Food grade stainless steel refers to the part of stainless steel machinery that contact directly with food that must meet the requirements of food safety, that is, limit the content of lead, cadmium and other alloy impurity elements, to avoid the food production process of acid and base substances. The harmful elements of stainless steel mainly include sulfur, phosphorus, lead, 6 chromium and so on.
We all know that stainless steel contains chromium, which may precipitate polyvalent chromium and may harm human health when this migration of heavy metals over a certain amount. Therefore, stainless steel cookers need to find a balance between corrosion resistance and safety. If the content of nickel and chromium is high and the anti-corrosion function is enhanced, but the output will also increase, that increases the risk of safety and safety.、
Food grade stainless steel should also meet the requirements of the surface finish. The higher the finish of the inner and outer surface, the less the adhesion of the medium, which is conducive to corrosion resistance and in-pipe washing, especially for pharmaceutical and food industries.
Most importantly, food-grade stainless steel “needs to meet two conditions: brand and heavy metal precipitation. The grade determines the corrosion resistance of stainless steel, and then detect the precipitation of heavy metals, the stainless steel can be referred to as “food-grade stainless steel”. We suggest all kinds of food storage containers and food processing machinery should use austenitic stainless steel. 304 and 316 stainless steel is the most commonly used food-grade stainless steel, their corrosion resistance,and high-temperature resistance, good processing performance is better than 430 stainless steel, has been widely used in food, milk processing, beverage industry and medical industry, such as some high-grade stainless steel tableware, bathroom kitchen utensils. To determine whether 304 or 316 is better, firstly take a look at their chemical analysis:
| TYPE | C | Mn | P | S | Si | Cr | Ni | Mo | N |
| S30400 | 0.07 | 2.00 | 0.045 | 0.030 | 0.75 | 17.5-19.5 | 8.0-10.5 | － | 0.10 |
| S30600 | 0.08 | 2.00 | 0.45 | 0.030 | 0.75 | 16.0-18.0 | 10.0-14.0 | 2.00-3.00 | 0.10 |
It can be seen that 316 has 2%-3% more nickel and 2% more Mo (Mo) than 304, and at the same time reduces the Cr content. It greatly improves the corrosion resistance, significantly improves the intergranular corrosion resistance, oxide resistance, chloride stress corrosion resistance and reduces the hot cracking tendency during welding. It can be used in the chemical industry, seawater and other environments, often used in pure water, distilled water, medicine, sauce, vinegar and other occasions where need high health requirements and medium corrosion performance such as drinks, beer, milk processing, drug manufacturing, etc.
The strength and hardness difference of food-grade 304 and 316 stainless steel is similar, but 316 has better corrosion resistance and heat resistance than 304. In terms of actual use, 304 stainless steel encountered carbonated drinks, milk and other food may be corroded, but there is no trouble if it is 316 stainless steel, but also have to face the defects, that is, the cost of 316 stainless steel is higher than 304, so generally used in higher requirements of the environment.
