Hot-Dip Galvanizing (HDG)

Hot-dip galvanizing is the process of immersing pre-cleaned steel fasteners in a bath of molten zinc at approximately 450°C. This creates a metallurgical bond between the zinc coating and the steel substrate — producing a layered zinc-iron alloy structure that is integral to the fastener rather than merely a surface deposit.

Asia Bolts Industries operates an in-house hot-dip galvanizing facility at our Dubai Investment Park complex, capable of processing high-volume fastener batches. This eliminates the 3–7 day lead time penalty of external galvanizing and maintains our full chain of traceability from raw bar to finished, galvanized fastener.

Governing Standards:

• ASTM A153, Class C: Covers zinc coating on iron and steel hardware — minimum coating weight 1.30 oz/ft² (Class C)

• ASTM F2329: Specific to HDG of bolts, nuts, washers, and similar threaded fasteners

• ISO 1461: International standard for HDG on fabricated iron and steel articles

Key Technical Parameters:

• Coating Thickness: Minimum 45 µm (average); typically 55–85 µm on structural fasteners

• Salt Spray Resistance: 1,000+ hours • Operating Temperature: Up to 200°C (above 200°C zinc-iron alloy layers are preserved; outer zinc layer may volatilize above 250°C)

• Nut Oversize: Nuts are tapped oversized after galvanizing per ASTM A563 to allow assembly

Applications include structural steel bolting (ASTM A325, A490, F3125), offshore platform anchor bolts, utility pole hardware, bridge construction fasteners, coastal petrochemical plant structures, water treatment facility hardware, and heavy infrastructure projects throughout the GCC.

All HDG fasteners from Asia Bolts are supplied with coating thickness test reports (per ASTM E376 / ISO 2808), coating weight certificates, and full MTCs.