A method of forming a seal between two tubular members comprising providing a first tubular member having an internal surface and an external surface describing a first diameter, with a recess in the external surface at a seal portion of the first tubular member. A deformable circumferentially extending sealing member is located in the recess, the sealing member describes an external diameter no greater than the first diameter. The first tubular member is located within a second tubular member and the seal portion of the first tubular member is expanded such that the sealing member engages an inner surface of the second tubular member.