316 / 316L is the Food and Marine grade Stainless Steel
The Food Safety Act of 2013 states that standards shall be established on the basis of science, risk analysis, scientific advice from expert bodies, from other countries, existing Philippine National Standards and the standards of Codex Alimentarius Commission (Article IV, Republic Act 10611).
In ensuring that the right grade of stainless steel is used in food processing plants, the Bureau of Philippine Standards partnered with the American Society of Testing and Materials (ASTM) to adopt these measures.
A Favorite of Many Regulating Bodies
Among these, they specify AISI 316 / 316L as the non-magnetic stainless steel materials best suited for food processing in manufacturing plants and stainless steel kitchens. The most commonly accepted characteristics for equipment hygienic design and construction are adequately cleanable, corrosion resistant and nontoxic. In all these, type 316 or 316 L passed the requirements.
Generally, the materials used in food equipment design, construction and maintenance are not directly addressed but the stringent practices are implied to a varying degree under the Hazard Analysis And Critical Control Point (HACCP) and by the Food and Drugs Administration (FDA).
These regulating Agencies require that the operators of any commercial process, including food processing and packaging, should actively look for potential threats to health, safety and hygiene. A ‘threat’ is defined as anything from infection resulting from poor design or lack of hygiene, through the degradation of materials by erosion or corrosion, to component failure by fracture or fatigue. HACCP systems must now consider the possibility of materials contaminating the foods with which they are in contact.
Stainless steels are widely used in food and beverage manufacturing and processing industries for manufacture, bulk storage and transportation, preparation and presentation applications for good reasons.
Why is stainless steel ideal for food contact surface?
It is easy to create smooth, non-absorbent surfaces on stainless steels. They are also impervious, free of cracks and crevices, non-porous, non-contaminating, non-reactive, and non-toxic even after it is welded. Food contact surface equipment must avoid the use of materials containing heavy metals (e.g., lead, cadmium, hexivalent chromium or mercury). More importantly, these surfaces should be fabricated, operated, and maintained in a manner such that these criteria are not compromised.
Aside from these, the other advantages of stainless steel are as follows:
- high strength, high hardness, high modulus
- availability of a wide range of product forms
- relative ease of machining and fabrication
- quite easy to clean
- more economical for it requires very little maintenance once installed
Shiny appearance not only makes the kitchen look clean and elegant but the polished look enhances the strength of the oxide layer in stainless steel. It removes the microscopic flaws in a surface that could harbor bacteria.
Molybdenum is its Secret Ingredient
And 316 is often referred to as the food grade among the 300 series. Mainly, it contains 2-3 % Molybdenum which gives it higher corrosion resistance to chloride, high temperature and acidic environments. Also known as the marine grade stainless steel for its resistance to salt or sea water, 316 has components that can withstand more corrosive foods (e.g. meat/blood, foods with moderate salt contents).
Lower grade austenitic stainless steel alloys (e.g., AISI 100 and 200 Series) are generally not recommended for use in food equipment.
Not only can food-grade stainless steel stand up to high temperatures that would melt plastic and other porous materials, the protective oxide layer helps prevent the formation of rust that could contaminate foodstuffs.
Type 316 is usually selected for all parts in contact with the product because of its inherent corrosion resistance and greater assurance of product purity particularly in chemical and pharmaceutical production.
Type 316L is an extra low carbon grade of 316 and is generally used for delicate steel watches, medical surgical instruments, and many industrial applications involving processing chemicals, nuclear reprocessing plants, as well exclusively in the fabrication of reactor pressure vessels for boiling water reactors.
Some other applications of the 316 and 316L are:
Aircraft parts that require high resistance to corrosion and low magnetic permeability
- Machines and equipment used in processing textile and paper products
- Architectural applications in urban and coastal conditions
- Swimming pool fittings and fixtures