Re: Requirement of Annula PlateFrom: JRESTREPOB 
Date: Tuesday, December 20, 2011
Time: 12:19:10 AM
Remote Name: 184.108.40.206
CommentsExisting tanks do not need to be updated to a later or the current edition of the Code unless there is a change of service, a re-construction, an alteration that requires to do so or a jurisdictional requirement. Otherwise all items pressure vessels, tanks, pipelines, etc should be updated whenever Codes change. So in my opinion if the tank did not require an annular bottom plate at original construction then it will not requires it unless a change as mentioned before.
By the way, what group of material is the one you mentioned for the bottom course of the shell JIS? As JIS materials can be used for API 650 current edition tanks, as a national standard material from Japan it should be grade 275 and therefore group IV per table 4-4 to require annular bottom plate. Other two grades of national standards are group I to IIIA and do not require the annular plate.