Flash Butt Welding
Patil Group has proved its presence in the field of Flash Butt Welding for Railway through its Flash Butt Welding plants. Patil Group has constructed india’s largest welding depots in Moulali secunderabad and in New Bongaigaon Assam India for Indian Railways. Adequate infrastructural facilities have been provided in these plants to facilitate the welding of 20 Rail panels. These Plants have facilities for mechanised unloading of free rails, movement of welded panels on rollers, loading and unloading of welded panels by motorized gantries. We have imported an advance Flash Butt Welding Machine from USA and deployed in New Bongaigaon Assam FBW depot.
Introduction
In Flash Butt welding process of rails, rails are welded by the heating, using the Flashing Technique with the help of Hydraulic Control System, Rail ends are heated as a result of their Electrical resistance using current with high amperage at low voltage and forging them at an appropriate temperature and upset force. No foreign material is needed and welding process is continuous. The heat-effected zone is limited to the smallest possible area. The preselected configuration best suitable for a particular type of rails in accordance to its metallurgy ensures high quality weld. The welding cycle take place by the lateral compression of the rail ends by the means of the two pairs of jaws. The jaw clamped rail ends also act as electrodes for flow of high intensity current.
WELDING SEQUENCE
Following sequence is followed during a welding cycle.
- Preflash
- Flash
- Boost
- Upset
- Forge
- Trimming Upset Metal
The individual rails of 13 m/ 26 mtr. length received from steel rolling plants are initially sent to Flash Butt Welding Plant. The individual rails are then welded into rail panels of 10-rail length by flash butt welding technique Flash butt joints have very high fatigue strength and are preferred to other types of welds. The rail panels of 10-rail length and 20-rail length formed by flash butt welding are transported from the Flash Butt Welding Plant to the field locations by loading into specially designed railway flat wagons. These panels are unloaded at the site through specially designed end unloading chutes fitted to the rearmost wagon.
Important advantages of flash butt welding compared with other joining methods
- Reduces maintenance costs
- Saves track time
- Eliminates corrugation
- No weld filler material
- Smaller heat affected zone
- Smaller annealed zone
- Consistent hardness
- Highest fatigue resistance
- Average life equal to the rail