After blast furnaces, converters, and other furnaces are shut down, 3D measuring industrial endoscopes can conduct in - depth inspections of the erosion and spalling of refractory bricks and castables in the lining. They can measure the depth and area of erosion pits and the remaining thickness of refractory bricks, predict the lining life in combination with historical data, plan maintenance rationally, and reduce the risk of furnace leakage.