In this type of welding, the necessary heat is produced by the combination of oxygen and acetylene gases. The rail ends to be welded are brought together and heat is applied through a burner connected to oxygen and acetylene cylinders by means of regulators and tubes. A temperature of about 1200°C is achieved. At this temperature, the metal of the rail ends melts, resulting in the fusion and welding together of the ends.
The rails to be welded are clamped at the wall by applying a pressure of 401 pressure, heated to a temperature of about 1200°C to 1400°C, and butted with an upset pressure of about 20 t. Then the joint is again heated to a temperature of 850°C and allowed to cool naturally. It has been seen that this method of welding is cheaper as compared to flash butt welding. The quality of this welding joint is also claimed to be quite good. There are both stationary and mobile units available for gas pressure welding.
The process, though simple, has not yet been adopted on a large scale by Indian Railways. The main reason behind this is its limited output and the difficult and irregular availability of gas. India has only one plant that offers gas pressure welding, which is located at Bandel on the ER (Eastern Railways) and the progress in this plant has been nominal.