Industrial Valve Types Overview: Working Principles, Structures, Applications & Standards

1. Working Principles of Industrial Valves

What Defines an Industrial Valve’s Working Principle

An industrial valve is a mechanical device that controls the passage of a fluid — gas, liquid, steam, or multiphase mixture — through a piping system by altering the geometry of the internal flow path. Every valve, regardless of type, executes this function through the same fundamental mechanical sequence: an external input (manual, pneumatic, electric, or hydraulic) displaces a closure element within the valve body, changing the effective flow area between the inlet and outlet ports. The fluid responds to this change in geometry through the governing relationship between flow area, velocity, and pressure — described by Bernoulli’s principle and the continuity equation. When the flow area is reduced, fluid velocity increases and pressure drops; when the flow area is increased, velocity decreases and pressure is recovered. The valve’s design determines how precisely, repeatably, and durably it can control this relationship across the full range of operating conditions it will encounter in service. For a complete industrial valve type breakdown, see the Industrial Valve Types Overview page.

The working principle of a specific valve type is inseparable from the geometry of its closure element. A spherical ball — as in the Ball Valve — rotates 90° to align or block a through-bore, providing a binary open/closed action with a Cv that approaches the equivalent pipe section when fully open. A flat or wedge gate — as in the Gate Valve — translates perpendicular to the flow axis, retracting completely out of the flow path in the open position and providing true full-bore passage. A conical or parabolic plug — as in the Globe Valve — translates axially toward or away from a circular seat, providing a continuously variable, inherently stable throttling characteristic across its full travel range.

Classification by Operating Mechanism

Industrial valves are classified by their closure element’s motion type into two primary mechanical categories: linear motion and rotary motion. Understanding this classification is fundamental to predicting a valve’s flow characteristic, actuation torque or thrust requirement, and response speed:

Linear motion valves — gate, globe, and needle valves — translate the closure element along the flow axis or perpendicular to it. Linear motion provides inherently fine positional resolution across the full stroke (multi-turn stem rotation translates to small linear displacement per turn), making these designs well-suited to throttling and precision flow adjustment applications. However, linear motion requires multi-turn actuation — typically 5 to 30 full stem rotations to travel from fully closed to fully open — which produces slower response time than quarter-turn rotary designs for the same actuator power.
Rotary motion valves — ball, butterfly, and plug valves — rotate the closure element about a fixed axis. The 90° quarter-turn from fully closed to fully open provides fast response: a typical pneumatically actuated quarter-turn ball valve completes a full open-to-close stroke in 1–3 seconds, compared to 15–60 seconds for an equivalently actuated multi-turn gate valve. The Check Valve occupies a distinct classification: it is self-actuating, responding to the direction and magnitude of fluid flow rather than external actuation. The disc, flap, or piston closure element opens under forward flow and closes under reverse flow — the closing speed (and resulting water hammer severity) depends on the valve geometry and the spring pre-load on spring-loaded designs.
Butterfly valve operating mechanism — the Butterfly Valve occupies a distinct position within the rotary category: its disc rotates about a diametrical axis that lies within the flow path, meaning the disc remains partially in the flow stream even when fully open. This produces higher fully-open pressure drop than a ball valve of equivalent bore, but enables extremely compact face-to-face dimensions and low weight for large bore sizes — a significant advantage for large-diameter low-pressure applications.

The operating mechanism directly determines the valve’s flow characteristic — the relationship between closure element position and Cv. Quarter-turn ball valves have a near-step function (near-zero Cv for the first 15–20° of opening, then rapid increase to maximum Cv) that is inherently unsuitable for precise throttling. V-port characterized ball valves modify this characteristic through ball geometry. Globe valves provide an inherently smooth, nearly linear Cv-versus-stroke curve that is predictable and stable across the full control range.

