valving

Valving refers to the use of valves to regulate, direct, or control the flow of fluids in piping systems, engines, and hydraulic and pneumatic circuits. A valve typically consists of a housing that contains a movable element such as a plug, disk, or ball which opens or closes against a seat to restrict flow. Valves can be operated manually or powered by electric, pneumatic, or hydraulic actuators, and they serve roles in isolation, throttling, or backflow prevention.

Common valve types include gate valves, globe valves, ball valves, butterfly valves, check valves, needle valves, and diaphragm valves. Gate valves provide low flow resistance and are suited to full-open or full-closed service. Globe valves offer precise throttling and control. Ball and butterfly valves provide fast shut-off and compact designs for larger lines. Check valves prevent reverse flow, while needle valves allow fine control of small flow rates. Diaphragm valves handle corrosive fluids or slurries and offer gentle flow control. Control valves, equipped with actuators and positioners, are used in automated process control to modulate flow in response to signals.

Sizing and selection depend on fluid properties, pressure and temperature, desired flow rate, and allowable pressure drop. Engineers consider materials of construction, leakage class, and seat design, often using flow coefficients (Cv or Kv) to compare performance. Installation requires appropriate orientation, support, and compatibility with upstream and downstream equipment. Maintenance includes inspecting seals and packing, lubricating stems, replacing seats or discs as needed, and testing actuators and positioners to ensure reliable operation.

Valving spans mechanical, chemical, and process industries, forming a foundational element of fluid control and automation systems.