API 650 Closed Tanks

[Cassidy G]

Good day, Engineers.

I'm designing Closed Storage Tanks using API 650 - 12th Edition.

Can anyone clarify the difference between top angle and top wind girder?

Because in my understanding. For Closed Tanks, top angle must be use. The top wind girder is only for Open Tanks.

Therefore, I'm not required to calculate the top wind girder. I should only use the table of top angles given by Section 5.1.5.9, and I'm must check if intermediate wind stiffener is necessary.

Any advice.Thank you.

 

[HTURKAK]

- Top wind girder is for open top tanks and floating roof tanks while top angle is also used for the compression ring purpose for fixed roof tanks.. Regarding the details , for top wind girder , and stiffening rings pls look Figure 5-24. and for compression ring app. F Figure F-2—Permissible Details of Compression Rings..

- Regarding the closed tanks , i think you mean fixed roof tanks..In this case, depending on the interior and exterior pressure the compression ring will also serve tension ring.

- I suppose you have a fixed roof and you do not want to calculate the top wind girder.. That is O.K but you need to comply with the compression ring requirements .

There is a forum for storage tanks ..Next time. you may write your thread to that forum to get better responds.

 

[LittleInch]

Often / mostly you would get the vendor to do the design as they are fully experienced with this.

Why are you designing it to this extent?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Cassidy G]

Sir HTURKAK

Yes, it is fixed roof.

For top curb angle, can I use double angle and form it like a channel? Or can I use Channel diectly.

Because minimum required participating area is larger than the area provide by shell, roof plate, and angle.

Thank you.

 

[Cassidy G]

Sir LittleInch,

My company is for indusrial. Before my company has designers for large tanks.

For now, they only have me with 1 year experience. I'm interested with this therefore I giving my best to design it.

No other engineer can help me here in my company.

 

[HTURKAK]

The minimum top angle size is defend at item 5.1.5.9 . ( Roof and Top-Angle Joints ).

The Permissible Details of Compression Rings defined at Figure F-2 and the use of channel or double angles are not defined .Notice that the unstiffened length of the angle or plate (Le) is limited with ( [3000/(Fy)1/2] * ta ) for lbf , in...

How did you calculate the minimum required participating area ?
What is the internal design pressures and who defined these ?
What is the service?

You are saying that you have only one year of experience but the level of questions implies that you will need the supervision of an experienced senior engineer..If this is not a simple tank such as water storage for swine farm, i will not encourage you to design.. Better to ask the services of a professional..

Good Luck..

 

[IFRs]

A fixed roof tank does not need to be evaluated for a top wind girder - it is assumed that the fixed roof provides adequate bracing, but you will still need to review wind loading for intermediate wind girder(s).

For the top angle on a fixed roof tank you are limited to those configurations shown in figure F.2. Be sure to evaluate for frangibility, or you'll need additional venting.

If you can, use the 13th edition which replaced the 12th edition.

 

[Cassidy G]

Sir HTURKAK

I have sample of tank design. The designer used API 650 11th edition (Section 5.1.5.9 and Annex F Fig. F-2.

The minimum participating area at roof to shell junction used by the designer is

A = [D^2/(0.432sinθ)](T/2.2)

At 12th edition
A = pD^2/8Fatanθ

I'm using 12th edition.

But I compared the two. 12th edition has smaller required area.

Thank you.

 

[Cassidy G]

Sir IFRs, ok sir I will look for 13th edition. But for now I will use the 12th edition. Thank you.