Ball Valve Double Ball - Trunnion Mounted DBB Compact Manifold | Neway

Neway Double Ball Trunnion Mounted DBB

The Neway Double Ball Trunnion Mounted DBB is a compact manifold ball valve arrangement for double block and bleed isolation on high-pressure or large-bore lines. The range covers DN50–DN600 / 2"–24" and ASME Class 150–2500 / PN16–PN420.

Construction

The trunnion-mounted design mechanically supports both balls and reduces operating torque under high differential pressure. Body materials include carbon steel, stainless steel, alloy steel and duplex stainless steel. End connections are flanged RF or RTJ.

The compact DBB body replaces two separate isolation valves and an intermediate spool, reducing face-to-face length, flange joints and potential external leak paths.

DBB Function

Two independent ball closures isolate upstream and downstream pressure. The cavity between the two balls is fitted with a bleed connection for pressure verification, venting, draining or safe depressurisation before maintenance work.

Typical Applications

• refineries, petrochemical units and hydrocarbon processing
• gas processing, fuel gas, condensate and liquid hydrocarbon lines
• metering skids, analyser take-offs and custody transfer systems
• isolation of pressure vessels, filters, pig traps and compressors
• installations requiring compact DBB isolation instead of two valves and a spool piece

Suitable Media and Operating Conditions

• clean or filtered liquids, gases and vapours compatible with selected trim and seat materials
• natural gas, LPG, crude oil, refined products, process gas and utility hydrocarbons
• high differential pressure service where low operating torque is required
• temperature range depends on seat selection, elastomers and body material

Standards and Specification Points

• commonly specified to ASME B16.34 and API 6D requirements where applicable
• flange dimensions typically to ASME B16.5 or ASME B16.47 depending on size
• pressure testing should be defined according to API 598, API 6D or project specification
• fire-safe design to API 607 or API 6FA should be specified when required by service

Sealing and Trim Options

• soft seats such as PTFE, RPTFE or PEEK for tight shutoff in clean service
• metal-seated variants for higher temperature, erosive or dirty service
• anti-static device, blowout-proof stem and cavity pressure relief as project requirements
• NACE MR0175 / ISO 15156 materials for sour service when specified

Actuation Options

Available with manual gear operator, pneumatic actuator, electric actuator or hydraulic actuator. Actuator sizing should consider line pressure, maximum differential pressure, seat material, operating frequency and required fail position.

Variant Selection

• Soft-seated DBB: preferred for tight isolation in clean gas or liquid service.
• Metal-seated DBB: used where temperature, solids or erosion exceed soft-seat limits.
• Manual operation: suitable for infrequent isolation duties.
• Automated operation: used for ESD, remote isolation, metering skids or interlocked process systems.

FAQ

Why use a double ball DBB valve?
It provides two independent isolation barriers with an intermediate bleed point in one compact assembly.

Can the bleed port confirm isolation?
Yes. With both balls closed, the cavity can be vented and monitored to confirm pressure decay before maintenance.

What should be checked before selection?
Line size, pressure class, medium, temperature, corrosion allowance, seat leakage requirement, actuation method and applicable plant standards.