A metal pipe of 1 m diameter contains a fluid having a pressure of 1 N/mm2. If the permissible tensile stress in the metal is 20 N/mm2, then the thickness of the metal required for making the pipe will be
A. 5 mm
B. 10 mm
C. 15 mm
D. 25 mm
Answer: Option D

Given data:diameter=1m=1000mm
Tensile stress ∆=20N/mm^2
Thickness=?
Pressure, p=1N/mm^2
Formula using, ∆=pd/2t
20=1*1000/2*t
Using simplification, Thickness=25mm
hoop stress = pd/2t.
12.5 should be answer
Stress= pd/2t