Galvanizing refers to a method of preventing corrosion in iron or steel structures by coating them with a protective layer of zinc. The process is used widely across construction, automotive, power, telecommunication, and manufacturing industries.
The galvanizing process typically involves immersing the iron or steel article in a bath of molten zinc. The zinc coating bonds metallurgically with the base metal, forming a series of zinc–iron alloy layers. This creates a durable and corrosion-resistant barrier that protects the underlying metal from exposure to moisture, oxygen, and other corrosive elements.
Corrosion Protection: The zinc coating acts as a sacrificial layer, corroding in place of the underlying metal — extending the lifespan of the iron or steel article.
Durability: Galvanized coatings are highly resistant to abrasion, providing long-lasting protection in the toughest environments.
Cost-Effectiveness: Galvanizing delivers the lowest lifecycle cost of any corrosion protection technique — no repainting, no touch-ups.
Easy Inspection: The appearance of a galvanized coating provides a visual indication of its condition — making it easy to assess protection levels.
The 8-step hot dip galvanizing sequence — applied to every article at the LTL Galvanizers plant, to BS EN ISO 1461:2022.
Our galvanizing line operates 24 hours per day with 6.2 MT/hour total capacity across two baths. Computer software records every production step — fabrication, galvanizing, shop assembly, packing, final inspection, and delivery — ensuring timeliness and full traceability for every order.
Proper design for hot dip galvanizing is critical to coating quality, article integrity, and long-term performance. A well-designed article galvanizes cleanly with minimum distortion and uniform coating thickness.
Venting & Drainage: All hollow sections must have adequate vent and drain holes to permit zinc flow and prevent explosive pressure build-up. Venting area should be > 30% of the enclosed cross-section.
Steel Selection: Si and P content in steel affect coating thickness. Steels with 0.04% < Si < 0.15% or Si > 0.22% (Sandelin) produce heavier coatings than recommended.
Minimising Distortion: Use symmetric sections where possible; minimise variations in thickness within a single article to reduce thermal stress.
Article Size: Article must fit within bath dimensions. Our Bath 1 (7m × 1.3m × 2.1m) handles up to 13.5 m via double-end dipping.
Contact Surfaces: Avoid large overlapping surfaces where acid and flux can be trapped. Seal or separate such surfaces fully.
Handling Points: Provide lifting holes or lugs positioned so the article can be suspended and dipped without support damage.
Fabrication practices directly affect galvanizing outcomes. Poor fabrication choices — surface contamination, improper welding, trapped residues — lead to coating defects that are difficult and expensive to fix after dipping.
Welding: All welding to AWS D1.1 — full penetration, continuous seals (no stitch welds on enclosures). Remove weld slag, spatter, and flux residue completely.
Surface Cleanliness: Remove paint, grease, oil, markings, and foreign matter before submission. Acid pickling alone cannot remove paint or oily coatings.
Identification Marks: Use low-stress hard-stamped or die-marked identification — do NOT use paint, marker, or adhesive labels.
Bolted Assemblies: Deliver bolted assemblies disassembled. Fasteners galvanized to BS EN ISO 10684:2004 and ISO 1461:2022 separately.
Touch-up: Minor damage (< 0.5% surface area) repaired per ASTM A780 with zinc-rich paint or sprayed zinc.
Handling: Avoid stacking galvanized parts in direct contact with moisture — white rust forms on freshly-galvanized surfaces in humid conditions.
Packing: Products placed on pallets with spacers to avoid moisture trapping, then secured with coated metal strapping. Each package numbered with prepared packing lists.
How to specify a galvanized coating — and how we inspect and certify every batch to the world's leading standards.
| Article Thickness | Min. Average Coating (µm) | Min. Local Coating (µm) |
|---|---|---|
| Steel ≥ 6 mm | 85 | 70 |
| Steel 3 mm to < 6 mm | 70 | 55 |
| Steel 1.5 mm to < 3 mm | 55 | 45 |
| Steel < 1.5 mm | 45 | 35 |
| Castings ≥ 6 mm | 80 | 70 |
Reference: BS EN ISO 1461:2022 — Hot dip galvanized coatings on fabricated iron and steel articles. 1 µm = 0.0254 mils.
Hot dip galvanized coatings on fabricated iron and steel articles — primary specification.
Standard specification for zinc (HDG) coatings on iron and steel products.
American Welding Society Structural Welding Code — Steel.
Mechanical properties of structural fasteners — property classes for bolts and screws.
Fasteners — hot dip galvanized coatings on threaded fasteners.
Thermal spraying — zinc, aluminium and their alloys for corrosion protection.
Protective paint systems for corrosion protection of steel structures.
Quality Management System — certified by SBcert.
Environmental Management System — certified by SBcert.
Our technical team provides free coating consultation for your project — specification, design review, and compliance guidance.