Common Operating Modes

The operating mode — the mechanism by which the closure element is actuated — is determined by the valve’s function, frequency of operation, required response time, fail-safe requirements, and installation environment:

Manual actuation: Handwheel (multi-turn for gate and globe valves), lever (quarter-turn for ball and plug valves), and gear operator (for large-bore or high-torque applications that exceed comfortable manual effort). Manual actuation is appropriate for infrequently operated valves in accessible locations where response time is not safety-critical. The Plug Valve is commonly manually actuated in small and medium bore sizes by a lever or wrench on the plug stem, providing visual open/closed indication from the lever position relative to the pipe axis.
Pneumatic actuation: Spring-and-diaphragm, spring-return piston, or double-acting piston pneumatic actuators provide fast response (1–10 seconds for typical industrial valve sizes) and inherent fail-safe capability — spring-return designs fail open or fail closed on loss of instrument air supply, a critical safety function for Emergency Shutdown (ESD) valves. Pneumatic actuation is the dominant choice for automated on-off and control valves in process plants where instrument air is available.
Electric actuation: Multi-turn electric motor actuators (for gate and globe valves) and quarter-turn electric actuators (for ball and butterfly valves) provide high output torque, precise positional control, and full diagnostic feedback capability — including partial stroke testing for ESD valve functional safety verification per IEC 61511. Electric actuation is preferred in offshore and remote locations where instrument air supply is not available, and for modulating control applications requiring continuous position feedback.
Hydraulic actuation: Hydraulic scotch yoke or piston actuators provide the highest output torque for a given actuator size and weight — making them the preferred choice for very large bore trunnion-mounted ball valves (above 24 inches at Class 900 and above) where pneumatic actuators would require excessively large cylinder diameters. Needle Valve applications in instrument tubing are exclusively manually actuated — their fine-thread stem and small port area make pneumatic actuation impractical for the low-force precision adjustment that is their defining characteristic.

2. Structural Anatomy of Industrial Valve Types

Core Structural Elements Shared Across Types

Every industrial valve — regardless of type, size, or pressure class — is comprised of the same set of fundamental structural elements. Understanding these elements and their engineering functions provides the basis for understanding type-specific structural variations:

Valve body: The primary pressure boundary component — the outer casing that contains all internal valve components and the process fluid. The body provides the structural envelope that must contain the design pressure at the design temperature over the valve’s service life. Body wall thickness is governed by the applicable design standard (ASME B16.34 for most industrial valves; API 6D for pipeline service), which specifies minimum wall thickness as a function of bore size, pressure class, and body material group. Body material is selected based on the pressure-temperature rating requirement, fluid chemical compatibility, sour service hardness limits (NACE MR0175/ISO 15156 for H₂S service), and low-temperature impact toughness requirements. Common body materials include carbon steel (ASTM A216 WCB), low-alloy steel (WC6, WC9), austenitic stainless steel (CF8M, equivalent to 316SS), duplex stainless steel, and high-nickel alloys for severely corrosive service.
Bonnet: The secondary pressure boundary component — the upper closure of the valve body cavity through which the stem passes. The bonnet connects to the body either by bolting (bolted bonnet — the standard configuration for most industrial valves in Class 150 through Class 600), threading (screwed bonnet — limited to small bore, low-pressure service), or pressure-seal geometry (pressure-seal bonnet — used in Class 900 and above gate and globe valves, where the sealing force is generated by the line pressure acting on the bonnet ring, providing superior sealing performance at high pressure). The bonnet houses the stem packing — the dynamic seal between the stem and the bonnet bore that prevents process fluid leakage along the stem to atmosphere.
Closure element (trim): The moveable internal component that changes the flow geometry — the ball in a ball valve, the gate in a gate valve, the plug in a globe or needle valve, the disc in a butterfly or check valve. The closure element defines the valve type and its fundamental flow characteristic. In metallic valves, the closure element’s seating surface is precision-machined and typically hardened (Stellite overlay, Inconel overlay, or tungsten carbide coating) to resist the wear, erosion, and impact forces it experiences at each closure cycle.
Stem: The mechanical link between the actuator and the closure element. The stem transmits the actuator’s torque (for rotary closure elements) or thrust (for linear closure elements) to the closure element with adequate stiffness and strength. API 6D and ISO 17292 mandate blow-out proof stem design — the stem geometry must prevent the stem from being ejected from the valve body under internal pressure, even in the event of complete stem packing failure. This is achieved by a stem shoulder that is larger in diameter than the stem bore through the bonnet, so the stem can be retained by the bonnet even with no packing in place.
Seats and seals: The static and dynamic sealing components that prevent leakage in the closed valve (seats) and through the stem-bonnet interface (stem packing). Seat design — soft seat insert versus metal-to-metal hard-faced seat — is the single most consequential material selection within the valve and is governed by the temperature, pressure, fluid chemistry, and required leakage class of the service. Stem packing is typically flexible graphite (for high-temperature and general service) or PTFE/PEEK compound (for corrosive service or low operating torque requirements). The Ball Valve and Globe Valve represent the two primary seating geometry architectures in industrial service — pressure-energized seat contact in the ball valve, and mechanically-driven axial contact in the globe valve.
End connections: The interface between the valve and the pipeline — flanged (ASME B16.5 or B16.47 raised face, ring joint, or flat face), butt-welding (ASME B16.25), socket weld, or threaded (ASME B1.20.1 NPT). End connection type is determined by pipeline pressure class, piping material specification, and maintenance accessibility philosophy. Flanged connections allow valve removal from the line without cutting the pipe; butt-welding connections provide a leak-free permanent joint that is preferred for high-pressure, high-temperature, or corrosive services where flange face sealing reliability is a concern.

