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WELDING OF CRANE RAILS
There a number of welding methods in use throughout the world. Appropriate method is chosen depending upon the design, location, available personnel, equipment and consumables.
Cranes operate best when the rails on to which they run are welded into continuous lengths. However rails are difficult to weld as they
• Have high carbon content to give them wear resistance
• Have a high carbon equivalent and must be welded using special techniques
• Are considered to have a large and awkward section for welding
Rail welding methods ideally require
• Rails to be cut square
• High preheat to cater for the steel composition
• High weld metal deposition rates
• Acceptable defect level for the fracture resistance of the steel
Rail welding methods adopted
• Aluminothermic welding
• Enclosed arc/puddle arc welding
• Flash butt welding
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
Enclosed arc welding is widely used throughout the world for welding crane rails. Gallant engineering employ skilled technicians and workers who can carry out the work in an efficient way. In this method the two rail ends to be joined are cut square, placed about 15 - 20 mm apart, preheated and welded using special arc electrodes.
Aluminothermic welding uses a refractory mould around the two square cut rails ends. After preheating the rail ends the gap of about 25-30 mm is filled from a crucible containing a chemically heated charge of molten steel.
Flash Butt Welding
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.