How does the seamless steel pipe carry out the pickling process?

Seamless steel pipes have a hollow cross-section and are widely used as pipes for transporting fluids, such as pipes for transporting oil, natural gas, gas, water, and certain solid materials. Compared with welded steel pipes, steel pipes are lighter in weight when they have the same flexural and torsional strength, and are economical section steels.

Precision seamless steel pipe pickling overview

The method of using an acid solution to remove scale and rust on the steel surface is called pickling. Iron oxides (Fe3O4, Fe2O3, FeO, etc.) such as scale and rust react chemically with the acid solution to form salts that are dissolved in the acid solution and removed. Pickling acids include sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid and mixed acids.

Common media for pickling of precision seamless steel pipes

Sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid. Be sure to add pickling corrosion inhibitor during pickling to prevent acid from corroding metal.

Precision seamless steel pipe pickling process

There are mainly immersion pickling method, spray pickling method and acid paste derusting method. Generally, the dipping pickling method is used, and the spraying method can be used in mass production. Steel parts are generally pickled in 10% to 20% (volume) sulfuric acid solution at a temperature of 40°C. When the iron content in the solution exceeds 80g/L and the ferrous sulfate exceeds 215g/L, the pickling solution should be replaced. Under normal temperature, use 20% to 80% (volume) hydrochloric acid solution to pickle steel, so that over-corrosion and hydrogen embrittlement are not easy to occur. Because acid has a strong corrosion effect on metals, it is necessary to add corrosion inhibitors. After cleaning, the metal surface becomes silvery white, and the surface is passivated at the same time, improving the corrosion resistance of stainless steel. In order to eliminate surface adsorption of diatomaceous earth carrier and reduce chromatographic peak tailing, the carrier needs to be acid-washed or alkali-washed before use. Pickling is to soak the carrier with 6mol/L hydrochloric acid for 2h or concentrated hydrochloric acid for 30min, filter, wash with water until neutral, and dry. Pickling can remove iron, aluminum, calcium, magnesium and other impurities on the surface, but cannot remove silanol groups. Acid-washed supports are suitable for the analysis of acidic samples.

The role of precision seamless steel pipe pickling

Degrease and derust the surface of the precision seamless steel pipe to prepare for the next process. In the production process, the pickling process is to remove the surface oxide scale. After lubricating treatment (carbon steel-phosphorus saponification, stainless steel-tallow lime, copper aluminum tube-oiling), using the old process-copper plating), and then drawing deep processing. If the steel pipe is not pickled, there may be oxides and oil stains on the surface, which cannot be removed by the nuclear energy of the phosphating solution, and the phosphating quality will be reduced.

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