Type-Specific Structural Variations

While all valve types share the structural elements above, each type’s specific closure element geometry and body architecture produce distinct structural characteristics that define its functional capabilities and maintenance requirements:

Ball valve body architecture: The ball valve body must incorporate two opposing seat rings (upstream and downstream) precisely positioned to engage the spherical ball surface within close tolerances. In floating ball valves, the seats are spring-loaded to maintain contact with the ball under all operating conditions. In trunnion-mounted designs, the seats are spring-loaded and pressure-assisted, while the ball is held axially by trunnion bearings in the top and bottom of the body — a structural arrangement that transfers differential pressure thrust through the body casting rather than the seats. The body may be a single piece (one-piece, requiring end connections to be welded directly), two-piece (split at the equator of the ball for seat access), or three-piece (removable middle body section for in-line maintenance without pipe cutting). The Butterfly Valve body, by contrast, is minimal — just a short cylindrical ring (wafer), lug, or flanged body with the disc mounted on a central shaft — enabling face-to-face dimensions 3–5 times shorter than a ball or gate valve of equivalent bore.
Gate valve body architecture: The gate valve body is elongated along the flow axis to accommodate the full stroke of the gate — the gate must retract entirely out of the flow bore when open, requiring a bonnet cavity with height equal to at least the full bore diameter above the body flow channel. This produces the characteristic tall bonnet profile of gate valves that distinguishes them from all other valve types. The gate itself may be solid wedge (single-piece angled gate that compresses both seats simultaneously on closing), flexible wedge (solid gate with machined groove that allows slight flexibility to accommodate seat misalignment), split wedge (two-piece gate whose halves can self-align independently to each seat), or parallel slide (two parallel-face plates with a spreader mechanism — used for high-temperature steam service where thermal expansion causes binding in wedge designs).
Globe valve body architecture: The globe valve body directs flow through an S-curve path — inlet port at one level, an internal baffle with a circular seat port, and outlet port at the same or different level. The stem and plug travel axially through the bonnet, perpendicular to the seat face. This flow path geometry — with its change in direction — is the source of both the globe valve’s higher pressure drop (compared to ball or gate) and its inherently stable throttling characteristic. Globe valve body designs include the Z-body (standard, with inlet and outlet at the same height on opposite sides of a horizontal seat), the Y-body (angled at approximately 45°, with reduced pressure drop compared to Z-body), and the angle-body (inlet and outlet at 90° — used for high-pressure-drop service where the change in flow direction helps absorb the pressure energy). The Check Valve body architecture varies by design type: swing check valves have a hinged disc in a full-bore body cavity; axial flow check valves have a spring-loaded piston or disc that travels parallel to the flow axis, providing the fastest closing speed and lowest slam energy of any check valve design.

