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Help CenterMarine Pump Stop Check Valve With Mill Test Report, Manufactured to GB/T1855
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As a leading valve manufacturer established in 2016, Shanghai Zhibang Valve Manufacture Co., Ltd specializes in providing high-performance fluid control solutions for demanding marine environments. Our Marine Pump Stop Check Valve, manufactured strictly to the GB/T1855 standard, represents our commitment to reliability, safety, and precision engineering. This valve is engineered to prevent backflow in marine pump discharge lines, a critical function for protecting pumps and ensuring the operational integrity of onboard systems. With our products successfully exported to markets across North America, Europe, Asia, and beyond, we understand the stringent requirements of the global maritime industry. Each valve is backed by a comprehensive Mill Test Report, providing full traceability and verification of material properties and manufacturing quality, giving shipbuilders, shipyards, and marine engineers the confidence they need.
Core Function & Design Philosophy:
This valve combines the functions of a stop valve (isolation) and a check valve (non-return) into a single, compact unit. Its primary role is to be installed on the discharge side of centrifugal pumps, boiler feed pumps, and other critical marine pumping systems. When the pump is operating, the valve allows forward flow. When the pump stops, the disc automatically closes to prevent reverse flow and water hammer. It can also be manually closed via its external stem for positive isolation during maintenance. This dual functionality saves space, reduces installation points, and enhances system reliability.
Key Features & Technical Advantages:
- Robust Construction for Harsh Environments: Manufactured from high-grade cast steel (WCB) as standard, with optional materials like stainless steel (CF8M/316) or ductile iron available for specific corrosive service (e.g., bilge, ballast, seawater cooling). All materials are verified by the supplied Mill Test Report.
- Precision Machining & Sealing: Critical sealing surfaces, including the seat and disc, are precision machined to ensure a bubble-tight seal when closed, preventing even minimal leakage. The stem is typically made of stainless steel for smooth operation and corrosion resistance.
- Reliable Swing Check Mechanism: Utilizes a hinged disc (swing type) design. The disc swings freely on a pin, offering low flow resistance in the open position and quick, positive closure when flow diminishes or reverses. An external lever or handwheel allows for manual override.
- Enhanced Safety & System Protection: Effectively prevents backflow which can cause pump reversal, damage impellers, and induce dangerous water hammer pressures that can rupture pipes and fittings. This protects valuable marine assets and ensures crew safety.
- Compliance & Traceability: Manufactured in full compliance with the Chinese national standard GB/T1855 for stop-check valves. Our ISO9001 certified quality management system governs every production step, from raw material inspection to final testing.
Detailed Technical Specifications:
| Parameter | Specification / Option |
| Design & Manufacturing Standard | GB/T1855 |
| Nominal Pressure (PN) | PN16, PN25, PN40 |
| Nominal Diameter (DN) | DN15 (1/2"), DN20 (3/4"), DN25 (1"), DN32 (1 1/4"), DN40 (1 1/2"), DN50 (2"), DN65 (2 1/2"), DN80 (3"), DN100 (4"), DN125 (5"), DN150 (6"), DN200 (8"), DN250 (10"), DN300 (12") |
| Body Material (Standard) | Carbon Steel (WCB) |
| Alternative Body Materials | Stainless Steel (CF8/304, CF8M/316), Ductile Iron |
| Disc & Seat Material | Stainless Steel (Standard), with optional hard-faced sealing surfaces for erosive services |
| Connection Type | Flanged (RF, FF per GB/T, ANSI, JIS standards), Threaded (NPT, BSPT/BSPP) |
| Operating Temperature | -29°C to +425°C (for WCB material, dependent on seat material) |
| Operation | Manual (Handwheel/Lever), with optional gear operator for large sizes |
Benefits for Your Marine Operations:
- Space & Cost Efficiency: Replaces the need for separate stop and check valves, saving valuable space in crowded engine rooms and reducing overall piping component costs.
- Reduced Maintenance: Robust design and quality materials lead to longer service intervals and lower lifetime maintenance costs compared to inferior products.
- Improved System Uptime: By preventing pump damage from reverse flow, this valve minimizes unplanned downtime, a critical factor for vessel operational efficiency.
- Simplified Procurement & Documentation: The inclusion of a Mill Test Report with each valve simplifies your quality assurance and regulatory compliance processes for class societies.
- Global Supply Chain Support: With annual export values between US$1-1.5 million and major shipment ports in Shanghai, Guangzhou, Hong Kong, and Beijing, we offer reliable logistics to shipyards and clients worldwide.
Frequently Asked Questions (FAQ):
Q1: What is the main difference between a standard check valve and this stop check valve?
A: A standard check valve only prevents backflow automatically. A stop check valve adds a manual override feature via an external stem and handwheel. This allows an operator to forcibly close the valve regardless of flow direction, providing positive isolation for maintenance, which a standard check valve cannot do.
Q2: Can this valve be used for both freshwater and seawater applications on a vessel?
A: Yes, but material selection is key. The standard carbon steel (WCB) version is suitable for non-corrosive fluids like freshwater, lubricating oil, or fuel. For seawater, ballast, or bilge applications, we strongly recommend the stainless steel (CF8M/316) or other corrosion-resistant alloy option to ensure long service life.
Q3: What exactly is included in the Mill Test Report (MTR)?
A: The MTR is a certificate from the material mill. It typically includes the heat/charge number, chemical composition analysis, mechanical property test results (yield strength, tensile strength, elongation), and any supplementary tests performed, providing full traceability for the valve body and major component materials.
Q4: Is the valve suitable for vertical installation?
A: The swing check design generally requires that the valve be installed in a horizontal pipeline with the disc hinge pin horizontal. Installation in vertical lines may not allow the disc to swing freely and is not recommended. Please consult our engineers for specific orientation requirements.
Q5: Do you offer valves with certifications from marine classification societies (e.g., ABS, DNV, LR)?
A: While our standard production follows GB/T1855 and our factory is ISO9001 certified, classification society certification (type approval) is typically a project-specific requirement. We can arrange for third-party inspection and certification upon request and with adequate lead time. Please provide your specific class requirements when inquiring.
Q6: What is the lead time for an order?
A: Lead time depends on the size, material, quantity, and any special testing requirements. For standard sizes and materials in moderate quantities, typical production lead time is 4-8 weeks. We maintain close communication throughout the manufacturing process.
Q7: Can you supply valves with flanges matching international standards like ANSI or JIS?
A: Absolutely. While we manufacture to GB/T1855 for the valve design, the end connections (flanges) can be produced to match ANSI, JIS, DIN, or other international standards as required by your piping specifications. This ensures easy integration into your global vessel projects.
Q8: How does the valve handle water hammer?
A: By closing quickly upon flow stoppage or reversal, the valve prevents the column of water from moving backward and colliding with the closing pump impeller, which is a primary cause of water hammer. Its fast-acting swing disc mechanism is effective in mitigating this risk.
Trust in a manufacturer with a proven global track record. Shanghai Zhibang Valve Manufacture Co., Ltd. exports to key maritime regions including North America, Europe, Southeast Asia, and the Middle East, demonstrating widespread acceptance of our quality. Our ISO9001 certification underpins a consistent, controlled manufacturing process. The provided Mill Test Report is not just a document; it's your guarantee of material integrity and performance. By choosing our GB/T1855 Marine Pump Stop Check Valve, you are investing in a component that enhances safety, protects expensive equipment, and contributes to the reliable operation of your vessel. Contact us today to discuss your specific requirements, request a detailed quotation, or obtain technical drawings. Let us be your reliable partner for marine valve solutions.
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