Lift Check Valve for Cryogenic Service
Description
Lift Check Valve for Cryogenic Service – ASTM A351 CF8
Model: LCV-CR-CF8
Product Description: Extended bonnet, spring-loaded lift check valve designed for unidirectional flow in cryogenic applications down to -196 °C. All pressure-containing parts are cast ASTM A351 CF8 (304 stainless steel). The valve prevents reverse flow and protects upstream equipment in liquefied gas and low-temperature process lines.
1. Main Design Codes and Standards
| Item | Standard / Code |
|---|---|
| Valve Design | API 602, ASME B16.34, BS 6364 |
| Face-to-Face Dimensions | API 602 (B16.10 long pattern for Class 300/600) |
| End Connections | ASME B16.5 (Flanged RF), ASME B16.25 (Butt Weld), ASME B16.11 (Socket Weld) |
| Pressure-Temperature Ratings | ASME B16.34, Material Group 2.1 (A351 CF8) |
| Cryogenic Service Requirements | BS 6364, ISO 28921-1 |
| Testing & Inspection | API 598, ISO 5208 (with cryogenic seat test) |
| Bonnet Design | Extended cold-insulating bonnet (gas column) |
2. Main Technical Parameters
| Parameter | Specification |
|---|---|
| Nominal Size Range | 1/2″ (DN15) to 2″ (DN50) – larger sizes on request |
| Pressure Class | Class 150, 300, 600 |
| End Connections | Flanged RF, Butt Weld BW, Socket Weld SW |
| Body Construction | Bolted extended bonnet, lift check disc |
| Seating Surface | Integral or welded-in seat ring, hardfaced with Stellite Gr.6 |
| Spring | Inconel X-750 or SS316 (assisted closure for low cracking pressure and no slam) |
| Flow Direction | Uni-directional – flow under disc, vertical or horizontal with upward flow |
| Design Temperature Range | -196 °C to +200 °C (seat/spring may set lower upper limit) |
3. Pressure-Temperature Ratings (ASME B16.34, Group 2.1 – ASTM A351 CF8)
Austenitic stainless steel retains full strength down to -196 °C; no cryogenic derating required. Ratings below are maximum allowable non-shock working pressures.
| Temperature (°C) | Class 150 (bar / psi) | Class 300 (bar / psi) | Class 600 (bar / psi) |
|---|---|---|---|
| -196 to 38 | 19.8 / 285 | 51.1 / 740 | 102.2 / 1480 |
| 50 | 18.4 / 265 | 47.8 / 690 | 95.7 / 1380 |
| 100 | 13.8 / 200 | 40.0 / 580 | 80.0 / 1160 |
| 150 | 10.3 / 150 | 34.5 / 500 | 68.9 / 1000 |
| 200 | 8.6 / 125 | 30.0 / 435 | 60.0 / 870 |
Note: For continuous cryogenic operation, standard PTFE or graphite gaskets and soft goods must be cryogenically compatible. Spring material Inconel X-750 is rated for the full temperature range.
4. Materials of Main Parts
| No. | Part Name | Material | Remarks |
|---|---|---|---|
| 1 | Body | ASTM A351 CF8 | 304 stainless steel casting, fully solution annealed |
| 2 | Bonnet (Extended) | ASTM A351 CF8 | Gas column extension thermally calculated to keep top flange above 0 °C |
| 3 | Disc | ASTM A351 CF8 | Seating face hardfaced with Stellite Gr.6; fully guided |
| 4 | Seat Ring | ASTM A351 CF8 + Stellite Gr.6 overlay | Renewable or integral; lapped to disc |
| 5 | Spring | Inconel X-750 (UNS N07750) | Cryogenic compatible, assists silent closure |
| 6 | Bonnet Gasket | SS316L/Graphite spiral wound | Cryogenic-rated |
| 7 | Bolting | ASTM A193 B8M / A194 Gr.8M | Stainless steel for corrosion resistance |
| 8 | Guide Bushing | PTFE / PEEK | Low friction, prevents galling |
No stem packing is required as the valve operates automatically without external actuation. The extended bonnet provides a thermal barrier to prevent ice formation around the disc and guide areas.
