Stainless steel is one of the most important raw materials in stainless steel tank manufacturing. In addition to its excellent corrosion resistance, it offers a hygienic surface, high mechanical strength, and precise machinability, while its aesthetics and chemical neutrality also make it a common choice. The processing of stainless steel in tank production can be divided into four main areas: cutting, forming, welding, and surface treatment, each of which involves different methods depending on the application. These will be presented in our article.
Why is stainless steel ideal for tank manufacturing?
In tank production, several materials are used, but one of the most important is stainless steel. This is a type of steel alloyed with at least 11% chromium, which creates a protective oxide layer on the surface. This layer naturally prevents rusting.
Stainless steel is ideal for the production of wine fermentation tanks, chemical storage tanks, as well as agricultural and fertilizer tanks, and in all areas where a clean, resistant surface and durable structure are essential.
How to choose a cost-effective stainless steel material for a tank?
The first step in processing is sourcing the raw material. Two key factors need to be considered here: quality and cost-effective packaging.
Material quality should never be compromised, which is why we source only from suppliers that guarantee the highest standards. However, by choosing the optimal material format, significant cost savings can be achieved.
The raw material used for the shell of the tanks is available either as flat sheets or in coils. Up to a thickness of 3 mm, coils are the most economical choice, as they allow cutting exactly the amount of material needed for each tank.
Since sheet coils are available in different widths, we select the most optimal one for each tank to maximize material efficiency and minimize waste.
For thicker materials, flat sheets are often required. In such cases, efficient use of sheets remains important, which may even involve ordering custom-sized plates directly from the rolling mill based on the specifications.
In tank and steel structure manufacturing, we work not only with flat sheets but also with pipes, structural steel profiles, and various hollow sections. These too are always ordered in a way that ensures the most efficient processing with minimal waste.
Main steps of stainless steel processing in tank manufacturing
After sourcing the raw material, stainless steel processing typically consists of the following steps:
- Sheet cutting or sectioning
- Forming
- Welding
- Finishing
Stainless steel sheet cutting technologies: shear, laser, waterjet
The first step in processing is cutting to size. For sheets, straight cutting is the most common method, with the most cost-effective option being the use of sheet metal snips. Shears can be used efficiently for thicknesses up to 10 mm.
Cutting stainless steel sheet to size with a plasma cutter.
For thicker sheets and shaped cuts, laser cutting is a better solution, while waterjet cutting is recommended for thicknesses above 15 mm.
The advantage of both laser and waterjet cutting is the ability to cut any shape. This means that, besides cutting to size, holes and connector positions can also be prepared in advance when using these technologies.
It is important to keep in mind, however, that the sheet will be formed afterward. For example, if a circular opening is required on a cylindrical shell, an oval shape must be cut while the sheet is still flat.
Tube laser cutting in stainless steel processing
When cutting pipes, structural steels, and hollow sections, tube laser cutting is the most cost-effective method. This technology ensures highly precise dimensions and can not only cut material to length but also process it at various angles. It can even create holes or any other cutouts, all without requiring further machining.
Bending stainless steel sheets: production of U and L profiles
After cutting to size, the sheets must be rolled to give the cylindrical shell of the tanks its final shape. Thin and medium-thickness sheets (up to 15 mm) are formed on a plate rolling machine, while thicker sheets require a special, higher-capacity rolling machine.
In both tank and metal structure manufacturing, sheet bending is also frequently used to create various, typically product-specific, custom L or U profiles.
Tanks are manufactured using both CO and TIG welding.
Tank welding from stainless steel: CO and TIG technologies
After sheet forming, the next step is welding. The tank shell is closed with a horizontal weld, and at this stage the legs and various connectors are also attached.
Two technologies are used: gas-shielded arc welding with CO₂ (CO welding) and argon-shielded arc welding (TIG welding).
It is important to note that both the welding company and the welder must hold certification for the specific technology applied, covering everything from the type of process and material thickness to the welding position.
The installation of fittings and openings usually takes place after the tank shell has been welded together.
How are fittings and openings made on stainless steel tanks?
Tanks can be equipped with multiple openings and fittings according to the customer’s exact requirements. For tanks made of thinner sheets, these openings are created after the tank shell has been welded together.
Smaller openings are made using drills or hole saws, while larger ones are cut with an angle grinder. For thicker sheets, openings are already prepared during the cutting-to-size process, but after assembly they must be checked and precisely adjusted.
Surface treatment in stainless steel processing
Stainless steel generally does not require surface treatment, but if the application demands an especially smooth finish, the weld seams, sheet surfaces, and all connector areas must be treated.
A cold-rolled 2B steel has an average surface roughness of 0.8 μm. However, in certain industries, such as wine fermentation and chemicals, it is essential to prevent contamination and bacterial growth on the tank surface, which is why a surface roughness below 0.8 μm is specified.
In such cases, special grinding tools and discs are used to achieve the required surface roughness on the tank walls, weld seams, and the inner surfaces of connectors.
Scalping and polishing for stainless steel wine tanks
Just like the interior, the exterior of stainless steel tanks generally does not require treatment. However, polishing can be applied for aesthetic purposes, and scalping is particularly popular in the case of wine fermentation tanks.
What makes scalping unique is that there is no industrial machine solution available for this technology. Since no suitable scalping equipment was available on the market, we developed our own device for production, which we continue to use to this day.
The cooling jacket is manufactured using a specialized punching machine.
How is the cooling jacket of a stainless steel tank made?
The production of the cooling jacket requires special processing, as it allows precise control of the temperature of the liquid stored inside the tank.
The cooling jacket is a sheet with holes placed at a defined density, each with a minimal edge. The placement and size of these holes are determined by precise calculation and created using a specialized punching machine.
Custom stainless steel tank manufacturing from Duna Steel Tech
Stainless steel tanks are a long-term investment, which is why, based on our decades of experience, we manufacture custom tanks tailored to each client’s specific application. During production, we always carefully select the most suitable processing steps. If you have custom tank manufacturing needs or questions about stainless steel processing, feel free to contact us.
Frequently Asked Questions
What types of stainless steel are used for manufacturing industrial tanks?
What is considered an appropriate surface roughness for hygienic tanks?
What is the difference between CO and TIG welding?
What certification is required for welding stainless steel?
Why are steel grade and its certification important in tank manufacturing?
