The reason why the seamless pipe is etched

The destruction of seamless steel pipes due to the organic chemical action or photocatalytic action of substances is called corrosion. The main corrosion methods of seamless steel pipes are uniform corrosion (surface corrosion) and localized corrosion. Localized corrosion includes stress corrosion, pitting corrosion, crevice corrosion and stress corrosion. According to the survey, uniform corrosion accounts for only 10% of seamless steel pipe corrosion damage accidents, and local corrosion accounts for about 90%.

Causes of seamless steel pipe corrosion

1. Chemical corrosion
1) Surface environmental pollution: oil, dust, alkali, salt, etc. attached to the surface of the product will chemically change with certain parts of the stainless steel plate to cause chemical corrosion.
2) Surface scratches: All kinds of scratches destroy the oxide film, reduce the maintenance work ability of the stainless steel plate, promote the reaction to organic chemicals, and cause chemical corrosion.
3) Cleaning: After pickling, if the cleaning is not clean, the residual liquid will immediately corrode the stainless steel plate components (chemical corrosion).

2. Electrochemical reaction
1) Carbon steel environmental pollution: Carbon steel parts digest and absorb carbon steel components, and the key rechargeable batteries that produce corrosive substances cause electrochemical reactions.
2) Laser cutting: Mucus, splashes, etc. are attached to the etchant to form an initial charging battery to cause an electrochemical reaction.
3) Baking correction: The composition of the flame heating range is changed to a metal material mechanism, and the electrochemical reaction is caused by the etching substance.
4) Electric welding: Physical defects and organic chemical defects in the electric welding area and etching medium produce primary and intermediate rechargeable batteries and cause corrosion of power engineering compounds.
5) Raw materials: Organic chemical defects (asymmetry, S, P residues, etc.) and surface physical defects (pores, sand, cracks, etc.) in the steel plate promote electrochemical reactions of corrosive substances to produce primary and intermediate rechargeable batteries.
6) Passivation treatment: The actual effect of phosphating treatment is not good, resulting in unevenness or thinning, which is convenient for electrochemical reaction.
7) Cleaning: chemical corrosion of phosphating residual components.

Methods to prevent corrosion of seamless steel pipes
The main anti-corrosion technology is the use of air oxidation membrane separation technology, anti-corrosion coating technology and desulfurization agent technology. Among various safety protection technologies for seamless pipe corrosion, desulfurizer technology has become one of the most effective and commonly used methods because of its simple processing technology and wide application range. However, desulfurizers have significant technical limitations.
Among the most commonly used high-efficiency liquid substances, the desulfurizer must have a certain solubility and must exceed a certain concentration value. Traditional desulfurizers have severe side effects and cause environmental pollution to the natural environment. At the same time, due to the small amount of desulfurizer used for seamless pipes, small external changes will cause great harm to the management system.

Article source: https://article-realm.com/article/Finance/36788-The-reason-why-the-seamless-pipe-is-etched.html