Description

The DBB (Double Block and Bleed) ball valve offers dual shut-off, dual isolation, and bleed functions. It is ideal for use with various pipelines that carry aviation kerosene, light oil, natural gas, liquefied gas, pipeline gas, and chemical media, serving as an optimal solution for controlling media flow.

The core working principle of the DBB ball valve lies in the operation of two sealing slides installed on the plug. This valve optionally incorporates an automatic relief device. Once the valve is fully closed, this device helps prevent any abnormal pressure increase within the valve chamber, ensuring the valve’s effective functioning.

Moreover, the valve features a switch indicator that synchronizes with the switch position, offering an accurate display of the valve’s operational status. This feature enhances usability and allows for precise valve control.

Features of the DBB Ball Valve

1. Minimal Friction and Wear: During the valve’s opening and closing process, the valve body’s sealing surface does not come into contact with the sliding plate’s sealing surface. This absence of contact prevents friction and wear, extending the valve’s service life and reducing the opening and closing torque.
2. Convenient Maintenance: The DBB ball valve’s design allows for easy maintenance. There is no need to remove the valve from the pipeline for servicing; one only needs to disassemble the valve bottom cover and replace a pair of slides.
3. Cost Reduction: The reduced diameters of the valve body and plug contribute to cost savings.
4. Durable and Smooth Sealing Area: The inner cavity of the valve body is plated with hard chromium, resulting in a complex and smooth sealing area that enhances the valve’s durability and performance.

We have many products with  DBB Ball Valves, such as a chemical injection with a DBB valve

Understanding DBB and DIB: Definitions and Tests

A DBB (Double Block and Bleed) valve features two sealed seats and a discharge device in the middle chamber. When the valve is closed and the discharge device is opened, both ends of the valve are pressurized simultaneously. The sealing valve seat can block the pressure at both ends of the valve.

To meet the DBB definition, a valve must have two conditions and one function:

• Condition 1: The valve must have two sealed seats.
• Condition 2: The valve’s middle chamber must include a discharge device (for venting, blowdown, etc.).
• Function: When the discharge device in the middle chamber is opened, both ends of the valve are pressurized, and the sealing valve seat can block the pressure at both ends.

Testing a DBB valve involves the following steps as specified in Appendix H₉ of API 6D 24:

1. Start with the valve half open and fill the valve and valve chamber with a test medium (usually freshwater).
2. Close the valve and open the discharge device in the valve cavity, allowing the test medium to overflow from the discharge port.
3. Pressurize both ends of the valve until the pressure reaches 1.1 times the rated pressure of the valve shell material at 38°C.
4. Check for leakage through the discharge port in the valve cavity. The acceptance criterion for a soft seal is zero leakage, while for a hard seal, leakage should not exceed Class D as per iso5208.

Note that DBB valve seats do not have an isolation function. Conversely, DIB (Double Isolation and Bleed) valves come in two types: DIB-1 and DIB-2.

The DIB-1 valve requires an external automatic safety relief valve, as its seat cannot automatically relieve pressure. If pressure builds up in the valve chamber, the valve might explode. The relief pressure of the external relief valve should be between 1.1 and 1.33 times the rated pressure of the valve shell material at 38°C, and the reset pressure should not be less than 1.05 times.

A DIB valve has two sealed seats. When the valve is closed and the discharge device is opened, one end of the valve is pressurized, and the sealing valve seat can isolate the pressure.

In the case of a DIB-1 valve, both sealing seats have isolation functions. For a DIB-2 valve, one seat has a blocking function, and the other has an isolation function (generally, the blocking function seat is set at the upstream end of the valve).

To meet the DIB definition, a valve must have two conditions and one function:

• Condition 1: The valve must have two sealed seats.
• Condition 2: The valve’s middle chamber must include a discharge device (for venting, blowdown, etc.).
• Function: When the discharge device in the valve cavity is opened, one end of the valve is pressurized, and the valve seat can isolate the pressure at one end.

Conclusion

In conclusion, the Double Block and Bleed (DBB) ball valve serves a critical role in various industries, providing optimal control over different media flow in pipelines. Its unique features, such as minimal friction and wear, convenient maintenance, cost-effectiveness, and a durable, smooth sealing area, significantly enhance operational efficiency and safety.

Understanding the definitions, functions, and testing procedures for DBB and Double Isolation and Bleed (DIB) valves is vital for their appropriate use and maintenance. These valves, through rigorous testing procedures as outlined in industry standards like API 6D 24, ensure reliability and performance, promising improved safety, reduced installation costs, and less susceptibility to problems caused by vibration. Thus, embracing these technologies enables industries to achieve superior operational efficiency and safety.

Our Services

We provide a wide variety of DBB Ball Valves, each tailored to meet a diverse range of specific requirements. Do not hesitate to contact us to find the solution that best suits your needs. To demonstrate the high quality of our products, we give clients the option to request sample units.

We take great pride in delivering prompt customer service. Our team is always on hand to provide immediate responses and address your inquiries. We aim to deliver your orders as swiftly as possible, ensuring timely receipt of your purchases. Our online support operates 24/7, ready to serve you at any time.

Packaging & Delivery
Our products are carefully packaged in CASES, which offer several advantages:

1. They are lightweight and aesthetically pleasing, offering insulation and high strength without being prone to deformation.
2. They eliminate the need for fumigation, thus streamlining the shipping process and making it more efficient.