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Performs required nozzle calculations for shell type heat exchanger nozzles.
The HEI Standard evaluates the allowable loads on shell type heat exchanger nozzles.
Section 3.14 of the HEI bulletin discusses the computational methods used to compute these allowable loads. The method employed by HEI is a simplification of the WRC 107 method, where the allowable loads have been linearized to show the relationship between the maximum permitted radial force and the maximum permitted moment vector.
If this relationship is plotted (using the moments as the abscissa and the forces as the ordinate), a straight line can be drawn between the maximum permitted force and the maximum permitted moment vector, forming a triangle with the axes. For any set of applied forces and moments, the nozzle passes if the location of these loads falls inside the triangle. Conversely, the nozzle fails if the location of the loads falls outside the triangle.
Because the pressure is greater than zero, the software calculates a pressure thrust
force and combined it with the radial force modified to include both the plot of the
allowables and the location of the current load set on this plot. The HEI bulletin
states that the effect of internal pressure has been included in the combined stresses;
however, the effect of the pressure on the nozzle thrust has not. This requires combination
with the other radial loads. CodeCalc automatically computes the pressure thrust and adds it to the radial force if you
selected Add Pressure Thrust on the HEI Nozzle tab.