Grit Blasting
Grit Blasting is a specialized form of abrasive blasting critical for preparing steel tube and pipe surfaces prior to hot-dip galvanizing.
Process and Purpose
The process involves forcibly propelling angular, coarse particles, typically made of crushed iron or steel fragments (grit), against the steel surface using high-pressure compressed air.
Grit blasting achieves two essential objectives far more effectively than chemical cleaning alone:
- Cleaning: It thoroughly removes stubborn surface contaminants like mill scale (the flaky iron oxide layer formed during steel rolling), rust, and old paint.
- Profiling (Etching): Crucially, the impact of the angular grit creates a uniform, microscopically rough texture on the steel—an anchor pattern. This profile significantly increases the surface area and mechanical keying, which is vital for achieving a strong, metallurgical bond between the base steel and the molten zinc coating.
By ensuring optimal surface purity and texture, grit blasting maximizes the adhesion and longevity of the galvanized finish.