More protection Surface brightness ≠ surface roughness!

Is the inner surface of the pipe as bright as possible? To explain the above problem, it is necessary to understand why the inner surface of the pipe rolled out of the same steel plate is so smooth and brighter than the outer surface after treatment.
This is because the inner surface in contact with the material must reach a certain surface roughness to meet the design needs
of transportation and hygiene.
Surface roughness 1.
Refers to the small spacing and micro-peak-valley unevenness
of the surface of the product.
2.
The distance (wave distance) between its two peaks or two troughs is very small (below 1mm), and it belongs to the microscopic geometry error
.
3.
The smaller the surface roughness, the smoother
the surface.
The size of the surface roughness has a great impact on the performance of the pipeline, mainly in the following aspects: sliding property, air tightness, adhesion, corrosion resistance, appearance, strength, etc
.
Stainless steel surface surface roughness can not be directly linked to the surface brightness, in fact, the earliest domestic use of surface finish standard, is proposed by human visual effect view: the surface of the diffuse reflection of light is strong, closer to the mirror effect, the gloss is high, vice versa, the gloss is low
.
Because the surface roughness is proposed according to the actual surface microgeometry, and the surface finish is proposed according to the visual point of view of people, the roughness is more scientific and rigorous
than the finish.
In order to be in line with international standards (ISO), China adopted surface roughness and abolished surface finish after the 80s
.
After the promulgation of the national standards GB3505-83 and GB1031-83 for surface roughness, the surface finish is no longer used
.
Compared with surface roughness, in addition to expressing brightness, there are no more stringent surface quality requirements, and modern surface roughness has merged surface finish: both roughness is high, its finish must be good, and vice versa
.
Therefore, the inner surface of the sanitary stainless steel pipe cannot be judged by the finish alone, and the surface roughness value is the most standard judgment basis
at present.
High surface brightness≠ good surface roughness Clean grade sanitary pipeline, should use 2B grade cold-rolled steel coil as the base metal, the weld bead must be completely welded and penetrated, can not have trachoma or impurities, and after the weld bead flattening, to achieve the surface of the inner weld bead without depression or protrusion, is to meet the requirements of
sanitary pipeline 。 Surface treatment process of commonly used pipes · Bright annealing (BA for short) Pickled/Chemically Polished, abbreviated as CP · Passivated/Chemically Polished, abbreviated as CP · Mechanically Polished, called MP · Electro-Polished abbreviated as EP Xinlai stainless steel pipe adopts bright annealing (BA) process, online bright solid solution + passivation, so the inner surface of Xinlai BA stainless steel pipe can be surface roughness value R ≤0.
8
without machine polishing.
Other food-grade stainless steel pipes mostly use atmospheric solid solution + pickling passivation, or simply no solid solution treatment, need to be thrown by a cloth turbine (usually using polishing paste containing animal fat), so as to obtain a better surface bright effect
.
Cloth wheel polishing (BP) has a perfect visual effect, and the use of polishing paste containing animal grease is even more harmful! In the next issue, Xinlai will continue to introduce you to the harm of these two points, so stay tuned
.