The difference in the reservoir level and the lowest point of the water mains is 180 m. The
expected pressure due to water hammer is 7.5 kg/cm2
in a pressure conduit of diameter 1 m.
Assuming the efficiency of the riveted joints of the pipe as 0.6 and minimum cover 3 mm for
corrosion, the thickness of the pipe materials, is
(A) 10 mm
(B) 15 mm
(C) 20 mm
(D) 25 mm