ASTM A475 establishes requirements for five grades of metallic-coated steel wire strand (Utilities, Common, Siemens-Martin, High-Strength, Extra High-Strength), designed for structural applications such as guys, messengers, and span wires. Strands consist of multiple round steel wires coated with zinc in four weights (Class 1, A, B, C) and four types (Type 1, 2, 5, 10).
Base Material: Commercial-quality steel with purity ensuring uniform wire quality post-drawing and coating.
Strand Construction:
Mandatory left-lay configuration with uniform wire tension.
Wires stranded tightly to eliminate gaps between layers.
Coating Integrity: Zinc coating must withstand close-helix wrapping without cracking/delamination.
Mechanical Performance: Minimum breaking strength defined per grade (Section 7); elongation/ductility requirements specified.
Wire Joints:
Limited to brazed-lap or electric-butt-welded types.
Post-weld zinc coating must provide corrosion protection equivalent to base wire.
Coating Compliance: Metallic coating weights adhere to Class 1/A/B/C minima (Section 10).
Units: Primary standards in inch-pound units (SI conversions for reference only).
Corrosion Protection: Zinc coatings (Types 1/2/5/10) ensure durability in harsh environments.
Mechanical Reliability: Uniform tension and tight stranding prevent deformation under load.
Specialized Grades:
Siemens-Martin grade for high-ductility needs.
Extra High-Strength grade for extreme-tension applications.
Utility Infrastructure: Guy wires for transmission towers, substation bracing.
Telecommunications: Messenger cables supporting fiber/coaxial lines.
Transportation: Span wires for traffic signals, street lighting.
Marine/Industrial: Corrosion-resistant rigging in coastal/chemical exposure zones.
