BS 6755 Ball Valves
What BS 6755 requires for ball valves — applicability, key and testing requirements, the alternative standards, and compliant supply with full certification.
What does BS 6755 require for ball valves?
BS 6755 (Testing of Valves - Production Pressure Testing and Fire Type Testing Requirements, British Standards Institution (BSI)) sets the design, material and testing requirements for ball valves in its scope. BS 6755 is the British Standard for valve testing, covering production pressure testing (Part 1) and fire type testing (Part 2). It is widely referenced in UK, Middle East, and Indian project specifications as an equivalent to ISO 5208 (production testing) and ISO 10497 / API 607 (fire testing). BS 6755 Part 1 defines leakage rate classes A through D, and is the most-cited valve leakage acceptance criterion in British-influenced project specifications.
Applicable Pressure Classes
Key Requirements
- Part 1, Leakage Rate A: Zero leakage (bubble-tight) at test pressure - the tightest class, typically required for toxic, hazardous, or zero-leakage applications
- Part 1, Leakage Rate B: Maximum 0.006 cm³/min per mm of nominal bore - applicable for gas and vapour service
- Part 1, Leakage Rate C: Maximum 0.18 cm³/min per mm DN - for general liquid service
- Part 1, Leakage Rate D: Maximum 1.8 cm³/min per mm DN - used for lower-criticality liquid isolation duties
- Shell hydrostatic test: 1.5× rated pressure at 38°C for a minimum duration per valve size
- High-pressure seat test: 1.1× rated pressure - checks seat sealing integrity under operating conditions
- Low-pressure seat test (Part 1): 0.6 ± 0.1 bar (air test) - verifies seat seal at near-atmospheric pressure, critical for gas valves
- Part 2 fire testing: valve must remain operable and maintain acceptable leak rate after 30-minute fire exposure at 750–1000°C
Testing Requirements
- Shell hydrostatic test at 1.5× pressure rating (production test on every valve)
- High-pressure closure test at 1.1× pressure rating
- Low-pressure air seat test at 0.6 bar ± 0.1 bar
- Duration per BS 6755 Table 1 (varies by valve size, NPS 1/2" through NPS 60")
- Temperature: ambient (10–40°C) for production tests
Alternative Standards for Ball Valves
Other standards that also govern ball valves — useful for spec cross-acceptance.
Related Standards
Connected Engineering
Need BS 6755 ball valves?
We supply BS 6755-compliant ball valves with full certification — share your size, class and service for a 24-hour quote.