In addition to the brand, material origin, and production and processing technology, a key factor that directly affects the price of 316L stainless steel pipe is the surface treatment method. To further improve the characteristics of 316L stainless steel pipe, the specific methods for processing the inner and outer surfaces of the pipe are divided into several types: pickling passivation (AP), mechanical polishing (MP), bright annealing (BA), and electrolytic polishing (EP) treatment processes. According to test data and actual results, the roughness of 316L stainless steel pipe is reduced and the surface adsorption is weakened. In this case, what is the difference between AP grade, MP grade, BA grade, and EP grade stainless steel pipe? Please refer to the following:

AP (Acid Pickling) Pickling Treatment
The corrosion resistance of stainless steel mainly comes from the chemical reaction between the chromium element contained in it and oxygen to form a dense oxide film on its surface. The role of the pickling process is to allow it to react in advance to improve the corrosion resistance of 316L stainless steel pipe. During the pickling process, the oil stains and dirt attached to the surface of the 316L stainless steel pipe and some substances contaminated during production will be completely removed. The inner and outer surfaces of the pipe are relatively rough, and suspended impurities and residues are easily attached.

BA (Bright Annealing) Bright Annealing
The polishing wheel or polishing belt uses the abrasive in the polishing agent to grind and polish the surface of the 316L stainless steel pipe so that the surface of the 316L stainless steel pipe can achieve a smooth polishing effect. Its brightness depends on the type of processing technology. In addition, although mechanical polishing is more beautiful, it will also reduce corrosion resistance. Therefore, when used in a corrosive environment, it needs to be passivated, and there is often polishing material residue on the surface of the 316L stainless steel pipe.

MP (Mechanical polishing) Mechanical polishing
During the production process of 316L stainless steel pipes, the grease grains used for lubrication may be deformed due to production and processing. To avoid grease residue in 316L stainless steel pipes, high temperature is reasonably used to use argon as the furnace atmosphere during the annealing process. Argon gas is combined with carbon and oxygen on the surface of 316L stainless steel pipes to burn, and the surface of 316L stainless steel pipes is further cleaned to form a bright surface effect. This method of using pure argon gas for annealing, heating, and rapid cooling to brighten the surface is called bright annealing. Although this method can keep the 316L stainless steel pipe clean and free of any external pollution, the brightness on this surface will feel matte compared with other polishing methods such as mechanical, chemical, and electrolytic. Of course, its effect is also related to the content of argon gas and the number of heating times.

EP (Electro Polishing) Electropolishing
Electropolishing is a method of anodic treatment. According to the principle of electrochemistry, the voltage, current, acid composition, and polishing time are appropriately adjusted. It can not only make the surface bright, smooth, and clean but also enhance the corrosion resistance of the surface. Therefore, it is a good method for brightening the surface. Of course, its cost and technology will also increase a lot.