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Dear All I am designing an ammonia tank with API 620. I'd like to know if it is mandatory to consider API 650 App.V for external pressure or not? By considering API 650 App.V it is required to use a top stiffener on the compression ring area. Regards Roohol

Dear all Can anyone tell me how much corrosion alloance shall I consider for inner side and outer side of inner shell of a full containement ammonia storage tank? please tell the refernce. Some manufacturer consider 1.5 mm on inner side and 1.5 on outer side and some other just consider 1.5 mm...

Dear All; Centerline-stacked or Flush-stacked method, which one is better for storage tank installation? esspecially for ammonia tank and with air roof raising? please clarify advantages and disadvantages of each method. Regards; Roohol

Hi; there is an ambiguity in the API 650 about roof types. based on my experiences and searches i have found that up to 5 m diameter it is better to select a cone self support roof ( without any structure and just plate), 5 < D < 15-17 meter, self supporting cone roof (with rafter & girder) ...

Thanks IFRs Please clarify why you consider both? is allowable stress different for full+seismic and empty+seismic? since we do not consider wind and seismic, can we assume that outer full liquid and seimic will not be happened simultaneously?

Hi; Does any one know if it is required to consider siesmic bending moment + buckling in case of leakage (full liquid in outer shell)? or buckling shall be analysed based on seismic load related to empty outer shell? thanks roohol

Dear friends! I have a question about anchor strap; When it is essential that anchor strap pass thru the outer bottom plate of double or full containmnet storage tank, how we can seal the intersection area? Welding this area is a solution but I think it is not a good solution because when...

Thank you IFRs; According to ASCE7-10, I need S1 and Ss for seismic calculation of pressure vessels and storage tanks. I have these two parameters based on Sp (S1=1.25 Sp, Ss=2.5 Sp). According to your reply I have found that Sp= 0.4 for zone 4 , Sp=0.3 for zone 3,... . Is it correct? Please...

dear all in seismic calculation of API 650, can we assume that sp is equal to seismic zone factor? for example if zone factor is 4 in a site, then Sp is equal to 0.4 or not? how can estimate Sp if we dont have exact site condition?

Thanks a lot IFRs Calculated shear load is more than friction resistance, please answer if strap can bear the shear or not.

Can we use anchor strap in the cryogenic storage tanks when we have wind or seismic shear load? I am not sure that anchor strap can bear shear laod beacuse of its flexibility!

if this tank is double wall, 2 annular plate are needed too. and if there is an annular plate that is built with 2 layer of plate it may be because of needed thickness.

Storage tanks & equipment is a very good book to refer to.

Dear freinds! As per API 650 2011 5.10.5, a dome or cone roof type with rafter & girder and without column is a supported or self supported roof? And thk of this roof shall be calculated from 5.10.5 formula or 5+C.A is sufficient? Regards; Roohol