Guide device for welding curvilinear pipe surfaces

Guide device for guiding a welding carriage for welding a pipe surface, said guide device comprising:

• a welding carriage comprising a sensor;
• a metal band provided with a guide for the welding carriage;
• said metal band having a length;
• and
• a tensioner for tensioning the metal band around the pipe surface;
• wherein the metal band is provided along the length thereof with indicators arranged according to a determined pattern;
• and
• wherein said sensor is configured to move relative to the indictors, and to optically detect a portion of the determined pattern represented by one or more of said indicators, said portion of the determined pattern being such that a determined position along the metal band is inferred based on a detection of said indicators by said sensor when the welding carriage and sensor are stationary with respect to the metal band,
• wherein the portion of the determined pattern detected by the sensor allows a unique location of the welding carriage on the metal band to be determined;
• wherein said metal band has a first outer end and a second outer end, wherein the indicators arranged according to the determined pattern comprise at least one row of indicators;
• wherein said at least one row of indicators extends between said first outer end and said second outer end;
• and
• wherein adjacent indicators of said at least one row of indicators being spaced apart by a mutual distance, said mutual distance gradually increasing from said first outer end to said second outer end.