Abstract: A rapping hammer system adapted for periodically rapping and cleaning tubes of a heat exchanger unit to remove undesired deposits from outside the tubes. A plurality of rapping hammers are each pivotably attached to a radial arm extending outwardly from and spaced apart along a rotatable shaft. A spring device is attached to each radial arm and arranged to contact the rapping hammer with sufficient force so as to substantially restrain repeated striking movements of the rapping hammer against an impact stem of the heat exchange unit following an initial impact of the hammer. A method is also disclosed for operating the rapping hammer system for periodically rapping and cleaning the outside surface of heat exchanger tubes such as boiler tubes of accumulated ash and soot deposits.