Corrosion Resistance of Marine Butterfly Valves

The corrosion resistance of marine butterfly valves is a critical factor in their selection and application, especially in marine environments. Due to the presence of salt spray, high humidity, and seawater’s corrosive nature, marine equipment requires superior corrosion-resistant properties. Below are key aspects related to the corrosion resistance of marine butterfly valves:

1. Material Selection

Material plays a crucial role in determining the corrosion resistance of marine butterfly valves. Common materials include:

  • Stainless Steel(e.g., 316, 316L): Offers excellent resistance to corrosion and is suitable for saltwater and corrosive chemical media.
  • Bronze: Resists saltwater corrosion and is commonly used in seawater piping systems.
  • Duplex Stainless Steel: Combines high strength with resistance to pitting and crevice corrosion, making it ideal for harsh marine environments.
  • Plastic Linings(e.g., PTFE, PVDF): Plastic-lined valves enhance corrosion resistance, making them suitable for handling highly corrosive media.

2. Coating and Protection

Marine butterfly valves often feature coatings or surface treatments to improve corrosion resistance:

  • Epoxy Coatings: Enhance resistance to corrosion, particularly in seawater contact areas.
  • Thermal Spray Coatings: Application of corrosion-resistant alloys (e.g., nickel-based alloys) provides additional protection.
  • Anodizing(for aluminum alloys): Improves surface hardness and resistance to oxidation.

3. Design Features

  • Seal Material Selection: Resistant materials such as EPDM or fluororubber are often used for seals to prevent failures due to corrosion.
  • Optimized Structure: Minimizing gaps and dead zones reduces the accumulation of corrosive substances.

4. Environmental Impact

  • In marine environments, salt spray and electrochemical corrosion require special attention to pitting and crevice corrosion resistance.
  • For valves submerged in seawater for extended periods, electrochemical corrosion prevention methods such as cathodic protection are essential.

5. Standards and Certifications

The materials and corrosion resistance of marine butterfly valves must comply with international or industry standards, such as:

  • ISO 15156(Standards for materials resistant to sulfide stress corrosion).
  • DNV GL, ABS, BV Certifications: International classification societies impose stringent requirements for corrosion protection in marine equipment.

6. Maintenance and Care

Regular inspection and cleaning of the valve surface, along with timely replenishment or replacement of coatings, can effectively extend the service life of marine butterfly valves.

In summary, the corrosion resistance of marine butterfly valves depends primarily on material selection, surface treatment technologies, and appropriate adaptation to specific environmental conditions. During design and selection, it is crucial to consider factors such as media properties, operating temperature, and pressure comprehensively.

Shaft Materials in Marine Valve

Shafts in marine valves are critical components that connect the actuator or handwheel to the valve’s internal components, allowing for control of fluid flow. The material selection for marine valve shafts depends on the application, operating environment, and fluid type. Common shaft materials in marine valve applications include:

1. Stainless Steels

  • Grade 316/316L:
    • High corrosion resistance, particularly against seawater and marine atmospheres.
    • Suitable for most marine applications, including those handling water, oils, and certain chemicals.
  • Duplex Stainless Steels (e.g., 2205):
    • High strength and superior corrosion resistance.
    • Excellent performance in environments with high chloride concentrations (e.g., seawater).
  • Super Duplex Stainless Steel (e.g., 2507):
    • For highly aggressive environments, including high-pressure seawater systems.

2. Bronze and Brass Alloys

  • Aluminum Bronze (e.g., C95400, C95800):
    • Excellent resistance to marine corrosion and biofouling.
    • Commonly used in seawater applications.
  • Nickel-Aluminum Bronze:
    • Provides higher strength and wear resistance.
    • Often used in valves for seawater and hydraulic systems.

3. Monel (Alloy 400)

  • High resistance to corrosion, particularly in saltwater and acidic conditions.
  • Ideal for highly corrosive environments, including marine chemical systems.

4. Hastelloy (e.g., C276, C22)

  • Exceptional resistance to chemical corrosion.
  • Used in marine environments with aggressive chemicals or extreme conditions.

