TRI-BLOCK Double Block and Bleed valves provide redundant isolation in critical process systems where leakage cannot be tolerated. The design integrates two triple-offset butterfly valves within a single body, separated by a bleed port that allows operators to safely vent or monitor the cavity between the sealing surfaces.
This configuration provides two independent sealing barriers against process pressure. When the valve is closed, the cavity between the seals can be depressurized through the bleed port to confirm that both sealing surfaces are performing correctly. This capability improves safety during maintenance, shutdowns, and system inspections.
Because both shafts are mechanically linked, the valve can be operated using a single actuator or gearbox. This innovative linkage allows both sealing surfaces to move in unison while maintaining reliable sealing performance.
The TRI-BLOCK design reduces footprint, simplifies piping layouts, and eliminates the need for multiple valves and fittings in applications requiring double isolation.
Features
Key Features & Benefits
- True Double Block and Bleed Isolation: Two independent sealing surfaces isolate the upstream and downstream pipeline sections. The bleed port allows operators to safely vent trapped pressure and confirm seal integrity.
- Single Valve Body Design: Traditional double block and bleed systems often require two separate valves with intermediate piping. TRI-BLOCK integrates this functionality into one valve, reducing system complexity and potential leak points.
- One Actuator Operation: A patented shaft linkage allows both sealing surfaces to operate simultaneously using a single actuator or gearbox, simplifying automation and reducing equipment cost.
- Zero-Leakage Performance: The metal-seated design provides dependable sealing even in extreme conditions and meets industry standards such as API 598 and EN 12266 leak testing.
- Compact and Lightweight: Butterfly-based designs require less material and space than comparable ball or gate valve systems, helping reduce weight and installation cost.
- Reliable Operation in Severe Service: The triple-offset geometry minimizes friction between sealing surfaces, resulting in longer service life and consistent shutoff performance.
Specifications
Design & Technical Specifications
TRI-BLOCK valves are engineered for demanding process environments and critical isolation duties.
- Valve Type
- Double Block and Bleed (DBB) triple-offset butterfly valve
- Sealing System
- Metal-to-metal laminated seal
- Dual sealing surfaces for redundant isolation
- Size Range
- 3" – 24" (DN 80 – DN 600)
- Pressure Classes
- ANSI Class 150 – 300
- Temperature Range
- Cryogenic temperatures up to approximately 815°C depending on materials
- Body Materials
- Carbon steel
- Stainless steel
- Alloy steels and specialty alloys
- End Connections
- Double-flanged face-to-face configuration
- Compliance & Testing
- API 598 / EN 12266 leakage testing
- Fire-safe designs available
- Suitable for vacuum service and bi-directional sealing
Applications
Typical Applications
TRI-BLOCK Double Block and Bleed valves are ideal for processes where double isolation and safety verification are required.
- Pipeline Metering Stations: Allows operators to isolate sections of pipeline and verify sealing performance before maintenance or calibration.
- Multi-Product Manifolds: Prevents cross-contamination between different products transported through shared pipeline systems.
- Tank Storage Terminals: Ensures reliable isolation between tanks and transfer lines while allowing safe pressure release.
- Fueling and Hydrant Systems: Provides dependable isolation in systems where leakage could create safety or environmental risks.
- Chemical and Petrochemical Plants: Used where hazardous media or high-value process fluids require dependable double isolation.
Q & A
TRI-BLOCK Double Block and Bleed Valves Q & A
A standard DBB configuration often uses two separate valves installed in series with a bleed point between them. TRI-BLOCK valves integrate both isolation functions and the bleed port into a single valve body. This reduces equipment count, minimizes leak paths, and simplifies installation while still providing two independent sealing barriers.
Double block and bleed valves provide two layers of isolation plus a method for venting trapped pressure between them. This design allows operators to confirm that both seals are holding pressure before maintenance work begins, improving safety and preventing unintended product release.
These valves are commonly used in industries where leak prevention and process safety are essential, including:
- Oil and gas production and refining
- Chemical and petrochemical plants
- Power generation facilities
- LNG and cryogenic services
- Tank storage terminals
Yes. TRI-BLOCK valves use metal-seated sealing systems designed for high temperatures and aggressive media. Depending on materials and configuration, they can operate in extreme environments ranging from cryogenic conditions to very high process temperatures.
The bleed port between the two sealing surfaces allows operators to vent or monitor the cavity between the seals. If pressure is detected in the cavity, it indicates that one of the seals may not be holding. This feature provides a simple and effective way to verify isolation integrity.
Downloads
Download TRI-BLOCK Double Block and Bleed Valves Brochure
If you have any questions or are just looking for some help, we're happy to discuss your application with you. Reach out to us at (855) 737-474714 or fill out our online form.