Polishing Techniques and Quality Requirements for Stainless Steel Reactors

Crucial Role of Polishing in Stainless Steel Reactors

Types of Polishing Techniques

1. Mechanical Polishing
   • Process: Involves both rotational and linear polishing methods. For rotational polishing, equipment includes a power-driven polishing disc and specialized polishing wax.
   • Benefits: Offers a consistent finish, smoothing out surface imperfections and creating a uniform base for further treatment.
2. Electrochemical Polishing (Electrolytic Polishing)
   • Principle: The inner surface of the stainless steel tube undergoes electrolysis in a specialized polishing solution. During this process, two simultaneous reactions occur: the formation and dissolution of a passive film (mucous membrane layer) on the metal surface.
   • Advantages: Microscopic protrusions dissolve faster due to higher current density (tip discharge effect), rapidly flattening the surface. This results in an ultra-smooth finish with a surface roughness of Ra 0.2–0.4 μm. Additionally, the process strengthens the passive layer, significantly boosting corrosion resistance.

Quality Requirements

• Passivation Layer: Both mechanically and electrochemically polished surfaces must form a robust passivation layer, ensuring long-term protection against corrosion.
• Surface Finish: Internally and externally, reactors require a high-gloss finish to reduce media adhesion and prevent residue buildup.
• Hygiene Compliance: In pharmaceutical applications, the reactor’s inner surface must enable effortless cleaning, minimizing the risk of contamination.

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