Maximum width of shell inserts

[LarryDavid]

A client's flat bottom water storage tank is corroded and requires repair.

The tank is 12m diameter, 9m tall.

Over half the circumference of the shell to bottom weld is cracked and corroded, including the first 100mm or so of shell which requires replacement.

API653 does not specify the maximum width (circumference) of shell which can be replaced at a time (without having to jack the tank), to avoid the tank buckling/collapsing.

Apart from FEA, are there any methods/guideline/rule of thumb to working this out?

Any help would be appreciated.

Cheers

P.S. Sorry to post this in two forums, I haven't had much help in the API forum..

 

[unclesyd]

You asked one those it depends type of questions. Things like the tank design and construction especially the welding along with a whole bunch of other parameters.

Your best course of action would be to get a tank company that to evaluate the existing tank and recommend a course of action. There is a lot to evaluate like the condition of the bottom plate at the bad weld or how high the wall plate needs to be replaced.

If you have problems At the T-joint make sure to check the welds at the top.

Cracked wells in a water tank are unusual. may I ask what is the material of construction and if known the composition of the weld metal.