Repair of cone roof tank

[adamjin]

I have a scenario where there is diesel tank of 24m dia and 12.8m height.

the inspection report recommends renewal of the top 3 courses of shell. the tank roof is ok.

can someone advise if ti can be done without removal of the roof? or do i have to remove it?

how to remove it? the roof plates are just laid onto the rafters.

any one with solution please provide an answer

[lgwsaw]

There are a few things to think about here---
How is the access around the tank?
Is there a platform or bridge across?
I would propose to remove the roof skin and roof rafters- this would allow good and safe access for your shell replacement.
If the thickness of the roof plate is 3/16, I would also propose to replace is with new material. Be sure to guide the center column off before the last few rafters are remove.
Plan on 5 men 2 weeks for this.
If removing the roof is not a option. plan on replacing small sections (20') at a time starting at the bottom and completing the whole ring before jumping up to the next level.

Regards
LGW

[adamjin]

1. There is access around the tank
2. there is no platform on top
3. roof skin is at 5mm hence no need for renewal
4. do rafters have to be removed individually after removing the plates? is there no way where the roof structure can be reinforced and removed as one whole structure? my concern is that for removal of the skin, there is need of cutting and gouging the joints and it would create a lot of distortion. and the end product would not be good enough to refit it back.

anyone who has faced such a scenario? kindly advice

[lgwsaw]

Most offen the skin would need to be replaced, just like you said do to the thickness (3/16) arc gouging could be a mess. Removing the rafters are the easy part.
If you don't want to go this route you could--
Cut a door sheet in the tank large enough for forklift access (10'x 10' min), install vertical support beams/pipe at each area attached to the roof rafters. There are many ways to raise the support pipe up. We use a forklift to raise the support and a manlift to make the tie in (weld) at the roof line.
Depending on how many sheets you remove at a time-- you could just install vertical supports on the inside attached to the shell. Install your new plate from the outside and just move out inside supports beams around as you proceed.
I hope I have made myself clear.
If you need a quick sketch or drawing let me know I have several.
Good Luck
LGW

[adamjin]

lgwsaw,

Thanks for your advice. i would be most appreciative if you could provide a sketch or drawing.

thank you in advance.

regards,
Adam

[lgwsaw]

Adam,
I have attached two pics for your referance.

Regards
LGW

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[nonaxanon]

with what software you made that ?

Adam,
I have attached two pics for your referance.

Regards
LGW

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[m.boka]

Hi,I think The best way is cutting shell 200 mm under rafter to shell junction.So You can put roof part down with crane and renewal. After your repair will finish you can put the roof part on the shell and weld it.

[Danny_Harris]

Generally offen the skin might need to be displaced, much the same as you said do with the thickness (3/16) bend gouging could be a mess. Evacuating the rafters are the simple part.

In the event that you would prefer not to go this track you could- -

Reduce an entryway sheet in the tank vast enough for forklift access (11'x 11' min), establish vertical back beams/pipe at every region joined to the top rafters. There are numerous approaches to raise the backing speak up. We utilize a forklift to raise the backing and a manlift to make the tie in (weld) at the top line.

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[lgwsaw]

Goggle Sketch up----- Fast and easy