| Nominal Valve Size | DN15 to DN300 and larger (approximately NPS 1/2 to NPS 12) | Select a valve with a nominal bore that matches the connected pipe size. For most full-port gate valves, the flow passage is intended to provide low resistance when fully open. | Confirm the nominal size standard used by the piping system, such as DN under ISO/EN practice or NPS under ASME practice. Do not select a valve based only on the outside diameter of the pipe. |
| Small-Bore Service | DN15–DN50 (NPS 1/2–NPS 2) | Threaded or socket-welded connections are commonly used where the line is compact and installation space is limited. Flanged versions are also available for easier maintenance. | Check thread form, thread direction, pipe schedule, sealant compatibility, and the available space for the electric actuator. |
| Medium-Bore Service | DN65–DN200 (NPS 2 1/2–NPS 8) | Flanged valves are often preferred for water, HVAC, utility, and general industrial piping because they allow removal without cutting the pipe. | Verify flange outside diameter, bolt-hole pattern, bolt size, gasket type, and face-to-face dimension against the piping standard. |
| Large-Bore Service | DN250 and above (NPS 10 and above) | Use a valve designed for the pipeline's operating conditions. Larger valves require particular attention to actuator torque, stem load, mounting orientation, and structural support. | Confirm lifting provisions, actuator output torque, emergency manual override, installation clearance, and the maximum allowable stem thrust. |
| Pressure Rating: ASME Class | Class 150, 300, 600, 900 and higher | Choose a pressure class equal to or higher than the maximum design pressure and temperature combination of the piping system. | ASME Class ratings are pressure-temperature ratings, not a single pressure value. The allowable pressure changes with valve body material, trim material, and operating temperature. Check the applicable pressure-temperature table. |
| Pressure Rating: EN PN | PN10, PN16, PN25, PN40 and higher | PN16 is commonly used in many water and utility systems, while higher PN ratings may be required for higher-pressure services. | PN designations must match the flange drilling and the valve's certified pressure-temperature limits. PN16 and ASME Class 150 are not automatically dimensionally interchangeable. |
| Operating Pressure | Normal pressure, maximum working pressure, and design pressure | Base the selection on the maximum design pressure, not only the normal operating pressure. Include possible pump shutoff pressure and pressure surges. | Consider water hammer, rapid pump starts or stops, trapped pressure, and pressure relief arrangements. The actuator must also be suitable for the differential pressure across the gate. |
| Temperature Range | Ambient, cold water, hot water, steam, or process temperature | Select body, seat, stem packing, gasket, and actuator materials for the complete minimum and maximum temperature range. | Pressure capacity generally decreases as temperature rises. Check elastomer limits, insulation requirements, actuator temperature limits, and condensation protection. |
| Connection Type: Flanged | Raised face, flat face, or ring-type face depending on the system | Select flanged valves when reliable disassembly, inspection, and replacement are important. Common dimensional references include ASME B16.5, ASME B16.47, EN 1092-1, and EN 558. | Match flange standard, pressure class or PN rating, facing type, bolt-hole arrangement, gasket material, and face-to-face length. |
| Connection Type: Threaded | Female NPT, BSPP, or BSPT, depending on the piping system | Suitable mainly for smaller pipe sizes and services where frequent removal is not required. Use the same thread standard on the valve and the pipe or fitting. | NPT, BSPP, and BSPT threads have different profiles and sealing methods. They should not be treated as automatically interchangeable. Confirm pressure limits and installation orientation. |
| Connection Type: Butt-Weld | Weld ends sized for the pipe wall thickness | Suitable for high-integrity systems where a permanent, compact, low-leakage connection is required. | Match outside diameter and wall thickness. Follow the approved welding procedure, verify material weldability, and protect the valve seat and actuator from welding heat. |
| Connection Type: Socket-Weld | Primarily used on small-bore piping | Provides a compact permanent connection for compatible piping systems and higher-pressure small-bore applications. | Confirm socket dimensions, pipe insertion requirements, welding clearance, and the applicable piping and welding standard. |
| Valve Body Material | Ductile iron, carbon steel, stainless steel, or other specified alloys | Select the body material according to pressure, temperature, fluid chemistry, corrosion risk, and mechanical requirements. | Check corrosion resistance, chloride exposure, low-temperature toughness, compatibility with the fluid, and any applicable material certificates. |
| Gate and Seat Arrangement | Wedge gate, resilient-seated gate, or metal-seated gate | Resilient-seated designs are commonly used for clean water and utility isolation. Metal-seated designs may be preferred for higher temperatures, abrasive service, or demanding industrial applications. | Gate valves are generally intended for fully open or fully closed isolation, not continuous throttling. Confirm leakage class, seat material, and fluid cleanliness. |
| Actuator Output Torque | Torque sized for breakaway, running, seating, and unseating conditions | Choose an electric actuator with sufficient torque and thrust for the valve at the maximum differential pressure and worst-case operating condition. | Do not size the actuator from valve size alone. Include packing friction, seat friction, pressure effects, safety margin, duty cycle, and the valve manufacturer's torque/thrust data. |
| Actuator Control Mode | On/off, modulating, local control, or remote control | Use on/off control for isolation duties. Use a properly rated modulating actuator only when the system requires controlled positioning and the valve is suitable for that duty. | Confirm control signal, feedback requirements, position indication, fail position, interlocks, and compatibility with the control system. |
| Electrical Supply | Single-phase or three-phase AC; low-voltage DC where specified | Select an actuator that matches the available voltage, frequency, phase, and starting-current capacity. | Verify motor protection, overload protection, enclosure rating, cable entry, grounding, ambient temperature, and hazardous-area certification where required. |
| Installation Position | Vertical stem, horizontal stem, or manufacturer-approved orientation | Install the valve in the orientation recommended for the specific design, preferably with adequate clearance for actuator removal and manual operation. | Avoid placing the actuator where it can be flooded, exposed to excessive heat, or obstructed by adjacent equipment. Confirm stem orientation and maintenance access. |
| Applicable Standards | ASME B16.10, ASME B16.34, ASME B16.5, EN 1074, EN 1171, EN 558, ISO 5210, or project-specific standards | Select standards based on the industry, country, piping code, and service category. | Confirm that valve design, testing, face-to-face dimensions, flange dimensions, actuator mounting, and pressure testing requirements are covered by the selected standards. |
| Final Ordering Information | Size, rating, connection, material, seat, actuator, power, control, and accessories | Prepare a complete valve specification before purchase to prevent mismatched components and installation delays. | Always verify the final selection against the system design pressure, temperature, fluid, applicable codes, certified product data, and the valve manufacturer's sizing information. |