Lubrication of interacting surfaces of an expansion tool and a tubular to be expanded

A tribological system of lubricating an interface between an expansion device 12 and a tubular member 16 during a radial expansion and plastic deformation of the tubular member 16 comprises a first lubricating film 300 coupled to the surface of the expansion device 12 which has a surface texture 12a; a second lubricating film 302 coupled to an interior surface 16a of the tubular member 16; and a lubricating material 306 disposed within an annulus 304 defined between the expansion device and the tubular member. The first lubricating film 300 can have a greater resistance to abrasion than the second film 302. The lubricant films are defined as having maximum thicknesses and variances of those thicknesses as measured in nanometres (nm). The first lubricant 300 can comprise chromium nitride; the second lubricant 302 can comprise PTFE (polytetrafluoroethylene). The co-efficient of friction for the interface can be less than or equal to 0.125 or around 0.06.