R-wave method for nondestructive electromagnetic testing onbroken wires in the prestressed concrete cylinder pipe

Prestressed concrete cylinder pipes that are widely used in the water supply projects suffer from the risk of pipe burst induced by broken prestressing wires inside the pipe wall. Based on the remote field eddy current testing theory, a new method named R-wave method is proposed to detect the longitudinal position of the broken wires. The difference between R-wave method and conventional method is the coil arrangement. Two coils are used; one is exciter, and the other is the receiver. The two are put on the opposite ends of the pipe diameter in one section. The normal direction of the exciter is parallel to the pipe axis and that of the receiver is orthogonal to the pipe axis. It is found through the finite element analyses that the remote field is arranged along the circumferential direction of the pipe wall. Finite element simulation also points out that the sensitivity and range of the broken wire detection can be adjusted by changing the distance between the two coils along the longitudinal direction of the pipe. The patent of this method has been approved in both China and United States, and it has been applied in the water supply project in China,which proved its effectiveness.