Food-grade 316/304 Stainless Steel Tube
Food-grade 316/304 stainless steel tube Finishing 316L stainless steel assemblies for handling food and beverage applications is more complicated than non-sanitary applications. Knowledge of the tools, consumables, and techniques is critical, but likewise the contractor must be familiar with...
Food-grade 316/304 stainless steel tube
Finishing 316L stainless steel assemblies for handling food and beverage applications is more complicated than non-sanitary applications. Knowledge of the tools, consumables, and techniques is critical, but likewise the contractor must be familiar with sanitary standards so the system and its finish are optimal the demands for this type of application.
Designing, fabricating, assembling, finishing, and cleaning equipment for food-grade applications, regardless of the alloy used, has myriad requirements that must be met every step of the way. The term food-grade 304 and its many variants refers to surfaces that have, in the federal government’s terminology, a sanitary finish—a finish that is safe for processing food products and can easily and reliably be cleaned and sanitized.
The grinding, sanding, and finishing of food-grade stainless steel must result in surfaces devoid of areas that encourage bacteria growth. The surfaces must be free of lines, grooves, pits, or divots. Additionally, the surfaces must withstand corrosion from the food being handled and the chemicals used to sanitize the equipment. Also note that stainless steel isn’t a single material; many stainless alloys are used in food-oriented applications.
Judge a Book by Its Cover, and the Story Inside
In the majority of applications, a finish at the high end of No. 4 is considered food grade316. This finish is achieved using a high-grit abrasive in the range of 150-220 and is identified by short, parallel lines that run the length of the material. The success of the finish can ultimately be determined by a surface roughness average (Ra), measured by height in millionths of an inch (µin.), or microinches. A profilometer determines Ra values by moving a diamond stylus across the workpiece’s surface for a specified distance and using a specified contact force. It measures small surface variations and calculates their average to determine the roughness. In most food-grade applications, 0.8u Ra is achieved with professional technique by Huzhou Zhongrui. Because milk products spoil more quickly and carry more bacteria than other food and beverage items, dairy applications should have a finer finish, No. 4A, which is 40-24 Ra and achieved with a 220-grit abrasive or finer.
Keep in mind that the abrasive’s grit value isn’t the only determinant of the surface finish; other factors are the condition of the abrasive, the particular tool, its speed, and the operator’s technique.