Food-grade stainless steel: description, legislation and types

The design of industrial plants for the food industry requires compliance with very high hygiene standards and meticulous assessment of the materials used. During the production, transfer and storage of food and beverages, surfaces that come into direct contact with process fluids must prevent every risk of chemical, sensory or microbiological contamination. This makes stainless steel the best choice for pipes, tanks and mechanical components. The right choice of alloy ensures the chemical stability needed not only to preserve the quality of the end product, but also to prevent corrosion during exposure to aggressive fluids or high-temperature cleaning processes, a principle on which Granzotto bases the design of its modular pigging systems, dispensing systems and distribution systems for the food industry.

What is the best food-grade stainless steel?

Stainless steel is an iron-carbon alloy containing chromium (minimum 10.5%), capable of forming a protective layer of passive oxide. Not all stainless steels, however, meet the performance requirements for contact with food. Food-grade stainless steel must contain specific percentages of chromium and nickel to withstand the corrosive action of organic acids, salts and chemical detergents used in washing cycles.

Determining the best stainless steel for use with food depends on the operating temperature and the characteristics of the process fluid, the pH and the presence of chlorides. There is no single ideal alloy. The best choice depends on the specific application. This is why Granzotto runs preliminary tests on the chemical and physical compatibility of the products involved, in order to identify the most suitable food-grade stainless steel alloy for each section of the custom-designed plant.

Characteristics of food-grade stainless steel

The benefits of food-grade stainless steel stem directly from its metallurgical and physical properties.

High resistance to corrosion: its ability to spontaneously reform the passivation film in the presence of oxygen prevents oxidation when it comes into contact with acid or saline substances.
Chemical inertness and prevention of food contamination: it releases no harmful substances or heavy metals and does not alter the smell or taste of food and beverages.
Resistance to high temperatures and thermal shock: essential for withstanding high-temperature sterilisation and sanitisation cycles (CIP and SIP).
Smooth and easy to clean: high-precision surface finishes prevent the adhesion of bacteria and organic residues, making it possible to maintain very high hygiene standards.

Not sure which stainless steel grade is best suited to your process fluids?

Request a preliminary consultation with a Granzotto Impianti expert.

What is the difference between 304 and 316 stainless steel?

When choosing food-grade stainless steel, the comparison is usually between the two most popular austentic options: 304 steel and 316 steel.

Both types fall within the American classification system based on the American Iron and Steel Institute (AISI) food-grade stainless steel rating.

AISI 304 (EN 1.4301) offers ideal performance for most applications and is often referred to as 18/10 (18% chromium and 10% nickel). It offers excellent resistance to corrosion in neutral or mildly aggressive environments and is widely used in the dairy, beer and general liquid food-handling industries.
AISI 316 (EN 1.4401 or 1.4404 for the low-carbon variant 316L) differs from 304 in that it contains added molybdenum (between 2% and 3%), which increases resistance to pitting corrosion caused by chlorides, salts and high-acidity fluids (such as tomato juice, brine or vinegar).

Choosing between 304 and 316 food-grade stainless steel requires a careful analysis of investment costs and operating risks. Granzotto uses AISI 304 in piping systems for transporting fluids in general-purpose applications and uses AISI 316L food-grade stainless steel for sections that come into contact with aggressive products or undergo intensive chemical cleaning cycles.

Other stainless steel alloys used in the food industry

In addition to the traditional austenitic steels in the 300 series, there are other alloys which are used in specific markets. One of these is 430 stainless steel, a ferritic alloy containing chromium but no nickel. While offering lower resistance to corrosion, it provides good thermal conductivity and is cheaper, making it suitable for external structural components, machinery panels or equipment intended for contact with dry foods.

Legislation on stainless steel in the food industry: the basic principles

The use of materials intended to come into contact with food (FCS) is governed by specific national and international legislation designed to protect public health and food safety.

Compliance with legislation ensures that the equipment does not release substances in quantities sufficient to pose a risk to human health or to impair the sensory characteristics of the products.

Granzotto designs and manufactures its own industrial plants, providing full traceability of materials and a statement of FCS suitability for every component installed.

International certifications for food-grade stainless steel

For companies operating on foreign markets, the legislative framework extends globally:

Regulation (EC) no. 1935/2004 establishes the European rules on food contact substances to ensure that food-grade stainless steel does not release harmful substances, enforcing the principle of chemical inertness and traceability along the whole supply chain.
FDA (Food and Drug Administration) Standards: outside the EU, particularly in the United States, these standards define the chemical compliance of the materials used in food processing.
EHEDG guidelines and 3-A Sanitary Standards set the parameters for the hygienic design of machinery, ensuring that it can be completely sanitised and that there are no dead spots in the pipes.

How Granzotto selects stainless steel for industrial food processing plants

The choice of alloy, surface finish and appropriate level of surface roughness plays a decisive role in the durability, safety and efficiency of an industrial food processing plant. Choosing the wrong material can lead to early corrosion, unexpected machine downtime or the risk of contamination of the final product.

To meet these engineering requirements, Granzotto develops advanced solutions for food processing plants, combining metallurgical expertise with advanced distribution, pigging and CIP systems. Every project is custom-made, ensuring strict quality control to the selection of raw materials to guarantee maximum hygiene and the continuous operation of the plant.