EXTERNAL FLOATING ROOF TANK- API 650

[MOHAMMED89]

What is the a[highlight #FCE94F]cceptable submergence[/highlight] of the external floating roof tank (Single Deck).

API 650 didn't specify any criteria for this one.

Whether 100% submergence of outer rim is accepted?

I check in few EFR vendor calculation, Some of them are taking margin of 90% submergence of outer rim is acceptable.

Please advice me with any guideline / reference available for acceptable / safe submergence.

Thanks in Advance :-)

 

[JStephen]

Not sure what the question is exactly- but on a typical arrangement, if 100% of the rim is submerged, the floating roof sinks.
If you mean, can the top of the rim be exactly at the product level at the worst theoretical condition- possibly- that isn't specified by API.
I would assume that at the worst conditions, including allowance for erection tolerances, sloshing, calculation approximations, etc., you'd still have SOME definite length of rim above the product, and that sounds like what they're doing with the 90%.