Swing Check Valve – Diagram, Types, and Applications

I. Overview of Swing Check Valve: A Core Industrial Valve

II. Structural Analysis and Working Principle

• Valve Body: Adopts a full-bore streamlined design with smooth internal flow paths, achieving a drag coefficient as low as 0.5–1.2 to significantly reduce fluid pressure loss. Available in straight-through, Y-type, and other shapes to fit different installation space requirements.

• Disc: Connected to the valve body via a hinge shaft, allowing free swinging. Disc materials can be metal (e.g., carbon steel, stainless steel) or composite materials, with surface hardening to enhance wear resistance.

• Sealing Seat: Works with the disc to achieve sealing, divided into metal seals (suitable for high-temperature and high-pressure conditions) and elastic seals (suitable for corrosive media). Sealing performance complies with API 598, with a leakage rate controlled below 0.15×10⁻³ mm³/s.

1. Forward Flow: When fluid acts on the disc with a forward pressure of ≥0.5 psi, the disc swings upward around the hinge shaft at an opening angle typically between 60°–90°, allowing unobstructed fluid passage.

2. Backflow Cut-off: When fluid flow stops or reverses, the disc quickly falls back to the sealing seat under its own gravity and reverse pressure, forming a tight seal to prevent backflow. The entire process requires no external power, with a response time ≤0.3 seconds to ensure system safety.

• Pressure Classes: Ranging from Class 150 (PN10) to Class 2500 (PN400), with a maximum working pressure of 450 bar, meeting full-range needs from low-pressure civil use to high-pressure industrial applications.

• Temperature Range:

• • Metal-sealed type: -35°C to 450°C, suitable for high-temperature media like steam and thermal oil;

• • Elastic-sealed type: -20°C to 230°C, ideal for low-temperature liquids and chemically corrosive media.

• Bore Range: DN15 (1/2″) to DN900 (36″), with support for custom extra-large bores to meet special engineering requirements.

• Connection Types:

• • Flanged connection: Complies with international standards such as ANSI B16.5 and ASME B16.47 for easy integration with different pipeline systems;

• • Threaded connection: Uses standard threads like NPT and BSP for quick installation in small-bore pipelines;

• • Butt-weld connection: Integrates with pipelines via groove welding to ensure sealing under high-pressure conditions.
    

    

• Structural Features: The disc is vertically installed in the valve body, featuring a simple structure and low manufacturing cost as the most commonly used basic model.

• Technical Advantages: Optimized flow path design minimizes pressure loss; gravity-driven disc requires no auxiliary devices, enabling easy maintenance.

• Application Scenarios: Water, air, and light oil transportation in municipal water supply, HVAC systems, and general industrial pipelines.

• Structural Innovation: No independent valve body; installed by clamping between two flanges, with an overall length 1/3 that of the standard type, saving up to 50% space.

• Performance Enhancement: Adopts a spring-assisted closing mechanism to increase closing speed by 30%, effectively reducing water hammer effects; lightweight disc design lowers the minimum opening pressure to 0.3 psi.

• Application Scenarios: Compact pipeline systems (e.g., ships, offshore platforms), high-viscosity media (syrup, slurry) transportation, and scenarios requiring rapid response.

• Design Highlights: The disc is installed at an inclination (15°–30°), increasing the flow area by 20% compared to the standard type, suitable for low-flow and low-pressure difference systems.

• Technical Breakthrough: Floating sealing structure automatically compensates for sealing surface wear, extending service life; optimized flow path design reduces pressure drop by 15%, with significant energy-saving effects.

• Typical Applications: Aeration systems in wastewater treatment plants, farm irrigation pipelines, and chemical raw material transportation, especially suitable for media containing particulate impurities.

• Structural Advantages: Y-shaped valve body with a detachable inspection port, allowing maintenance of the disc and sealing seat without pipeline disassembly, reducing inspection time by 40%.

• Performance Features: Larger flow path curvature radius further reduces fluid resistance, with a Kv value 25% higher than the standard type; can be configured with a dual-disc design to improve stability under high-flow conditions.

• Application Fields: Sterile pipelines in the food and pharmaceutical industry (e.g., beverage filling lines, pharmaceutical pure water systems), and inlets/outlets of fine chemical reactors, meeting high cleanliness requirements.

1. Material Preparation:

• • Casting Process: Uses resin sand casting technology to control valve body wall thickness deviation within ±0.5mm; high-temperature annealing eliminates internal stress, increasing pressure resistance by 20%.

• • Forging Process: For high-pressure valves (Class 600 and above), die forging is used to align material grains along the stress direction, improving fatigue resistance by 30%.

2. Precision Machining:

• • CNC lathes machine discs and sealing seats to IT7-level fit precision, with surface roughness Ra≤1.6μm;

• • Laser cladding technology is used to overlay Stellite alloy on sealing surfaces, with a cladding layer thickness of 0.5–1.0mm and hardness uniformity error ≤5HRC.

3. Surface Treatment:

• • Internal and external surfaces are sandblasted to Ra≤12.5μm and coated with epoxy resin (thickness ≥200μm), achieving a salt spray test life ≥1500 hours and meeting ISO 12944 C5-M anti-corrosion standards.

• Performance Testing: Each valve undergoes a 1.5x nominal pressure strength test and 1.1x sealing test; helium mass spectrometer leak detectors are used for leakage rate detection with a precision of 1×10⁻⁹ mbar·L/s;

• Nondestructive Testing: Ultrasonic testing (UT) and magnetic particle testing (MT) are performed on valve bodies to ensure no internal cracks or inclusions;

• Life Testing: Simulated working condition fatigue tests verify that valve opening/closing cycles ≥100,000 times with no sealing performance degradation.

