Hasmid Your question for calculation of internal thickness and Corr Allowance as per ASME sec VIII Div 1UG 27: Please note that Corr. Allowance is always discounted for calculation as per UG 27 for internal pressure. Corrosion allowance is to be added for the particular service design and design temperature taking into accuont the process service corrosion practised by the industry. Para UG 25 -ASME Sec VIII Div 1 is clear that corrosion allowance is to be additionally provided from the minimum calculated design thickness . t This is separate from internal pressure calculation to meet UG 27 for cylindrical shells or spherical shells. See also UG 16 (b) for minimum thickness to be provided where C.A. is discounted. Trust this answers your querry. C.V.Srinivasan Nishi Engineers Pvt Ltd Indai August 09,2006 E-mail: nishi@vsnl,com >Dear Expert, > >I believe the calculation for MRT for shell under internal >pressure is based on ASME VIII Div I Part UG-27. I want to >know if the Corrosion Allowance is specified, how to include >this into the formula? Is it MRT = pressure design >thickness, t + CA? Or is it the CA (corrosion allowance) is >included in the inside radius of the shell? > >If we refer to API 510, there is clause mentioning that the >required thickness is before the corrosion allowance and >manufacturer tolerance being add up. > >Please advice