I Need to design a Vertical cylindrical water tank to be build by Fiberglass. I need to calculate the tank also for 7.5 m bar pressure and 2.5 m bar vacuum pressure. Tank Dimensions to be 4m Dia, 5 m High (60000 Liters). I have Fiberglass laminate of 6 mm Thk and Modules is 1470000 psi. I have 50mm Dia plastic pipe ribs (rings) in an every 500 mm intervals on tank outside wall. How do I calculate this tank? Please help me.