished finish, which is a #4 finish with welds ground smooth and polished suitable for food production or for when a smoother finish is required to promote cleaning. See our surface finish guide for more detail.
You can submit the requirements for your tank by completing the INDCO tank data worksheet or contacting customer service or engineering. We’re always happy to assist you and we can optimize your complete mixing system design with consideration for your material properties, batch size and type of mixing process.