TWI

Two friction stir welding (FSW) procedures, a sacrificial anvil method and a hybrid FSW/arc welding technique, were developed to assure consistent full penetration welds during the construction of offshore and onshore pipelines, respectively. The offshore pipe materials comprised X52 and X65 carbon manganese steels with an outside diameter of 323.9 mm and a wall thickness of 6.35 or 12.7 mm, whereas the onshore linepipe steels were X42 grade (outside diameter 323.9 mm, wall thickness 12.7 mm) or X70 grade (outside diameter 762 mm, wall thickness 15.9 mm). The FSW tool materials were Q70 and MS80 polycrystalline cubic boron nitride. Sacrificial anvil FSW was performed using force control at loads of 3630 or 6350 kg for the lower and higher wall thickness pipes, respectively. The hybrid FSW/arc method employed MAG welding with an ER 70S-6 filler rod to weld the root. A MegaStir pipe welding machine was used in all cases. Welded joints were characterised by metallography and radiography as well as tensile, Charpy impact, root and face bend, and nick break tests.

10th International Symposium, 20-22 May 2014, Session 9A: Techniques III, Paper 04