Food-grade stainless steel must be approved by the FDA and contain at least 16% chromium. The chromium content helps prevent stainless steel from rusting and corroding by forming a chromium oxide film or coating that blocks oxygen diffusion, thereby preventing corrosion from spreading to the internal structure of the steel‌1. 304 stainless steel (also known as SAE 304 SS, A2 stainless steel, or 18/8 stainless steel) is the most popular food-grade stainless steel because it contains 18% chromium and 8% nickel, which provides excellent corrosion resistance‌1.

Other related standards

In addition to FDA standards, food-grade stainless steel also needs to be approved by other agencies, such as ANSI and NSF. Stainless steel used in food equipment must be SAE 200 series (chrome-nickel-manganese alloy), SAE 300 series (chrome-nickel alloy), or SAE 400 series (chrome alloy). The chemical composition and concentration of these stainless steels vary, but they provide the necessary chromium content to make them acceptable food contact materials‌1.

Specific standards and test items

FDA food contact material testing items include:

Composition analysis (for grades 200, 300, and 400 series stainless steel)

Lead dissolution test (175.300+7117.05)

These tests ensure that stainless steel does not release harmful substances during food contact.