Introduction. The finite element method is often used to shape the design geometries of pipes and fittings. Analysis studies made with different types of fasteners have been investigated in the literature. It has been observed that the studies related to the pliable pipe connections commonly used in in-building installations are lacking. No study has been conducted on the flow analysis of the fasteners used in the transition from metal pipes to plastic pipes. Material and methods. The 32 series set necklace provides fluid flow between the metal pipe and the plastic pipe. The assembly model has been designed using the Solid Works program. Surface stresses due to cavitations are calculated in the fluid analysis Flow Simulation module. These values were chosen as the pressure acting on the static analysis module. Results. In the water network system, the transition from metal pipe to plastic pipe has been investigated. Internal pressure changes and cavitations were calculated. The effect of this fluid's pressure changes on the surfaces of the assembly design parts has been investigated. Conclusions. Quantities and safety coefficients of plastic pipe, metal pipe, connecting bolt, rear cap and frontal mask were calculated. In the literature, the internal pressure changes which are not included in the static analysis are calculated by this study and the effect on the results is examined.