The Critical Role of Seawater Pumps in LNG Regasification
In LNG receiving terminals, Open Rack Vaporizers (ORV) rely on seawater as the heat source to vaporize liquefied natural gas from approximately -162°C to ambient temperature. This heat exchange process demands a continuous, reliable supply of massive seawater volumes—typically exceeding 13,000 m³/h per pump. The seawater pump is therefore the heart of the ORV system, and its performance directly impacts terminal efficiency, reliability, and operational costs.
However, seawater is one of the most challenging fluids for pumping equipment. Its high chloride content causes rapid pitting, crevice corrosion, and stress corrosion cracking in standard materials like cast iron or 304 stainless steel. In fact, at temperatures above 20°C, even 304L stainless steel shows significant pitting corrosion, while 2205 duplex stainless steel can withstand up to 80°C and 2% chloride ion concentration before pitting occurs.
Why Duplex Stainless Steel for LNG ORV Seawater Pumps?
Unmatched Corrosion Resistance
Duplex stainless steels offer a dual-phase austenite-ferrite microstructure that combines the best properties of both phases. The Pitting Resistance Equivalent Number (PREN) is the key indicator for localized corrosion resistance, calculated as: PREN = %Cr + 3.3%Mo + 16%N.
| Grade | PREN | Critical Pitting Temperature (ASTM G48) | Yield Strength |
|---|---|---|---|
| Duplex 2205 | 34–36 | ~35°C | 450 MPa |
| Super Duplex 2507 | 42–43 | ~65°C | 550 MPa |
| 316L (for reference) | 24 | — | — |
Duplex 2205 (PREN 34–36) offers excellent resistance to chloride stress corrosion cracking and is suitable for most seawater applications at ambient temperatures. In saline water environments, Duplex 2205 and Super Duplex 2507 have become the standard selection for offshore oil and gas industries.
Super Duplex 2507 (PREN 42–43) provides superior resistance to pitting, crevice corrosion, and stress corrosion cracking in high-chloride, hot environments. It is the specified grade for seawater systems, desalination plants, subsea equipment, and high-pressure sour service where 2205 may not provide adequate margin. As industry practice confirms, all seawater-contacting components in LNG receiving station pumps should be manufactured from super duplex stainless steel for maximum reliability.
High Mechanical Strength
Beyond corrosion resistance, duplex stainless steels deliver significantly higher strength than standard austenitic grades. Super Duplex 2507 offers approximately 22% higher yield strength (550 MPa vs. 450 MPa) and 28% higher tensile strength (795 MPa vs. 620 MPa) compared to 2205. This allows for thinner wall sections at the same design pressure, reducing weight and partially offsetting the higher material cost.
Proven Industry Application
Leading LNG terminals worldwide specify duplex and super duplex materials for seawater-handling equipment. In China’s Caofeidian Xintian LNG receiving terminal—a national key energy project with an annual design receiving capacity of 12 million tons—the seawater intake pump system uses 2205 duplex stainless steel for all flow-wetted parts. The system delivers 80,000 m³/h total water volume through 11 kilometers of pipeline.
Hunan Durafort VS1 Duplex Stainless Steel Vertical Turbine Pump
Hunan Durafort Pumps is a professional pump manufacturer in China, producing a comprehensive range of pumps including XSP split case pumps, LC vertical turbine pumps (vertical line shaft pumps), HD vertical mixed flow pumps, and ZLB vertical axial flow pumps. The company offers a full spectrum of corrosion-resistant materials: carbon steel, ductile iron, SS304, SS316L, Duplex SS2205, Super Duplex SS2507, 904L, CD4MCu, Titanium, and more.
The Durafort VS1 type LC vertical turbine pump is engineered specifically for demanding seawater applications in LNG ORV systems.
