Reasons for stainless steel polishing for beer equipment

• Friday January-06 2023 10:42:49
• Blog

Reasons for stainless steel polishing for beer equipment

As we all know, the inner shell of the beer brewing tank will directly contact the brewing water, wort or beer, so most breweries will pay great attention to the internal polishing accuracy. Therefore, how to improve the polishing accuracy becomes very important. Generally speaking, we will use "RA" to indicate the polishing accuracy. The lower the RA, the higher the polishing precision and the higher the hygiene level. For example, RA 0.2 is better than RA0.4. Micet led us to compare the polishing accuracy, two different manufacturing technologies of polishing and pickling passivation.

The manufacturing process of the inside of the polishing tank

1. Roll weld the stainless steel plate into a cylinder and a cone bottom.

2. The pit plate is welded around the cylinder and the cone bottom.

3. Sand the inside of the tank.

First, workers manually polish to remove some obvious weld slag. Secondly, use professional machines with different abrasive belts for further polishing, 80 mesh belt (RA=0.2mm)→120 mesh belt (RA=0.12mm)→240 mesh belt (RA=0.6um)→400 mesh belt (RA=0.2 microns).
 

When the mesh belt is 240 mesh, the RA inside the tank is 0.4-0.6um, the inside of the tank is hygienic and can be used for brewing beer. For some strict brewers, they will require RA to be lower than 0.4um, so we will use a 400-mesh sand belt to improve the polishing accuracy.

Main function of polishing

1. Prevent rust

Because fermenters are mostly made of stainless steel, this stainless steel material is mainly an alloy. The molecules of this metal are inactive, and it is not easy to chemically react with the air, but it does not mean that stainless steel will not rust, it depends on the way and place of use. Therefore, one of the functions of surface treatment of the inner tank is to prevent rust and enhance the corrosion resistance of stainless steel.

2. Improve service life

After the stainless steel is polished mechanically, a protective film is formed on the surface of the stainless steel by squeezing the surface of the stainless steel. This film can better isolate the chemical reactions produced by other molecules such as water and air, make the molecules on the surface of stainless steel more compact and firm, and improve the service life of stainless steel.
 

Steps for surface treatment of beer brewing equipment fermentation tank liner

1. Tank polishing

First of all, the entire fermenter, the outer wall and the inner tank must be polished. Surface polishing is a key technical item for making beer fermenter. In order to eliminate the rough state of the surface of the inner liner of the tank and obtain a higher quality of surface roughness (0.6μm), the polishing method is adopted. Due to the large surface area, large polishing workload and high surface roughness requirements, we use tank polishing machines for polishing to ensure the surface requirements of the tank. Ensure that the roughness inside the tank meets the design requirements and the surface quality is less than 0.6μm.

2. Configure pickling passivation solution

Then configure the pickling solution, the pickling solution formula can be as follows: nitric acid (specific gravity 1.42) 20%, hydrofluoric acid 5%, water 75%. When preparing, slowly add nitric acid and hydrofluoric acid into water and stir well.
 

3. Apply the liner

The prepared pickling and passivation solution is pumped into the tank with a corrosion-resistant chemical pump and washed by rotating washing balls until the entire surface is silvery white. Especially at the weld seam and the heat-affected zone, the place that is not easy to wash off should be repeatedly scrubbed with a stainless steel wire brush.

4. Clean the liner

Mainly, it can be rinsed with clean water, and then dried with compressed air or with natural ventilation.
 

The above is the answer to why the inner liner of the fermentation tank of craft beer equipment should be surface treated. The main purpose is to prevent the inner tank from rusting and enhance the corrosion resistance of the material. Although stainless steel is a non-rusting material, it cannot be completely guaranteed that it will not rust. In addition, surface treatment can also improve the service life of the fermenter.