Proposed Equation of Maximum Principal Stress for Feedwater Heater Tubes with Circumferential Hoop Flaw Defect

Feedwater heater tubes with local wall-thinning defects are often found in the heat exchangers of thermal power plants. One of the most typical local wall-thinning shapes is circumferential hoop flaw defect. Determining the maximum stress acting on the tube with a circumferential defect is essential to ensure the safe operation of the heat exchange system before the tube can be failure due to stress concentration at the local thinning.