Wind Girders

Try this.

Yes it is satisfying answer. I have seen a cone roof tank with wind girders. it puzzled me. can you justify it?

The only justification for anything is the business need and the applicable standard, such as API-650. No-one outside the original poster's operation can read the business need document.

Invitation declined.

NO, only floating roof. (API 650 Appendix H)

H.4.6.10 Consideration shall be given to the use of fixed supports for the operating position (low level) of internal floating

roofs, which utilize cable supports suspended from a fixed roof. These supports are typically not adjustable, are sealed to prevent

emissions, and are for the operating position (low level) set at a level as specified by the Purchaser. The use of fixed supports for

the low level position are intended to reduce the frequency of fixed roof loading. The operating position (low level) and length of

the cables shall be such that sinking and/or collapse of the internal floating roof will not apply loads to the support cables.

H.4.6.11 If cable supports are used, the supports shall be adjustable from the fixed roof while the floating roof is floating and

with the cables unloaded.

H.4.6.12 Cables, cable segments, or cable connections which support the floating roof are prohibited from using a fusible link

or other devices which are designed to fail at a specified load limit.

H.4.6.13 Cables used to support internal floating roofs shall be 300 series stainless steel and shall be flexible to facilitate

repeatable lay down patterns on the floating roof as it travels up and down within the tank. Lay down patterns shall be positioned

to avoid rim seals and floating roof appurtenances that could prevent the cable from freely extending as the floating roof lowers

But if we are talking about wind grinders not about support cables is a different matter.

The necessary shell stiffener, some time the engineer will be calls such as top angle, wind girder, intermediate wind girder etc, but all the purpose to avoid shell plate from buckling, oval, un roundness, plumbness, peaking, banding etc and these all API 650, will be guide you, what are the simple explanation make sense to you?

Wind buckling of the shell must be checked for all tanks, open-top and fixed-roof. When there is a cone roof, the top of the tank is braced so a top wind girder is not needed, but an intermediate wind girder may still be needed.

Top and Intermediate wind girder can be apply to all type of tanks...
Depends on tank height, thickness and especially wind speed where tanks located...
You can check if these are required or not...and how many quantity will be needed...

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Simplest answer: "to avoid the potential consequences of not using them".

Not all buckling will be the same, depending on how giant the tank is and how far a point on the side wall is from the lid welded cone seam.

I suspect buckling could take place at some lower point about midway up the profile, for example.

I suspect buckling could take place at some lower point about midway up the profile, for example.

Yes, this would also depend on the size/geometry/mass of the roof as well as the contents (substance and fill level) of the tank.

Do you know what a wind girder is, and why they are used? If the tank is large enough, yes, it needs a wind girder, no matter what style the roof is, to prevent side wall buckling under wind load.