Although in theory the welded pipe does not rust, the rust is not a stainless steel industrial welded pipe, it may be a steel problem. Such a view belongs to the lack of understanding or one-sided understanding of the welded pipe. In fact, the welded pipe will also rust under certain conditions. In theory, the welded pipe has the ability to resist atmospheric oxidation-that is, stainless steel, and can also be resistant to corrosion in media containing acids, alkalis, and salts-that is, corrosion resistance. However, the corrosion resistance of steel depends on its own chemical composition, The state of interaction, conditions of use, and type of environmental media vary. Such as 304 steel pipe, it has good corrosion resistance in a dry and clean atmosphere, but it is moved to the seaside area and contains a lot of salt in the sea fog, which will rust for a long time; 316 steel pipe has good performance .. Therefore, it is not any This kind of welded pipe is resistant to corrosion and does not rust in any environment. The corrosion of stainless steel welded pipe is mainly reflected in the appearance of brown rust spots (spots) on the surface

In addition to the above reasons, there are several types of daily use:

1. The accumulation of dust on the surface of the tube contains dust containing other metals or heterogeneous metal particles in the humid air, and the connection between the condensate pipes is connected to the minute division to two, so that the electrochemical reaction, the protective film is destroyed, known Electrochemical corrosion.

2. Organic juice (such as vegetables, soup, sputum, etc.) adheres to the surface of the tube, and the water present therein forms acid oxygen, and the organic acid grows due to corrosion of the metal surface.

3. The attachments on the surface of the welded pipe contain acid, alkali and salt substances (such as alkali water and lime water splashed from the decorated wall), causing local corrosion ..

4. In the case of air pollution (for example, air containing a large amount of sulfide, carbon dioxide, and nitrogen oxides) and condensate, sulfuric acid, nitric acid, and acetic acid solution points are formed, causing chemical corrosion.

The above conditions will cause corrosion, damage to the protective film on the surface of the welded pipe, and cause the appearance of "rust" such as color rust and spots (spots).