3. Comparative Advantages and Limitations

Engineering Advantages of Different Valve Types

Each valve type’s design provides specific engineering advantages that make it the preferred choice for its optimal application domain:

Ball Valve advantages: Lowest fully-open pressure drop of any isolation valve type (full-bore designs have Cv equivalent to a straight pipe section); fastest quarter-turn actuation; compact face-to-face dimensions relative to pressure class; excellent zero-leakage soft seat shutoff capability (Class VI per ANSI/FCI 70-2) in temperatures up to 200°C (PTFE) or 250°C (PEEK); bidirectional flow capability; inherently self-draining body geometry that prevents fluid accumulation in the body cavity; the widest available pressure class range (Class 150 through Class 4500) and bore size range (½ inch through 60 inch and beyond) of any valve type; and — in trunnion-mounted designs — Double Block and Bleed (DBB) capability for safe maintenance isolation per API 6D.
Gate Valve advantages: True full-bore passage in the fully open position — the gate retracts completely out of the flow path, providing zero intrusion into the pipeline bore. This full-bore pass-through is essential for services requiring pipeline pigging (mechanical cleaning or inspection), where even the small disc intrusion of a butterfly valve or the reduced bore of a reduced-bore ball valve would obstruct the pig. Gate valves also provide inherently low fully-open pressure drop, simple body construction with minimal internal components, and well-proven long-service-life performance in high-temperature steam and refinery applications where the rising stem and multi-turn actuation are accepted operational characteristics.
Globe valve advantages: Inherently stable and precise throttling characteristic — the parabolic or linear plug profile against a circular seat produces a smooth, predictable Cv-versus-stroke relationship that is well-suited to manual and automated flow regulation. The multi-turn stem mechanism provides high positional resolution and inherent self-locking against stem displacement under differential pressure — the stem will remain at any set position without continuous actuator power, unlike quarter-turn designs where the actuator must be sized to resist the closing torque from differential pressure on the disc or ball.
Butterfly valve advantages: Extremely compact face-to-face dimensions and low weight for large bore sizes — a 24-inch wafer-body butterfly valve weighs approximately 5–10% of an equivalent full-bore ball valve. This weight and dimensional advantage is the primary driver of butterfly valve selection in large bore, low-pressure services (water treatment, HVAC, cooling water) and where structural support capacity or installation space is limited. Triple-offset metal-seated designs extend the butterfly valve’s applicability to moderate and high pressure services while retaining the weight advantage.
Check valve advantages: Self-actuating — no external energy input or operator action required to prevent reverse flow. The check valve responds immediately and automatically to flow reversal, providing passive protection for pumps, compressors, and heat exchangers without relying on operator response or control system action.

Engineering Limitations and Tradeoffs

Each valve type has characteristic limitations that define the boundaries of its application envelope and the conditions under which another valve type should be selected instead:

