Valves : Principles , Operation & Designs

Explore valve designs, components, and operation across petroleum, refining, petrochemical, and power industries, with 3d graphics, including dismantling and assembling valves, actuators, control valves, head loss, and cavitation.

Explore valve components, principles of operation, and how they regulate fluid flow, with three-dimensional animations, cross-sectional views, and engineering drawings such as piping and instrumentation diagrams, plus a valve catalog.

Learn how a valve controls fluid flow and pressure through stopping, starting, and varying flow, and review its basic parts: body, bonnet, trim, actuator, packing, gate valve cross section.

The valve body, or shell, is the primary pressure boundary and framework that supports piping connections, partitions for the seat opening, and the throttling orifice, often with a bonnet.

The valve bonnet covers the opening in the valve body, may support internals such as the stem, disc, and actuator, and forms the second pressure boundary.

Explore valve trim, including disc, seat, stem, and sleeve, and how the disk-seat interface and disc position govern flow; compare rotational and linear trim designs and their flow changes.

Explore how valve discs act as pressure-retaining boundaries that regulate flow, with forged hard-faced discs, and seating surfaces or seal rings that ensure sealing when closed.

The stem connects the actuator to the valve disk, positions the disk, and may be rising or non rising, with threaded or welded joints and packing near the seal.

Explore the principles and operation of valve actuators, including manual hand wheel, motor operator, solenoid operator, pneumatic operator, and hydraulic operator. Note bonnet or yoke supports and boundary placement.

Learn how valve packing seals the stem against the bonnet, using flax or teflon, and how to replace and properly compress the packing to prevent leaks.

Explore valve types such as globe, gate, butterfly, diaphragm, pinch, plug, and safety valves, and the four flow-control methods used to meet varied applications.

Explore how flow control adapts to system fluids and conditions, compare valve designs, and learn to identify valve types and describe their main applications and functions in design and operation.

Gate valves start or stop flow with a disk seal, offering 360-degree sealing when closed and minimal flow resistance when open, but they are not suitable for throttling.

A 3-d dismantling guide for a rising stem gate valve, detailing steps to unscrew gland nuts, remove packing, bonnet nuts, valve body, stem, gland, hand wheel, and bonnet.

Explore gate valve disc designs, including solid, flexible, split, and parallel discs, their replaceable seats, and how each type prevents binding and handles thermal expansion and erosion in steam systems.

Explain gate valve stem design, comparing non rising stems that stay within packing and rising stems that lift out of the flow path, including bonnet-threaded and through-hand-wheel variants.

Explore gate valve seat designs, comparing integral seats with seat rings threaded, pressed, or welded to the body, noting welded seats for high temperatures and hard-faced rings for steam services.

Explore globe valves, a linear motion valve used to stop, start, and regulate flow. See how disc-seat perpendicular motion enables throttling with high head loss.

demonstrates three-dimensional dismantling of a globe valve, guiding step-by-step from unscrewing gland and bonnet nuts to removing the valve body, disc, stem, gland, and bonnet.

Dismantle a globe valve using two 2D cross sectional views by unscrewing gland nuts, removing packing and bonnet, then rotating the disc and stem clockwise to slide out components.

Explore the z-body globe valve design, the simplest, most common for water applications, featuring a z-shaped diaphragm and a horizontal, right-angle stem and disk that simplify manufacturing, installation, and repair.

Wide body globe valves remedy high pressure drops with a 45-degree seat and stem that provide a straight flow path at full opening, ideal for high pressure and severe services.

Explore the angled body globe valve, a simple modification that enables a single ninety degree flow turn and both valve and piping elbow functions, illustrated by a 3D animation.

Explain how globe valves use three disk designs: ball, composition, and plug, to control flow, resist erosion in steam or hot water, and enable throttling with various configurations.

Explore globe valves by examining two disk-to-stem connections: tea slot construction and disc nut construction, including how the disk slips over the stem or is screwed into it.

Explore globe valve seat design, including integral or screwed seats and back seats, and how back seats seal the stem to bonnet to prevent pressure from bending the packing.

Globe valves guide pressure under the disk for low-temperature service, easing operation and protecting packing. In high-temperature steam, position pressure above the disk to direct flow and prevent stem contraction.

