Tube bundles of shell and tube-type heat exchangers often fail because of vibrations produced in tubes due to flow. The turbulence in the flow is the primary cause of vibrations in the tubes. In this study, a tube positioned in the third row of the tube bundle was considered to determine the vibrational response of the heat exchanger tubes. The tube bundle was parallelly arranged in a triangular (60°) configuration having a pitch to diameter (P/D) ratio of 1.44. The internal tube flow velocity ranges from 0 to 0.371 m/s and the shell side velocity ranges from 0.5 m/s to 2 m/s. The experimentation shows that the amplitude of vibration without flow inside the tube is less as compared to the amplitude with the flow. Furthermore, as the velocity of internal tube flow escalates; the amplitude of tube vibrations tends to escalate as well even when the shell side flow velocity is kept constant. The data points from experiments tend to reside in the unstable region of the stability map and particularly on the map’s left side, although the tube shows stable vibration behaviour as confirmed by the experimental results. Thus, further, development can be done by modifying the theoretical models to predict the realistic stability behaviour of tubes with internal tube flow.