When Should Anchor Bolts Use Dacromet Coating?

2026-06-15

A practical guide to selecting Dacromet-coated foundation bolts, stud bolts, hex bolts, and fastener assemblies for corrosive and high-demand industrial environments.

WHAT IS DACROMET COATING?

Dacromet (also spelled Geomet or Dacrotized) is a water-based, chromium-free zinc-flake coating applied to carbon steel fasteners — including anchor bolts, foundation bolts, stud bolts, hex bolts, flange bolts, nuts, and washers. The thin, silver-grey film (typically 8–12 µm) provides outstanding salt-spray resistance exceeding 720 hours, far surpassing standard hot-dip galvanizing or electroplating on threaded components such as M12–M72 hex bolts and screws.

KEY APPLICATION SCENARIOS FOR DACROMET ANCHOR BOLTS

Choosing Dacromet coating for foundation bolts and structural fasteners is most justified in the following six scenarios:

SCENARIO	DETAILS & FASTENER TYPES
Coastal & Marine Environments	Saltwater spray corrodes unprotected carbon steel bolts and screws within weeks. Dacromet anchor bolts — from M16 foundation bolts to M48 stud bolts — resist chloride attack, making them the first choice for port cranes, offshore platforms, jetty structures, and seaside wind-turbine towers.
Petrochemical & Chemical Plants	Reactor foundations, pipeline supports, and vessel anchor bolts are exposed to acids, alkalis, and chemical fumes. Dacromet-coated heavy hex bolts and stud bolts (Grade 8.8 / 10.9) maintain integrity where standard zinc plating fails, reducing unplanned maintenance on critical process equipment.
Wind & Solar Power Structures	Tower anchor bolt cages and solar-rack screws must endure 20+ years outdoors. Dacromet coating on M30–M72 anchor bolts eliminates the hydrogen embrittlement risk associated with electroplating — essential for high-strength (Grade 10.9) structural bolts used in turbine foundations.
Road, Bridge & Tunnel Infrastructure	Expansion joints, guardrail bolts, drainage bolts, and tunnel rock-bolt anchors face road salts, deicing chemicals, and groundwater. Dacromet fasteners comply with corrosion-protection standards for steel structures in highway and rail bridge projects.
Automotive & Heavy Equipment	Chassis foundation bolts, suspension screws, and brake-system fasteners demand thin-film coatings that preserve precise thread tolerances. Dacromet's uniform 8 µm layer does not alter nut-bolt fit on M8–M24 fine-thread screws, unlike thicker hot-dip galvanized coatings.
Underground & Embedded Concrete Anchors	Anchor bolts cast into concrete foundations for heavy machinery, steel columns, and prefabricated structures benefit from Dacromet's adhesion to steel and compatibility with cementitious environments. This is particularly valuable for J-bolts, L-bolts, and headed anchor rods in industrial plant foundations.

DACROMET VS. HOT-DIP GALVANIZING: A QUICK COMPARISON

PROPERTY	DACROMET	HOT-DIP GALVANIZING
Coating Thickness	8–12 µm	45–85 µm
Thread Tolerance	Unaffected	May require re-tapping
Salt-Spray Resistance	≥ 720 hrs	≥ 500 hrs (typical)
H₂ Embrittlement	None	Possible (electroplating)
Operating Temp.	Up to 300 °C	Up to 200 °C
Typical Bolt Sizes	M6–M72	M10–M100
Best For	Precision threads, high-strength Grade 10.9 bolts, thin-wall screws	Structural steel, large anchor bolts

DACROMET ANCHOR BOLT SPECIFICATION HIGHLIGHTS

Standards: ISO 898-1, DIN 931, ASTM F1554, GB/T 799

Material Grades: Grade 4.8 / 8.8 / 10.9 carbon steel; 40Cr alloy steel

Size Range: M6 × 20 mm to M72 × 2500 mm (custom lengths available)

Bolt Types: J-bolt, L-bolt, double-end stud bolt, hex head bolt, flange bolt, foundation bolt, anchor rod

Coating Process: Dacromet 500 / Geomet 321 / Geomet 500; thickness 8–12 µm

Certification: SGS salt-spray test report ≥ 720 h available on request

RELATED PRODUCTS & KEYWORDS

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