Technical Specifications
| Parameter | Range |
|---|---|
| Flow Rate | 50 – 8,400 m³/h |
| Head | 15 – 150 m |
| Speed | 980, 1,480, 2,970 r/min |
| Temperature | Up to 150°C |
Material Options for Seawater Service
The VS1 pump is available in a full spectrum of corrosion-resistant materials:
- Duplex Stainless Steel 2205 – Excellent chloride resistance, PREN 34–36
- Super Duplex Stainless Steel 2507 – Maximum pitting and crevice corrosion resistance, PREN 42–43
- SS304 / SS316L – For less aggressive environments
- 904L – Enhanced resistance to reducing acids
- CD4MCu – High-strength duplex alloy
- Titanium – Ultimate corrosion resistance for extreme conditions
- Carbon Steel / Ductile Iron – For non-corrosive applications
Design Features
- VS1 configuration – Vertical suspension, single-layer casing with discharge pipe passing through the riser
- Wet pit installation – Ideal for seawater intake from open water sources
- Pull-out design – Allows rotor assembly removal without dismantling the outer barrel, simplifying maintenance
- Multiple impeller types – Axial, mixed flow, or radial flow configurations for optimized hydraulic performance
- Wide hydraulic coverage – Flows from 50 to 8,400 m³/h and heads from 15 to 150 meters
Applications in LNG ORV Seawater Heating Systems
The Durafort VS1 duplex stainless steel vertical turbine pump is specifically designed for:
Seawater Intake for LNG Vaporizers
LNG receiving terminals require massive seawater flows for ORV operation. The VS1 pump delivers the required flow rates with the corrosion resistance needed for long-term reliability in marine environments. Vertical turbine pumps have been designed to handle clear or slightly polluted fluids in water and industrial applications, including LNG receiving terminals for seawater intake for LNG vaporizers.
Circulation and Cooling Water Services
Beyond ORV duty, these pumps serve auxiliary cooling water systems in LNG terminals, power plants, and petrochemical facilities.
Desalination and Brine Handling
The same corrosion-resistant construction makes the VS1 ideal for seawater desalination intake, brine backwash, and other aggressive fluid applications.
Duplex 2205 vs. Super Duplex 2507: Which to Choose?
| Criteria | Duplex 2205 | Super Duplex 2507 |
|---|---|---|
| PREN | 34–36 | 42–43 |
| Critical Pitting Temperature | ~35°C | ~65°C |
| Yield Strength | 450 MPa | 550 MPa |
| Relative Cost | Baseline | 30–50% premium |
| Best For | Ambient seawater, moderate chlorides | Hot seawater, high-chloride brines, subsea |
Duplex 2205 is sufficient for most seawater applications at ambient temperatures without crevices, moderate-chloride process streams, and mildly sour oil and gas production.
Super Duplex 2507 is specified when the environment exceeds 2205 capabilities: direct seawater service at elevated temperatures (>20°C), high-chloride produced water (>50,000 ppm Cl⁻) at temperatures above 80°C, and subsea production systems where combined chlorides and H₂S/CO₂ exceed 2205 limits.
Why Choose Hunan Durafort VS1 for Your LNG Terminal?
1. Material Flexibility
Choose from cast iron to titanium, with duplex and super duplex options specifically engineered for seawater chloride environments. 2205 offers excellent corrosion resistance for most seawater applications, while 2507 delivers maximum protection for the most aggressive conditions.
2. Engineered for Seawater Service
The VS1 pump’s material options—particularly Duplex 2205 and Super Duplex 2507—are specifically designed to handle demanding fluids, typically seawater, brackish water, brines, or other corrosive liquids, especially those containing chlorides or abrasive particles.
3. High Efficiency
Optimized hydraulic design minimizes energy consumption—a critical factor given that seawater pumps are the primary energy consumers in ORV operations.
4. Low Maintenance
Features like pull-out design and renewable wear rings allow for quick restoration of clearances and efficiency without major disassembly.
5. Proven Chinese Manufacturing
Hunan Durafort represents the next generation of Chinese pump manufacturers capable of delivering world-class equipment for critical energy infrastructure.
For LNG ORV seawater heating systems, the VS1 Duplex Stainless Steel Vertical Turbine Pump from Hunan Durafort delivers the perfect combination of corrosion resistance, high flow capacity, and reliable performance. Whether you need Duplex 2205 for standard seawater service or Super Duplex 2507 for maximum chloride protection, Durafort provides a tailored solution that ensures your LNG terminal operates safely, efficiently, and cost-effectively.
Contact Hunan Durafort Pumps today to discuss your LNG ORV seawater pump requirements.
