DIB-1 Carbon Steel Trunnion Ball Valve

The DIB-1 configuration, as defined by API 6D. This ensures that each seat provides a seal against pressure from a single source, and both seats must be compromised before downstream leakage occurs . This design is particularly suited for high-risk applications where zero tolerance for leakage is required, such as gas transmission, sour service, and critical process isolation.

DIB-1 Functionality (Double Isolation & Bleed)

As defined in API 6D, a DIB-1 valve is a single valve with two seating surfaces, where each seat provides a seal against pressure from a single source, with a means of venting/bleeding the cavity between the seating surfaces .

In the DIB-1 configuration. This means:

• Upstream seat: Seals against upstream pressure; if upstream pressure leaks into the cavity, cavity pressure exerts thrust on the downstream seat, forcing it more tightly against the ball .

• Downstream seat: Seals against downstream pressure; provides a redundant barrier if the upstream seat fails .

• Key distinction from DBB: In a DBB valve, if one seat leaks, the other seat does not provide backup sealing in the same direction . In a DIB-1 valve, both seats seal in the same direction, providing double isolation .

• Cavity relief: Because DIB-1 seats do not self-relieve (unlike self-relieving seats in DBB configurations), over-pressurization of the cavity must be managed via an external relief valve or other approved method .

Typical Applications

• Oil & Gas Pipelines: High-pressure transmission and distribution

• Gas Compression Stations: Isolation and venting for compressor units

• Refineries & Petrochemical Plants: Critical process isolation, where zero leakage is mandatory

• High-Temperature Applications: PEEK seats provide excellent thermal stability

• Critical Safety Appl