1st Operation Roll Seam
Double Seam Terminology - A Finished Double Seam
1st Operation Roll Seam

Measurements of the 1st Operation Seam consist of, Thickness, Width and Countersink. These dimensions should be recorded for future reference after the final seam has been qualified as acceptable. The 1st Operation Seam plays a major roll in the final seam. A correctly formed 1 st Operation Seam must be achieved before the 2nd Operation Seam can be formed.