Ball valves are rotational motion valves using a spherical plug to start and stop flow; turning the handle aligns the hole with the inlet and outlet to open.

Identify ball valve components—body, spherical plug, seats, spindle, and handle—and how a quarter-turn closes flow. Compare venturi port, full port, and reduced port designs.

Dismantle a ball valve using a 3d model by removing the handle, unscrewing the spindle nuts and seal ring, then sliding out the bowl and spindle to reveal valve body.

Dismantle a ball valve using a 2d model by unscrewing the spindle nut, removing the seal ring, and then sliding out the bowl, spindle, and valve body.

Explore ball valve actuators, including quick acting designs requiring a 90-degree handle turn. Compare planetary gear actuators that use a small hand wheel to operate large valves with less force.

Highlight ball valves' low cost, low maintenance, quick quarter-turn operation, compact design, and tight sealing with low torque, while noting poor throttling and erosion risk at high velocity.

Compare ball valve port patterns, recognizing reduced port and full port designs. Note that the full port design has a bore equal to the pipe inside diameter.

Analyze cross section of a ball valve in the open position, where the ball plug hole aligns with inlet and outlet, and the stem rotates the ball via bowl slot.

Learn how ball valves open and close with a 90-degree rotation, with or without stops, and how handle position or groove markings indicate the flow path.

Explore plug valves that start or stop fluid flow, using a solid plug with a right-angle passage that aligns with ports when open and blocks flow at 90 degrees.

Inspect a simplified plug valve model, identify components—the lubricant screw, gland cover, gland packing, plug, and body—and show how handle position—90 degrees to close, along the axis open—controls flow.

Dismantle a plug valve using a simplified 3D model, removing the handle, gland nuts and cover, packing, bolts, cover, body, and finally the valve plug.

Demonstrates a simplified 2d dismantling of a plug valve, guiding the step-by-step removal of gland nuts, gland cover, pecking, cover nuts, cover, stem plug assembly, and valve body.

Explore plug valves in lubricated and non lubricated designs, with a variety of port opening styles and plug configurations. The lecture previews detailed exploration in the upcoming videos.

Explore plug valve designs, including rectangular, round, and diamond port plugs, and learn how port size defines full port, standard round port, and throttling via Venturi restricted flow.

Explore three- and four-port multiport plug valves for transfer lines and fluid diverting services, noting advantages, incomplete shutoff risk, and the need for proper port arrangements or secondary valve.

Explore the lubricated design of plug valves, where the lubricant acts as a plastic sealant, creating a hydraulic jacking action that ensures positive sealing and easy turning.

Explore non-lubricated plug valves, including lift type and elastomer sleeve designs, with external lever or cam actuation, PTFE sleeves, and a durable, low-friction, self-lubricating seal.

Explore the plug valve internals and gland designs—single, screwed, and bolted—that secure the stem to the body and keep the plug seated without over-tightening.

The diaphragm valve is a linear motion valve used to start, regulate, and stop flow, with a flexible diaphragm isolating the fluid and enabling leakage-free, moderate throttling, low-pressure service.

Dismantle a diaphragm valve with a simplified 3D model, removing the bonnet and body. Unscrew the diaphragm from the stem, then rotate the hand wheel to release the compressing stem.

Demonstrate dismantling a diaphragm valve with a 2D model, detailing unscrewing the bonnet, detaching the diaphragm from the stem, and removing the compressing stem and related parts.

Compare straight-through and weir diaphragm valves, showing how the compressor stem lowers to seal the diaphragm against the body or contoured bottom, for corrosive fluids and slurries, and throttling.

Learn diaphragm valve construction, where the diaphragm shields the operating mechanism from the fluid, preventing contamination and enabling high-temperature, chemically resistant operation with elastomeric materials under suitable limits.

Diaphragm valves use a quick opening bonnet and lever operator. The bonnet is interchangeable with standard bonnets on wear-type bodies and sealed evacuated bonnets protect in vacuum service.

Explore pinch valves, offering simple throttling from 10% to 95% of flow, with an externally operated, isolated mechanism, rubber sleeves, and clamp or flange configurations for slurries and corrosion-sensitive fluids.

Examine pinch valves with molded, fabric-reinforced bodies and sleeves; learn 250 degrees Fahrenheit limits and the pressure range from 100 to 15 per square inch, plus wheel-screw and pneumatic actuation.

