Exhaust heat recovery boiler

An exhaust heat recovery boiler comprising:

• a duct casing in which exhaust gas flows;
• a tubular extending portion extending upward from the duct casing;
• a heat exchanger tube located in the duct casing;
• a hammering rod connected to the heat exchanger tube in the duct casing and passing through an inside of the extending portion, the hammering rod including an upper part projecting to an outside of the extending portion;
• and
• an annular sleeve attached to the upper part of the hammering rod through a packing, wherein:
• in a state in which the sleeve is attached to the upper part of the hammering rod, the sleeve is movable relative to the extending portion in a radial direction relative to a central axis of the extending portion, and
• the extending portion includes an upper flat surface which is located at an upper end of the extending portion, realizes a seal between the upper flat surface and a lower surface of the sleeve, and is annular and flat.