Forming Strain Calculation -

This how to calculated Forming Strain in Manufacturing for Plate, pipe or tube based on ASME code Standard :

after this factor found in ( %), its multiplied to nominal thickness of material used.

for example :

ef = 2.5%
thickness of material = 14 mm
then, the forming strain must be = 2.5% x 14 mm = 0.35 mm.

in workshop, the finishing for material always performed, for polishing finishing process in my company depend on workshop capability.

for example :

thickness of material = 14 mm
spare for polishing process 10% from 14 mm = 1,4 mm.

so, if the thickness calculation result for minimum thickness required based on design parameters about 10 mm ( for example ). if the part had forming process and finishing by polishing process, the
requaired thiclkness are =

thickness from calculation + (ef * thickness from calculation), and must be more or at least same with thickness of material used - (10% * thickness of material used).