Improving Casing Integrity by Induction Brazing of Casing Connections

Brazing technology allows metallurgical joining of dissimilar materials using a filler material. In this paper brazing technology applied to casing connections is presented. The initial application was triggered by challenges with mechanical and pressure integrity after expansion of casing connections. Creating a strong bond between the pin and the box could resolve this. Brazing was selected because of the combination of ductility and high bond strength and the relatively fast process to create the bond. The brazing process or temperature-torque-time process (TTT) is performed using regular casing connections, a filler material deposited by flame spray and a flux. Two processes were developed, one for expandable (VM50) grade material and one for quenched and tempered grade material. For this a rig ready (CLASS 1 DIV 1) prototype brazing system was developed consisting of an induction coil as the heat source, an environmental chamber to shield the hot work, and a modified power tong to provide torque. The results of a series of brazing trials on 8-5/8″ and 9-5/8″ casing connections are presented. The brazed connections were subsequently capped end pressure tested, expanded (when applicable) and load cycled. It is concluded that both processes produced leak tight casing connectors before and after expansion (when applicable) as shown by full scale tests.