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API 594 Flanged Check Valve
API 594 STANDARD · CLASS 150–2500 · SWING & TILTING DISC
The API 594 Flanged Check Valve is a heavy-duty automatic
non-return valve manufactured to API 594 standards for
critical backflow prevention in oil, gas, refinery, and power
generation pipeline systems. Rated from Class 150 to Class
2500 per ASME B16.34, it reliably protects pumps,
compressors, and upstream equipment from reverse flow
damage under extreme pressure and temperature operating
conditions.
| API 594 / API 6D | |
|---|---|
| Pressure Class | Class 150 / 300 / 600 / 900 / 1500 / 2500 |
| Size Range | NPS 1" – 40" (DN25 – DN1000) |
| Body Material | WCB · CF8 · CF8M · WC6 · WC9 |
| Valve Type | Swing Check / Tilting Disc |
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— Full Specifications
API 594 Flanged Check Valve - Parameter Table
| PARAMETER | SPECIFICATION |
|---|---|
| Standard | API 594 / API 6D |
| Pressure Class | Class 150 / 300 / 600 / 900 / 1500 / 2500 (ASME B16.34) |
| Size Range | NPS 1" – 40" (DN25 – DN1000) |
| Body Material | WCB (ASTM A216) / CF8 (ASTM A351) / CF8M / WC6 / WC9 |
| Disc Material | WCB+STL / CF8M / F316 / CF8 / F304 |
| Seat Material | WCB-STL, CF8, CF8M |
| End Connection | Flanged RF / RTJ – ASME B16.5 / B16.47 |
| Valve Type | Swing Check Valve / Tilting Disc Check Valve |
| Installation | Horizontal / Vertical (Upward Flow) |
| Cracking Pressure | ≤ 0.03 MPa (Type Dependent) |
| Leakage Class | API 598 / API 6D |
| Test Standard | API 598 (100% Shell & Seat Pressure Test) |
| Temperature Range | -29°C ~ +425°C (Material & Class Dependent) |
| Applicable Media | Crude Oil / Natural Gas / High-Pressure Steam / Refinery Media |
Our Production Process
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This Product Spec Sheet
Single-page datasheet for API 594 Flanged Check Valve.
- Full parameter table
- Dimensional drawing
- Materials & standards list
- Ordering code guide
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— WHY bAUTU
Why Specify This Valve from Bautu
Swing Check vs Tilting Disc Design
The swing check valve is recommended for large-diameter, moderate-velocity pipelines, offering low pressure drop and simple reliable operation. The tilting disc (Nozzle) check valve features a spring-assisted disc that closes rapidly before reverse flow develops, minimizing water hammer effects in high-velocity pump discharge and compressor outlet lines — making it the preferred choice for critical rotating equipment protection
API 598 Full Pressure Testing & Certification
Every valve undergoes 100% shell hydrostatic test and seat leakage test per API 598. Full material traceability (MTR), NACE MR0175 compliance for H2S service, and third-party inspection by TUV / BV / Lloyd's are available upon request, meeting international project specifications for oil & gas pipeline procurement across upstream, midstream, and downstream applications.
— FAQ
Frequently Asked Questions
What is an API 594 flanged check valve?
API 594 is the American Petroleum Institute standard governing wafer- and lug-style check valves, and it also covers flanged check valves used in oil, gas, and petrochemical pipelines. A check valve allows flow in one direction only, automatically preventing backflow without any manual or actuated operation. Bautu manufactures API 594 flanged check valves in pressure classes from Class 150 to Class 2500, in body materials including WCB carbon steel, CF8M stainless steel, and LCB low-temperature steel, suitable for high-pressure and high-temperature process service.
What is the difference between swing and tilting disc check valves?
A swing check valve uses a disc hinged at the top of the body that swings fully open with forward flow and drops shut on flow reversal — ideal for low-velocity, horizontal pipelines with infrequent flow changes. A tilting disc check valve features a disc pivoted near its center of gravity, which opens and closes at a much smaller angle. This reduces water hammer on closure and allows installation in both horizontal and vertical pipelines, making it the preferred choice for high-velocity pump discharge lines, compressor outlets, and systems sensitive to pressure surge. Bautu offers both types; our engineers can recommend the right design based on your flow velocity, pipe orientation, and system pressure.
What is the standard lead time, and can Bautu handle custom configurations?
Standard API 594 flanged check valves are delivered in 4–6 weeks from order confirmation. High-pressure classes (Class 900–2500) or large bore sizes typically require 6–8 weeks. Bautu supports custom configurations including Stellite-hardfaced seating surfaces for abrasive service, special trim materials (Duplex, Inconel), spring-assisted closure for vertical upward flow, and third-party inspection (SGS, BV, TÜV). Submit your datasheet or project specifications for a fast quotation within 24 hours.
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