Steel may be specified as hot dip galvanized in a BOQ, but coating quality is influenced much earlier at the design and fabrication stage. Batch galvanizing involves immersion in cleaning solutions, flux and molten zinc, so the fabrication must allow liquids and air to move safely through the component. For UAE contractors, steel fabricators and EPC teams, designing for galvanizing before production can reduce rework and improve processing.
Why Fabrication Design Matters for HDG
ISO guidance for articles galvanized after fabrication highlights design detailing, venting, drainage, steel selection and fabrication methods. Industry guidance similarly recommends early communication between designer, fabricator and galvanizer, particularly for hollow, enclosed or complex assemblies. Bonn Group’s hot dip galvanizing service supports project-based steel requirements.
Technical and Project Considerations
| Design Detail | HDG Function |
| Venting | Allows trapped air and gases to escape during immersion. |
| Drainage | Allows solutions and molten zinc to leave the fabrication. |
| Accessible openings | Help process liquids reach internal surfaces. |
| Correct geometry | Reduces pockets where zinc or solutions may collect. |
Hollow Sections Need Particular Attention
Closed and partially closed sections cannot be treated like open platework. Air needs an escape route and process liquids need to enter and drain. This applies to tubular fabrications, hollow structural sections, pipe assemblies and enclosed details. Vent and drain openings should be considered in the fabrication design rather than added only when material arrives at the plant.
Gussets, Stiffeners and End Plates
Details that form pockets can interfere with drainage. Industry design guidance recommends arranging gussets, stiffeners, end plates and bracing so zinc and cleaning solutions can flow freely. Cropped corners or correctly located openings may be required depending on geometry. This is particularly relevant to industrial supports, frames and cantilevers.
Welding and Fabrication Before Galvanizing
Weld configuration, residues and different steel chemistries can influence the final galvanized surface. Welding should meet the project requirement and residues that normal pretreatment will not remove should be addressed before submission. Mixed steel sections may also develop visibly different coating appearances after galvanizing.
Why Early Drawing Review Saves Time
Changing a fabrication after welding is complete can affect cost and schedule. Reviewing galvanizing requirements while drawings are being finalized allows venting, drainage and handling considerations to be incorporated before production. For repetitive components, resolving the detail once can prevent the same issue across an entire batch.
Project Enquiry Checklist
- Identify every hollow or enclosed area
- Provide practical venting and drainage paths
- Check gussets and stiffeners for liquid traps
- Complete required fabrication and welding before galvanizing
- Share unusual geometry and project specifications early
Frequently Asked Questions
Why are vent holes needed?
They allow trapped air and gases to escape during immersion.
Why are drain holes important?
They allow process liquids and excess zinc to leave the fabrication.
Can hollow sections be galvanized?
Yes, when they are suitably designed for venting, drainage and immersion.
When should the galvanizer review the design?
Preferably before fabrication drawings are finalized for complex or enclosed items.
Does Bonn Group galvanize structural items?
Bonn Group lists structural items, angles, channels, beams, pipes and cantilevers among products supported by its galvanizing capability.
Conclusion
Designing for HDG is an engineering task rather than a finishing-stage correction. Venting, drainage, welding and geometry influence processing, coating practicality and safety. Early coordination can prevent modifications after fabrication and support more predictable project delivery.
Discuss Your Requirement with Bonn Group
For hot dip galvanizing services, galvanized steel products or project-specific manufacturing requirements, review Bonn Group’s hot dip galvanizing services, explore the industrial product range or contact Bonn Group with your drawings, quantities and project specification.