I. Prioritize Selection Based on Core Operating Conditions
Ordinary Indoor Dry Environment: Phosphating + Rust-Inhibiting Oil Coating – Low cost, meets short-term rust prevention and machining lubrication needs.
Outdoor/Damp Environment: Hot-dip galvanizing – Zinc layer thickness ≥85μm, salt spray life over 500 hours, long-term corrosion resistance.
Highly Corrosive/High-Cleanliness Scenarios: Passivation treatment – Compatible with stainless steel pipes, forms a dense protective film, resistant to chloride ion corrosion.
Food/Pharmaceutical/High-Purity Fluid Scenarios: Electrolytic polishing – Surface roughness Ra≤0.1μm, residue-free and easy to clean, meets sanitary standards.
II. Avoid Pipe Material Issues
Carbon Steel Pipes: Prioritize galvanizing and phosphating with oil coating – higher cost-effectiveness, no need for additional high-cost passivation.
Stainless Steel Pipes: Prioritize pickling and passivation, electrolytic polishing – avoid damaging the inherent corrosion-resistant structure of stainless steel.
Alloy Pipes: Hot-dip galvanizing at temperatures >450℃ is prohibited; epoxy zinc-rich primer + topcoat coating is recommended.
III. Considering Subsequent Processing Adaptability If the pipe will be welded or cut later, pickling and shot blasting pretreatment should be given priority to thoroughly remove the surface oxide scale, avoid weld porosity and accelerated tool wear, and ensure processing accuracy.
