A student decides to build a boiler for a model steam engine. He cuts some thin sheet metal into a strip, rolls it into a spiral, and puts on end caps, as shown in the diagram. The diameter of the cylinder $D = 27$ $mm$ and wall thickness $t = 2.2$ $mm$. The student has some fancy glue, and uses it to secure the spiral seam. After applying the glue, he applies a torque $T$ to clamp the edges of the seam shut. With the torque still applied, he puts some water inside, heats the boiler, and a steam pressure $p = 145$ $kPa$ is created. After a while, the student notices that the heat has caused the glue to melt and run out. However, even when the cylinder is pressurized, the torque $T$ is still sufficient to keep the seam closed so that no water leaks out. Determine the angle theta degrees that requires the minimum torque $T$ to keep the seam closed. (Hint: use Mohr's circle). Give the answer in degrees.

$\theta=$$^{\circ}$