Aluminum Dome Roof Tank

[22320ajv]

Hi for everyone.Regarding API 650 APP.G parag. G.1.3.1, The Storage tanks with Dome roof shall be designed (wind girder)according parag. 3.9, nevertheless 3.9.4 says (It shall preferably be located 42" below the top). My question is: It's mandatory or not; could be less of 42". Same question for EFR Tanks.
Thanks a lot for your replies.
A.V

 

[BigInch]

Shall is a mandatory... preferably is not. Translation: "Do it, unless you have an iron clad reason why its absolutely impossible."

 

[JStephen]

That's sure not my interpretation of "preferably". Normally, where an aluminum dome roof is to be used, the wind girder would be placed near the top of the shell. The 42" dimension is so that the shell forms a standard railing on the tank side when the wind girder is used as a walkway, and that isn't an issue when a dome roof is installed.

 

[IFRs]

Iv'e seen many dome roof tanks without windgirders, witn windgiders at the tank top and lower down. In my opinion, the tank and the dome are separate items unless the customer wants them to be designed together. So, the tank gets a windgirder if it is needed, sized and located as needed for the tank. The dome gets plunked down on top. If on the other hand, the customer wants the dome's tension ring to be integrated into the tank, that's a different story. Or, if the customer wants to be able to walk around the windgirder for dome inspections, the windgirder then gets designed differently. It is your option when "shall" is not used.

 

[JStephen]

I just pulled out the standard and re-read that paragraph, 3.9.4. The title of the paragraph is "Stiffening Rings as Walkways". IF you use a wind girder as a walkway, then it should preferably be 42" below the top of the shell, be 24" wide, etc. This isn't saying all wind girders should preferably be 42" below the top of the shell. Notice 3.9.1 says "at or near the top of the top course".

 

[JoeTank]

FYI... the 42" dimension comes from the OSHA handrail height requirement.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com