Wind Overturning and Sliding of API-650 Tank

[arbitrader]

thread809-159697

I am looking for some guidance on 5.11.2.1 (API-650 13th Edition) regarding overturning.

Calculating OT resistance and sliding resistance for Wind, but need clarifiation on the Parameters M-DL, and M-DLR. The tank is a new 52'D x 32' open top tank that will have an aluminum geodome roof, and a steel internal floating roof. M-DL is defined as the OT moment from the weight of the shell and roof structure supported by the shell that is no attached to the roof plate., and M-DLR is the momenat of the roof plate plus any attached structural. I am not sure how these parameters are calculated for an aluminum geodome roof. Also, since this calculation is based upon an empty tank, can I take credit for the weight of the steel internal floating roof, since it would be sitting on its legs? The equations don't address this.

For sliding from wind, what is included in the weight that can be used to resist sliding, other than tank shell,roof, and floor? Can the steel internal floater also be included in this resisting load?

Finally, since this tank will be on a concrete ringwall, Can I use the maximum COF of 0.40 since the interface would be the concrete ring against steel, would likely be higher than sand to steel of the tank bottom, or sand to HDPE leak detection membrane.

 

[HTURKAK]

In your case , ( tank with geodesic aluminum roof );

M-DL= is the moment about the shell-to-bottom joint from the nominal weight of the shell ( without roof and bottom plates )

M-DLR= is the moment about the shell-to-bottom joint from the nominal weight of the aluminum roof plate plus aluminum
structural frame.


No! The internal roof even sitting on its legs together with base plates will not resist to overturning. In order to assume partial contribution of IFR and base plates , a substantial uplift must occur which is not acceptable.

The weight of roof, shell , bottom plates and IFR if resting on the bottom could be included .




Clause 5.11.4 Sliding Friction
Unless otherwise required, tanks that may be subject to sliding due to wind shall use a maximum allowable sliding
friction of 0.40 multiplied by the force against the tank bottom.

The COF =0.4 shall be adopted .

I hope my respond answers your questions ..








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