DBB (Double Block and Bleed)
A valve arrangement (or single valve body) providing two independent seating surfaces that isolate from both upstream and downstream sides, with a bleed/vent port between them to confirm isolation and drain the cavity. Required by API 6D and many oil & gas plant procedures for safe isolation of equipment for maintenance.
Related Terms
Related Products
Applicable Standards
Frequently Asked Questions
What is DBB (Double Block and Bleed)?
A valve arrangement (or single valve body) providing two independent seating surfaces that isolate from both upstream and downstream sides, with a bleed/vent port between them to confirm isolation and drain the cavity. Required by API 6D and many oil & gas plant procedures for safe isolation of equipment for maintenance.
What are the acceptance criteria for DBB (Double Block and Bleed)?
Acceptance criteria depend on the applicable standard. API 598 and ISO 5208 define leakage rate classes from zero (Rate A) to defined allowable drops (Rate D/F) based on valve size and test type. For dimensional and visual inspections, ASME B16.34 and the applicable valve standard define tolerances. Vajra Industrial Solutions provides full inspection documentation including shell test, seat leakage test, and dimensional check records.
What documents does Vajra provide for valve quality?
Vajra Industrial Solutions supplies valves with: (1) Material Test Certificates (MTC) per EN 10204 Type 3.1 for all pressure-retaining components, (2) Hydrostatic test reports to API 598 or ISO 5208, (3) Dimensional inspection certificates, (4) PMI (positive material identification) reports for alloy valves, and (5) Third-party inspection (TPI) by SGS, Bureau Veritas, Intertek, or TPIA as required. Contact sales@vajravyuh.com for a sample documentation package.
Need a Quote?
API 6D certified valves. Ships to 357+ cities worldwide. 24h response.
Request QuoteContact EngineerAll Categories
Technical Support
Have a Technical Question?
Our valve engineers can help specify the right valve for your application. Full project documentation available: MTCs, test reports, dimensional inspection, and third-party inspection coordination.