API 600 V.S API 594
Scope & Purpose
| Aspect | API 600 | API 594 |
|---|---|---|
| Governed Valves | Gate Valves (primary), Globe, Lift Check Valves | Check Valves (Swing, Dual-Plate, Lift, Tilting Disc) |
| Core Mission | Sealed isolation under high pressure/temperature | Rapid closure to prevent backflow |
| Critical Risk | Leakage → Process shutdown/environmental damage | Backflow → Equipment destruction (e.g., pump impeller) |
Design & Performance
| Parameter | API 600 | API 594 |
|---|---|---|
| Sealing | Bidirectional zero-leakage (ISO 5208 Rate A) | Unidirectional; allows minor leakage (low pressure) |
| Operation | Slow linear motion (prevents system shock) | Instant automatic closure (triggers on flow reversal) |
| Structural Focus | Forged body, fire-safe design (API 607) | Lightweight, water-hammer resistance |
Application Directive
Use API 600 when:
Isolating hydrocarbons/steam in pipelines (≥Class 300)
Bidirectional sealing is mandatory (e.g., refinery feed lines).
Use API 594 when:
Protecting pumps/compressors from backflow
Preventing water hammer in rapid-shutdown systems.
API 600/A594 valve in stock
