What will be the thickness of metal required for a cast iron main 800 mm in diameter for water at a pressure head of 100 m if the maximum permissible tensile stress is 20 MN/m2 and weight of water is 10 kN/m3. [Take g = 10 m/s2]
1
15 mm
2
20 mm
3
25 mm
4
30 mm