Fabrication Blasting Workflow
In heavy steel fabrication, surface preparation is the bottleneck between the welding shop and the paint hall. To maintain project schedules for bridges, stadiums, and high-rise structures, the technical approach focuses on maximum media recycling and Sa 2.5 consistency.
1. Mill Scale Removal
Blast-cleaning raw plates and I-beams to Sa 2.5 to remove the brittle mill scale layer, ensuring the mechanical bond for long-term corrosion protection.
2. Weld Edge Preparation
Focused cleaning of fabricated assembly weld seams to remove slag, spatter, and technical oxidation before multi-layer coating application.
3. Profile Consistency Check
Using Surface Profile Gauges to ensure the anchor pattern matches the primer's requirements (typically 50-75 microns for standard epoxies).
Steel Grit Economics
For repetitive indoor fabrication, Steel Grit is the superior technical choice. Capable of 200+ recycle cycles in an Automatic Blast Room, it provides the lowest cost-per-ton and creates the aggressive anchor profile needed for heavy structural primers.
The Flash Rust Window
Structural steel is highly reactive. Primer must be applied within the "technical window" (usually 4-6 hours) after blasting. High-capacity Cartridge Dust Collectors ensure the blast room environment remains clean, extending the window before moisture-induced flash rust occurs.
Fabrication Throughput Audit
- Automated Recovery: Floor scraper systems for zero-downtime media turnover.
- Cyclone Cleaning: Integrated separators to remove oversized debris and dust.
- High-Build Coating: Utilizing Airless Painting Pumps for rapid fabricated assembly protection.
Frequently Asked Questions
What surface preparation is required for structural steel in buildings?
Building structural steel: Sa2 (Commercial) minimum per SSPC-SP10 for maintenance painting. New structural steel: Sa2.5 for primary structural members exposed to weather, Sa2 for enclosed/protected members. Profile: 30-75µm Rz per ISO 8503. Steel must be dry before coating. Primer must be applied within the recoating interval (typically within 4 hours in tropical climates).
What blast pot size is recommended for structural steel fabrication?
For structural steel fabrication: 200L pot for light fabrication work (1-2 operators). 300L pot for standard fabrication (2-3 operators). 500L pot for heavy fabrication and large plate work (3+ operators). Rule: 300L is the industry standard for fabrication shops. Estimate ~1.5 kg of abrasive per m² of structural steel at Sa2.5.
What causes inconsistent profile on structural steel?
Inconsistent profile causes: (1) Variable pressure at nozzle — undersized hose or excessive hose length. (2) Different substrate hardness — thick flange vs thin web. (3) Variable abrasive quality — inconsistent mesh gradation. (4) Improper nozzle distance. (5) Operator technique variation. Maintain 150-200mm standoff at 90° angle. Standardize one person holds the nozzle, 30-50% pattern overlap, consistent speed.