Metal Seated Triple Offset Butterfly Valve
Description
Metal Seated Triple Offset Butterfly Valve – Fully Lugged, Drilled Through Hole, with Lockable Gear Operator
Product Technical Data Sheet
1. General Description
This product is a metal seated triple offset butterfly valve with a full‑bore flow path. The valve body features fully lugged ends with drilled through holes. It is equipped with a manual worm gear operator with lockable function (lockable gear). The design allows end‑of‑line service and online maintenance without breaking the pipeline.
The valve seat is hardfaced with Stellite alloy, and the disc sealing ring is made of laminated metal or metal + graphite composite. It offers high temperature resistance, high pressure resistance, wear resistance, and long service life. The triple offset design ensures bi‑directional zero leakage, minimal friction during opening/closing, and reliable sealing under severe service conditions.
2. Triple Offset Principle
| Offset | Direction | Function |
|---|---|---|
| First offset (X‑axis) | Stem centerline offset from seat centerline | Quick separation of disc and seat during operation, reducing friction |
| Second offset (Y‑axis) | Stem centerline offset from body centerline | Further reduces friction between disc and seat |
| Third offset (Z‑axis) | Seat cone axis offset from body axis | Creates a cam‑controlled conical seal, eliminates friction during opening/closing, achieves zero leakage |
The triple offset design results in almost no friction between the disc sealing surface and the seat during operation, leading to low torque, long seal life, and bi‑directional zero leakage capability.
3. Main Technical Parameters
| Parameter | Range / Value |
|---|---|
| Product Type | Triple offset metal seated butterfly valve |
| Nominal Diameter (DN) | DN50 ~ DN1200 (up to DN2000+ available) |
| Nominal Diameter (NPS) | 2″ ~ 48″ (up to 80″ available) |
| Nominal Pressure (PN) | PN10 / PN16 / PN25 / PN40 / PN64 |
| Pressure Class (ASME) | Class 150 / Class 300 / Class 600 (up to Class 2500 available) |
| Temperature Range | -196℃ ~ +600℃ |
| Suitable Media | Water, steam, oil, natural gas, flammable gases, chemical fluids, corrosive media, high‑temperature flue gas, cryogenic liquids (LNG/LPG), etc. |
| Leakage Rating | API 598 Rate A / ISO 5208 Rate A (zero leakage) |
| Sealing Type | Metal‑to‑metal (optional: laminated graphite composite) |
| Fire Safe | Compliant with API 607 / API 6FA |
4. Operator (Lockable Worm Gear Operator)
| Parameter | Specification |
|---|---|
| Operation | Manual worm gear operator with lockable function |
| Locking Feature | Self‑locking worm gear design (prevents reverse rotation) |
| Gear Ratio | Standard: 30:1 ~ 60:1 (matched to valve size) |
| Output Torque Range | Up to 700 N·m (for DN200~DN300); higher torque available on request |
| Handwheel | Cast iron; optional folding or extended handwheel |
| Position Indicator | Top pointer with open/closed indication plate |
| Travel Stops | Built‑in mechanical travel stops, field adjustable (0° ~ 90°) |
| Housing Material | Cast iron / Ductile iron (O‑ring sealed for outdoor use) |
| Protection Class | IP65 (standard; higher grades available) |
| Lubrication | Lifetime grease filled |
The worm gear operator provides self‑locking to maintain any valve position. It includes mechanical travel stops and a clear open/closed indicator. The top flange conforms to ISO 5211 for easy adaptation to pneumatic or electric actuators.
5. End Connection Type (Fully Lugged, Drilled Through Hole)
| Parameter | Specification |
|---|---|
| Connection Type | Fully lugged ends |
| Bolt Hole Type | Drilled through holes (continuous holes through the lug) |
| Compatible Flange Standards | ASME B16.5 / EN 1092 / GB/T 9113 / JIS B2220 |
| Installation | Suitable for end‑of‑line service (no downstream pipe needed for isolation) |
| Facing Type | RF (raised face) / RTJ (ring type joint) optional |
| Maintainability | Valve can be removed without breaking the pipeline |
Fully lugged ends with drilled through holes allow bolting from either side. This design is ideal for both line‑mounting and end‑of‑line mounting, simplifying installation and maintenance.
6. Parts Materials List
| Part | Standard Material | Optional Material |
|---|---|---|
| Body | Cast steel (WCB / A216 WCB) | Stainless steel (CF8 / CF8M / CF3M), Duplex steel, Alloy steel, Ductile iron |
| Disc | Stainless steel (SS304 / SS316) | Cast steel + hardfacing, Duplex steel, Monel, Hastelloy |
| Stem | Stainless steel (SS410 / SS420 / SS304 / SS316) | 17‑4PH, Monel K‑500, Inconel 718 |
| Seat Sealing Surface | Stellite hardfacing (cobalt base) | SS304 + graphite laminate / SS316 + graphite laminate |
| Disc Seal Ring | Laminated metal seal (SS + graphite composite) | PTFE / R‑PTFE / hard coating |
| Stem Packing | Flexible graphite (low‑emission grade) | PTFE V‑ring, Graphite + stainless steel braid |
| Bearings / Bushings | Self‑lubricating metal (tin bronze + PTFE) | High‑strength engineering plastic composite |
| Fasteners | Stainless steel (SS304 / SS316) | Alloy steel (ASTM A193 Gr.B7 + A194 Gr.2H) |
| Gearbox Housing | Cast iron (HT200) | Ductile iron (QT400‑15), Aluminum alloy |
| Handwheel | Cast iron (anti‑rust coating) | Stainless steel, Aluminum alloy |
| External Coating | Epoxy (≥250 μm) | Polyurethane topcoat, Galvanized + passivation, PTFE coating |
7. Applicable Standards
| Category | Standard |
|---|---|
| Design & Manufacture | API 609 Category B, ASME B16.34, EN 593, ISO 10631, GB/T 12238, MSS SP‑68 |
| Face‑to‑Face Dimensions | API 609, ASME B16.10, ISO 5752, GB/T 12221, EN 558 |
| Flange Connections | ASME B16.5, ASME B16.47, EN 1092, GB/T 9113, JIS B2220 |
| Lugged Design | MSS SP‑68, ASME B16.34 |
| Pressure‑Temperature Rating | ASME B16.34, API 609 |
| Inspection & Testing | API 598, ISO 5208, GB/T 13927, EN 12266 |
| Fire Safety | API 607, API 6FA |
| Low Emission | ISO 15848‑1 (Class C / Class B) |
| Anti‑static Device | API 609, BS 5351 |
| Blowout‑Proof Stem | API 609 |
| NACE Compliance | NACE MR0175 / ISO 15156 (optional) |
8. Dimensional Reference (Example)
Note: Below dimensions are for PN16 / Class 150 as reference. Final dimensions per approved GA drawing.
