Old tank repair to current API 653 ; what API 650 version to address 1

[FrCivEng]

This is an existing API 650 tank which floating roof is to be replaced ; current API 653(3rdEd_Dec2001_Add3_Feb2008_Err_Apr2008) will govern the repair design and works ; when the API 653 addresses the API 650, what is the API 650 version to be considered ?
Is it the one which governed the tank original design and construction or is it the current API 650 11th Ed ?
Thank you for your help

 

[JoeTank]

Bonswa, IFR,
Did you mean Appendic C for EFRs? There have been a few significant changes in this appendix over the last 20 years or so. That would become a factor if the old roof drawings were based on a set of drawings older than about the mid-1980s.

Regarding IFRs, every roof has to be matched to the existing tanks so construction issues (such as rim space, column well size, types of seals, fixed roof interference, mixers, shunts, bonding, etc) will have to be addressed on a case-by-case basis. Appendic H has also undergone major revisions in recent years, so again the age of the existing IFR comes into play in respect to replacement in-kind. One item that comes to mind is the issue of allowable stresses for design. For many years API was silent on that, but has recently added references for allowable stress levels.

Joe Tank