Design Criteria:

Assume the acceleration of gravity to be 9.81m/sec²

Assume that 1litre of rain water = 1kg

Note that 1Mpa = 1000Pa and that (1Pa = 1N/m²)

Area of a pipe = 0.7854(D₂ - d²) m²

Load = kg x 9.81m/sec² and that 1000kg = 1tonne

Force = Newton: (Where 1N = 1kg/m²)

Stress = Load/Area (Where Resistance = Load)