Top Curb Angle or Top Wind Girder?

[MohdYaseen2010]

(A) I have Understood that Top Curb Angle (Figure F.2) shall be provided if 5.9.5.2 condition met (Top Wind Girder (per Table 5.19a & Figure 5.24) is located more than 0.6 m below the Top of Shell) or in case of Open Tank.
Am I correct?
Also, when Top Wind Girder as per 5.9.5 shall be provided?
(B) 5.9.5.2 stated that Top Curb Angle shall be 65 x 65 x 6 mm and 75 x 75 x 6 mm for Shells 5 mm Thick and for Shells > 5 mm Thick respectively; while as per 5.1.5.9 (e), the Top Curb Angle shall be 50 x 50 x 5 mm, 50 x 50 x 6 mm, 75 x 75 x 10 mm for D ≤ 11 m, 11 m < D ≤ 18 m and D > 18 m respectively.
Which when shall I follow?
(C) Is Top Curb Angle or Top Wind Girder is the same as the End Stiffener mentioned in V.8.2.3 (particularly Top Stiffener)?
Mohd Yaseen

 

[IFRs]

I might have this mixed up but here goes:
[ol A]
[li]Use 5.1.5.9 curb angle for a cone roof tank or if the top stiffener (windgirder) of an open top tank is less than .6m below the top of the tank.[/li]
[li]Use 5.9.5.2 curb angle for the top of an open-top tank when the top stiffener more than .6m below the top of the tank.[/li]
[li]"External stiffener" is a synonym for "windgirder" - they look the same and serve the same purpose. They can also be on the inside of the tank.[/li]
[li]A shell stiffener is needed if your wind buckling or external pressure (vacuum) analysis reveals that one or more are required.[/li]
[/ol]

 

[MohdYaseen2010]

Dear IFR:

Thanks for your responds;

- In case of calculations resulted, NO intermediate W.G is required, is that means Top Curb Angle shall be used regardless the tank type (with fixed roof or open roof)?

- What about question (B), different sizes for Top Curb Angles based on different judgment (5.9.5.2 judge based on Shell Thick) while (5.1.5.9 (e) judge based on Tank Diameter)? which one shall I follow 5.9.5.2 or 5.1.5.9 (e)?!

Mohd Yaseen

 

[IFRs]

I could be mistaken, but this is how I read the standard:

You can't have a tank without a top curb angle unless there is a windgirder / stiffener within 24" of the top of the tank.

If there is a wind girder but it is more than 24" from the top of the tank, use 5.9.5.2

Otherwise use 5.1.5.9

 

[MohdYaseen2010]

Dear IFRs;

I could Say:
Top Wind Girder (As per 5.9.5 & V.8.2.3 (if applicable) SHALL be provided at all cases.
Top Curb Angle (As per 5.1.5.9) SHALL be Provided in cases stated in (5.1.5.9) being fulfilled + Top Wind Girder located @ distance > 0.6m from Top of Shell.

Mohd Yaseen