5. Titanium

  • Excellent resistance to seawater corrosion and lightweight.
  • Used in specialized, high-performance applications (e.g., submarines, desalination systems).

6. Carbon Steel (with coatings)

  • Less expensive but requires protective coatings (e.g., epoxy, galvanizing) to prevent corrosion in marine environments.
  • Typically used in less demanding applications.

7. Nickel Alloys

  • Provides excellent resistance to oxidation and chloride-induced corrosion.
  • Often used in valves for extreme marine environments.

Material Selection Factors:

  • Corrosion Resistance: Seawater and chlorides are particularly aggressive.
  • Strength and Durability: High-pressure systems require stronger materials.
  • Temperature Resistance: Some applications involve elevated temperatures.
  • Chemical Compatibility: Fluids handled by the valve may demand specific material compatibility.
  • Cost: Balancing performance with budget constraints.

When designing or selecting shafts for marine valves, proper consideration of operating conditions and regulatory standards (e.g., ABS, DNV, or IMO) is crucial to ensure reliability and compliance.

Rubber Seats in Marine Butterfly Valves

Rubber seats are widely used in marine butterfly valves, particularly in the design of centerline butterfly valves. These rubber seats offer excellent sealing performance, prevent medium leakage, and resist corrosion and wear in the marine environment. Below are some key characteristics and applications of rubber seats in marine butterfly valves:

marine valve seat

marine valve seat

1. Excellent Sealing Performance

Due to their flexible material, rubber seats can tightly fit the valve disc, ensuring good sealing. Even under low-pressure conditions, they effectively prevent leakage, which is crucial for the safety of ship systems.

2. Corrosion Resistance

As ships operate in marine environments, their piping systems are often exposed to seawater. Rubber seats, typically made from materials such as neoprene (CR), EPDM, and nitrile rubber (NBR), offer excellent corrosion resistance and can withstand exposure to seawater, oils, and other mediums, thereby extending the valve’s service life.

3. Wear Resistance and Aging Resistance

Rubber seats in marine butterfly valves are typically resistant to wear and aging. This allows the valve to maintain good sealing performance over long periods without aging or failure, making them especially suitable for systems with frequent opening and closing operations.

4. Easy Replacement and Maintenance

The design of rubber seats makes them easy to replace, particularly in the maintenance of marine piping systems. Due to the elasticity of the rubber material, installation and removal are relatively simple, reducing maintenance time and cost.

5. Adaptability to Different Temperatures and Pressures

Rubber seats used in marine systems are typically capable of handling a wide range of temperatures and pressures, making them suitable for various ship applications, including cooling water systems, ballast water systems, and firefighting systems.

Common Materials and Applications

  • Neoprene (CR): Suitable for seawater, oils, and other mediums, widely used in seawater cooling and ballast water systems.
  • EPDM: Offers excellent acid, alkali, and heat resistance, making it ideal for freshwater and air systems.
  • Nitrile Rubber (NBR): Has strong oil resistance, suitable for fuel systems.
  • fluororubber (Viton or FKM):typically withstanding temperatures above 200°C, making it suitable for high-temperature piping systems.

Rubber seats are an essential component in marine butterfly valves. Their sealing performance, corrosion resistance, wear resistance, and ease of maintenance make them indispensable in the marine industry.

Tianjin Tanghai Valve Co., Ltd. is a professional marine valve manufacturer, including butterfly valve, check valve, gate /Knife gate valve. We have certificates: CE, ISO, BV, DNV foundry and products approval. Now we have our own independent R & D, manufacturing, assembly and warehousing workshops; we have professional pre-sale and after-sale technical support and perfect services. Below is our wafer butterfly valve of marine valves,if you need to check more information, please click here:   https://www.tanghaivalve.com/wafer-type-butterfly-valve-th-btv-aw/

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The Booming Development of China’s Shipbuilding Industry

China’s shipbuilding industry has experienced remarkable growth in recent years, establishing itself as a global leader. Several key factors are driving this rapid expansion:

Policy Support: The Chinese government has provided strong policy support to the shipbuilding industry, viewing it as a vital strategic sector, particularly under initiatives like the “Belt and Road” and “Maritime Power” strategies. A range of supportive policies, such as financial subsidies, favorable financing, and R&D support, encourage the development of large ships, high-value vessels, and eco-friendly ships.