Explore how butterfly valves operate as rotary motion valves, stopping, starting, and regulating flow with a 90-degree handle turn that moves a disc from fully closed to fully open.

The diagram shows butterfly valve seat design, where the disc seals against a seat to stop flow, using elastomeric seals or seal rings and a backing ring to prevent extrusion.

Explore how butterfly valves secure the disk to the stem—via bolts or pins or a squared/hex stem for a floating disk—ensuring uniform sealing in corrosive applications.

The needle valve enables fine flow adjustments with a long tapered needle acting as the disc, allowing gradual throttling of the opening and serving as a component in other valves.

Learn to dismantle a needle valve with a simplified 3D model: unscrew the nut, remove the handle and gland, and slide out the valve stem.

Explore how needle valves in constant pressure pump governors minimize fluctuations in pump discharge pressure. See how they enable very precise flow regulation in automatic combustion control systems.

Explore bar stock and bostock body designs for needle valves, and note how a stem-seating ball enables precise rotation for metering, with a 40 threads-per-inch stem for fine linear flow.

Explain how needle valves use two stem packing styles: an o-ring with ptfe backing rings or a toffee packing cylinder, and highlight replaceable seats for easy maintenance.

Check valves prevent backflow in piping by opening with forward flow and closing against reverse flow, using weight, back pressure, or springs; types include swing and tilting disc check valves.

Learn how swing check valves allow flow and automatically close to prevent backflow as pressure falls. Explore internals, seating options, and straight vs Y-pattern designs.

Dismantle a swing check valve using a simplified 3D model by removing the cap nuts, cap, disk hinge pin, disk hinge disk assembly, and seat.

Dismantle a swing check valve using a simplified 2D model, outlining steps to unscrew the cabinet, remove the cap, disk hinge pin, disk hinge disk assembly, and seat.

Tilting disk check valves offer low fluid resistance and turbulence with an airfoil design and straight-through flow, opening when the disk lifts from the seat and sealing before reverse flow.

Explore lift check valves used with globe valves for flow control in horizontal and vertical lines, suitable for gas, water, and high-velocity vapor lines, with internal components and operation explained.

Dismantle a lift check valve with a simplified 3D model, unscrew cap nuts, remove the cap guide assembly, then extract the disk and the valve body with the seed ring.

Dismantle a lift check valve in a simplified 2d model by unscrewing cap nuts, removing the cap guard, and sliding out the disk, revealing a grey body and pink component.

Explore the piston check valve, a dashpot‑cushioned lift valve with a piston and cylinder, its installation and flow characteristics mirroring lift valves in water, steam, and air systems.

Understand butterfly check valves, with a disc that moves freely inside a bore to reduce slamming. Learn the internal assembly—clamp plate, hinge clamp, hinge post—and ventilation and air conditioning applications.

Examine the stop check valve, a blend of lift check and globe valves, with a stem that seals the seat and limits the disc travel when opened.

Relieve over pressurization in systems; relief valves gradually open above the set point for incompressible fluids, while safety valves rapidly vent and reset below the set point for compressible fluids.

Understand a safety valve’s pop action as a pressure relief valve actuated by inlet static pressure, used with compressible fluids like steam and air, and the role of blowdown rings.

Explain the three safety valve pressures—set pressure, overpressure, and reset pressure—and how blowdown is the difference between actuating and reset pressures, with overpressure ranges 3–10% (compressible) and 10–25% (incompressible).

Dismantle a safety valve using a simplified 3d model, removing the wire, cap, spring, bonnet, disk assembly, blowdown rings, and finally the valve body.

Dismantle a safety valve using a simplified 2D model by removing the seal wire, rotating the cap and spring adjuster counterclockwise, and disassembling the blowdown rings, nozzle, and the valve body.

Explain how a pressure relief valve opens gradually as inlet pressure rises above the set point to relieve excess pressure in liquid systems, unlike safety valves that pop fully open.

Observe a 2D cross-sectional view of a relief valve. When pressure exceeds the set point, the disk lifts to relieve excess pressure and maintains constant pressure, closing as pressure falls.

Dismantle a pressure relief valve using a simplified 3D model, removing the seal wire, unscrewing the cap and spring adjuster, and extracting the disk, stem, and spring.

