Abstract: Methods and apparatus are provided for obtaining a secure mechanical connection and a pressure-tight seal in the overlapping area of two telescoping tubular bodies. The two bodies, including the overlapping area, are radially expanded to increase the inside diameter of the bodies. The expansion forces an annular seal in the overlapping area into a pressure-sealing engagement between the bodies. A string of pipe assembled from joints secured to each other by telescoping, threadedly engaged expanded pin and box connections may be radially expanded into a surrounding well bore to provide a cased well having an internal diameter greater than the original internal diameter of the pipe string. The seal in the connection comprises an annular elastomeric seal ring and an annular Teflon spacer ring carried in a specially dimensioned groove formed in either the box or the pin, or both members of the connection.