The difference between food grade 304 stainless steel pipe and industrial pipe

[guidebook] : For food grade 304 stainless steel pipe and industrial pipe, although both are stainless steel pipe, but there is a certain difference between them. Not to mention other things, there is a gap in the field of application, and the use of the two determine the implementation of standards, process requirements, surface and so on.

For food grade 304 stainless steel pipe and industrial pipe, although both are stainless steel pipe, but there is a certain difference between them. Not to mention other things, there is a gap in the field of application, and the use of the two determine the implementation of standards, process requirements, surface and so on.

1, Heavy metal content

The difference between food grade 304 stainless steel pipe and industrial pipe mainly lies in the heavy metal element content of food grade 304 stainless steel pipe is much lower than the heavy metal content of industrial pipe. According to the standard GB 31604.34-2016 "National Standard for Food Safety Food Contact Materials and Products Determination of Lead and Determination of Migration", the requirements of food-grade 304 stainless steel pipe in acetic acid immersion, dissolved lead content ≤ 0.05; and industrial pipe, such as martensitic stainless steel on the lead content does not have to make clear provisions.

2, Surface

The most obvious difference lies in the surface, food grade 304 stainless steel pipe surface should at least reach the BA level, that is, the bright surface; and industrial pipe for the surface has no requirements, the surface is often rougher, the key to high corrosion resistance.

3, Process requirements

For food grade 304 stainless steel pipe in direct contact with food, the finish inside the pipe is very important. However, the inner wall of the tube needs to be polished and bright annealed, so that the inner wall of the tube becomes smoother, if there is a liquid medium inside, it can prevent clogging.

Industrial tubes are often used in polluted environments, so the antioxidant properties of the tubes are required to be relatively high, so they are usually pickled and passivated. Pickling passivation can generate a layer of dense oxide film on the surface of the tube, greatly improving the corrosion resistance of the pipe.

4, The implementation of standards

The reference standard for food grade 304 stainless steel pipe is shown in QBT 2467-2017 "Stainless Steel Pipe Standard for Food Industry"; and the standard for industrial pipe is divided into a number of varieties depending on its use, such as GB/T 31929-2015 "Stainless Steel Welded Steel Pipe for Ships", GB/T 32569-2016 "Stainless Steel Welded Steel Pipe for Seawater Desalination Devices", GB/T 24593-2018 Standard for Austenitic Stainless Steel Welded Steel Pipes for Boilers and Heat Exchangers, GB 30813-2014 Austenitic Stainless Steel Welded Steel Pipes for Nuclear Power Plants and so on.

The above standards mainly stipulate the surface roughness of food 304 stainless steel pipe and hygiene requirements, etc., while the industrial pipe mainly stipulates the chemical element content, mechanical properties, size, shape, etc..

5、Application scope

Food grade stainless steel pipe is generally used in food, beverage, alcohol, pharmaceuticals and other production equipment and assembly lines; and industrial pipe is commonly used in boilers, heat exchangers, mechanical parts, sewage piping, chemical pressure piping and so on.

The above is the difference between food-grade 304 stainless steel pipe and industrial pipe, we learned that the difference between the two heavy metal content, surface, process requirements, implementation standards, scope of application, of course, in addition to these differences there are prices, production methods and so on.