Twin-Ball Double Block and Bleed Valve

NSV Twin-Ball Double Block and Bleed Valve

This DBB valve integrates two independent trunnion-mounted balls and a central bleed port in one forged body, delivering true double block with verified cavity venting. Unlike single-ball DBB designs, the twin-ball configuration provides two fully independent mechanical barriers—ensuring fail-safe isolation even if one ball or seat fails.

 Standard materials include A105 carbon steel, F316 stainless steel, or duplex grades F51, F53, and F55, selected for sour service, cryogenic LNG, or offshore environments. Metal-to-metal seating meets API 607 fire-safe requirements.

Key Features

Valve Type Twin-ball DBB ball valve

Operation Manual gear (standard); electric/pneumatic/hydraulic optional

Body Material A105 / F316 / Duplex SS (F51, F53, F55)

Seating Metal-to-metal, fire-safe per API 607

Pressure Rating Class 150 to Class 2500

Size Range 2" to 48" (DN50 to DN1200)

End Connection Flanged (RF/RTJ), Butt-Weld, or Socket Weld

Standards API 6D, ASME B16.34, ISO 17292; ISO 15848-1 fugitive emission compliant

Performance

Both balls seal independently against full differential pressure. The bleed port enables safe cavity depressurization without system shutdown. Compact design reduces weight, flange count, and external leak paths versus separate valve arrangements.

Typical Applications

Used in LNG terminals, offshore platforms, subsea manifolds, natural gas pipelines, refineries, and chemical plants where dual independent isolation, regulatory compliance (e.g., API RP 14C), and personnel safety are critical.

Quality Assurance

Tested per API 598 and API 6D (shell, seat, cavity relief). Full material traceability with EN 10204 3.1 (MTC 3.1) certificates. Optional NDE, PMI, and helium leak testing.

FAQ

1. Q:Do you have customized valve?

A:Yes,we can supply customized valves.

2. Q: What kinds of valves do you manufacture?

A: We usually manufacture valves made of various materials such as cast Iron/ carbon steel,stainless steel,Alloy steel and industrial valves such as ball, gate, globe, check, bellows seal and ETC. For detail information, please refer to " Download>E-Catalog” of homepage.

3. Q:What’s the packing for shipping?

 A:Its carton for small valves(sample) and plywood case(don’t to fumigate).

4.Q:How can I visit your company?

A: We always welcome you to factory. However, your visit intention shall be pure. You can visit factory conveniently by noticing your visit to the department in charge depending on your visit purpose in advance. For the way to factory, please refer to map“About Us” of homepage.