Rods and cables

Tata Steel Product Range

Tata Steel supplies high carbon wire rod in diameters ranging from 5.0mm to 13.5mm, in plain and microalloyed compositions to a range of tensile strengths, to EN 10016: 1995.

Cable Types

The wire rod supplied by Tata Steel may be drawn into 5mm diameter bridge wire for use in suspension bridge cables and hangers, or 7mm diameter wire for cable-stayed applications. The bridge wire may be site spun into strand using aerial spinning equipment, or delivered to site in prefabricated bundles or strands. There are four types of strand used to form the main cables of bridges:

Spiral Strand

Spiral strands consist of large diameter galvanised round wires helically spun together. The wires are stranded in one or more layers, mainly in opposite directions, to achieve the required diameter. This is the most versatile structural cable, with high breaking strength and a good strength to weight ratio. 

Locked Coil Strand

Locked coil strands consist of a centre of one or more layers of large diameter galvanised round wires helically spun together. Stranded on top of this centre are one or more layers of large diameter galvanised shaped wires, mainly in opposite directions, to achieve the required diameter. The closed construction and smooth outer layers offer high resistance to deformation and specific pressures.

Structural Rope

Structural ropes are usually of 6 strand construction helically spun around a steel core, comprising smaller diameter galvanised wires giving a high degree of flexibility. Structural ropes have a low modulus and are unsuitable for most structural applications. However, they offer an economic solution for temporary structures, and where greater flexibility is required.

Parallel Wire Strand

Parallel wire strands consist of galvanised round wires laid up in a hexagonal form, with a long helix. The product is then encased in a tight fitting High Density Poly Ethylene tube. Parallel wire bundles are ideal for cable stayed bridges, offering high axial stiffness and an especially high modulus.

Principal Applications

Typical Range of Properties

Grades

Suspension main cables are stranded from galvanised round wire with a minimum tensile strength of 1770N/mm². In recent years Tata Steel has contributed to the significant increases seen in wire tensile strength, giving rise to improved strength to weight ratios and longer span bridges. Research is continuing to develop wires with high tensile strengths in excess of 2000N/mm² for the next generation of bridges.

Corrosion Protection

The corrosion protection system for bridge cables may consist of many layers. The individual wires are galvanised, various proprietary compounds may be applied to both the interior and exterior of cables, or a High Density Poly Ethylene coating can be vacuum/pressure exuded onto the cable at the factory.