Double Block and Bleed Ball Valves are aimed to get a double barrier on the piping, and bleed the fluid trapped between the two balls from a dedicated drain line. Body construction can be either forging or centrifugal casting. Wide range of materials: carbon steels, austenitic or martensitic SS, duplex-superduplex SS, nickel-based alloys.
Valve design can be either Trunnion or Floating type, anti blow-out stem and typically SPE seat design. Drain port is normally provided with a floating ball valve, to be fitted with Final User drain line. Valve seats can be soft or metal to metal hard-faced.
Main reference codes:
- Standard design in accordance with API 6D / ASME B16.34 / API 6A.
- Antistatic design as per API 6D and ISO 17292.
- Valve ends can be flanged (RF, FF, MF or FF, RTJ), according to ASME B16.5 (up to 24”) or ASME B16.47 (26” and above), Butt-Welding according to ASME B16.25, or Hub, according to customer Requirements.
- Fire Safe according to BS6755 / API 6FA / API 607, since each sealing point is provided by a secondary fire-safe seal in graphite. Valve soft seats also are provided with secondary metal-to-metal seal in case of fire.