| DN | NPS | L (face‑to‑face) | Flange bolt circle (D1) | Bolt holes – diameter |
|---|---|---|---|---|
| 50 | 2″ | 108 | 125 | 4-Ø18 |
| 80 | 3″ | 114 | 160 | 8-Ø18 |
| 100 | 4″ | 127 | 180 | 8-Ø18 |
| 150 | 6″ | 140 | 240 | 8-Ø22 |
| 200 | 8″ | 152 | 295 | 12-Ø22 |
| 250 | 10″ | 165 | 355 | 12-Ø26 |
| 300 | 12″ | 178 | 410 | 12-Ø26 |
| 350 | 14″ | 190 | 470 | 16-Ø26 |
| 400 | 16″ | 216 | 525 | 16-Ø30 |
| 500 | 20″ | 229 | 650 | 20-Ø33 |
| 600 | 24″ | 267 | 770 | 20-Ø36 |
Dimensions according to GB/T 12221 and API 609. Lugged ends conform to ASME B16.5 / EN 1092.
9. Gearbox Torque Matching (Reference)
| Valve Size DN | Operating Torque (N·m) | Recommended Gear Ratio | Gearbox Output Torque (N·m) |
|---|---|---|---|
| 50 ~ 100 | ≤ 50 | 30:1 | ≥ 80 |
| 125 ~ 200 | 50 ~ 150 | 40:1 ~ 50:1 | ≥ 200 |
| 250 ~ 350 | 150 ~ 350 | 50:1 ~ 60:1 | ≥ 500 |
| 400 ~ 500 | 350 ~ 600 | 60:1 ~ 80:1 | ≥ 700 |
| 600 ~ 800 | 600 ~ 1200 | 80:1 ~ 100:1 | ≥ 1500 |
| 900 ~ 1200 | 1200 ~ 2500 | 100:1 ~ 120:1 | ≥ 3000 |
Note: Actual torque depends on pressure, temperature and seal type. Final selection must be based on actual service conditions.
10. Inspection and Test Requirements
| Test | Test Pressure | Hold Time | Acceptance Criterion |
|---|---|---|---|
| Shell Strength Test | 1.5 × pressure rating | ≥ 60 sec | No visible leakage or damage |
| High‑Pressure Seal Test | 1.1 × pressure rating | ≥ 60 sec | API 598 Rate A – zero leakage |
| Low‑Pressure Air Seal Test | 0.4 ~ 0.7 MPa | ≥ 60 sec | Zero visible bubbles |
| Stem Packing Fugitive Emission | Per ISO 15848‑1 | — | Class C / B |
| Fire Safety Test | Per API 607 | — | Leakage within standard limits |
Every valve is shell tested and seat tested per API 598 before shipment, meeting Rate A zero leakage. Low‑emission packing (ISO 15848‑1) is available as an option.
11. Applications
The triple offset metal seated butterfly valve is widely used in severe service conditions, including high temperature, high pressure, corrosive media, and abrasive fluids:
-
Oil & Gas: Crude oil, natural gas, product pipelines, offshore platforms, refineries
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Petrochemical: Chemical feedstocks, reactor inlet/outlet, toxic/corrosive fluid lines
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Power Generation: Boiler steam systems, cooling water, turbine bypass, thermal power stations
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Metallurgy: Blast furnace gas, coke oven gas, dust collection systems
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Marine & Offshore: Ballast systems, seawater cooling, LNG/LPG carriers
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LNG / Air Separation: Cryogenic services down to -196℃
-
Municipal & Utilities: District heating, water supply, gas distribution
-
Pulp & Paper: Pulp, black liquor, white liquor
12. Ordering Information
Please provide the following when ordering:
-
Valve size (DN / NPS)
-
Pressure rating (PN / Class)
-
Medium type and characteristics (corrosive, temperature, solids content, etc.)
-
Operating temperature range
-
Flange standard and facing (fully lugged with through holes is standard)
-
Body and disc material
-
Sealing material (standard Stellite hardfacing or laminated metal + graphite)
-
Operator type (lockable gear, pneumatic, electric, hydraulic, etc.)
-
Additional requirements: low‑emission packing, NACE MR0175, third‑party inspection, etc.
Important Note: The technical data and dimensions in this document are for general reference only. Final specifications are subject to the approved technical data sheet and valve drawings. The manufacturer reserves the right to revise this document without prior notice.
