More experience = better estimates
You also need to know some details.
Such as do I expect general corrosion or localized corrosion?
Will attack be worse in the liquid phase or gas phase or at the interface?
LI is correct, if you think that you need more than 5 or 6mm then you need a more robust approach.
"By knowing the expected rate of corrosion and the expected service life of a plant or parts, industries can compute the additional thickness needed for corrosion resistance of equipment in the design process."
No book will tell you a corrosion allowance, only the time and experience, normaly corrosion alloances in petrolleum industries go from 1.2mm, 3.2mm up to 6mm.
Were you going to tell us about the CA for specific fluid and a specific Vessel MOC ?
It is impossible to answer your question for ALL liquids, gasses and temperature ranges ... Others may agree ..
Your selection, for example, of a Carbon Steel pressure vessel with a 0.25 inch CA may be cheaper than OR more expensive than the same 304/316 Austenitic Stainless vessel with a 0.00 inch CA ... Increase the operating temperature by 200 degrees and it's the other way around !
... and when your boss rushes in at the last moment and tells you the client says the process stream now has 1,000 ppm of chlorides .... change the design, material selection (and the CA) again !!!
