1st ring shell replacement

[bhart192]

during floor repairs a section of 1st ring shell is to be cut out to permit access for plate installation ,typically called a doorsheet , contractor wants to cut the shell plate 3" above the shell to bottom weld and re install this plate after floor is finished. looking @ API 653 under section 9 it seems the minimum dimension for horizontal welds to the bottom weld is 6" anyone agree

 

[Duwe6]

Concur that is what the book says. The Tank Engineer or the API 653 Inspector for that tank could waive that requirement in writing [file this in the tank's file]. Practically, 6" is not that much farther up on the shell, and allows for a larger 'heel' of remaining slop & crud left in the tank. I'd need a fairly compelling Reason [vs. contractor's 'we always do it this way'] to waive this minimum spacing requirement.