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Hygienic Grade 316L Stainless Steel Pipe (referred to as “Hygienic Pipe 316L”) refers to a type of pipe product that meets the hygiene requirements of food, pharmaceutical, cosmetics and other industries. It is based on 316L austenitic stainless steel, processed through special techniques, and can directly contact materials (food, pharmaceuticals, daily chemical products). It is mainly used in fluid transportation systems and must meet key requirements such as non-toxicity, anti-pollution, and easy cleaning. II. Material and Chemical Composition Standards 1. Basic Material Requirements – Must use low-carbon 316l stainless steel with a carbon content ≤ 0.03% (to avoid the risk of intergranular corrosion); – Key alloy element content: Chromium (Cr) 16.0%~18.0%, Nickel (Ni) 10.0%~14.0%, Mo 2.0%~3.0%ensuring corrosion resistance and stability; – Limit of harmful elements: Lead (Pb) ≤ 0.01%, Cadmium (Cd) ≤ 0.005%. Alloys containing migratory harmful substances such as lead, cadmium and copper are strictly prohibited. 2. Material Compliance Basis – Domestic standards: GB/T 3280-2015 “Stainless Cold-Rolled Steel Plates and Strips” (base material requirements), GB 4806.9-2023 “National Food Safety Standard for Metal Materials and Products in Contact with Food” (food contact scenarios); – International standards: US FDA 21 CFR 177.1520 (chemical composition and migration limits), EU EU 10/2011 (general requirements for food contact materials). III. Surface Treatment and Physical Performance Requirements 1. Surface Roughness (Core Hygiene Index) – Inner wall roughness: The inner wall directly in contact with materials shall have Ra ≤ 0.8μm; for the food and beverage industry, Ra ≤ 0.5μm is recommended; for pharmaceutical sterile systems, Ra ≤ 0.2μm (SF4 standard) is required; – Outer wall roughness: Usually Ra ≤ 1.6μm, and defects such as pits, scratches and scale shall be avoided to prevent microbial growth. 2. Surface Treatment Process – Must undergo mechanical polishing or electrolytic polishing to form a mirror finish, ensuring no material residue on the wall; – After polishing, pickling and passivation treatment shall be carried out to form a dense chromium oxide protective film, improving corrosion resistance. After passivation, oil-free cleaning shall be performed to ensure no oil residue (qualified by grease analyzer detection). 3. Corrosion Resistance Requirements – Salt Spray Test: After 48 hours of neutral salt spray test, the surface shall be free of rust and pitting, and the corrosion resistance grade shall not be lower than Grade 8 (GB/T 10125-2021 standard); – Acid and alkali resistance range: Can withstand the medium environment of pH 2~11 (suitable for cleaning and process fluids in food and pharmaceutical production). IV. Structural Design and Manufacturing Standards 1. Pipe Structure – No welding dead ends: Adopt integral forming or seamless welding process. The weld seam shall be smooth and flat, free of false welding, missing welding and cracks, and the roughness of the welding area shall be consistent with the pipe body (Ra ≤ 0.8μm); – Connection method: Priority shall be given to clamp-type (complying with ISO 2852) or thread-type (complying with DIN 11851) connection. The seal shall be FDA-certified EPDM or PTFE material, with a temperature resistance range of -20℃~150℃ and no risk of dissolution. 2. Dimensional Tolerance – Outer diameter deviation: According to the pipe diameter specification, the deviation shall be controlled within ±0.1~±0.3mm; – Wall thickness uniformity: The wall thickness deviation shall be ≤ 10% to avoid corrosion or pollution accumulation caused by local weakness. #sanitarypipe #seamlesspipe #Hygienicpipe