Flash Butt Welding

Patil Group of Industries has proved its presence in the field of Flash Butt Welding for Railway through its Flash Butt Welding plant at Moulali, Secunderabad, India. But, in order to explore the opportunities in various upcoming Metro Projects and DFC, Management has decided to expand this business. We are in the advance stage of procurement of Flash Butt Welding Plant from USA.

Introduction
Unlike arc welding that is 'line welding' in which the welding point moves along a prescribed line, flash butt welding is 'plane welding' in which the opposed planes are welded at a stroke. Therefore, this welding method is extremely efficient. As far as application of flash butt welding is concerned, on-site welding of line pipes, welding of rails and welding of marine structures etc. can be cited.

Flash-Butt Welding of Rails
Basics

Flash-butt welding is an electrical resistance welding procedure. Electrical current is conducted through the rail butts and is heating them up to the almost liquid phase. Under high pressure, the rail butts are joint-welded.

Flash welding is a development of resistance butt welding and is particularly suitable for butt welding complex or larger sections. It is used for a wide range of component shaped and sizes from bicycle wheel rims to rails. More efficient energy input, and a more localized and evenly heated zone can be achieved, compared with resistance butt welding.

WELDING SEQUENCE
Following sequence is followed during a welding cycle.

  1. Preflash
  2. Flash
  3. Boost
  4. Upset
  5. Forge
  6. Trimming Upset Metal

The individual rails of 13 m. length received from steel rolling plants are initially sent to Flash Butt Welding Plant at Moulali, Secunderabad. The individual rails are then welded into rail panels of 10-rail length by flash butt welding technique, which involves pre-heating of rail ends by passing high ampere low voltage current and then the rail ends are cyclically brought closer and separated, which results in heavy sparking between the rail ends. After the rail ends are brought to a molten state, butting of rail ends is done under pressure.

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