Annular ring to bottom conection

[JONI101]

Hello

I am inspecting water storage tank which designed according awwa d100 and api 650 standards, 13.5 m diameter, sa 516 gr 70
In the original design there is an annular ring which ofcourse welded by butt weld and also bottom plates which are also welded by butt weld, the connection between them is lap welded.
The contractor wants to connect them by butt weld which means all the floor will be butt welded.
Is it ok according to api 650 or awwa?

Many thanks

 

[JStephen]

Yes. Lap welding on bottoms is generally used due to being faster and cheaper, but butt welding can always be used in lieu of lap welding.

 

[JONI101]

Thank you very much Jstephen
Do you have idea for proper welding squence in this case?
I am afraid it will be hard to match the sketchs to the annular ring for butt weld after the annular ring welding will be completed.
Maybe in this case its not smart to start with the annular ring welds and itd better to start welding the internal sketches first?

Thanks,
Joni

 

[IFRs]

The Boilermaker Manual might have suggestions.
Is your floor flat, cone up of cone down?

 

[JONI101]

Hello IFRs
The floor is flat

 

[HTURKAK]

Hello JONI101 (Industrial),

I just looked to your post . You did not mention the thickness of bottom plates and annular plates. But i think both should be 6 mm. ( Minimum specified by codes ..)

I know BS 2654 which allows the use of rectangular and sketch plates ( without separate annular ring ) up to dia 12.5 m.

The relevant page copy and pasted below=

I will suggest similar set up with butt welded version if the annular plt thk. is the same with bottom plates.

The code allows butt welded bottom plates ( 5.5.1 thru 5.5.5)

Good Luck..

 

[JONI101]

Thank you very much for the information HTURKAK