Side weld penetration technique of all position narrow gap and thick walled pipe welding is developed.

A tungsten electrode oscillating controller for all position narrow gap and thick walled pipe welding is developed about tungsten electrode oscillating control,tungsten electrode oscillating orbit analysis and welding arc length adjusment.

The synthesizing control scheme is put forward based on the requilement of narrow-gap all-position welding technology in terms of the moving track of tungsten electrode.

Based on the experiment of twin-wire narrow gap welding in single pool mode by employing alternative pulsed arcs, the influences of welding parameters on the appearance of weld and welding process stability were investigated.

Lateral oscillation arc welding, high-speed-rotating arc welding, twin-wire welding, and ultra NGW(narrow gap welding) can all assure the fusion of side wall and improve the oppearance of weld in relatively small welding variables.

The hollow-axis motor drives the offset nozzle and rotates the arc on the tip of wire at high speed,so as to ensure enough penetration into the sidewalls in narrow gap welding.

There are many errors such as the adjusting error and the error due to the actual place behind the place measured by sensor and the error due to arc interaction and the error of optical parameter and the initial error and the error due to demarcating parameter in the narrow-gap welding Automatic following system with CCD figure treatment.