Abstract: An indicator device is disclosed for indicating that a heat exchanger has been disassembled, cleaned, inspected, reconditioned and subsequently reassembled and rebrazed. The device includes an elongate housing which defines an inlet and an outlet port. A first and a second tube plate are spaced axially within the housing and a plurality of heat exchange tubes extend through and between the plates. A first seal is disposed between the plates and the tubes for sealing the tubes relative to the plates and a second seal is disposed between the tube plates and the housing for sealing the tube plates within the housing.