• Low Flow Resistance Design: Full-bore streamlined flow path combined with an optimized disc structure increases the Kv value by 25% compared to traditional check valves, reducing system energy consumption by 15%–20%;

• Rapid Response Capability: Spring-assisted valves have a closing time ≤0.2 seconds, effectively suppressing water hammer pressure to protect pipelines and equipment.

• Wide Temperature and Pressure Range: Covers -35°C to 450°C and 0.1–450 bar, adapting to extreme media such as steam, LNG, and strong acids/alkalis;

• Contamination Resistance: Tilting disc and Y-type valves can pass impurities up to 5mm in diameter, reducing blockage risks in complex media conditions.

• Modular Design: Replaceable vulnerable parts such as discs, sealing seats, and hinge shafts reduce maintenance time by 50% and spare parts inventory costs by 30%;

• Long Service Life: Through hardening treatment and wear-resistant materials, the disc wear rate ≤0.01mm per 1000 cycles, extending service life by over 20% compared to similar products.

VII. Industry Application Scenarios

• Crude Oil Transportation: Installed at the inlets/outlets of refinery atmospheric and vacuum distillation units to prevent high-temperature crude oil backflow from damaging pumps;

• Chemical Reactions: Prevents material backflow in polymerization kettle and reactor pipelines to ensure process safety;

• LNG Storage and Transportation: Cryogenic valves (-196°C) used in LNG storage tank vapor balance pipes to ensure sealing reliability.

• Water Supply Systems: Prevents water hammer impacts in pressurized pump stations and high-rise building water pipelines, protecting pumps and pipe networks;

• Wastewater Treatment: Applied in aeration tank return pipes and sludge pump outlets to avoid activated sludge backflow;

• Flood Control: Installed at stormwater pump station outlets to prevent flood backflow into urban pipelines.

• Thermal Power Systems: Prevents steam backflow in steam turbine condensate recovery pipelines to improve thermal efficiency;

• Nuclear Power: Safety-class valves used in reactor coolant circulation systems, meeting seismic (Class 1) and sealing requirements;

• New Energy: Prevents oil backflow in wind turbine hydraulic circuits to ensure stable pitch system operation.

• Food Processing: Sterile-grade valves (surface roughness Ra≤0.8μm) used in beverage filling lines and dairy sterilization equipment, complying with FDA and GMP hygiene standards;

• Pharmaceutical Industry: High-purity stainless steel valves (316L material) applied in pure water and liquid medicine pipelines to avoid media contamination;

• Paper and Printing: Controls unidirectional flow in pulp transportation and steam pipelines, reducing equipment downtime due to faults.

1. Media Properties:

• • Corrosive media: Choose 316L stainless steel or duplex steel bodies with PTFE or Viton seals;

• • High-viscosity media: Prioritize wafer or tilting disc valves to reduce opening resistance.

2. Operating Parameters:

• • Calculate valve bore size based on maximum flow (recommended velocity ≤3m/s) and select pressure classes according to system pressure-temperature curves;

• • In low-temperature environments, use extended bonnets to prevent packing Envelope icing and failure.

3. Installation Space:

• • Choose wafer type for compact scenarios (short length); prioritize flanged connections for large-bore pipelines.

• Flow Direction Confirmation: Install strictly according to the arrow identification on the valve body; reverse installation will cause valve failure;

• Pipeline Support: Set fixed supports at both ends of the valve with a spacing ≤5 times the pipe diameter to avoid pipeline stress transfer to the valve body;

• Sealing Treatment: Use gaskets compatible with media properties (e.g., spiral-wound metal gaskets, rubber gaskets) for flanged connections, and tighten bolts uniformly according to standard torque.

• Regular Inspections: Clean valve internal impurities every 6 months and lubricate hinge shafts annually with food-grade grease (for hygiene-class valves);

• Leakage Handling: When detecting seal leakage, first check for wear or foreign objects on the sealing surface; lightly worn surfaces can be ground, and severely damaged components should be replaced;

• Performance Testing: Conduct pressure and sealing tests every 2 years to ensure valve performance meets design requirements.

• Design Standards: API 6D (Petroleum and Natural Gas Industry), API 594 (Wafer Check Valves), ASME B16.34 (Valve Pressure-Temperature Ratings);

• Testing Standards: API 598 (Leak Test), ISO 15848-1 (Volatile Organic Compound Emissions), BS 6755-2 (Water Hammer Test);

• Certifications: CE, UL, FM, SIL 3, and compliance with safety specifications such as EU PED and US ASME BPVC, meeting market access requirements in major global regions.

1. Intelligent Upgrades: Integration of pressure sensors, temperature transmitters, and IoT modules enables remote valve status monitoring and fault early warning; predictive maintenance technology reduces downtime by 40%;

2. Green Manufacturing: 3D printing for complex flow path components increases material utilization from 60% to 95%, reducing carbon emissions by 30%;

3. High-Pressure and Corrosion-Resistant Demand: With the development of deep-sea oil and gas extraction and new energy material processing, demand for Class 2500+ high-pressure valves and special alloy valves resistant to strong acids/alkalis continues to grow.

• Self-Cleaning Sealing Technology: Nano-ceramic coating (50–100μm thickness) on the disc surface with a hardness of HV1500+ effectively prevents scaling and particle adhesion, reducing maintenance frequency;

• Low-Noise Design: Fluid dynamics simulation optimizes disc contours, combined with damping spring components, reducing valve operating noise from 85dB to 72dB, compliant with ISO 3744 industrial noise control standards;

• Lightweight Material Application: Development of titanium alloy (TA2/TC4) valve bodies, reducing weight by 40% compared to stainless steel, suitable for special fields such as aerospace and deep-sea exploration.