| Experimental and numerical investigations are carried out to study the effect of weld parameters on the temperature-time history at the back of a tubesheet (adjacent to the gasket) of a shell-and-tube heat exchanger. Experiments are conducted for a carbon steel tubesheet as a base case for weld of 20 second, weld temperature 700°C, tubesheet diameter, 0.375 m, and tubesheet thickness of 0.025 m to validate the predictions of numerical model. The predictions obtained for the base case agreed very well with experimental results. Parametric studies were carried out using the model developed. These parameters including: weld duration (20 to 40 seconds), weld temperature (ranging from 700°C to 1500°C), tubesheet size (0.375 m ≤ diameter ≤ 1.5 m, and 0.025 m ≤ thickness ≤ 0.038 m), tubesheet material and sequence of welding. The results indicate that the weld duration has a significant effect on the magnitude of the maximum temperature at the back surface of the tubesheet adjacent to the gasket. Doubling the weld duration increases the maximum temperature by more than 40%. The results indicate that the weld temperature has a significant effect on the value of the peak temperature adjacent to the gasket by more than 90%. A reduction of more than 65% is observed for the value of the peak temperature at the back of the tubesheet adjacent to gasket by using stainless steel tubesheet material. Increasing the diameter and the thickness of the tubesheet results in temperature reduction at the back of the tubesheet near the gasket. An increase of more than 20% in the peak value of temperature at the back of tubesheet near the gasket is predicted for five consecutive welds with time gap of 10 seconds, whereas, welding of tubes with scattered arrangement (diagonally opposite) give the least value of peak temperature. |
