Pickling process of seamless steel pipe

The process of pickling seamless steel

pipes involves immersion pickling, spray pickling, and acid paste rust removal. The dipping pickling method is commonly used, while the spraying method is suitable for mass production. Steel parts are pickled in a 10% to 20% (volume) sulfuric acid solution at a temperature of 40°C. It is recommended to replace the pickling solution when the iron content exceeds 80g/L and the ferrous sulfate exceeds 215g/L. When pickling steel with a hydrochloric acid solution ranging from 20% to 80% (volume) at room temperature, it is important to use corrosion inhibitors to prevent over-corrosion and hydrogen embrittlement.  The acid has a strong corrosive effect on metals, and after cleaning, the metal surface will become silvery white and passivated, which improves the corrosion resistance of stainless steel. Sulfuric acid pickling is the process of using a 5% to 20% concentration aqueous solution of sulfuric acid to remove scale and adhered salts from the surface of a workpiece. Industrial concentrated sulfuric acid, typically containing a mass fraction of H2SO4 between 75% and 97%, is commonly used. Brown industrial sulfuric acid solution, containing a mass fraction of H2SO4 between 75% and 78%, can also be used.

To reduce chromatographic peak tailing and eliminate surface adsorption of the diatomaceous earth carrier, it is necessary to acid-wash or alkali-wash the carrier before use. Pickling involves soaking the carrier in 6mol/L hydrochloric acid for 2 hours or concentrated hydrochloric acid for 30 minutes, filtering, washing with water until neutral, and drying. This process can remove impurities such as iron, aluminum, calcium, and magnesium from the surface, but it cannot remove silanol groups. Acid-washed supports are suitable for analyzing acidic samples.