Ball valve limitations: Standard ball valves (floating configuration, soft seat) are structurally excluded from large-bore, high-pressure service due to excessive seat contact loads — above approximately 4 inches at Class 600, the hydraulic thrust force on the downstream seat (F = ΔP × bore area) exceeds soft seat structural capacity, requiring either a trunnion-mounted configuration (significantly higher cost) or an alternative valve type. The quarter-turn actuation characteristic produces a near-step Cv response near the closed position, making standard ball valves unsuitable for precise throttling in ranges below approximately 20% of full-open Cv without characterized ball or trim.
Gate valve limitations: Strictly an on-off device — gate valves must never be used in partially open (throttling) position. The gate is subject to severe erosion from high-velocity flow through the narrow gap at partial openings, rapidly destroying the seating surfaces and rendering the valve unable to provide tight shutoff. Gate valves also require significantly longer actuation time than quarter-turn valves — the multi-turn stem mechanism requires 15–40 full rotations to travel from fully closed to fully open, which is acceptable for infrequently operated block valves but impractical for frequently cycled or automated service.
Globe valve limitations: Higher fully-open pressure drop than ball or gate valves — the S-curve flow path through the body introduces 3–10 times the pressure drop of an equivalent ball valve at the same bore and velocity. This additional pressure drop consumes pump or compressor head, reducing system efficiency. Globe valves are also heavier and have larger face-to-face dimensions than ball valves at equivalent bore sizes, and their multi-turn stem mechanism produces slower actuation than quarter-turn designs.
Plug Valve limitations: Standard lubricated plug valves require periodic injection of sealant lubricant into the plug-body interface to maintain sealing performance and prevent plug seizure — an ongoing maintenance requirement that is incompatible with unattended remote operation. Non-lubricated sleeved plug valves (with PTFE sleeve) eliminate this requirement but are limited to moderate pressure classes and temperatures within the PTFE thermal limit. Plug valves also require high actuation torque relative to their bore size due to the large contact area between the plug and body, particularly at high differential pressure.
Needle Valve limitations: Needle valves are inherently limited to small bore sizes (typically NPS ½ and below in standard designs) and low flow rates — their fine-port geometry that provides precision flow control also produces a very low maximum Cv that makes them unsuitable for any application requiring significant flow capacity. The needle’s sharp geometry makes it highly vulnerable to erosion from fluid-borne particles or from cavitating liquid flow at high differential pressure — needle valves must be protected from any significant solids content in the fluid and must be evaluated for cavitation risk in high-pressure-drop liquid service.
Butterfly valve limitations: The disc permanently intrudes into the flow path even in the fully open position, preventing pipeline pigging and creating a flow obstruction that produces measurable turbulence and pressure drop at high velocities. Standard concentric resilient-seated butterfly valves are rated only to Class 150–300, cannot achieve fire-safe qualification without a secondary metal seal, and cannot achieve Class VI (zero-leakage) shutoff in gas service. Triple-offset designs address these limitations partially — they achieve fire-safe qualification and tighter shutoff — but at significantly higher cost that approaches large-bore ball valve pricing.

4. Industrial Applications and Use Cases

Application Mapping by Industry Sector

Different industry sectors impose distinct combinations of pressure, temperature, fluid chemistry, flow control precision, and safety requirements that consistently favor specific valve type selections:

