The invention relates to the field of automated welding, and more particularly, to an automated, gas metal arc welding apparatus for externally welding abutting sections of pipe. The strut members are disposed in a circumferentially, substantially equally spaced-apart relationship, and extend in a substantially axial direction. The screw shaft is rectilinearly movably disposed, surrounds the rotation transmission shaft, and engages with an outer cylindrical surface of the rotation transmission shaft on an inner cylindrical surface of the screw shaft.