This study analyzes low, medium, and high-pressure fittings in hydraulic and pneumatic systems, highlighting their main components, materials, and performance under extreme conditions. Stainless steel 316 fittings were tested, with emphasis on double ferrule models for low pressure (up to 15,000 psi) and conical and threaded fittings for medium and high pressure (up to 150,000 psi). Hydrostatic tests indicated that lowpressure fittings failed at 37,000 psi, while medium and high- pressure fittings withstood over 75,000 psi without failures. It is concluded that selecting the appropriate fitting depends on the pressure class, fluid type, and application, making it essential to strictly follow assembly specifications. Future investigations into collapse pressures are suggested, as this gap was identified in the consulted catalogs.