Dear Sir,

I have To design Tanks based on Code UL-142.Code has mentioned Min. thk for shell,Bottom,Roof in tabular form based on Tank Oeientation & Type.My questin is say for Example if as per the code min. thk is say 3 mm for roof plate & client has given say 6mm corossion allowance.If you think logically we should provide 3+6=9 mm to Roof.But nowhere they have mentioned that those mentioned min. thk ( are wether excluding / including corossion allowance).
Regards
Ashish P.