DBB is an abbreviation for Double Block and Bleed. This design typically involves two shut-off valves (usually ball valves) connected in series, with a vent valve between them. When both main valves are closed, the intermediate chamber can be pressure-released or sampled through the vent valve, thus achieving double isolation and verifying a tight seal. This configuration is primarily used in applications requiring a higher level of isolation safety, such as during maintenance, repairs, or when reliable isolation of pipeline sections is necessary to ensure that upstream and downstream media do not cross-contaminate.
Operating Principle
Closed Position:
The ball rotates to the closed position, and the valve seats on both sides fit tightly against the ball, forming a double seal.
The middle valve chamber is isolated from the media on both sides, and residual media or pressure can be discharged through the drain port.
Open Position:
The ball rotates to the open position, allowing the media to flow freely through the valve, and the drain port is closed.
Maintenance and Repair:
Quick pressure relief is possible through the drain port, facilitating valve disassembly or seal replacement.
Partial maintenance can be performed without completely emptying the system, reducing downtime.
Core Advantages
Dual Sealing Redundancy
With two independent sealing pairs, even if one valve fails, the other valve remains shut off, significantly improving system safety.
Rapid Discharge and Maintenance
The intermediate discharge chamber can release residual media in real time, avoiding safety accidents or economic losses caused by media leakage during maintenance.
Reduced Leak Points
The integrated design replaces the traditional multi-valve series configuration, reducing the risk of pipeline system leakage.
Suitable for High Pressure and Hazardous Media
The valve body is forged from high-pressure resistant alloys (such as A105, 316L, and F11), suitable for pressure ranges from 2.5MPa to 100MPa and temperature ranges from -60℃ to 450℃, applicable to oil and gas, chemical reagents, liquefied hydrocarbons, and other scenarios.
Applications:
DBB ball valves are widely used in industries such as petroleum, chemical, metallurgy, and power, primarily for switching and regulating in fluid control systems. Examples include:
1. Pipeline systems in oil and gas extraction processes;
2. Fluid transport and distribution systems in chemical production processes;
3. Smelting and casting processes in the metallurgical industry;
4. Cooling water systems for boilers, steam turbines, and other equipment in the power industry.