Joint Sealing by Hand Seaming

All metal joints that are to be sealed should be mechanically joined. Seaming is one acceptable method of joining two pieces of metal. 

The two pieces are folded so each hooks into the other and then they are locked together by the means of a hand seamer or groover. 

The material allowance depends on the hook dimension, but it is usually 6 mm. That means the extra allowance for the is 18 mm, because there are four thicknesses of material.

This type of seam can be used on a flat surface or round surface.