Welding

Welding experts at Corus have extensive experience of all welding techniques commonly used on railways throughout the world. These include:

• Flash butt welding – plant-based. This is the most common form of joining new rail and requires the rail ends to be held in water-cooled dies that act as electrodes. It is a three-stage process of ‘burn-off’, pre-heating and final flashing. The flash butt welding system offers superior weld geometry performance over other systems identified, the weld integrity is excellent.
• Mobile flash butt welding. This is a similar process to plant-based flash butt welding except that it is a single-stage process of a continuous flash. The weld integrity is generally good.
• Gas pressure welding. Predominantly used on Japanese railways, this process involves the application of a fixed hydraulic pressure to the rail ends. The rail ends are then heated, using an oxy-acetylene burner, to approximately 1200 – 1300 degrees Celsius and butted together under the pre-applied pressure.
• Aluminothermic welding. This process relies on the chemical reaction between compounds to form a weld between two rail ends. The process is dependant on the control of human factors but is a good and cost-effective solution for closure welds and emergency repairs.

As part of its comprehensive welding-related service, Corus also provides trend analysis and advises customers on the metallurgical aspects of welding such as the properties of the heat affected zone in comparison to the parent rail.