This guide outlines key design considerations and best practices to help customers optimise fabrication for the galvanising process.
Fabrication Considerations and Material Preparation
Steel Surface Things to Note
Example of Epoxy-coated Seamless Pipes
For permanent identification, recommended methods include:
- Heavily embossed markings.
- Punched Markings.
- For temporary identification before galvanizing, the recommended methods are water-based paints or markings pens.
Non-acceptable identification methods include.
Oil-based paint or marking pens.
Distortion Considerations
Thin or asymmetrical steel sections may experience distortion during galvanising due to high process temperatures.
Vent & Drain Hole Requirements
Vent and drain holes allow treatment solutions, air and molten zinc to flow freely during the galvanizing process.
Inadequate venting may result in trapped air, poor coating quality or safety risks during immersion. Please refer to “Common Issues & Recommendations” for some of the issues that may occur.
Location of Vent and Drain Holes General Guide
Common Issues & Recommendations
Example 1
Issue 1: Insufficient drainage holes.
Possible Result 1: Ash entrapment or uneven coating.
Recommendation 1: Provide adequate vent and drain openings at suitable locations.
Example 2
Issue 2: Blow Out.
Possible Result 2: Surface irregularities or localised coating defects caused by residue or trapped moisture escaping during immersion.
Recommendation 2: Ensure weld areas, overlaps and hollow sections are properly cleaned, vented and drained.
Example 3
Issue 3: Bare Spots.
Possible Result 3: Localised uncoated areas due to surface contamination, weld slag, paint or excessive residue.
Recommendation 3: Ensure steel surfaces are free from contaminants prior to galvanising.
Example 4
Issue 4: Distortion.
Possible Result 4: Minor warping of thin or asymmetrical fabricated sections due to process temperatures.
Recommendation 4: Use balanced fabrication design and consult prior to galvanising oversized or thin materials.
