Methods and apparatus relating to pipe welding

A method of aligning a first pipe and a second pipe end-to-end in a position ready for welding, wherein

• the first pipe and the second pipe each have an end bevelled with a shape which has been scanned and stored in a memory of a control unit,
• a plurality of machine readable codes are located at known circumferential positions distributed around a circumference of the first pipe, wherein each of the machine readable codes identifies a different circumferential position;
• and
• the method comprises the following steps performed after the shape of each of the bevelled ends has been scanned and stored in the memory of the control unit:
• effecting relative movement of the bevelled end of the first pipe and the bevelled end of the second pipe towards each other;
• while the bevelled ends are spaced apart:
• reading at least one of the machine readable codes with a reader,
• measuring a position of at least two different points on the first pipe, and
• determining a position and orientation of the bevelled end of the first pipe with the use of:
• (a) information provided by reading the at least one machine readable code with the reader, (b) the measured position of the at least two different points, and (c) the shape of the bevelled end of the first pipe stored in the memory of the control unit;
• and
• ascertaining, with use of the control unit, a relative movement between the first pipe and the second pipe required to align the first pipe and the second pipe in accordance with a target orientation that aligns the first pipe and the second pipe for welding;
• wherein the first pipe has a longitudinal axis and the information provided by reading the at least one of the machine readable codes with the reader includes information about the orientation of the bevelled end of the first pipe about the longitudinal axis.