The invention relates to a method of forming a pipe socket having a sealing ring (8) at the inner surface of the pipe socket wall. The sealing ring has a fastening portion (16) and a sealing portion (20) connected therewith. The sealing portion (20) is displaceable in the axial direction of the pipe socket to be able to take different positions therein in order to adapt to different tolerances. It is a problem that the sealing portion (20) because of its displacability is not adapted to constitute such a surface around which the pipe wall can be formed. In order to obviate this drawback the pipe wall is formed so that the sealing portion (20) is positioned outside the pipe socket during the forming operation, whereupon the sealing portion is folded into the pipe socket after the forming operation.