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Triple Offset Butterfly Valve – Metal Seated (TOBV)
The triple offset butterfly valve represents the pinnacle of butterfly valve technology. With three geometric offsets creating a conical sealing surface, it achieves zero-friction metal-to-metal sealing suitable for the most demanding applications including high pressure, high temperature, and cryogenic services.
The Three Offsets Explained
1st Offset: Stem behind disc centerline
2nd Offset: Stem offset from pipe centerline
3rd Offset: Conical seat angle (typically 3-5°)
This creates zero friction during rotation - contact only at final closing moment.
Key Standards & Certifications
Size: DN50 - DN1500 (2" - 60") | Pressure: Class 150-2500, PN10-PN420
Technical Specifications
Valve Type
Triple Offset (Triple Eccentric)
Design Standard
API 609, ASME B16.34, BS EN 593
Face to Face
API 609, EN 558-1 Series 13/14/25
Testing Standard
API 598, BS EN 12266, API 6D
Pressure Rating
Class 150-2500, PN10-PN420
Size Range
DN50 - DN1500 (2" - 60")
End Connection
Wafer, Lug, Double Flanged, BW
Flange Standard
ASME B16.5, B16.47, EN 1092-1
Operation
Gear, Pneumatic, Electric, Hydraulic
Seat Type
Metal-to-Metal (Laminated/Solid)
Temperature Range
-196°C to +815°C
Leakage Class
Class VI / Zero Leakage
Material of Construction Options
Pressure-Temperature Ratings
Key Advantages
Zero Friction Sealing
Conical seat geometry ensures disc contacts seat only at final closing moment, eliminating wear during operation.
Fire-Safe Design
Metal-to-metal sealing maintains integrity during fire. Certified per API 607 and API 6FA standards.
Extreme Temperature Range
From cryogenic LNG (-196°C) to high-temperature steam (+815°C) - one valve design for all extremes.
Bi-Directional Sealing
Bubble-tight shutoff in both flow directions. Can replace gate valves in many applications.
Compact & Lightweight
Up to 70% lighter than gate valves. Reduces piping support requirements and installation costs.
Long Service Life
Zero friction means minimal wear. Stellite-faced seats provide 100,000+ cycle life.
Applications
Oil & Gas
Pipelines, refineries, FPSOs, terminals
LNG & Cryogenic
LNG terminals, regasification, ethylene
Power Generation
Steam, feedwater, cooling systems
Petrochemical
Reactors, distillation, storage
Subsea & Offshore
Platforms, risers, manifolds
Steel & Metals
Blast furnace gas, coke oven
Frequently Asked Questions
What is a triple offset butterfly valve?
A triple offset butterfly valve (TOBV/TOV) has three geometric offsets: 1st offset - stem behind disc center, 2nd offset - stem offset from pipe center, 3rd offset - the seat cone angle creates a conical sealing surface. This design provides metal-to-metal sealing with zero friction during operation.
What is the 3rd offset in a triple offset butterfly valve?
The 3rd offset is the cone angle of the seating surface. The seat and disc sealing surfaces are machined at an angle (typically 3-5°) to create a conical shape. This geometry ensures the disc contacts the seat only at the final moment of closing, eliminating friction during rotation.
Why is triple offset butterfly valve called zero friction valve?
Due to the conical seat geometry (3rd offset), the disc does not contact the seat during 99% of its rotation. Contact occurs only at the final moment of closing. This eliminates rubbing friction, reducing wear and torque requirements while extending valve life significantly.
What is the maximum pressure rating for triple offset butterfly valve?
Triple offset butterfly valves can handle pressures up to ANSI Class 2500 (approximately 420 bar/6000 PSI) depending on size and material. They are suitable for the most demanding high-pressure applications.
What is the temperature range for triple offset butterfly valve?
Triple offset butterfly valves can operate from cryogenic temperatures (-196°C for LNG applications) up to +815°C (1500°F) for high-temperature steam and thermal oil. The temperature range depends on body and seat materials selected.
Is triple offset butterfly valve fire-safe?
Yes, triple offset butterfly valves with metal seats are inherently fire-safe. They are tested and certified per API 607 and API 6FA. The metal-to-metal sealing maintains integrity even after the fire destroys soft seals.
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