Valves are devices used to control, regulate and open/close the flow and/or the pressure of a pipeline and/or a piping system. Valves are extremely critical and expensive components and one of the determining factors of pipelines reliability, safety, and performance. There are many different types of valves, most often used in combination, which perform specific functions within the piping system or the pipeline. Thousands of possible valve specifications are possible, originating from the combinations of multiple parameters such as valve type, subtype, size (bore size and class), manufacturing norm (main ones are ANSI/ASME and EN/DIN), body and trim materials, type of valve operation (manual or actuated), etc. “>In terms of valve body construction, valves are classified in cast and forged type (forged bodies are used for valves below 2 inch. or for larger valves that require specific mechanical performance). Finally, valves may be operated manually (levers, wheels, gears) or via an automated actuator (the main types of actuators are: electric, pneumatic, hydraulic and gas over oil).

The main type of valves used in the petrochemical and oil & gas industry are the following:
• Gate (API 600 cast gate, API 602 forged, API 603 cast stainless steel gate, API 6D expanding gate, API 6D slab gate, knife gate, pressure seal gate, etc.)
• Globe (BS 1873 cast globe valve, API 603 stainless steel globe, API 602 forged globe valve, y-globe, pressure seal globe)
• Check (swing check, piston check, ball check, spring check, pressure seal check, etc.)
• Ball (floating, trunnion)
• Butterfly (concentric, double eccentric, triple eccentric)
• Strainers (Y-shape, T-shape or basket strainers)
• Plug (API 6A plug, API 6D plug)
• Pinch
• Pressure relief/safety valve
• Diaphragm
• Control valves (ball, butterfly, and globe type)
• Cryogenic valves “> (used when the operating temperature falls below 100° F – 73° C).
• Actuator Valves
• Axial Flow valve
• DBBV- Double block and bleed valve
• Ball Valves
• Butterfly Valves
• Check Valves
• Control Valves
• Cryogenic Valves
• Rising stem ball valve
• Gate Valves
• Globe Valves
• Instrumentation Valves
• Needle Valve
• Plug Valve
• Solenoid Valve