A Long-range Guided Wave Detection of a Hole Defect in a Carbon Steel Piping Mock-up using a Magnetostrictive Strip Sensor

A pipe leak takes place from corrosion, or erosion of nuclear power plant pipes under a high temperature and pressure. Accurate inspection of a corrosion and cracking in a pipe is required because a leak from primary pipes leads to a diffusion of a radioactive activity. A thinning of a pipe in a nuclear power plant is believed to be due to a flow-accelerated corrosion(FAC). FAC is affected by environmental factors such as the temperature, pressure, and pH. Thus, nondestructive techniques are required for a corrosion inspection of the pipes in a nuclear power plant. All the vibration modes can be generated and received by using a magnetostrictive strip sensor technique. Torsional vibration modes, longitudinal vibration modes and flexural vibration modes can be possible by a combination of a direction of DC magnetic bias and an alternative magnetic field. In order for a demonstration of an effectiveness of the long-range guided wave technique, a real scale piping mock-up with a length of 21 m with an elbow was manufactured. Dimension of this piping mock-up is diameter of 6 inch, and thickness of 11mm. An artificial hole was fabricated to locate a defect. A relationship between the amplitude and the cross section area of hole was obtained and a detectable limit of the hole defect was determined