Today, most beer brewing tanks are made of hygienic stainless steel. We know that the smoothness of the inside of the tank is very important for beer brewing, and this is mainly expressed in the roughness.
Especially the bottom of the tank and the discharge arm, the roughness must be small to prevent bacteria from surviving. In general, the roughness of the weld line must be 0.4-0.5um after polishing.
The diameter of the yeast is around 6-10um and it cannot hide inside the material. But for bacteria, its size is only 0.7-4um and if we can’t make it survive inside the welding line smoothly, then the beer may be contaminated.
That’s why polishing is very important in the manufacturing process of beer brewing tanks. We at TNT generally use pickling passivation to remove the oxygen from the welding first and then form a protective layer on the surface of the tank. The precision of the tank will reach 0.2-0.4um.