Inspection device and inspection method for boiler furnace water wall tubes

An inspection device for boiler furnace water wall tubes, which inspects reduced wall conditions of multiple water wall tubes extending in a vertical direction along inner wall surfaces of a boiler furnace and arranged adjacent to each other, comprising:

• a leg placed upright and fixed by a magnet onto a surface of a water wall tube;
• a support frame fixed to the leg to support a displacement sensor producing laser light to be irradiated onto the surface of the water wall tube;
• a moving mechanism for moving the displacement sensor in an axial direction of the water wall tube relative to the support frame;
• and
• a signal processing unit configured to calculate an amount of reduced wall thickness of the water wall tube from a difference between data of a surface shape of the water wall tube along a direction substantially perpendicular to the axial direction of the water wall tube obtained by the displacement sensor and data of a reference shape without reduction in wall thickness in order to evaluate a reduced wall thickness condition, the signal processing unit including a reference position calculating section for calculating a reference position for superposition between the data of the surface shape and data of the reference shape.