The connector includes a sleeve (4) which is screwed on to a thread (18) provided on an upper axial end of the lower riser section (1). The sleeve (4) encloses a lower end of an upper riser section (2) and is retained thereto. Once the sleeve (4) is secured to the lower riser section, this loosely secures the upper riser section (2) to the lower riser section (1). A tensioning tool then stretches the sleeve (4) upwardly and a retaining collar (5) is then maneuvered in order to retain the sleeve (5) in this tensioned state after the release of the tensioning tool. This creates a preloaded connection between the upper riser section (2) and the lower riser section (1).