Dismantle a simplified two-dimensional relief valve model by removing the seal wire, turning the cap counterclockwise, unscrewing the locking pin, removing the inlet connection, then the disk, stem, and spring.

Throttle the flow of a fluid using a controller signal to regulate process conditions such as temperature, pressure, or level in a pneumatic control valve.

Explore control valves trim arrangements, including single port and double port designs, their effects on unbalanced force, stem expansion and seating wear, and tight shutoff under high temperature fluids.

Examine the direction of action in control valves, contrasting air to close with air to open, including direct acting and reverse acting, and how emergency considerations guide the choice.

Dismantle a plug-type control valve using a simplified 3d model, detailing the step-by-step removal of packing, diaphragm, spring, yoke bonnet, and stem to expose the valve body.

Disassemble a plug valve with a diaphragm actuator using a simplified 3D model, unscrewing the packing adjuster and removing components down to the valve body.

Identify construction details and operating principles for manual, electric motor, pneumatic, and hydraulic valve actuators.

Explore torque and the need for automatic actuation in valve actuator selection. Review manual and automatic options, including hand wheel, lever, electrical motor, pneumatic solenoid, hydraulic piston, and self actuated.

Operate valves manually with hand wheel actuators and gear heads on the valve bonnet; use pinion shafts or portable air motors to speed operation and reduce binding in high temperatures.

Enable manual, semi-automatic and automatic valve operation with electric motor actuators, including open/close and precise positioning through a reversible high-speed motor, gear train, handrail engagement, and limit switches.

Pneumatic actuators use air or nitrogen pressure to power linear and quarter-turn valves, producing linear force or rotary motion. Explore single acting, double acting, fail open/closed configurations, and simple conversions.

Examine a single acting spring return actuator for a quarter-turn butterfly valve, detailing its body, position indicator, springs, and two pistons, with gas pressure driving torque and returning the valve.

Explore single acting spring-return actuators, featuring a piston, piston rod, yoke, and position indicator, where gas pressure rotates the valve and the spring returns it when pressure drops.

Explore how a springless double acting pneumatic actuator uses gas pressure on both sides of the piston to move the valve open or closed, with fail‑as‑is behavior.

Explore double acting actuators with two cylinders and pistons, where gas on both sides moves the valve to open or closed positions, with a fail-safe preserving position on gas failure.

Convert a single acting actuator to a double acting actuator by removing the spring and applying gas pressure on both sides of the piston to open and close the valve.

Demonstrates converting a fail closed single-acting spring-return actuator to fail open by rotating 180 degrees, reversing the spring action to open the valve when gas supply is absent.

Convert a fail closed rack and pinion actuator to fail open by reversing pistons and reassembling springs, enabling air pressure to open the valve on failure.

Compare rack and pinion and scotch yoke pneumatic actuators, highlighting torque profiles, cycle times, and cost; explain suitability for throttling, valve types, and fail open/closed configurations.

Hydraulic actuators position valves automatically or semi-automatically with a piston that converts signal pressure into valve stem motion, using oil or water as hydraulic fluid directed by solenoid valves.

Use the system fluid to position self-actuated valves, including relief valves, safety valves, and check valves that rely on fluid energy.

Select valve actuation based on safety, speed, energy to achieve fast isolation or slow opening by adjusting orifices, gear ratios, or spring pressure, using hydraulic, pneumatic, or electric actuators.

Explore remote and local valve position indications for field and control room operators, using lights to indicate open or closed states. Learn rising stem indicators reveal position when lights fail.

Explore valve types, components, operation, and virtual hands-on demos, then learn design calculations, head loss, pressure drop, and cavitation; finally study valve symbols, standards, and failure modes in P&IDs.

Explore the theory and formulas for pipe flow and valve and fitting resistance to calculate pressure drops using charts, diagrams, and the Flow of Fluids Excel workbook.

Classify valve designs by resistance to flow, from straight-through paths like gate, ball, plug, and butterfly valves to globe and angle valves with higher resistance.

Learn about branching, reducing, expanding, and deflecting fittings in piping systems, including tees, crosses, elbows, reducers and bushings, noting that couplings and unions are not covered.

Analyze how valves and fittings disturb flow, causing turbulence and extra pressure drop beyond a straight pipe, quantified by resistance coefficients (k) and delta p components.

