The pipe (15) is clipped onto the connection collar (11). The pipe and the connection collar together are in contact with a spherical surface (13) so that the pipe can be adjusted into different angular positions on the collar in the form of a joint. The pipe is in the form of a short connecting pipe. The end of this pipe is joined to a further connection collar (20) also in the form of a joint so that an additional pipe can be attached over the further connection collar.