Technological Innovation and R&D: Chinese shipbuilders have steadily increased their investment in technological innovation, establishing an advanced shipbuilding technology system. In recent years, they have made significant strides in high-end ships such as LNG carriers and very large crude carriers (VLCCs). In addition, progress in intelligent vessels and autonomous ships has propelled technological upgrades across the industry.

Production Capacity and Economies of Scale: China’s shipbuilding industry has extensive production capacity and economies of scale, allowing for mass production of various types of vessels to meet global demands. The country’s top three shipbuilding groups—China State Shipbuilding Corporation (CSSC), China Shipbuilding Industry Corporation (CSIC), and China Merchants Heavy Industry—play a pivotal role in the global market, with strong production capacity and large-scale operations.

Market Demand and Globalization: With the growth of global trade, especially in the Asia-Pacific and African regions, demand for large transport vessels continues to rise. Additionally, the global shift towards green shipping has driven the research and production of low-emission, energy-efficient ships. China’s shipbuilding industry actively engages in international collaboration and mergers, continuously expanding its market share.

Complete Industry Chain: China has a comprehensive shipbuilding supply chain, covering steel, electrical equipment, communication, and automation industries, ensuring efficient integration of materials and equipment. Moreover, related logistics, ports, and service facilities are continuously improving, creating a complete ecosystem for shipbuilding.

China’s share in the global market is steadily rising, with shipbuilding orders in 2023 surpassing those of South Korea and Japan, reflecting the industry’s competitive strength. It also highlights Chinese enterprises’ breakthroughs in high-end and green shipping sectors. As China advances in smart manufacturing and green energy, its shipbuilding industry is expected to continue expanding its influence on the global stage.

Disc Materials of Butterfly Check Valve(dual plate check valve)

The disc of a butterfly check valve plays a crucial role in controlling the flow of fluids by pivoting on a central axis to either open or close the valve. Depending on the application, pressure, and the fluid being handled, different materials are used for manufacturing the disc. Below are common materials used for butterfly check valve discs:

1. Stainless Steel

  • Grades: 304, 316, 316L
  • Characteristics: High resistance to corrosion, good mechanical properties, and durability. Suitable for water, steam, chemical, and food-grade applications.
  • Common Uses: Petrochemical, food and beverage, and water treatment industries.

2. Carbon Steel

  • Characteristics: Strong and cost-effective, but less corrosion-resistant than stainless steel. Usually requires coatings for corrosion protection.
  • Common Uses: General-purpose industrial applications where corrosion resistance is not a primary concern.

3. Ductile Iron

  • Characteristics: Combines strength and flexibility, offering good toughness and ductility. Requires coating (e.g., epoxy) for corrosion resistance.
  • Common Uses: Water distribution, wastewater, and low-pressure applications.

4. Aluminum Bronze

  • Characteristics: High corrosion resistance, particularly in seawater and marine environments. Good strength and wear resistance.
  • Common Uses: Marine, seawater handling, and desalination plants.

5. Nylon-Coated Disc

  • Characteristics: Nylon coating provides enhanced wear resistance and some degree of corrosion protection. Suitable for mildly corrosive environments.
  • Common Uses: Low-pressure industrial applications.

6. Elastomer-Lined Disc (Rubber)

  • Materials: EPDM, NBR (Nitrile), FKM (Viton)
  • Characteristics: The disc is typically coated with elastomeric materials to provide a bubble-tight seal and resist specific chemicals. Different elastomers offer various resistances to temperature, chemicals, and abrasives.
  • Common Uses: Applications requiring chemical resistance or sanitary conditions, like food processing and chemical plants.

7. Hastelloy

  • Characteristics: Highly resistant to corrosive and harsh chemical environments, particularly acids and oxidizing agents.
  • Common Uses: Chemical processing, pharmaceuticals, and industries dealing with corrosive fluids.

8. Monel

  • Characteristics: Extremely resistant to corrosion, particularly from acids, alkalis, and seawater. Excellent mechanical strength.
  • Common Uses: Marine, oil & gas, chemical, and heat exchanger applications.

