Non-Rising Stem Metal Seated Gate Valve

Non-Rising Stem Metal Seated Gate Valve (NRS Metal Seated Gate Valve) is a heavy-duty shut-off valve adopting non-rising stem and metal-to-metal hard sealing structure. Unlike rising stem types, the stem only rotates without axial outward movement during operation, saving vertical installation space. It is widely used in valve pits, confined spaces, underground pipe galleries, heating networks, steam pipelines, petroleum and chemical systems, especially suitable for working environments where the valve stem cannot extend upward.

The core sealing component is a metal wedge disc. Sealing surfaces are precision machined and overlaid with Stellite alloy or wear-resistant hard alloy. This metal hard sealing structure features excellent high temperature resistance, wear resistance and scour resistance. It can steadily handle high-temperature steam, fuel oil, gas and other media, far exceeding the temperature bearing limit of rubber soft-seal valves. Rigid wedge, flexible wedge and double wedge structures are optional. The flexible wedge can offset thermal deformation caused by temperature changes, maintaining reliable sealing performance under variable working conditions.

Valve body materials cover cast carbon steel WCB, alloy steel WC6, stainless steel CF8/CF8M and ductile iron to adapt to different media. Connection forms include flanged RF, butt weld and threaded ends. Manufacturing standards can follow GB/T12234, API 600, DIN 3356 and ASME B16.34. Available pressure grades range from PN16 to PN100 and Class150 to Class1500, meeting medium and high-pressure industrial working conditions.

The non-rising stem structure is its most prominent feature. The stem thread stays inside the valve body all the time and will not stretch out when opening or closing. This design protects threads from dust, water vapor and external corrosion, lowering failure probability in closed and humid valve wells. The stem is made of alloy steel or stainless steel, equipped with high-temperature graphite composite packing to prevent medium leakage along the stem. Built-in blowout-proof stem structure effectively avoids safety hazards caused by pressure surges. Multiple driving modes are optional: manual handwheel, bevel gear and electric actuator for automatic pipeline control.

It should be emphasized that the NRS metal seated gate valve is only designed for fully open or fully closed cut-off operation. Throttling service is strictly prohibited. Long-term partial opening will cause continuous medium scouring, resulting in rapid abrasion of metal sealing surfaces and permanent leakage. All finished valves undergo shell hydrostatic test and seat tightness test in accordance with ISO 5208 before delivery.

Compared with OS&Y rising stem metal seated gate valves, the non-rising stem model occupies less vertical space and is more adaptable for buried installation and narrow valve chambers. Without exposed stems, the overall structure is compact and less vulnerable to external mechanical damage. It is extensively applied in central heating pipe networks, power plant auxiliary pipelines, natural gas stations and industrial process pipelines. Our factory can customize sealing overlay materials, anti-static structures and locking devices for flammable medium projects to satisfy diversified requirements from global engineering contractors.