Oil and Gas Production and Pipeline: This sector operates the broadest range of conditions — wellhead pressures up to Class 2500 (approximately 425 bar for carbon steel at ambient temperature), sour gas H₂S service requiring NACE MR0175 compliance, cryogenic LNG service to −196°C, and pipeline pressures typically in Class 300–900. Trunnion-mounted Ball Valves with metal seats, fire-safe design per API 607, and DBB configuration per API 6D are the dominant isolation valve type in hydrocarbon production and pipeline gathering applications. Swing and axial-flow Check Valves protect compressor and pump stations from reverse flow. ESD and process shutdown valves are typically fail-safe actuated trunnion ball valves with spring-return pneumatic or hydraulic actuators.
Petrochemical and Refinery Processing: Refinery applications span a wide range from atmospheric crude distillation to high-pressure hydrocracking, with temperatures from cryogenic alkylation to high-temperature catalytic reforming above 400°C. Corrosive and erosive fluid services (sulfuric acid, hydrofluoric acid, catalyst fines, high-velocity steam) require specialty alloy or lined valve bodies. Globe valves — including Y-body designs for high-pressure-drop letdown service — are extensively used for flow control and pressure regulation. Gate valves with pressure-seal bonnets are standard for Class 900 and above steam and high-temperature process services. Lined plug valves (PTFE-sleeved) and lined ball valves (PTFE-lined body) serve corrosive acid and chemical services where bare metal body exposure would produce rapid corrosion.
Power Generation: Steam turbine power plants operate gate valves and globe valves in Class 900 through Class 2500 superheated steam service at temperatures up to approximately 600°C — beyond the thermal capability of all soft seat materials and most standard trim alloys. Pressure-seal bonnet gate valves in alloy steel (ASTM A217 WC9 or C12A) with stellite-hardfaced seats are the standard for main steam isolation. Gate Valves provide the full-bore passage required for steam lines where pressure drop must be minimized, and their multi-turn actuation is accepted for the low-frequency operation characteristic of main steam isolation service.
Water and Wastewater Treatment: Large-bore, low-pressure systems (typically Class 150 and below, bore sizes 12 to 60 inches) handling clean water, raw water with suspended solids, and chemically treated effluent. Butterfly Valves with resilient rubber seats (EPDM or NBR) dominate this sector — their compact, lightweight, low-cost construction provides the most economical large-bore flow control solution for the moderate pressure and non-aggressive fluid conditions typical of water infrastructure applications. Rubber-lined ball valves and lined gate valves serve the chemical dosing and acid/alkali sections of water treatment where rubber-lined butterfly valves may be chemically incompatible.
Chemical Processing and Pharmaceutical: Chemical processing requires precise flow metering and regulation for reaction feed control, pH adjustment, and product blending — applications where the fine positional resolution of needle valves and globe valves provides the required Cv control range and repeatability. Needle Valves in 316L stainless steel or Hastelloy C-276 construction serve instrument impulse lines, sample connections, and precise chemical injection in corrosive service. High-alloy ball valves in Duplex stainless steel or Inconel 625 serve corrosive chemical isolation service at moderate to high pressure.

Typical Engineering Scenarios

The following engineering scenarios illustrate the integrated decision logic that links operating conditions to valve type selection:

High-temperature, high-pressure gas isolation (above 300°C, Class 900+): Trunnion-mounted ball valve with Inconel 625 metal seats, NACE MR0175-compliant body and trim materials for sour service, fire-safe API 607 qualification, spring-return hydraulic actuator sized for 2.0× calculated breakaway torque per API 6D. Pressure class confirmed from ASME B16.34 P-T table at design temperature — not from ambient-temperature class designation. For guidance on pressure class determination at elevated temperature, see Pressure Class Selection.
Cryogenic liquid isolation (below −100°C): Ball valve in austenitic stainless steel (ASTM A351 CF8M body) with cryogenic extension bonnet to keep stem packing above −29°C, PTFE seats (which retain flexibility and sealing compliance at cryogenic temperatures), and cryogenic-impact-tested body material qualification per ASME B16.34. Floating configuration is viable for bore sizes up to 3 inches at Class 600; trunnion-mounted required for larger bore. For detailed temperature-material interaction guidance, refer to Temperature Rating.
Corrosive gas service (H₂S, CO₂, HCl): High-alloy ball valve in Duplex 2205 (UNS S31803) or Inconel 625 (UNS N06625) body, with matching alloy seat rings and ball surface overlay. NACE MR0175/ISO 15156 Part 2 or Part 3 qualification for all wetted alloy components. Seat material selection must balance corrosion resistance with achievable hardness within NACE limits — Inconel 625 overlay provides excellent sour service corrosion resistance and is NACE-qualified in the annealed condition.
Precision flow regulation — chemical injection and metering: Needle valve in 316L stainless steel or Hastelloy C-276 for corrosive injection service, with PTFE stem packing and cone-and-ferrule or compression tube end connections for instrument tubing integration. Fine-thread stem provides resolution of approximately 0.1 mm per turn of the handwheel, enabling Cv adjustment precision of approximately 0.001 Cv per turn — orders of magnitude better than any ball or gate valve design. The flow coefficient at any given needle position is confirmed from the manufacturer’s Cv-versus-turns-open table and cross-checked against the minimum required Cv from the flow calculation. For the Cv sizing methodology, refer to Cv Value Explained.
Large-bore water main isolation and flow regulation: Double-offset or triple-offset butterfly valve in ductile iron or carbon steel body, with EPDM resilient seat for water service, gear-operated for manual actuation or electric actuated for remote operation. Face-to-face dimensions per EN 558 (formerly DIN 3202) — wafer or lug body enabling installation between standard pipeline flanges without dedicated valve flanges, providing significant weight and cost savings compared to flanged ball or gate valve alternatives in bore sizes above 16 inches.

