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[Damadria]

Hi All,

 

I'm working on a project where tank blanketing with nitrogen is the selected solution for avoiding oxygen ingress into the water system (produced water).

 

As you know the last edition of API 2000 and ISO 28300 provide two methods for calculating the venting requirements: one using the equations under chapters 4.3.2.2 and 4.3.2.3 and the other under Annex A.

 

Following the two methods different results are obtained.

 

E.g for a 1000m3 tank, with a 100m3/h, no insulated tank, temp 30C, fluid - produced water, and a latitude of 44 the results for inbreathing (thermal and pump capacity) are 478Stm3/h following the equation method and 270Stm3/h following the Annex A method.

 

The Annex A seems to be applied to "specific boundary condition" which are pretty clear unless the second one (below) which is for me, who I am not a good speaker of English, unclear.

 

“For tanks containing volatile liquids, the volatility characteristics are similar to petrol (gasoline), and the temperature of the liquid fed to the tank is less than the boiling-point temperature at the maxim operating pressure of the tank." - That means the Annex is applied only to the tanks containing volatile liquids or this just state the condition when we deal with volatile fluids?

 

Considering above please advise me if Annex A is to be used for produced water tank venting requirements and which are (if any) the risk and which is the "strong" argument to use this method against to the body standard method.

 

Thank you very much