Based on API 6D NPS 2-48 (DN 50-1200)-150 to 662°F (-101 to 350°C)double block and bleed ball valve

Technical specification
Design reference		API	ASME	rOCT
Design standard		API6D	ASME B16.34	/
Structural length	Flanged ends	API6D	ASEM B16.10	/
	Welded connection
Flanged ends		ASME B16.5/ASME B16.47		rOCT 33259 rOCT 12815
Butt-welding ends		ASME B16.25
Test&inspection		API6D	API598	rOCT 9544

 Notes:The sizes of valve connectingflange and butt-welding terminas can be designed according to customer's requirement.

                                                                                                                                                                                                                                                                                                                                                                   DN50~DN1200  PN10~PN420
                                                                                                                                                                                                                                                                                                                                                                   NPS2~NPS48  Class150~Class2500

                  

 

                                                                                                                                                                                                                                                                  

                                                                                  Full bore                                                                                                                                  Reduced-bore                                                                                                                 Worm Gearoperation

      

                                                                                                                                                       

A: The double block and blended ball valve is designed to provide dual isolation and discharge functions. It uses two independent sealing seats (upstream and downstream) to achieve complete fluid blockage, and includes a blended port to release pressure or residual fluid between the seats. This allows for verification of seal integrity and ensures system safety.

Conclusion: Therefore, the main function of the double block and blended ball valve is to provide reliable fluid isolation and pressure management mechanisms, ensuring the pipeline system remains safe during maintenance, testing, or emergency situations.

The principle of using double block and blended ball valve

Q: What is the working principle of a Double Block and Blended Ball Valve?

A: Its operation is based on the 90-degree rotation of the ball and a dual-sealing design. When the valve is closed, the rotating ball presses against two independent sealing seats (upstream and downstream), creating a double block that prevents fluid flow. A discharge port located between these seats allows operators to safely vent pressure from the intermediate chamber or take fluid samples, which verifies the integrity of the seals.

Conclusion: Therefore, the operating principle of the double block and blended ball valve relies on the rotating ball and dual-block design to ensure efficient and safe fluid isolation, combined with managed pressure release between the seals.

The operating conditions and advantages of double block and blended ball valve

Q: What are the common applications and key advantages of double block and blended ball valves?

A: This valve is widely used in harsh industrial environments like oil, gas, chemical, power, and water treatment industries. It is designed for pipeline systems handling high pressure, high temperature, corrosive fluids, or hazardous media. Its key advantages include:

• High Sealing Performance: The dual-seat design provides two independent seals, significantly reducing the risk of leakage.

• Enhanced Safety: The blend (or discharge) port allows for safe pressure release and verification of seal integrity, minimizing operational risks.

• Ease of Maintenance: Testing or fluid discharge can be performed without disassembling the entire valve, saving time and cost.

• High Reliability: Built to withstand harsh conditions, ensuring long service life.

• Space Saving: Its integrated design eliminates the need for multiple separate valves in the pipeline.

Conclusion: Therefore, the double block and blended ball valve provides a safe and reliable fluid control solution for demanding operating conditions. With advantages such as high safety, ease of maintenance, and strong adaptability, it is a key component in industrial pipeline systems.As a leading industrial valve manufacturer, SJ is proud to offer its high-performance double block and bleed valve solutions, specifically engineered for critical isolation in oil, gas, and chemical applications. Our double block and bleed ball valve features an advanced, space-saving integral design that houses two independent balls and a bleed mechanism within a single body, significantly reducing leak paths compared to traditional multi-valve setups. This specialized Dual Ball DBB Valve ensures absolute, zero-leakage isolation and reliable mid-chamber venting, allowing operators to safely perform downstream maintenance without shutting down the entire pipeline. With rugged construction in materials like LF2 low-temperature carbon steel and adherence to strict international standards, SJ delivers the safety, efficiency, and durability your process lines demand.