9. Titanium

  • Characteristics: Exceptional resistance to corrosion in seawater, chlorides, and acidic environments. Lightweight and highly durable.
  • Common Uses: Aerospace, marine, chemical, and desalination applications.

The selection of disc material in a butterfly check valve is based on factors like the type of fluid being handled, the operating temperature and pressure, and the desired longevity of the valve.

Tianjin Tanghai Valve Co., Ltd. is a professional marine valve manufacturer, including butterfly valve, check valve, gate /Knife gate valve. We have certificates: CE, ISO, BV, DNV foundry and products approval. Now we have our own independent R & D, manufacturing, assembly and warehousing workshops; we have professional pre-sale and after-sale technical support and perfect services. Below is our wafer butterfly valve of marine valves,if you need to check more information, please click here:   https://www.tanghaivalve.com/wafer-type-butterfly-valve-th-btv-aw/

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Body Materials of Butterfly Check Valve

Butterfly check valves, used to prevent backflow in piping systems, are made from various materials depending on the application, fluid type, and operating conditions. The most common body materials for butterfly check valves include:

  1. Cast Iron:

Usage: Often used in general water applications, HVAC, and non-corrosive fluid systems.

Properties: Economical, good strength, and durability, but prone to corrosion if not coated.

2. Ductile Iron:

  • Usage:Preferred in water and sewage systems, oil and gas applications.
  • Properties:Stronger and more flexible than cast iron, offers better corrosion resistance and can handle higher pressures.

3. Carbon Steel:

  • Usage:Suitable for high-pressure and high-temperature applications such as oil, gas, and steam systems.
  • Properties:Strong and durable, but requires corrosion protection (e.g., coatings or linings) when used with corrosive media.

4. Stainless Steel (304, 316):

  • Usage:Common in corrosive environments, such as chemical processing, food, and pharmaceutical industries.
  • Properties:Excellent corrosion resistance, especially in environments involving chemicals or saltwater. More expensive but ideal for long-term durability in harsh conditions.

5. Aluminum Bronze:

  • Usage:Often used in marine applications or systems involving seawater.
  • Properties:High corrosion resistance, particularly in seawater and other saline environments.

6. PVC (Polyvinyl Chloride) / Plastic:

  • Usage:Frequently used in low-pressure systems, particularly in chemical or water treatment applications.
  • Properties:Lightweight, corrosion-resistant, and economical, but limited by temperature and pressure constraints.

7. Titanium:

  • Usage:Used in highly corrosive environments, such as in the chemical industry.
  • Properties:Excellent corrosion resistance and high strength-to-weight ratio, but expensive.

Each material is selected based on the specific application requirements, such as pressure, temperature, fluid type, and environmental conditions.

Tianjin Tanghai Valve Co., Ltd. is a professional marine valve manufacturer, including butterfly valve, check valve, gate /Knife gate valve. We have certificates: CE, ISO, BV, DNV foundry and products approval. Now we have our own independent R & D, manufacturing, assembly and warehousing workshops; we have professional pre-sale and after-sale technical support and perfect services. Below is our wafer butterfly valve of marine valves,if you need to check more information, please click here:   https://www.tanghaivalve.com/wafer-type-butterfly-valve-th-btv-aw/

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Feature of Concentric Type Butterfly Valve with Carbon Steel Body

A concentric butterfly valve with a carbon steel body is a common type of valve used in industrial applications for regulating or isolating the flow of fluids. The concentric design means that the valve disc and stem are aligned on the same axis, making it suitable for low-to-moderate pressure applications. Below are the key features of this type of valve:

  1. Concentric Design (Centerlined)

Shaft and Disc Alignment: The shaft (or stem) is centrally located in the valve body, and the disc rotates on the same axis as the shaft. This allows for even pressure distribution on the valve seat.

No Offsets: Unlike offset butterfly valves, concentric valves have no displacement of the shaft relative to the seat and disc, making them simpler and easier to maintain.

  1. Carbon Steel Body

Material Strength: Carbon steel is strong and durable, suitable for applications that involve moderate pressure and temperature.