5. Applicable Standards and Codes

International Standards Overview

Industrial valve design, manufacture, and qualification are governed by a coordinated framework of international standards. Each standard addresses a specific scope of valve types, design parameters, or testing requirements:

API 6D — Specification for Pipeline and Piping Valves: The primary standard for ball valves, gate valves, plug valves, and check valves in oil and gas pipeline and gathering systems. API 6D governs body wall thickness, bore geometry (full bore and reduced bore definitions), fire-safe design qualification (by reference to API 607 and API 6FA), anti-static device requirements, blow-out proof stem design, bidirectional sealing and DBB capability, pressure testing requirements (shell hydrostatic at 1.5× rated pressure; low-pressure gas seat test at 5.5–6.9 bar; high-pressure liquid seat test at rated pressure), and valve marking. API 6D requires that the valve drive train be designed for at least 2.0× the calculated breakaway torque — a requirement that directly constrains actuator sizing and stem cross-section for all valve types in pipeline service.
ASME B16.34 — Valves: Flanged, Threaded, and Welding End: The foundational pressure-temperature rating standard for all industrial valves with flanged, threaded, or butt-welding end connections, covering all valve types in pressure classes from Class 150 through Class 4500. ASME B16.34 provides material group pressure-temperature rating tables, minimum body wall thickness requirements, dimensional requirements for end connections, and marking requirements. The P-T tables in ASME B16.34 are the mandatory engineering basis for confirming that any valve’s rated pressure at its specific operating temperature meets or exceeds the design pressure — the ambient-temperature class designation alone is insufficient.
API 598 — Valve Inspection and Testing: The standard for factory acceptance testing of gate, globe, check, ball, plug, and butterfly valves. API 598 specifies three categories of acceptance tests: visual examination (confirming compliance with all applicable dimensional and marking standards); shell (hydrostatic body test at 1.5× rated pressure for 60 seconds minimum, verifying structural integrity of the pressure-containing body); and closure tests (seat leakage tests in both liquid and gas test media). API 598 defines the maximum allowable leakage rates for each valve type and seat configuration: gate and globe valves — zero leakage (bubble-tight) in liquid closure test; ball and plug valves — maximum 20 bubbles per minute gas leakage for DN ≤ 100 mm; check valves — 0.1 mL/minute per inch of seat diameter; butterfly valves — maximum 100 mL/minute per inch of seat diameter in gas test. [web:105] All valves built to API standards must meet API 598 leakage criteria before shipment from the manufacturer. [web:111]
ISO 17292 — Metal Ball Valves for Petroleum, Petrochemical, and Allied Industries: Governs the design, material qualification, anti-static device, blow-out proof stem, and fire-safe testing (ISO 10497) requirements for metal ball valves in DN 15 to DN 600 (NPS ½ to NPS 24). ISO 17292 mandates anti-static design with electrical continuity between ball, stem, and body (resistance ≤ 10 Ω) — essential for hydrocarbon service where electrostatic ignition is a hazard.
ISO 5208 — Industrial Valves: Pressure Testing of Metallic Valves: Defines a classification-based leakage rate system (Class A through Class G) for valve closure tests, providing an internationally consistent leakage acceptance framework that complements the API 598 pass/fail criteria. ISO 5208 Class A (zero leakage) corresponds to API 598 zero-leakage requirement for metal-seated gate and globe valves; Class D allows droplet leakage acceptable for general-purpose valves.

