Roof to Shell Compression Area 1

[99491]

When working out the roof to shell compression area as per Figure F-2 API 650 please advise if the shell thickness tc should be including the corrosion allowance. ie if the shell plate thickness is 6mm with a 3mm CA is tc 6mm or 9mm.

Thanks

 

[nickelkid]

I cannot find tc defined in API650 either. But I stumbled upon an ASME spec Welded Aluminum-Alloy Storage Tanks B96.1. Figure 21 provides permissible details and participating compression region details, with the same details as API 650. B96.1 clearly defines tc as exclusive of corrosion allowance, I hope that helps.

 

[IFRs]

Section F.5 says that the total required compression area at the roof-to-shell junction "A" is based on the nominal material thickness less any corrosion allowance