5. Dimensions & Weight – Typical Examples (Class 300, BW or Flanged)
Face-to-face per API 602 long pattern. Extended bonnet height varies with service temperature to ensure warm bonnet top.
| NPS | DN | Face-to-Face L (mm) | Height H (approx. mm) | Approx. Weight (kg) |
|---|---|---|---|---|
| 1/2″ | 15 | 216 | 185 | 3.2 |
| 3/4″ | 20 | 235 | 195 | 4.5 |
| 1″ | 25 | 254 | 210 | 6.0 |
| 1½” | 40 | 305 | 245 | 10.5 |
| 2″ | 50 | 371 | 280 | 16.0 |
For Class 150 or Class 600, face-to-face lengths will differ. Certified drawings with exact dimensions are available upon request.
6. Performance Testing
| Test Item | Test Medium | Test Pressure | Acceptance Criteria |
|---|---|---|---|
| Shell Hydrostatic | Water | 1.5 × rated CWP (e.g., 76.7 bar for Class 300) | No visible leakage or deformation |
| Seat Tightness – High Pressure | Water | 1.1 × rated CWP (56.2 bar for Class 300) | API 598 Rate A (zero leakage for resilient/metal-seated, as per specified seat type) |
| Seat Tightness – Low Pressure | Air / Nitrogen | 6 bar (87 psi) | Zero bubble leakage |
| Cryogenic Seat Test | Liquid Nitrogen (-196 °C) | 1.1 × rated CWP at test temp | BS 6364 / ISO 28921-1 leakage rate |
| Functional Test (Spring Closure) | Air | – | Disc closes smoothly, no sticking |
7. Cryogenic Design Features
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Extended Bonnet: The bonnet length is thermally analyzed to ensure the disc, spring, and guide area remain free of ice accumulation. The cold gas column keeps the bonnet top flange above 0 °C without external heating.
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Spring-Assisted Closure: An Inconel X-750 spring ensures positive disc closure even at very low flow rates or low backpressure. The spring-assisted design prevents water hammer and enables installation in horizontal or vertical upward flow lines.
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Hardfaced Trim: Stellite Gr.6 on both disc and seat provides excellent galling resistance at cryogenic temperatures and allows long-term bubble-tight sealing.
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CF8 Cryogenic Toughness: ASTM A351 CF8 retains excellent impact toughness at -196 °C (typically > 40 J), eliminating the risk of brittle fracture.
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Guided Disc: A full-length guide bushing in the bonnet ensures perfect disc alignment with the seat every time, reducing leakage and wear.
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No External Leak Path: The only potential atmospheric leak path is the bonnet gasket, which is a fully trapped spiral wound gasket. There is no stem packing, making the valve inherently low-emission.
8. Application Scope
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Suitable Media: Liquefied natural gas (LNG), liquid nitrogen (LIN), liquid oxygen (LOX – clean & degreased), liquid argon, liquid ethylene, and other cryogenic fluids compatible with 304 stainless steel.
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Temperature Range: -196 °C to +200 °C (continuous); spring and gasket materials determine the upper limit.
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Industries: Air separation units, LNG terminals, cryogenic storage and transport, industrial gas pipelines, chemical processing.
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Key Advantages:
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Zero external leakage design (no stem packing).
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Low cracking pressure and silent, non-slam operation.
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Compact and robust; suitable for high-pressure cryogenic lines.
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Extended bonnet protects internals from freezing and ensures reliable operation without lubrication.
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9. Optional Configurations & Accessories
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End Connections: Flanged (Raised Face), Butt Weld (Schedule matching), Socket Weld, or Hub.
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Seat Material Alternatives: Soft seat (PCTFE, PTFE) for absolutely zero leakage at cryogenic temperatures (limited to lower pressures).
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Spring Material: SS316 for less demanding temperature cycles; Inconel X-750 standard.
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Oxygen Service Cleaning: Degreased, cleaned, inspected and bagged per CGA G-4.1 or ASTM G93.
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NACE MR0175: Materials selected for sour gas service (CF8 with 22HRC max. hardness can be certified).
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Travel Indicator: External mechanical indicator to show disc position (open/closed).
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Welded Bonnet: For permanent installation with minimal leakage risk.
Disclaimer: This technical data sheet is intended as an engineering reference based on recognized industry standards (API 602, ASME B16.34, BS 6364). All dimensions, ratings, and material data are typical and may be changed without notice. The user must verify the valve’s suitability for the specific service conditions and obtain certified manufacturer’s documentation and material test certificates prior to installation.
