Triple Offset Valve

Triple Offset Valve (Metal & Graphite Seat / Solid Metal Seat)

When Triple offset Design is introduced to the market, Triple Offset Design (TOD) overcomed the limitations of Double Offset Design. Double Offset Design is prone to excessive wear from friction and abrasion between sealing components. To eliminate problems, TOD features a special sealing mechanism that consists of an inclined conical disc and a laminated seat. The unique characteristics of TOD are low torque operation, broad sealing width and bi-directional tight shut-off.

Design ASME B16.34 / API std 609 Category B
Rating ASME Cl. 150,300,600,900,1500
PN10, 16, 20, 25, 40, 64, 100
Size DN80(3“) to DN2000 (80”)
Connection Type Double Flanged / Lugged & Wafer / Butt Weld End
Temperature Range -50℃ ~450℃
Main Material Body : WCB, CF8, CF8M etc.
Disc : CF8, CF8M (With Stellite or ENP) etc.
Shaft : 17-4PH, 316SS etc.
Seat : 316ss + Graphite etc.
Operator Manual Worm Gear
Pneumatic Actuator
Electric Actuator
Application General Industrial & Petro Chemical Plant
Oil Refinery / Production
Gas / Pulp / Paper Industry
Steel and Iron Mill
District Heating / Water and Sewage
Combined / Nuclear power plant
Hydrocarbon storage and Transportation
Sugar Industry
Other Plant engineering
Option Stellite or ENP on Disc
Anti-static device
Manual operator with Locking device
Bonnet / Stem extension
Heating jacket
ISO 15848 Fugitive Emission packing
NACE MR 0103 / 0175

Designed to ensure fire safety.

Sealing System

Double Offset Design uses a sealing mechanism that disc presses on to a metal seat. such design is prone to galling and scratches on sealing components. it eventually causes malfunctions of valves. This is where Unicom’s Triple Offset Design has an advantage over Double Offset Design. Triple Offset Design is an elliptical sealing mechanism. it enables a seamless closure at the final position and operates with low torque as all contact surfaces of disc and seat immediately disengage upon opening. therefore, the sealing components are free from galling and scratches. Another important design point is that the seat ring is fixed in body by set screws with a retaining ring. Due to this unique design, the medium flows horizontally to the seat, which minimizes any possibilities of damage from medium.

Seat Mechanism

Laminated metal + graphite seat enables smooth mating, which makes TOD flawless not only in general application but also in LNG/LPG gas applications. Each individual layer serves a unique and independent sealing purpose. Along with Triple Offset Design, laminated seat ring shows excellent performance and help provide lower operating torque during opening and closing. Different types of materials are selected for laminated metal plate depending on applications. SOLID METAL SEAT RING IS ALSO AVAILABLE Solid metal seat can also be selected in Unicom’s TOD design. Currently, Unicom uses solid metal seats in heavy duty and high temperature applications.


1. Bi-directional tight shut-off
2. Triple Offset Design with inclined conical sealing system.
3. Solid Metal or Laminated Metal + Graphite seat available.
4. Robust single piece shaft with shaft bearing extension to disc.
5. Genuine fire safety feature with Triple Offset Design.
6. One piece structure – No fasteners on disc. : Field repairable.
7. Provides non-friction motion.
8. Efficient with worm gear, electric, pneumatic or hydraulic actuators.
9. Availability for various applications using a wide range of materials.
10. Providing durability within a specific temperature range.


1. TOD butterfly valve is a field proven high quality butterfly valve developed based on the technology Unicom has acquired through experiences in the industrial applications.
2. Unicom customize valve to exact requirements of customers, which serve specific operating conditions of size, pressure and materials.
3. Tripple Offset Design guarantees zero leakage in bi-directional application and provides a longer product life cycle as it is more resistant to problems of Double Offset Design.
4. While most triple offset designs are using a sealing mechanism of inclined surfaces of disc and seat, Unicom’s TOD is designed with a curved seat with an inclined surface of disc to provide bubble tight sealing performance.