Gate Valve

A gate valve closes by lowering a flat or wedge-shaped gate across the flow. Fully open, the gate is clear of the bore, so there is almost no pressure drop and no turbulence. It takes several turns of the handwheel to open or close, which makes it an isolation valve rather than a quick-acting one — used where a line is shut off rarely but must be shut off fully.

Two: the Stainless Steel Gate Valve in cast rising-stem OS&Y construction, and the Forged Steel Gate Valve for small-bore high-pressure lines. A lined version for corrosive duty is available as the PTFE Lined Gate Valve, and for slurry service see the Knife Gate Valve range.

Forged bodies are denser and stronger, so they carry higher pressure in small sizes — our forged range covers ½″–2″ (DN 15–50) at Class 800–1500 with threaded, socket-weld or flanged ends. Cast bodies are the practical choice above 2″, where forging becomes uneconomic — our cast stainless range covers ½″–24″ (DN 15–600) at Class 150–600 with RF or RTJ flanges. Line size and pressure usually decide it for you.

Choose a gate valve for infrequent full isolation where minimum pressure drop matters and cost per inch is important. Choose a ball valve where you need fast quarter-turn shut-off, frequent cycling or a tighter long-term seal. Choose a globe valve where you need to throttle. A gate valve does the isolation job cheaply; it does not do the other two jobs well.

Outside Screw and Yoke. The stem thread sits outside the body in a yoke rather than inside the fluid, so the thread never contacts the media and cannot be corroded or clogged by it, and the packing can be adjusted without draining the line. Because the stem rises as the valve opens, you can see the valve position at a glance from across the plant — which is why OS&Y is specified almost universally on process lines.

Cast bodies and bonnets in CF8/CF8M stainless (ASTM A351), CF3M, duplex, super duplex and 904L. Forged bodies in ASTM A105/A105N, F304L, F316L and alloy steels F11, F22 and F91. Wedges in CF8/CF8M stainless or flexible-wedge construction with a carbon steel core. Seats metal-to-metal, stellited on the forged range, or with PTFE and rubber (Viton/EPDM) inserts where a softer seal is needed.

A partly open gate leaves the disc edge exposed to high-velocity flow, which erodes the wedge and the seat faces until the valve no longer seals fully closed. The gate also vibrates in the flow stream, wearing the guides and the stem. If you need to regulate flow, use a globe valve, which is designed for the duty — and keep the gate valve fully open or fully closed.

Cast gate valves follow ASME B16.34 and B16.5 for design and flange dimensions at Class 150–600. Forged gate valves follow the API and ASME requirements for Class 800–1500. MVS is ISO 9001:2015 certified and supplies test certificates with each order.

Yes. Larger sizes and higher pressure classes are supplied with bevel gear operators to keep handwheel effort reasonable, and electric or pneumatic actuated assemblies are available where the valve must be operated remotely — though for frequently cycled automated duty a quarter-turn valve is usually the better answer.

MVS is a manufacturer — valves built at its own works since 1978, ISO 9001:2015 certified — exporting across several continents. The minimum order quantity is 20 pieces. Special alloys, trim options, gear operators and actuated assemblies are built to order.