Electromagnetic inspection method of carburization depth inside and outside of heating furnace steel tube

摘要

The crude oil which flows inside the steel tube of a heating furnace of an oil-refining plant is gasified by being heated with the burner from the surface outside the steel tube. Since this steel tube is used in Japan for 30 years or more, both the inner side and outer side of the steel tube is carburized. If the carburization depth is increased, the steel tube will be exploded suddenly and a big accident may occur. In this paper, the electromagnetic inspection method for measuring the carburized depth of both the inner side and the outer side of the steel tube is proposed. The both depth is obtained by evaluating the flux density in layers with and without carburization in the steel tube using the 3-D nonlinear FEM. It is shown that the inspection for the both depth is possible by using the differential electromagnetic characteristics of the layers with and without carburization in the steel tube.