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What is the difference between food grade stainless steel and ordinary stainless steel

Dec 10, 2019

Indicator requirements

Food grade stainless steel refers to the part of food machinery that comes into contact with food and must meet certain food safety requirements. Because food manufacturing process uses a lot of acid and alkali, and stainless steel contains chromium, unqualified stainless steel will dissolve chromium at various prices, and is toxic; and it is required to limit the content of various alloy impurities such as lead and cadmium.

The difference between food grade stainless steel and 304 stainless steel

When the heavy metals that stainless steel products migrate in use exceed the limit, it may endanger human health.

Therefore, the production of stainless steel cookware needs to find a balance between corrosion prevention and safety. If the content of nickel and chromium is high, the anti-corrosion function will be enhanced, but the amount of nickel and chromium precipitation will also increase, which means that the safety risks will increase.

Because of this, the National Food Safety Standard of "Stainless Steel Products" (GB9684-2011) has made strict regulations on the amount of chromium, cadmium, nickel, lead and other heavy metals in cooking utensils.

Why does the national standard not stipulate a migration limit for manganese?

One reason is that with the increase of the manganese content in stainless steel, there is a loss of functions such as corrosion resistance and non-rusting of the cooker. Once the manganese content reaches a certain value, this product cannot be used as a cooker or cannot be called a stainless steel cooker Already. But even such high levels of manganese generally have no effect on health.

Therefore, although the national food safety standard does not stipulate the content of manganese, it is clearly stated that the main part of the food container must be made of stainless steel materials that meet the national standard.

Food grade stainless steel is stainless steel that meets GB9684 standard

Food grade stainless steel, also called "GB9684 stainless steel", is the stainless steel material that passed the GB 9684-2011 stipulated in the "National Standard of the People's Republic of China / Hygienic Standard for Stainless Steel Food Containers". This stainless steel has a lower "lead" content than ordinary stainless steel. The corrosion resistance of the product has also increased. The requirements are: lead (calculated as Pb), mg / L 4% acetic acid soaking solution ≤ 1.0 1.0. Chromium (calculated as Cr), mg / L 4% acetic acid soaking solution Medium ≤ 0.5. Nickel (calculated as Ni), mg / L 4% acetic acid soaking solution ≤ 3.01.0. Tin (as Sn), ≤ 0.02 0.02 in mg / L 4% acetic acid solution. Arsenic (as As), ≤ 0.04 0.04 in mg / L 4% acetic acid solution. Note: The soaking conditions are boiling for 30min, and then at room temperature for 24h.

304 stainless steel is a very common stainless steel, also called 18-8 stainless steel in the industry. Its corrosion resistance is better than 430 stainless iron, corrosion resistance and high temperature resistance, good processing performance, so it is widely used in industry and furniture decoration industry and food and medical industry, such as: some high-end stainless steel tableware, bathroom kitchen appliances.

304 is a versatile stainless steel that is widely used to make equipment and parts that require good overall performance (corrosion resistance and formability).

In order to maintain the inherent corrosion resistance of stainless steel, steel must contain more than 17% chromium and more than 8% nickel.

Generally 304 stainless steel is not food-grade, and specially processed is food-grade.

As we all know, stainless steel products related to "edible" must use 304, 316 stainless steel. 316 stainless steel is expensive and is mostly used in high-end equipment, such as aerospace and food machinery. Food grade stainless steel used in daily necessities is usually 304 stainless steel, which has good acid and alkali resistance and strong corrosion resistance.

In comparison, 201, 202 stainless steel (commonly known as high manganese steel) is generally used in industrial products, and can not be used as tableware because:

● Nickel content is not up to standard, poor acid and alkali resistance, and easy to rust;

● Excessive manganese content, excessive intake of manganese in the human body will cause damage to the nervous system.

201 stainless steel contains less nickel and chromium, weak corrosion resistance, more manganese, good acid and alkali resistance, and cheaper price! In order to maintain the inherent corrosion resistance of stainless steel, 201 stainless steel must contain more than 16% chromium and more than 8% nickel. The surface is very bright with dark luster, and it is easy to rust with high manganese content. 304 contains more chromium, its surface is matte and does not rust. Compare the two together. The most important thing is that the corrosion resistance is different. The corrosion resistance of 201 is very poor, so the price is much cheaper. Because 201 contains nickel, the price is lower than 304, so the corrosion resistance is not as good as 304.

In daily life, we have a very high probability of contacting stainless steel products, and stainless steel electric kettles are one of them. Which ones are "201"? Which ones are "304"? Difficult to distinguish ~

To distinguish these different stainless steel materials, the laboratory method mainly detects the composition of the substance. For example, we now use the commonly used handheld fluorescence spectrometer to quickly analyze stainless steel of different materials and quickly obtain the content of all elements. There will be noticeable differences.

In general: Food grade stainless steel refers to the stainless steel material that meets the national GB9684 standard certification and can really contact food without causing physical harm. Therefore, GB9684 stainless steel is food grade stainless steel. At the same time, the so-called 304 stainless steel is not required to pass the national GB9684 standard certification. 304 stainless steel is not equivalent to food-grade stainless steel. 304 stainless steel is not only used in kitchen utensils, but also widely used in industry. At the time of purchase, regular products will be marked with "food grade 304 stainless steel" on the surface and inner wall of the product, and products marked with "food grade-GB9684" are more secure.