API 650 5.10.5.2 2

[Champ58]

Can anyone please tell me about the formula given in 5.10.5.2? Is this formula given to calculate compression area at roof to shell junction or it is the formula to calculate corroded thickness of shell?

 

[IFRs]

5.10.5.2 Calculates the minimum participating area. The wording could use some revision for added clarity. I have shown what I would propose...

The participating area at the roof-to-shell joint shall be determined using Figure F.2 and the nominal material thickness less any corrosion allowance AND shall equal or exceed the following:

 

[HTURKAK]

I have API 650 11 th EDITION. The formula given in 5.10.5.2 shall be understood as the minimum compression ring area which shall be provided. The compression area shall be determined using Figure F-2 as IFR (petroleum ) stated.

Notice that, the details shown at Figure F-2 (a to k) are all applicable details. In case of area calculated with ( roof participationn + shell participation ) does not satisfy the formula given in 5.10.5.2, you may add steel section or these areas may be increased by thickening the plating similar to shown at detail k .

Although the term compression ring, tension force develops for external loading and compression for internal loading.

 

[Champ58]

Thank you guys for your replies.
Also, I would like to ask you that if we calculated the minimum participating area from section 5.10.5.2, then we shall not use F.5 to find out the minimum compression area?

 

[HTURKAK]

Dear Champ58 (Mechanical),

API 650 5.10.5 is for self-Supporting Cone Roofs and the mentioned compression area Ac=(p*D**2)/(8Fa tanθ) .Notice that ,The load term p includes only external pressure+ gravity loads.

Appendix F is for small internal pressure. and the loading at F.5.1 formula contains only internal pressure .

Apparently , there is confusion for the interpretation of App F and 5.10.5 .If this is a real question, In order to get more valuable comments, please share the dimensions of the tank, internal pressure, roof type, shell wt...etc