METHOD FOR MEASURING STRESS OF HIGH-TEMPERATURE PIPE

PROBLEM TO BE SOLVED: To provide a method capable of measuring stress of a high-temperature pipe.SOLUTION: A method for measuring stress of a high-temperature pipe comprises a first step of attaching magnet plates 10 each having a lattice pattern 12 to a plurality of measuring points P on the high-temperature pipe 5, a second step of simultaneously imaging each of the lattice patterns 12 of the magnet plates 10 with a camera 20 in a state that the high-temperature pipe 5 has an initial temperature, a third step of simultaneously imaging each of the lattice patterns 12 of the magnet plates 10 with a camera 20 in a state that the high-temperature pipe 5 has a temperature higher than the initial temperature, a fourth step of determining displacement magnitude of each of the measuring points P due to the temperature change of the pipe from the image data of each of the lattice patterns 12 obtained in the second and the third steps by a sampling moire method, and a fifth step of determining stress distribution of the high-temperature pipe based on the displacement magnitude of each of the measuring points P determined in the fourth step.