Corrosion Resistance: Carbon steel provides moderate corrosion resistance but may require external coatings (such as epoxy) or internal linings to protect against aggressive chemicals or moisture.

Temperature Tolerance: Carbon steel can withstand relatively high temperatures (up to approximately 425°C or 800°F), making it appropriate for steam, oil, or gas applications.

Cost-Effective: Carbon steel is less expensive compared to stainless steel, making it a cost-effective solution for many industrial applications.

  1. Soft Seat

Elastomeric Seat: Concentric butterfly valves typically use soft seats made from elastomeric materials like EPDM, Nitrile (Buna-N), or PTFE. These materials provide a bubble-tight seal, especially in low-pressure applications.

Replaceable Seat: The seat is often replaceable, which allows for easy maintenance and longer valve life.

Leakage Protection: Soft seats offer good sealing performance and can achieve zero leakage (Class VI shutoff).

  1. Disc Design

Material: The disc is typically made of stainless steel, ductile iron, or other alloys to provide enhanced corrosion resistance in different environments.

Low Flow Resistance: When the valve is fully open, the disc is parallel to the flow of the fluid, resulting in minimal flow resistance and a low-pressure drop.

Tight Shutoff: The disc is designed to provide tight shutoff, making the valve ideal for applications where leakage prevention is critical.

  1. Bi-Directional Flow

The concentric butterfly valve is capable of controlling the flow of fluids in both directions, enhancing its versatility in piping systems.

  1. Low Torque Requirement

The concentric design requires low torque for operation. This makes the valve easier to operate manually and reduces the power needed for actuation when automated.

  1. Compact and Lightweight

Space-Saving: Butterfly valves are compact and lightweight compared to other valve types like gate or globe valves. This makes installation easier and reduces the weight on piping systems, especially in larger diameter applications.

  1. Wafer or Lug Type Connection

Wafer Type: Designed to fit between two flanges using long bolts that pass through both flanges and the valve body.

Lug Type: Features threaded inserts, allowing the valve to be installed between flanges and secured with bolts on each side. This enables removal of downstream piping without disturbing the upstream piping.

  1. Operation Options

Manual Operation: Operated using a handwheel or lever for simple, on/off control.

Automated Operation: The valve can be equipped with pneumatic, electric, or hydraulic actuators for remote or automated control.

  1. Applications

Suitable for low-to-moderate pressure and temperature applications in industries like:Water Treatment: Used in pipelines for water distribution and wastewater treatment.

HVAC Systems: Applied in heating, ventilation, and air conditioning systems for flow regulation.

Oil & Gas: Used in gas transmission pipelines, oil refineries, and other industrial applications involving non-corrosive fluids.

Chemical Processing: Ideal for handling non-corrosive chemicals, light acids, and alkaline solutions.

Power Generation: Common in cooling water and steam lines.

  1. Easy Maintenance

The simple design of the concentric butterfly valve with fewer moving parts allows for easy maintenance. The seat and disc are generally replaceable, reducing downtime and operational costs.

  1. Pressure and Temperature Range

Pressure Rating: Typically suitable for low to medium pressure applications (up to 300 PSI or higher depending on the design).

Temperature Range: Can handle a wide range of temperatures, especially when paired with appropriate seat materials. However, soft-seated valves are more suitable for moderate temperature ranges.

  1. Cost-Effective Solution

Concentric butterfly valves with carbon steel bodies offer an economical solution for applications where high durability, moderate pressure handling, and cost-efficiency are required, making them popular for general-purpose use in industries like water treatment, HVAC, and oil and gas.

Summary of Key Benefits:

Cost-Effective: Carbon steel is affordable, and concentric valves are simpler in design.

Durable: Withstands moderate temperature and pressure applications.

Compact: Saves space and reduces the overall weight of the piping system.

Easy to Maintain: Simple design with replaceable parts.

Versatile: Suitable for water, gas, steam, and light chemical handling.

 

These features make concentric butterfly valves with carbon steel bodies ideal for a variety of applications that require reliability, cost-efficiency, and easy maintenance.

