H-Beam Steel Pretreatment Process and Key Technical Points

Pretreatment of H-beams before welding or painting is a critical step to ensure material performance and durability. The process includes the following stages:

1. Surface Cleaning

Abrasive blasting (shot/sand blasting) removes mill scale, rust, and welding slag to achieve Sa2.5 cleanliness (ISO 8501-1 standard), ensuring optimal coating adhesion.

Oil and grease are eliminated using alkaline cleaners or organic solvents to prevent contamination.

2. Straightening & Flattening

Hydraulic straightening machines correct deformations in the flange and web caused by handling or cutting, maintaining straightness within ≤1mm/m .

3. Cutting & Beveling

Milling or flame cutting prepares weld joints with precise bevels (V-groove, K-bevel, etc.), ensuring:

Bevel angle tolerance: ≤±2°

Root face thickness deviation: ≤0.5mm

4. Primer Coating (Optional)

A zinc-rich epoxy primer (DFT ≥20μm) is applied for temporary corrosion protection. Note: Avoid coating weld zones if welding follows.

5. Quality Inspection

Surface roughness (Ra 30~70μm) is verified using a profilometer.

Coating thickness is checked with a magnetic gauge.

Bevel dimensions are inspected against technical drawings.

Pretreated H-beams must be stored in a dry, contamination-free environment to maintain quality before welding or painting.