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Welding Processes

Welding Processes

There are a number of welding methods in use on the rail network. The suitability of each method will depend on a range of local circumstances e.g. location, available personnel, equipment and consumables.  In the majority of cases specialist staff will be required and any welding should only be carried out by approved personnel.

The Rail welding methods ideally require:

  • Rails to be cut square (not bevelled as with structural welding)
  • High preheat to cater for the steel composition
  • High weld metal deposition rates
  • Acceptable defect level for the fracture resistance of the steel

Enclosed arc and aluminothermic welding meet these criteria. Flash butt is not suitable for most large section European rails.  Both aluminothermic and enclosed arc methods require the careful following of procedures by skilled operatives.

Puddle Arc Welding is widely used throughout the world for welding crane rails. In this method the two rail ends to be joined are cut square, placed about 20 mm apart, preheated and then welded using special manual metal arc electrodes.

Aluminothermic Welding uses a refractory mould around the two square cut rails ends. After preheating the rail ends the gap of about 20mm is filled from a crucible containing a chemically heated charge of molten steel. 

Flash Butt Welding is commonly used for welding railway rail in steel mills before shipment. It is sometimes used for site welding crane rails. It requires thousands of amps current and hence heavy expensive equipment. The rail ends are heated by the current passing between them. When hot enough they are forged together.