Fabrication of Pipe Strings Using Friction Stir Welding

摘要

A method of fabrication by friction stir welding (FSW) at an interface between adjoining components such as pipe lengths of a pipeline has layers of different metals on each side. FSW is performed from one side of the adjoining components by effecting relative movement of a first FSW tool along the interface. FSW is performed from an opposite side of the adjoining components by effecting relative movement of a second FSW tool along the interface. Advantageously, FSW is performed simultaneously from both sides of the adjoining components with the FSW tools applying loads in mutual opposition about the adjoining components.

主权项

1. A method of fabricating a pipeline by butt welding at a circumferential interface between components comprising lengths of pipe disposed end-to-end or between a length of pipe and a pipeline accessory, at least one of which components comprises internal and external layers of different metal separated by a boundary comprises:
performing external friction stir welding (FSW) by effecting relative circumferential movement along the interface of an inwardly-facing external FSW tool positioned outside the pipe, which tool spins about a first axis that is substantially radial with respect to a cross-section of the pipe; and performing internal FSW by effecting relative circumferential movement along the interface of the outwardly-facing internal FSW tool, which tool spins about a second axis that is substantially radial with respect to the cross-section of the pipe; wherein thermo-mechanically affected zones (TMAZs) produced by the external FSW tool and the internal FSW tool each extend partially through a wall of the pipe; wherein the TMAZ produced by the external FSW tool contacts, intersects or overlaps the TMAZ produced by the internal FSW tool; and wherein the TMAZs produced by the external FSW tool and the internal FSW tool have depths that extend to or overlap slightly beyond the boundary between the internal and external layers.