Axial Strength of Tube-to-Tubesheet Joints: Finite Element and Experimental Evaluations

Abstract

Because of their importance for the integrity of heat exchangers, the strength of tube-to-tubesheet joints, and particularly their axial strength, is of special interest. A finite element model of an expanded tube-to-tubesheet joint is proposed and examined experimentally with the objective of determining numerically its axial strength. Simplified analytical methods that were previously proposed by many authors to predict the joint axial strength are also used in this investigation. Experimental testing shows that the finite element model is highly accurate for calculating the joint axial strength. The experimental investigation also proves that the pull-out strength is overestimated when calculated using a simple analytical solution. A parametric analysis using the finite element results indicates that the pull-out force is normally lower than the push-out load and that both are lower than the estimations of the analytical solution. The results indicate that the pull-out force as given by the finite element model is generally 35 percent lower than that evaluated by the analytical solution. A difference of as much as 10 percent is also found between the push-out and pull-out loads.