u2032 and return flange 6 u2032 as a separate component and then attaching such component to the outer perimeter of the mating flange 4 u2032 may not be as efficient as spin forming the entire flange ring 10 u2032 as described above with respect to flange ring 10 also this u201c 2 step u201d method may result in a certain amount of distortion when the formed hem 5 u2032 flange 6 u2032 is welded to the mating flange 4 u2032 nonetheless the 2 step method may be carried out with less sophisticated tooling than required by the spinning method described above as a further alternative it is possible to produce the flanged ring 10 u2033 shown in fig2 by forming the insertion flange 3 u2033 as one component and the mating flange 4 u2033 hem 5 u2033 and return flange 6 u2033 as a second component the insertion flange 3 can be produced as shown in fig1 10b and as described above the mating flange 4 u2033 hem 5 u2033 and return flange 6 u2033 could be produced by roll forming or perhaps by stamping thereafter the two components can be assembled by welding the inside perimeter of the mating flange to the end edge of the insertion flange this alternative technique may suffer from the same disadvantages of the technique shown in fig2 above including a larger number of manufacturing steps as well as significant distortion or warpage of the flanged ring 10 u2033 due to the welding operation on the other hand it may be possible to produce the flanged ring 10 u2033 using less sophisticated tooling than used to produce the flanged ring 10 as described above fig2 a 23 b 23.