API 653 New Tank Bottom NDE requirements

[osers]

Hello All,

API 653 9.10.2.4 states: "Installation of a new tank bottom, after removal of the existing tank bottom, shall meet all requirements of API 650". That is exactly my case, I have an old tank whose tank bottom is being replaced. Questions: 1. All the NDE required by API 650 apply in this case or do I have to use API 653?. The specific case is for the shell-to-bottom joint and annular plates. For shell-to-bottom joint API 650 requirements in 7.2.4 are different to API 653 in 12.1.6, what should I use? 2. For annular plates, NDE requirements in API 650 is according to 8.1.2.9 and for API 653 requirements exist only for reconstructed tanks (12.2.1.4), this aspect is not clear.

 

[Duwe6]

You are to follow the 650 rules for a [new] floor. Includes 50% RT & 50% MT of Annular Ring buttwelds, diesel test of the shell-to-floor weld, and vac boxing the floor seams.