Inspecting the current thickness of a refractory wall inside an operational blast furnace using the impact echo method

In this study, a nondestructive testing method based on stress waves, the impact echo method, was applied to inspect the current thickness of a refractory wall inside a blast furnace. Blast furnaces are high-productivity structures that are prone to internal erosion hazards that majorly affect the lifespan of the blast furnace. Previous studies have applied heat flux and numerical methods to inspect the thickness of the refractory wall. Temperature variations were used to assess the condition of the blast furnace by installing an internal thermometer in the blast furnace during construction. However, these methods result in large errors. In this study, a simple formula using the thickness frequency obtained by the impact echo method was derived to back calculate the current thickness of the refractory wall inside a blast furnace. In this study, the inspection results of the experimental specimen and an in situ blast furnace also shows that inspecting the thickness of a refractory wall using the impact echo method offers substantial practical value.