Seamless steel pipe pickling passivation

Pickling and passivation are essential treatments for carbon steel, stainless steel (including seamless pipes), and ferrous metals (such as castings, forgings, and sheet metal parts). These processes remove rust and black oxide layers, enhancing the corrosion resistance and durability of the pipe surfaces. This article will introduce the seamless steel pipe pickling passivation.

Seamless Pipe (SMLS) Pickling Process:

The pickling process for seamless steel pipes involves several steps: degreasing, washing, pickling, washing, and applying a sealing agent. Typically, there are two common methods for pickling seamless steel pipes made of carbon steel:

Sulfuric Acid Method: Dilute sulfuric acid to approximately 20% concentration, then heat the solution to 60-65°C. The pipes are generally washed for 20-30 minutes.

Hydrochloric Acid Method: Similarly, hydrochloric acid is diluted to around 20% concentration. This method does not require heating; pickling is conducted at room temperature, typically lasting 20-30 minutes.

Features and Advantages of Pickling and Passivation:

Combined Pickling and Passivation: The solution for carbon steel combines pickling and passivation in one step, eliminating the need for water washing to remove rust and the black oxide layer, thereby significantly increasing labor productivity.

Ease of Use: The pickling and passivation process is straightforward, involving tank washing and soaking for small to medium-sized carbon steel pipe fittings. The treatment results in improved corrosion resistance and rust prevention on the pipe surface.

Optimal Operating Conditions: The solution operates effectively at temperatures between 5-30°C, and the pickling and passivation process takes about 5-15 minutes to achieve the desired effect.

Results of the Process:

Enhanced Corrosion Resistance: The treated carbon steel workpieces exhibit improved corrosion resistance. However, the effectiveness of rust prevention depends on various factors, including the material of the workpiece, surface condition, climate, air pollution levels, water quality used for dilution, construction methods, and stacking methods of the workpieces.

Environmental Safety: The pickling passivation solution is environmentally friendly, containing no harmful substances. The wastewater generated can be safely discharged after neutralization, posing no threat to the environment.

Precautions During Pickling and Passivation:

Ventilation: Conduct pickling and passivation operations outdoors or in a well-ventilated area.

Safety Gear: Operators must wear appropriate protective equipment to avoid direct contact with the pickling passivation solution. In case of accidental contact, rinse the affected area immediately with clean water.

Use of Acid-Resistant Materials: The containers and tools used for pickling and passivation should be made of acid-resistant plastic.

Waste Management: Treated residues and wastewater must be neutralized promptly with lime milk or sodium hydroxide to prevent environmental pollution.

Avoid Sunlight: Avoid performing operations under direct sunlight to prevent the pickling passivation solution from drying out, which can negatively impact the passivation effect.

These guidelines ensure the effective and safe application of pickling and passivation, resulting in high-quality, corrosion-resistant seamless steel pipes suitable for a wide range of industrial applications.