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Prestressing Strand and Wire

Prestressing Strand and Wire

We offer a wide range of high tensile wires and strands.

Our line of high quality wires includes different diameters and surfaces (smooth, indented and galvanised).

We offer three and seven wire strands. The latter can come with or without corrosion protection. The range of galvanised wires can also be protected with a polyethylene coating with either a wax or grease filling.

These different types of strands are used, in addition to standard precast concrete applications, for constructions that require high performance products such as nuclear plants, high velocity train sleepers, cyrogenic tanks and suspension and stay bridges.

Manufacturing Process

The manufacturing process begins with chemically treating the raw material in a process called "acid pickling".

Drawing consists of reducing the cross-section of the wire by passing it through a hard metal die. This produces a deformation in the microstructure of the steel and changes it to the direction of the deformation which raises the tensile strength but lowers ductility and elasticity.

"Stranding" is the process by which the wires are threaded together after acid pickling to form a strand. A strand of 7 wires comprises 6 exterior wires of equal diameter that twist into a helix around a core that runs through the centre defining the longitudinal axis and which has a slightly larger diameter.

Annealing is done by passing the material through an oven at high temperatures and applying force by means of two opposing capstans. This treatment is also known as "stress-relieving" and its main purpose is to achieve an improvement in the steel in terms of elasticity with heat and in terms of internal stresses with the induced force, as well as lowering relaxation by artificially ageing the material.

After annealing, the material is wound into a coil around large revolving reels called winding drums and it is from these that the final coils are cut, the length and dimensions being determined by the client's individual requirements.

Product Range

Although various types and diameters are available the most popular in the UK is the 7 wire strand with a 1860 N/mm2 tensile strength in the following diameters: 9.3mm, 12.5mm & 15.7mm.

The standard full load is 25 tonnes, however as we would only invoice on the catch weight it isn't possible to place your order online. Therefore if you have a requirement for our prestressing steel or would like further information please contact our Sales Office on 0870 011 2881 or email sales@rfa-tech.co.uk.

 

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