BS1868 Duplex Stainless Steel A890 4A Non-Return Valve
1. Product Overview
The BOPIN BS1868 Special Material Duplex Stainless Steel ASTM A890 4A Non-Return Valve is a high-performance industrial check valve designed for demanding pipeline systems where corrosion resistance, mechanical strength, and long-term reliability are essential. Manufactured strictly in accordance with BS 1868 design standard, this valve is widely used in oil & gas, petrochemical, offshore, seawater treatment, and chemical processing industries.
As a premium product from BOPIN Valve, this non-return valve adopts advanced duplex stainless steel metallurgy (ASTM A890 Grade 4A), offering superior resistance to pitting, crevice corrosion, and chloride-induced stress corrosion cracking.
2. Design Standard: BS 1868 Compliance
The valve is engineered based on BS 1868 swing check valve standard, which defines the requirements for cast steel check valves used in industrial service.
Key design characteristics include:
- Bolted bonnet structure for easy maintenance
- Swing-type disc mechanism for smooth opening and closing
- Low pressure drop during forward flow
- Reliable automatic backflow prevention
- Suitable for horizontal pipeline installation
BS 1868 valves are widely recognized for robust construction and stable sealing performance in high-pressure systems.
3. Body Material: ASTM A890 4A Duplex Stainless Steel
The core advantage of this valve lies in its duplex stainless steel A890 4A (CD3MN) body material.
Material properties:
- High tensile strength (higher than standard austenitic stainless steel)
- Excellent resistance to seawater and chloride corrosion
- Improved fatigue resistance under cyclic loading
- Good weldability and structural stability
- Suitable for high-pressure and aggressive media environments
This makes the valve ideal for offshore platforms, desalination plants, and chemical transport systems.
4. Working Principle
The BS 1868 swing check valve operates automatically based on fluid pressure:
- Forward flow enters the valve body
- Flow pressure pushes the disc open
- Fluid passes with minimal resistance
- When flow stops or reverses, gravity and back pressure close the disc
- The sealing surface prevents backflow effectively
This self-acting mechanism eliminates the need for external control or manual operation.
5. Structural Features
The BOPIN A890 4A non-return valve typically includes:
- Cast duplex steel body and bonnet
- Hinged swing disc assembly
- Precision-machined seat ring (metal-to-metal or optional soft seat)
- Replaceable sealing surface
- Pressure-tight bolted cover design
- Flanged RF/RTJ end connections
The internal flow path is optimized to reduce turbulence and pressure loss.
6. Standards and Compliance
This valve is manufactured in compliance with international standards:
- Design standard: BS 1868 / API 6D
- Pressure rating: ASME Class 150–600 (typical range)
- Face-to-face: ASME B16.10
- Flange standard: ASME B16.5 / EN 1092
- Testing standard: API 598
- Material specification: ASTM A890 4A
These standards ensure compatibility with global pipeline systems.
7. Performance Advantages
The duplex stainless steel BS 1868 non-return valve offers several technical advantages:
- Excellent corrosion resistance in seawater environments
- Strong resistance to erosion and cavitation
- Reduced maintenance frequency
- Stable sealing performance under high pressure
- Long service life compared to carbon steel valves
- Suitable for both clean and mildly contaminated fluids
8. Application Fields
This valve is widely used in:
- Oil and gas transmission pipelines
- Offshore drilling platforms
- Petrochemical processing plants
- Seawater desalination systems
- Power generation systems
- Chemical and fertilizer industries
- Marine engineering systems
Its durability under harsh environments makes it a preferred choice for critical service conditions.
9. Size and Pressure Range
Typical production range includes:
- Size: DN50 – DN600 (2” – 24”)
- Pressure class: Class 150 – Class 600 (higher on request)
- Temperature range: -40°C to +450°C (depending on trim and sealing)
10. Quality Testing
Each valve from BOPIN undergoes strict inspection procedures:
- Hydrostatic body test
- Seat leakage test
- Shell pressure test
- Dimensional inspection
- Non-destructive testing (NDT) if required
Testing ensures compliance with API 598 requirements and industrial safety standards.