Which is better, acid washing or polishing, for 304 stainless steel pipes

The stainless steel market at home and abroad is developing rapidly, and stainless steel pipes are being applied in an increasing number of industries. We know that based on different surface treatment methods, stainless steel pipes can be classified as acid-washed pipes and polished pipes. Which is better for 304 stainless steel pipes, acid washing or polishing? What are the benefits of acid washing and polishing in thin-walled stainless steel pipes? Today, we will compare which of these processing methods is more advantageous, so that you will know which type of pipe to choose when making purchases in the future. 

Pickling is the process of removing the oxide scale and rust from the surface of the pipeline using acid solution, creating a dense oxide film on the surface. Therefore, the production cost is relatively low. Polishing is achieved through mechanical, chemical or electrochemical means to reduce the surface roughness. Its characteristics are brightness and flatness, but it is prone to causing uneven wall thickness. Let's take a look at the features of these two treatment methods: 

The pickling of stainless steel pipes ensures the performance of austenitic stainless steel pipes. Most steel pipes are made using different types of austenitic stainless steel as raw materials, and they are non-magnetic or weakly magnetic. However, the polished stainless steel welded pipes can cause fluctuations in chemical composition, making the austenitic stainless steel magnetic. 

2. The wall thickness of the 304 stainless steel pipe after pickling remains uniform and has a strong pressure-bearing capacity. After manual polishing of the welded pipe, the wall thickness of the raw material will become thinner, especially at the weld area. The thinner the weld wall thickness, the lower the pressure-bearing capacity. Acid pickling is more effective than polishing. 

3. After the stainless steel pipe undergoes acid washing, a dense protective film will form on its surface, isolating it from the external environment and providing strong corrosion resistance. Polishing can only improve the surface smoothness and remove rust, reducing the contact area with the environment. It can temporarily prevent oxidation and corrosion within a short period of time, but the maintenance period is not long. 

4. The quality of stainless steel acid-washed welded pipes is more stable: The polished stainless steel pipes can cover up the splatters, thick skins and dents on the material surface. Even stainless steel pipes require multiple longitudinal and transverse weld joints for the welding connection. The quality of the raw materials for this polished stainless steel pipe cannot be guaranteed, and neither can the quality of the stainless steel pipes themselves. 

5. Acid pickling steel pipes are more practical: Industrial pipes mainly utilize the mechanical properties, corrosion resistance, or pipeline performance of the stainless steel pipes themselves. Except for decorative pipes and sanitary pipes, there is a lower requirement for the glossiness of the stainless steel pipe walls. Therefore, stainless steel industrial pipes do not need to use expensive and unstable polished stainless steel pipes.