Explain how pressure drop through valves scales with velocity in the turbulent zone, typically as the square of velocity, and the role of minimum lift velocity for full disc opening.

Explore how pressure-drop data for valves and fittings characterizes resistance using equivalent length, resistance coefficient, and flow coefficient. Emphasize using manufacturer data for calculations when available, extrapolate data when incomplete.

Head loss in piping systems results from flow path changes, obstructions, changes, and friction from surface roughness and fluid properties, with hydraulic resistance treated as a constant under non-laminar conditions.

Learn to determine valve and fitting hydraulic resistance via the equivalent length L/D and compute total head loss using the Darcy equation with Reynolds number and friction factor.

Explore Bernoulli energy components, including velocity head, in piping; examine valve head loss and the pressure drops they cause, and the resistance coefficient K equal to friction factor times L/d.

Calculate the overall pressure drop in a piping system by summing resistance coefficients in series. For parallel components, sum the inverse square roots of the resistances.

Explain the flow coefficient Cv and its Kv equivalent, defined as water flow in gpm at 60°F and 1 psi, and its use for valve capacity and strainers, nozzles, sprinklers.

Use the flow coefficient CV to determine the hydraulic performance of valve fittings and fixed-resistance piping components. Compute equivalent CV from flow rate and differential pressure to predict pressure drops.

Compute the equivalent total flow coefficient Cv to assess hydraulic performance of multiple piping components in series or parallel. In parallel, sum Cv values, while series requires a separate calculation.

Explore valves with reduced seats and venturi-style gradual transitions, and learn to calculate their resistance coefficients using the flow of fluids Excel workbook in the practice session.

Determine valve resistance coefficients using the Flow of Fluids Excel workbook, featuring a swing check valve example that selects pipe size and yields K = 1.8 for 3 inch diameter.

Apply the Darcy formula to calculate the flow rate (Q) of liquids through valves, fittings, and pipe, using the resistance coefficient K and accounting for entrance and exit losses.

Explore the flow of fluids with the Flow of Fluids Excel Workbook, a VBA tool that simulates small piping systems and calculates pressure drops, pipe sizes, and flow meters.

Discover control valve components and operation, including actuators and diaphragms, to throttle flow and control level, pressure, and temperature, and learn sizing and selection for compressible and incompressible fluids.

Explore valve components, including the actuator and valve body with internal trim, seat, plug, and stem, and learn how trim design shapes capacity, noise reduction, and cavitation control.

Explain how the inherent characteristic curve links valve position to flow coefficient CV, measured with 60°F water at 1 psi differential, across quick opening, linear, and equal percentage curves.

Describe how the installed characteristic curve plots valve position against percent maximum flow in real piping and shifts up and left from the inherent curve due to differential pressure.

Examine pressure, velocity, and energy profiles through a control valve, peak velocity at the vena contracta, Bernoulli conversion, and the liquid pressure recovery factor with CV data.

Explain cavitation in valves: vapor bubbles form at the vena contracta when downstream pressure drops below vapor pressure, implode, and cause erosion, noise, and deviations with choking or flashing risks.

Size and select a control valve by specifying flow rate, system pressure, and fluid properties, then compute the flow coefficient and iteratively adjust it using appropriate incompressible or compressible equations.

Learn to size valves for compressible flow using expansion factor Y, critical pressure drop ratio X_T, and choked flow conditions, considering density and vena contracta changes.

Convert the cv to kv using the equation which is used by European valve manufacturers.

Master valve symbology to read fluid system diagrams, identifying valve types like gate, ball, butterfly, operators, line types, instrumentation, and equipment such as pumps and heat exchangers.

Explore valve symbols, including gate, globe, ball, needle, butterfly, plug, diaphragm, and three-way and four-way valves, and learn how open or closed states are shown by white or black fills.

Learn how valve actuators add remote control capabilities to valve bodies, including diaphragm, electric motor, solenoid, and piston actuators, and how these integrate with control valves and positioners.

Explore how control valve designations use a balloon labeling system to identify the parameter controlled (flow, temperature, level, pressure), and indicate a controller and valve.

Learn valve status conventions, identify normal and standby positions, and interpret fails open, fails closed, and fails as is, with key symbols for actuated and three way valves.

Explore the principles, operation, and designs of valves included in this course.