as elliptical parabolic polyhedral square u shaped etc the elbow 10 in the illustrated embodiment is in the form of an arc extending through approximately 90 u00b0 so as to provide a right angled turn to the conduit although it will be understood that the elbow may extend through any suitable angle to provide an appropriate bend in an exhaust conduit and is not limited to 90 u00b0 the arc of the illustrated elbow 10 extends through a quarter circle in order to provide the 90 u00b0 angle however any suitable arc shape can be employed to form the desired angular bend to the exhaust conduit referring now to fig2 a first channel section 12 of the elbow 10 is illustrated which is shown in fig1 on the bottom of the elbow although it will be appreciated that the term u201c bottom u201d is used solely in reference to the figures and does not imply any spatial relationship or orientation between the components in use the elbow channel section 12 can comprise a shaped metal channel having a substantially semi circular cross sectional profile with flanges 16 18 along each side of the channel the channel may be curved such that it is in the shape of an arc extended through a quarter circle the flange 16 may be provided on the interior of the curve of the channel section 12 and may have approximately three raised tabs 20 spaced along the length of the flange the flange 18 may be.