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What else do I need to know about the Stainless Steel ?

100 years ago Stainless Steel was discovered, and today it has become a well-known feature to many products worldwide. It is used in an almost endless number of applications and industries.

More than 30% of about 38 million tons world annually is produced and used in the Food Industry alone.

“Stainless Steel” or “Inox Steel” (French: inoxydable – rust proved) is an iron-containing alloy that contains at least 10.5% of chromium. It is a large family of about 100 grade of stainless steel,which  belongs to the 4 metallurgical “families” (austenitic, ferritic, martensitic and duplex families). 

The most popular Stainless Steel that is used is the 300 series stainless steel (grade 304 and 316)

Another popular type of stainless steel is the 200-series (less nickel, less corrosion-resistance) became a very popular last decade, especially in the Far East countries as the result of a high nickel price. This series is also austenitic and difficult to distinguish from the 300 stainless steel grades. The incorrect labeling without the exact information about the stainless steel grade (303, 304, 316,….) has brought confusion in the world marketplace as customers are convinced that the offered stainless steel is 300-series (304-grade), when it's actually a stainless steel 200-series. 
It is not recommended for use in chemical environments, but has found its way into many household items.This is all due to its lower corrosion resistance. 

The common term "Stainless Steel 18/­8" is referring to the 18% chromium/8% nickel, and is used to designate products made from 300 series stainless steel. However, it is NOT a grade, because it’s only referring to two different alloys in the steel. 

The properties of the Stainless Steel depend on the chemical composition 

    Grade          Chemical Composition       
AISI C r   Ni   Mo
200   15.5 - 19.0      1.0 -   6.0   
304    18.0 - 20.0     8.0 - 10.5   
316   16.0 - 18.0     10.0 - 14.0     2.0 - 3.0  

Example: higher levels of chromium, molybdenum and nickel improve the corrosion resistance of the stainless steel.

From the Food Safety point of view the most important properties of stainless steel are: durability (stainless steel grade),and corrosion resistance(stainless steel grade). The other important properties are that it’s easy to clean (model, finish,etc.,), food flavour protection and hygienic design. Also the construction of a particular item is important. For example, fully welded & crevice free construction without “dead spaces” will prevent possible accumulation of dirt, moisture and pathogens.

Corrosion resistance

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Generally speaking the stainless alloy can withstand ordinary rusting. However, one is more resistant than the other.

304-grade

The 304 may be considered to perform similarly in most non-severe applications. This alloy withstands the corrosive action of various organic acids (found in fruits, meats, milk, and vegetables), it is immune to foodstuffs, sterilizing solutions, most of the organic chemicals and dyestuffs, and a wide variety of inorganic chemicals.

Application:
Its mostly used for sinks, tabletops, stoves, refrigerators, milk and cream dispensers, steam tables, mixing & handling equipment and other (cooking) utensils.

In the Food Industry stainless steel 304 is popular among:

- Dairy industry (milking machines, containers, sterilizers, including tanks, piping, valves, etc),
- Brewing industry (pipelines, yeast pans, fermentation vats, storage tanks etc.
- Fruit juice industry (handling, crushing, preparation, storage and hauling equipment)
- Mills & Bakeries,
- Meat processors
- Marine industry (fasteners and other items where strength and wear resistance are needed)

316-grade

The 316 grade may be considered to use in severe environments, and it is more resistant to solutions of sulfuric acid, chlorides, bromides, iodides and fatty acids at high temperature. In the pharmaceutical industry, stainless steels containing molybdenum are required in order to avoid excessive metallic contamination.

Its main advantage over grade 304 is its increased ability to resist pitting and crevice corrosion in warm chloride environments. It is also resistant to most food processing environments, can be readily cleaned, and resists organic chemicals, dyes and a wide variety of inorganic chemicals.

Applications:
In the marine industry as the main stainless steel,
Food and beverage processing equipment;
As well as hot water systems, pharmaceutical, petrochemical, mineral processing, photographic and other industries.

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All stainless steel products: http://www.atescoindustrialhygiene.com/products/stainless_steel_equipment.html