Rising Stem Flanged Gate Valve
Rising Stem Flanged · DN40–DN600 · PN16/25 · OS&Y
An OS&Y rising stem shows position at a glance — the stem rises as the valve opens, required for fire and above-ground piping.
Flanged per ISO 7005-2, with handwheel or gearbox for larger sizes.
Key Features
Tight Isolation
Wedge-to-seat geometry gives reliable shutoff with minimal leakage.
Low Pressure Loss
Straight-through bore keeps pressure drop near zero in open position.
Rising / Non-Rising Stem
OS&Y rising stem shows open/closed at a glance; NRS suits buried service.
Resilient or Metal Seat
EPDM/NBR for water; SS316/Stellite for steam and slurry.
Bi-Directional
Wedge disc seals in both flow directions for flexible installation.
Actuator Ready
Top flange accepts gearbox, pneumatic or electric actuators.
Technical Specifications
| Parameter | Specification |
|---|---|
| Body Material | WCB / SS304 / SS316 / Ductile Iron GGG50 |
| Wedge / Disc | Solid Wedge / Flexible Wedge / Parallel Slide |
| Seat Material | Resilient (EPDM / NBR) / Metal (SS316 / Stellite) |
| Size Range | DN40 – DN1200 (1.5" – 48") |
| Pressure Rating | PN10 / PN16 (ANSI 150 / 300) |
| End Connection | Flanged (ISO 7005-2 / ASME B16.5) / Butt-Weld |
| Stem Type | Rising Stem (OS&Y) / Non-Rising Stem |
| Operation | Handwheel / Gearbox / Pneumatic / Electric |
| Temperature | Resilient: -10→+80°C ; Metal: -40→+425°C |
| Leakage | Tight shutoff, bubble-tight with resilient seat |
| Standards | Design reference: API 600 / GB/T 12234 / EN 1171 — no API monogram held (API 609 applies to butterfly valves, not gate valves) |
| Certification | ISO 9001:2015, MTC available |
How to Specify a How to Specify a Rising Stem Flanged Gate Valve
Rising stem (OS&Y) and non-rising stem are not different valves — they are two stem configurations of the same gate valve. Getting the choice right is about access, indication and headroom.
Rising stem when position must be visible
The stem rises as the valve opens, so open or closed is obvious at a glance. This is why it is standard on fire protection and safety isolation.
Non-rising stem when headroom is limited
The stem rotates without travelling, so the valve needs no vertical clearance above the handwheel. Underground and low-clearance installations use it.
The extension requirement follows the choice
A buried rising-stem valve needs a stem extension and a valve box tall enough for the rise. A non-rising stem needs only an operating nut. Decide before the trench is dug.
Stem material for the environment
A stainless rising stem in a wet pit prevents the seized valve that appears at the first annual test.
The trade-off in one line
Rising stem gives visible position and costs vertical space. Non-rising stem saves space and hides position.
Installation & Maintenance
Measure the rise, not just the valve
For a rising stem valve, allow clear travel equal to the stem rise above the handwheel in the fully open position.
Protect an exposed rising stem
Dust, paint and rust on the thread travel into the stem nut. Where the valve is outdoors, keep the stem covered.
Use a guide on long stems
A long unsupported rising stem can bend. Fit the guide the design provides.
Mark the open position
On a non-rising stem valve there is no visual indication, so paint a mark or fit a position indicator at commissioning.
Common Specification Mistakes
Fitting a rising stem valve under a low ceiling
The stem hits the ceiling mid-travel and the valve cannot fully open.
Sending a buried valve without a stem extension
The valve has to be excavated to operate it.
Assuming the two versions are interchangeable
They are the same valve with different stems, but the installation requirements differ completely.
Frequently Asked Questions
When should I use a rising-stem (OS&Y) gate valve?
Use OS&Y where you need visual confirmation of open/closed position — typical for fire protection and above-ground piping. Non-rising stem suits buried or space-limited installs.
Resilient seated or metal seated?
Resilient (EPDM/NBR) seats give bubble-tight shutoff for clean water up to +80°C. Metal seats handle steam, slurry and temperatures up to +425°C.
Why choose a knife gate valve?
Knife gate valves have a sharpened disc that cuts through slurry, pulp and viscous media — ideal for mining, wastewater and bulk solids.
Applications & Use Cases
Water & Wastewater
Resilient-seated gate valves for mains, hydrants and treatment plants.
Fire Protection
OS&Y gate valves for sprinkler and hydrant systems.
Power & Steam
Metal-seated wedge gates for high-temperature steam lines.
Mining & Slurry
Knife gate valves for abrasive and viscous process streams.
