The DBB (Double Block and Bleed) Ball Valve is a specialized type of ball valve that integrates both double shut-off and bleed functions. It is widely utilized across industrial sectors-including petroleum, chemical, natural gas, and power generation-and demonstrates exceptional performance, particularly in applications requiring high levels of safety and reliability for fluid isolation.
Engineered for Extremes: High-Pressure DBB Ball Valves up to Class 2500
How Does a DBB Ball Valve Work?
Step 1: Closing the Valve: When the ball rotates 90 degrees to the closed position, the seats (one on the upstream side and one on the downstream) are pushed against the ball by internal springs and line pressure.
Step 2: Dual Isolation: Unlike floating ball valves, a DBB valve creates two separate seals. The upstream seat blocks the inlet pressure, while the downstream seat blocks any backpressure.
Step 3: The Bleed Function: This is the "B" in DBB. A small drain or vent valve is located on the valve body. By opening this, the operator can evacuate the "dead space" or cavity between the two seats.
DBB Ball Valve Design & Manufacturing Standards
| Item | Standard / Requirement | Description |
| General Design Standard | API 6D / ISO 14313 | Primary standard for pipeline DBB valve definitions |
| Pressure-Temperature Ratings | ASME B16.34 | Limits for pressure vs. temperature for various materials |
| Face-to-Face (F-F) | ASME B16.10 / API 6D | Ensures interchangeability for online valve replacement |
| Flange Dimensions | ASME B16.5 / ASME B16.47 | B16.47 Series A is typically used for sizes > 24" |
| Butt-welding End Standard | ASME B16.25 | For welded pipeline connections |
| Fire Safe Testing | API 607 / API 6FA | Ensures sealing integrity during high-temperature fire events |
| Pressure Testing | API 6D / API 598 | Includes mandatory DBB functional verification tests |
DBB Ball Valve Performance & Specification Range
| Parameter | Specifications | Remarks |
| Nominal Size | NPS 2" – NPS 60" | Preferred for large-diameter pipelines |
| Pressure Class | Class 150, 300, 600, 900, 1500, 2500 | Equivalent to PN20 – PN420 |
| Operating Temperature | -196°C to 550°C | Dependent on seat material (Soft vs. Metal Seated) |
| Bore Type | Full Bore (FB) / Reduced Bore (RB) | Full Bore is "Piggable" for pipeline cleaning |
| Leakage Class | Soft Seat: Rate A (Zero Leakage) | Metal seated typically meets Class V or VI |
| Operation Type | Lever, Gear, Pneumatic, Electric, Hydraulic | Selected based on torque and field conditions |
Material Configuration (Trim Chart)
| Part Name | Typical Materials (ASTM) | Seat Coating / Hard-facing |
| Body | A105, WCB, LCC, LF2, F316, F51 | Carbon, Low-Temp, Stainless, or Duplex Steel |
| Ball | A105+ENP, F316, F51, F53 | Hard-facing: Tungsten Carbide (TC) or Stellite |
| Seat Ring | PTFE, Devlon, Nylon, PEEK, Metal | Soft or Metal seated based on pressure/media |
| Stem | 4140+ENP, 17-4PH, F316, XM-19 | Features Anti-Blowout design |
| Seals / O-Rings | Viton (FKM), NBR, HNBR, AED | AED (Anti-Explosive Decompression) for gas service |
| Bleed / Drain Valve | SS316, SS304 | Located in the body cavity for pressure venting |
DBB vs. DIB
| Feature | DBB (API 6D 3.1.10) | DIB (API 6D 3.1.11) |
| Sealing Direction | Seals against pressure from a single source (Uni-directional). | Seals against pressure from either side (Bi-directional). |
| Cavity Relief | Automatically relieves pressure to the line. | May require external relief if both seats are bi-directional. |
| Safety Level | Standard for pipeline isolation. | Enhanced safety for critical or toxic media. |
GNEE DBB Ball Valve factory
Request a Technical Quote: Fast Delivery on API 6D DBB Ball Valves
FAQ
What is the difference between DBB and DIB ball valves
Double Block and Bleed (DBB) valves use two unidirectional seats to block pressure from both sides, whereas Double Isolation and Bleed (DIB) valves use bidirectional seats to seal against pressure from both ends independently.
What is DBB in ball valve
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.