This project involves the comprehensive 3D modeling and parametric design of various mechanical components using Siemens UG NX (Unigraphics NX) CAD software. The key objective is to create accurate, industry-standard models of critical components used in thermal and mechanical systems. The project covers the following categories: 1. Heat Exchangers Design of shell-and-tube and plate-type heat exchangers. Modeling includes baffles, tubes, headers, and shell assemblies. 2. Pressure Vessels 3D modeling of vertical and horizontal pressure vessels based on ASME standards. Includes flanges, nozzles, manholes, supports, and internal component 3. Machine Components and Subassemblies Design of shafts, bearings, gears, cams, and housing units. Subassembly modeling and constraint-based assembly techniques used.