Qualification of a Robotic Pipeline Orbital Welding

This work presents the procedure qualification for pipeline orbital welding using a robotic system. The system has four degrees of freedom, which allow the controlling of the stick out, the travel speed, the torch angle and the positioning. The arc voltage and welding current are also controlled during the welding, although the system uses a conventional power source. With the system it is possible to use the GMAW and FCAW processes. It was designed for pipes with 305 mm (12 inches) in diameter or more. The robot is not appropriate for root pass yet, since the groove is prepared without control. The biggest problem found in the root pass was the poor repeatability, because of the bisel preparation. The procedure qualification of the system has been prepared. The project standards used for the qualification were B31.4 for oil pipeline in industrial instalation following the welding standards ASME IX – 2003 Ad. 2005 and in field following the welding standards API 1104 – 1999 and B31.3 for refinery and pipeline in industrial instalation following the welding standards ASME IX – 2003 Ad. 2005. The mechanical tests accomplished were tension, bending, hardness, macrograph and nick break. The pipe welded had 500 mm (20 inches) in diameter with 15 mm of thickness wall. The quality was above the expected and even above the manual. The results assured the good use of the robot.