Abstract: Laser apparatus for performing operations on a workpiece (6) comprises a laser source (2) supplying a laser beam (4) which may be focused onto the workpiece (6) by a focusing unit (3). A representation of the surface of the workpiece (6) is generated by sensing means (7) which are associated with a computer (8). An image of the surface can be displayed on, for example, a VDU which allows an operator to determine a line across which the beam (4) should scan. The laser source (2) is then operated and the beam (4) is caused to scan along the selected line by appropriate movement of focusing unit (3) by a control unit (10) associated with the computer (8). Focusing unit (3) may be of variable focal length so as to ensure that the beam (4) is always focused on the surface of the workpiece.

Abstract: A pipe-welding assembly is provided in which single-pass welding of one pipe length to another is accomplished by gas lasers mounted to rotate around the axis of the pipes to weld the pipe ends together in the gap between two axially aligned spaced pipe clamps. Weld-testing units are similarly rotated around the pipe axis. The pipe-welding assembly is mounted on a gyroscopically-stabilized platform, which can be located on a pipe-laying land vehicle, or on a pipe-laying ship for laying pipe lines on the ocean bed. If the ship is equipped with a pipe feed tower, with the pipe-welding assembly positioned at the base of the tower and a drawbridge provided for elevating successive pipe lengths angularly into the tower, pipe laying can be performed in the "J" configuration. If the tower is mounted so that it can be inclined angularly into a position approaching the horizontal, and the pipe-welding assembly can be similarly rotated on its stabilized platform, pipe-laying can be performed in the "S" configuration.