A theoretical and experimental investigation of stress and stiffness coefficients for low entry nozzles in bulk liquid cylindrical storage tanks

The finite element method has been used to conduct a parametric study of the variation in nozzle/tank stiffness and stress at the nozzle/tank junction for a range of tank radii, R, wall thicknesses, t, and nozzle radii, a, at a centre-line height of 1·2 times the nozzle diameter above the foundation. The range of analytical results covered is $\text{R}\text{t}\text{= 500}$ to 2000 and $\text{a}\text{R}\text{= 0·01}$ to 0·04. In support of the analytical work, a series of experiments have been conducted to validate the results.Nozzle stiffness coefficients are presented for use in piping analyses, which avoids having to treat the tank as a rigid anchor. Non-dimensional stress coefficients are plotted in a similar form to WRC 107.¹ Additional equations have been derived to determine nozzle rotation due to static head of liquid, temperature change and annular plate moment.