The K-700 in-tube butt-welding machine is the largest in the world (11.6 m long, 1.4 m in diameter, and weighs 25,400 kg) complex multifunctional unit capable of independently moving inside a pipe, pulling and centering the joints of two pipes, connecting them with butt welding by reflowing and removing the inner beads while hot. This is one of the largest developments of the EO Paton Electric Welding Institute.

The K-700-1 machine is designed for flash butt welding of pipes with a diameter of 1420 mm with a wall thickness of 15 to 22 mm.

During welding, the K-700-1 machine moves inside the pipe from joint to joint. For this, the machine is equipped with a special electromechanical travel drive and a self-adjusting cybernetic welding process control system developed by the EO Paton Electric Welding Institute.