A NEW HIGH-SPEED CIRCUMFERENTIAL ROOT PASS WELDING FOR PIPELINE CONSTRUCTION

Steel pipes used are API 5LX X52 and X60, with 16 inch outer dia. The wall thickness is 0.5 inch for X52 and 0.25 inch for X60. Welding wire used is of 1.2 mm dia., containing REM. Chemical compositions of pipes and the filler wire are listed in attached Table 6.

The circumferential welding equipment and the internal clamper used are shown in Fig. 4. For X52 pipe, the groove geometry is shown in Fig. 10 and welding conditions listed in Table 7. The root and hot passes were made with machine welding, and the filler and cap passes with SMA welding.