Double Block and Bleed Ball Valve — Products & Sub-categories
Double Block and Bleed Ball Valve
Double block and bleed valves provide dual isolation and safe pressure release for maintenance and process safety.
African Valve supplies Double Block and Bleed Ball Valves in Nigeria for pipeline and process applications where dependable isolation is important. A DBB valve combines two isolation barriers with a bleed connection between them. Once the valve is closed, the space between the two sealing points can be vented or depressurized to check the isolation before maintenance or equipment servicing.
These valves are widely used in oil and gas, refineries, petrochemical plants, gas processing, pipelines, storage terminals and other industrial systems. They can also reduce the need for several individual isolation valves where a combined DBB arrangement is suitable.
Valve Design
The valve uses a quarter-turn ball mechanism. Turning the ball by 90° opens or closes the flow passage. In the closed position, the two seats isolate the pipeline from both sides. The cavity between the seats is connected to a bleed or drain point, allowing trapped pressure to be released.
African Valve can supply floating and trunnion-mounted designs, depending on valve size and pressure class. Full-bore and reduced-bore options are available, along with soft-seat and metal-seat configurations. The valve can be operated manually or fitted with a pneumatic, electric or hydraulic actuator.
Main Characteristics
| Feature | Available Options |
|---|---|
| Valve Design | Double Block & Bleed Ball Valve |
| Ball Type | Floating / Trunnion Mounted |
| Bore | Full / Reduced |
| Seating | Soft Seat / Metal Seat / Double Piston |
| Bleed Arrangement | Drain / Vent / Bleed |
| Operation | Lever / Gear / Pneumatic / Electric |
| End Connections | Flanged / RTJ / Butt-Weld / Socket-Weld |
| Size | Typically NPS ½–36 in |
| Pressure Class | ASME Class 150–2500 |
Materials and Construction
The body can be supplied in carbon steel, low-temperature carbon steel, alloy steel, stainless steel, duplex or super duplex, depending on the operating conditions. Common grades include ASTM A216 WCB, ASTM A352 LCB, ASTM A217 WC6/WC9, ASTM A351 CF8/CF8M and ASTM A995 duplex grades.
For the ball and stem, stainless steel, duplex, super duplex and nickel-alloy materials may be selected where the process requires greater corrosion or temperature resistance. Seat and sealing materials can include PTFE, RPTFE, PEEK, graphite and metal hard-facing.
Where DBB Ball Valves Are Used
For pipeline applications, designs can be supplied to relevant requirements such as API 6D, ISO 14313 and ASME B16.34, with pressure and leakage testing carried out according to the applicable project specification. Fire-safe, anti-static, anti-blowout stem and emergency sealant injection features can also be included where required.
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