Impact of Standards on Valve Design and Selection

The international standards framework shapes every engineering decision in valve design, specification, and procurement:

Pressure-temperature rating: ASME B16.34 P-T tables define the structural operating boundary for every valve type in every material group. No valve can be legitimately specified without confirming its rated pressure at the design temperature from these tables — temperature derating is mandatory, not optional. For large bore, high-temperature applications, the required pressure class may be one or two classes higher than the ambient-temperature nominal class, significantly affecting cost, weight, and procurement lead time.
Body wall thickness and structural design: ASME B16.34 Appendix A body wall thickness equations and API 6D body wall requirements constrain the minimum casting or forging dimensions for each valve type at each pressure class. These requirements ensure that the pressure-retaining shell has adequate structural margin over its service life, accounting for corrosion allowance and manufacturing tolerance. Non-standard body designs (e.g., three-piece ball valves with thin wafer bodies) must be verified against these minimum thickness requirements before specification.
Factory acceptance testing: API 598 acceptance criteria define the pass/fail threshold for leakage in all factory tests. Purchase requisitions must reference the specific test standard, test medium (liquid or gas), and acceptance leakage rate for each test. Misreference — for example, applying API 598 butterfly valve leakage criteria to a ball valve specification — produces incorrect acceptance thresholds that may permit leakage in the delivered valve that exceeds the process requirement. Ball Valve Standards and Butterfly Valve Standards each have distinct acceptance criteria within the API 598 framework that must be correctly referenced in the purchase specification.
Material qualification and traceability: All applicable standards require that body, bonnet, and trim materials be certified to the applicable ASTM (or equivalent EN/ISO) material standard, with mill test reports traceable to the manufacturing heat number. For sour service valves, NACE MR0175/ISO 15156 compliance documentation — including hardness test results for all wetted metallic components — must be included in the material certification package submitted with the valve data book at the time of delivery.

This overview page is the engineering entry point for the complete valve types cluster. Each of the following pages provides in-depth working principle, structural detail, application guidance, and standards reference for the specific valve type, consistent with the engineering selection framework established in the How to Select an Industrial Valve guide. Use this cluster in conjunction with the valve selection module — beginning with pressure class and temperature rating confirmation — to identify and fully specify the correct valve type for your service conditions:

Industrial Valve Types Overview — This page: the engineering summary of all valve types, working principles, structural anatomy, comparative advantages, and applicable standards
Ball Valve — Quarter-turn rotary isolation and control valve; floating and trunnion-mounted configurations; Class 150 through Class 4500; full bore and reduced bore designs; soft seat and metal seat variants
Gate Valve — Linear motion, full-bore isolation valve for on-off service; solid wedge, flexible wedge, and parallel slide gate designs; Class 150 through Class 2500; pressure-seal bonnet for Class 900 and above
Globe Valve — Linear motion throttling and flow control valve; Z-body, Y-body, and angle-body configurations; inherently stable throttling characteristic; Class 150 through Class 2500
Check Valve — Self-actuating non-return valve; swing check, lift check, dual-plate wafer, and axial-flow designs; passive reverse flow protection for pumps and compressors
Butterfly Valve — Quarter-turn rotary disc valve; concentric, double-offset, and triple-offset designs; compact and lightweight for large bore, low-to-moderate pressure service; rubber or metal seat configurations
Plug Valve — Quarter-turn rotary valve with cylindrical or tapered plug; lubricated, non-lubricated, and PTFE-sleeved designs; multi-port configurations for flow diversion; chemical and corrosive service
Needle Valve — Precision throttling valve with needle-shaped plug; high positional resolution for low-flow regulation; instrument impulse lines, sample connections, and chemical injection service