API 608

Covers — metal ball valves (floating and trunnion-mounted) with flanged (DN 15–600), butt-weld, socket-weld, and threaded ends for petroleum, petrochemical, and industrial service; design, materials, ratings, and testing.

Does NOT cover (exclusions) — the following are governed elsewhere:

• General-service ball valves (flanged/BW) → MSS SP-72; small threaded/SW ball valves → MSS SP-110.
• Pipeline ball valves → API 6D.
• Fire-type qualification → API 607 / API 6FA; ratings → ASME B16.34; testing → API 598.

API 608 is the process/petroleum-grade ball-valve standard; API 6D governs pipeline duty.

API 608 sets minimum requirements for metal ball valves:

• Materials — steel/alloy bodies rated to B16.34 with defined seats and trim.
• Design — floating or trunnion ball, port options, antistatic device, and (as required) blowout-proof stem and fire-safe features.
• Examination & Testing — shell and seat testing per API 598; fire test per API 607/6FA where specified.

API 608 is the standard for process-grade metal ball valves — quarter-turn isolation valves prized for fast operation and tight shutoff. Floating-ball designs suit smaller sizes/pressures; trunnion-mounted designs handle larger sizes and higher pressures.

Ratings follow ASME B16.34 and testing follows API 598, with fire-safe qualification (API 607/6FA) added for hydrocarbon service. General-service ball valves fall under MSS SP-72/SP-110; pipeline duty under API 6D.

Engineering Note: Ball valves are on/off devices; throttling erodes seats. For fire-exposed hydrocarbon lines, require fire-safe (API 607/6FA) certification, not just a fire-safe design claim.