A thin-walled pipe of 10 cm diameter is used to carry hot steam at a pressure of 2.5 MPa. The pipe is made with a steel with Young's modulus of 200 GPa, yield strength of 1000 MPa and fracture toughness (Kic) of 2.85x10 Nm32. Determine the minimum thickness of the pipe using the leak-before-break criterion assuming a semi-circular shape of the cracks in the vessel wall and a safety factor of 9.