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AC/OX CUTTING/WELDING/BRAZING

Introduction

The Acetylene/Oxygen flame is an efficient heat source which has been used for welding and related thermal processes since the early 1900’s. Acetylene is the fuel gas burning with the highest temperature, maximum approximately 3160 °C when mixed with oxygen (ratio 1 part acetylene to 1.5 parts oxygen).

Even the neutral flame used for welding (mix ration 1:1.1) has a

The energy (kJ/cm2• S) from the core flame of acetylene compared to propane at various mixing rates with oxygen.

5.01

466

temperature of 3100 °C, compared to e.g. propane 2800 °C.

This temperature difference, which in itself is not impressive, is one reason for the high efficiency of the acetylene flame. At temperatures around 3000 °C a relatively high degree of dissociation of hydrogen molecules takes place in the flame core. The molecules are split in free atoms, thereby storing energy. This stored energy is transfered through the flame and released immediately when the free atoms hit the workpiece and recombine to molecules. The total energy release from the acetylene/oxygen flame is therefore comparable to the energy from a theoretical flame with temperature 4500 °C.

Hydrogen molecules dissociate on the surface of the core flame and recombine on the surface of the workpiece.