 

Tianjin Tanghai Valve Co., Ltd. is a professional marine valve manufacturer, including butterfly valve, check valve, gate /Knife gate valve. We have certificates: CE, ISO, BV, DNV foundry and products approval. Now we have our own independent R & D, manufacturing, assembly and warehousing workshops; we have professional pre-sale and after-sale technical support and perfect services. Below is our wafer butterfly valve of marine valves,if you need to check more information, please click here:   https://www.tanghaivalve.com/wafer-type-butterfly-valve-th-btv-aw/

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Concentric type Butterfly Valve with Ductile Iron Body and Bronze Disc

A Concentric Type Butterfly Valve with a Ductile Iron Body and Bronze Disc is a reliable and versatile valve used for controlling fluid flow in various applications. Here’s a breakdown of its features:

Key Features:

Body Material: Ductile Iron

Ductile iron is a strong and durable material with excellent mechanical properties, including good tensile strength, flexibility, and resistance to cracking. It is preferred over cast iron due to its enhanced toughness.

Ideal for medium-pressure applications, ductile iron can withstand significant stress and offers long-term durability in harsh environments.

 

Disc Material: Bronze

Bronze is known for its superior corrosion resistance, particularly in water-based systems, and is often chosen for its ability to handle a wide range of fluids, including water, oil, and steam.

A bronze disc ensures smooth operation and longer service life in environments where metal-to-metal wear or corrosion could be a concern.

 

Concentric Design

In a concentric butterfly valve, the disc and the stem are centrally aligned. This provides a uniform sealing surface and is typically used in low- to medium-pressure systems.

The disc is centered within the valve body, and the valve opens and closes by rotating the disc 90 degrees on a shaft.Sealing Mechanism

Concentric butterfly valves typically use a resilient seat (like EPDM or NBR) that presses against the bronze disc to create a tight seal, preventing leaks.

Operation

This valve can be manually operated with a lever or gear mechanism or automated using pneumatic or electric actuators.

Common Applications:

Water Treatment and Distribution: Suitable for potable water, sewage, and wastewater systems.

HVAC Systems: Used for regulating flow in heating and cooling systems.

Irrigation Systems: Controls water flow in agricultural irrigation.

General Industrial Processes: Can be used in chemical, petrochemical, and other industrial applications where corrosion resistance is essential.

Advantages:

Cost-effective: The combination of ductile iron and bronze makes this type of valve both affordable and reliable.

Corrosion Resistance: The bronze disc ensures superior resistance to corrosion, particularly in water and steam applications.

Ease of Maintenance: Simple design allows for easy maintenance and repair.

This valve is a practical choice for a variety of fluid control systems due to its durability, ease of operation, and resistance to harsh environments.

 

Tianjin Tanghai Valve Co., Ltd. is a professional marine valve manufacturer, including butterfly valve, check valve, gate /Knife gate valve. We have certificates: CE, ISO, BV, DNV foundry and products approval. Now we have our own independent R & D, manufacturing, assembly and warehousing workshops; we have professional pre-sale and after-sale technical support and perfect services. Below is our wafer butterfly valve of marine valves,if you need to check more information, please click here:   https://www.tanghaivalve.com/wafer-type-butterfly-valve-th-btv-aw/

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Maintenance of the Concentric type Butterfly Valve in Ships

The maintenance of a concentric (centered) butterfly valve in ships is essential to ensure the valve’s optimal performance and longevity, especially in harsh marine environments. Concentric butterfly valves have the disc located in the center of the valve body, with a resilient seat that helps to seal the valve when closed. These valves are commonly used for fluid control in various ship systems, including seawater cooling, ballast systems, and bilge systems. Here’s a guide to maintaining a concentric butterfly valve on ships:

  1. Visual Inspection

External Inspection:Regularly check the valve for any visible signs of corrosion, wear, or damage, especially around the body, stem, and handle or actuator.

Marine environments are prone to corrosion due to saltwater, so special attention should be given to areas exposed to seawater.

Inspect for any salt deposits, marine growth, or other debris that may accumulate around the valve body and flanges.

Seal Inspection:Inspect the valve’s seat (usually made of rubber or elastomer) for wear or damage. The seal is crucial for the valve’s tight closure.

