Welding control of thick-walled steel pipes

1. Welding temperature control of thick-walled steel pipes

The welding temperature is affected by the high-frequency eddy current thermal power. The high-frequency eddy current thermal power is affected by the current frequency. The eddy current thermal power is proportional to the square of the current encouraging frequency; the current encouragement frequency is affected by the encouragement voltage, current, capacitance and inductance.


When the input heat is insufficient, the heated weld edge cannot reach the welding temperature, and the metal arrangement still adheres to the solid state, constituting a non-fusion or penetration; when the input heat is too much, the heated weld edge exceeds the welding temperature, which occurs over-burning or melting droplets make the weld to form a melt hole.


  1. Manipulation of the weld gap of thick-walled steel pipes

The strip steel is fed into the welded pipe unit, after being rolled by multiple rollers, the strip steel is gradually rolled up to form a round tube blank with an open gap, and the reduction of the kneading roller is adjusted so that the gap of the weld is controlled within 1 ~ 3mm. And make the welded ends flush. If the gap is too large, the nearby effects are reduced, the eddy current heat is lacking, and the weld inter-granular bonding is poor, causing non-fusion or cracking. If the gap is too small, the near effect of the composition increases, and the welding heat is too large, which constitutes a burnt weld. Perhaps the weld is kneaded and rolled to form a deep pit that affects the surface of the weld.

Post time: May-12-2020