For the past several years, USC has been involved in a major research project to study the seismic mitigation measures of nonstructural components in hospitals funded by the Federal Emergency Management Agency (FEMA). It was determined that piping was the one of the most critical components affecting the functionality of a hospital following an earthquake. Consequently, a substantial effort was spent on quantifying the behavior of typical piping components. During the loading of the threaded joint, it was common to hear a loud popping sound, followed by a small water leak. It was assumed that the sound and leakage were due to the sliding of the mating pipe threads. To confirm this theory, and to provide a tool to help understand the failure mode(s) for a wide class of threaded fittings, a detailed nonlinear finite element model was constructed using MSC/NASTRAN, and correlated to the measured failures. In this paper, a simplified model is presented first to demonstrate the modeling procedure and to help understand the sliding phenomenon. Next, a symmetric half 3D model was generated for modeling the physical experiments. It is shown that the finite element analysis (FEA) of the threaded connections captures the dominant mechanism that was observed in the experimental tests.