Hi
I am doing stress analysis of fire water tank connected to fire water pump. fire water tank is design as per LPCB type-A code(british standard) having 6m dia and 2mm thick only and gavanized steel material.Temperature may be 60 deg C.Line size from tank to pump is 10".
Does it required stress analysis as this is not API 650 Tank?
if yes, can we apply same design standards as API 650( tank dia is less than 36m)?
do I need to consider Tank bulging,settlement,thermal displacement as Tank dia and temp is very less and Water weight is not that much as in case of API 650 tank.

What should I consider while doing stress analysis of fire water tank.
Also find attached tank dwg.

For me it is not clear how many horizontal and vertical stiffeners tank has; note that API650 does not consider any vertical stiffeners.
Second, API650 considers for such tank min nominal thickness as 6mm for first course and 5mm for the rest of courses.
IMO you cannot apply API650 provisions, instead you may perform a FEA analysis to understand how the shell-nozzle connection responds to nozzle loads. Probably the conclusion of such exercise is that you cannot apply loads on nozzles!