A Cylindrical Tank Is Assembled by Welding Steel Sections in a Helical

A cylindrical tank is assembled by welding steel sections in a helical pattern with angle $\alpha = 50 ^ { \circ }$ . Tank diameter is 1.6 m, thickness is 20 mm, and internal pressure is 2.75 MPa. Modulus $2.75 \mathrm { MPa } \text {. }$ $E = 210 \mathrm { GPa }$ 210 GPa and Poisson's Ratio ν = 0.28. The longitudinal strain in the the wall of the tank is approximately:

A) $1.2 \times 10 ^ { - 4 }$
B) $2.4 \times 10 ^ { - 4 }$
C) $3.1 \times 10 ^ { - 4 }$
D) $4.3 \times 10 ^ { - 4 }$