How to Check FDA Compliance When Purchasing 904L Stainless Steel?
Leave a message
When purchasing 904L stainless steel, how to judge the authenticity of the FDA certification report provided by the supplier?
Third-party test report: must be issued by an FDA-approved laboratory (such as SGS, Intertek), including 904L brand (UNS N08904), test conditions (such as 4% acetic acid immersion), migration data (such as nickel precipitation ≤0.1ppm);
Material Certificate (MTC): Check whether the composition meets the ASTM A240 standard (such as Ni≥23%, Mo 4-5%, C≤0.02%), especially pay attention to harmful elements such as lead (Pb≤0.01%) and cadmium (Cd≤0.005%).
| Test Item | Compliance Standard | Test Method | Typical Performance of 904L (Superior to 316L) |
|---|---|---|---|
| Total Migration | ≤10mg/dm² (4% acetic acid, 70℃×2 hours) | Gravimetric method | 5–7mg/dm² (316L: 8–12mg/dm²) |
| Nickel Ion Migration | ≤0.1ppm (simulated acidic food) | ICP-MS instrument testing | 0.05ppm (316L may exceed 0.3ppm) |
| Microbial Adhesion | ≤10CFU/cm² (ISO 22196 standard) | Agar culture method | 5CFU/cm² (mirror-polished, Ra≤0.4μm) |
Roughness control:
The food contact surface needs to be mirror polished (Ra≤0.4μm), which can be tested on site with a portable roughness meter (such as Mitutoyo SJ-210). The industrial grade commonly used Ra≤1.6μm, which cannot be used directly in food scenes.
Passivation process:
Food-grade passivation solution (20% nitric acid, no chlorine/sulfur addition) must be used to avoid residual harmful ions, and passivation records (time, temperature, solution composition) are required.
Compliance traceability of the production process
Quality management system:
Suppliers must have ISO 22000 (food quality management) or GMP (good manufacturing practice) to ensure that the entire process from steelmaking to processing is controllable;
Batch traceability: Each batch of 904L must be accompanied by a COA (composition analysis certificate) and heat treatment records, which can be traced back to the furnace number and rolling process.
Welding process:
Food contact parts need to use ER385 welding wire (containing 4.5% Mo) to prevent the weld area from becoming a migration point exceeding the standard. A liquid penetration test report of the weld is required (ASTM E165).
