For carbon steel materials, what is the commonly used value for corrosion rate to determine remaining life of vessel or tank in number of years? The vessel is located in terminal approximately 1 kilometer from the seashore.
For a particular service, the corrosion rate will be based on emperical evidence of corrosion curently ongoing and recorded for the vessel in question. Changes in service characteristics will effect the corrosion rate. Established design corrosion rates in specific services are available. They very well may not apply to your specific vessel.
The 'design corrosion rate' is what the designer defines it to be. There are too many variables in the corrosion process, and too many corrosion processes, to have definitive off the shelf values fitting all situations. Try reviewing API RP 571 and picking how many different types of corrosion will apply to the vessel in question. API RP 581 may then help with some assessment formulae.