Check for cracks, deformities, or wear in the seal that could lead to leakage. The seal is one of the most critical parts, and its condition directly affects valve performance.

  1. Regular Cleaning

Valve Cleaning:Clean the exterior and interior of the valve regularly to remove any buildup of marine organisms, rust, silt, or debris that may impair its function.

Use approved marine cleaning agents that do not damage the valve’s materials. After cleaning, thoroughly rinse the valve with freshwater to remove any residual chemicals.

Seal and Disc Cleaning:Gently clean the valve’s disc and seat to remove any deposits. Marine organisms, like barnacles or algae, can settle on the disc, potentially impacting valve closure.

  1. Lubrication

Stem and Moving Parts:

Lubricate the stem and other moving parts of the valve as per the manufacturer’s recommendations. Marine-grade lubricants should be used to prevent corrosion and ensure smooth operation.

Avoid over-lubricating, as excess lubricant can attract dirt or debris.

Actuator Lubrication (for automated valves):

If the valve is equipped with an actuator (pneumatic, hydraulic, or electric), ensure that the actuator’s moving parts are adequately lubricated. Regularly check actuator connections to ensure they are secure and functioning smoothly.

  1. Operational Testing

Open and Close Testing:Periodically operate the valve by fully opening and closing it to ensure the disc moves freely. A valve that isn’t operated regularly may become stiff or difficult to operate due to corrosion, buildup, or seal hardening.

Ensure that there are no sticking points, and check the valve handle or actuator for any issues.

Leakage Testing:Perform a hydrostatic or pneumatic test at operating pressure to detect any leaks. If leakage is found, inspect the seat, seal, and disc for damage.

For valves under critical operation (e.g., seawater intake or discharge), this test should be part of routine inspections.

  1. Seal Replacement

Seal and Seat Maintenance:

The resilient seat is a key component that provides a bubble-tight seal in a concentric butterfly valve. Over time, the seat can wear out or become damaged due to constant use or exposure to chemicals, requiring replacement.

Replace the valve seat if you notice signs of cracking, deformation, or excessive wear that could compromise its sealing ability.

Stem Seals:

Inspect the stem seals (o-rings or gaskets) for wear. If these seals fail, it could lead to leakage around the stem area.

  1. Corrosion Protection

Protective Coating:

Apply protective coatings, like marine-grade anti-corrosive paints, to the external parts of the valve that are exposed to saltwater or humid environments.

If the valve is made from a material prone to rust (such as certain grades of cast iron), extra attention should be given to keeping the body protected from corrosion.

Material Compatibility:

Ensure that the valve material (body and disc) is suitable for the specific fluid or gas being handled. Corrosion-resistant materials like stainless steel or bronze should be used for seawater applications.

  1. Actuator and Control System Maintenance

Actuator Inspection:

For automatic valves, inspect the actuator system regularly. Check for signs of wear, corrosion, or malfunction in the actuator.

Ensure the actuator’s control signals are accurate, and the valve opens and closes fully when triggered.

Control System Calibration:

If the valve is part of an automated control system, periodically calibrate the system to ensure it operates at the correct parameters (e.g., pressure or flow settings).

  1. Bolts and Flange Check

Tightness of Flange Bolts:Periodically check the tightness of the bolts securing the valve to the pipe flanges. Marine vibrations can loosen these bolts over time.

Use the manufacturer-recommended torque settings when tightening bolts to avoid over-tightening or damaging the valve body.

  1. Gasket Inspection

Flange Gasket:Check the condition of flange gaskets between the valve and pipe flanges. If leaks are detected, the gasket may need to be replaced.

Gaskets exposed to high pressure, temperature, or aggressive fluids might degrade faster and require more frequent replacement.

Summary of Key Maintenance Practices:

Regular inspection: Visual and operational checks for corrosion, leaks, and damage.

Cleaning: Routine cleaning of valve components to remove marine growth and deposits.

Lubrication: Ensure moving parts are lubricated using marine-grade products.

Seal and gasket maintenance: Inspect and replace the valve seat, stem seals, and flange gaskets as needed.

Operational tests: Open and close the valve to ensure smooth operation.

Corrosion protection: Apply anti-corrosion coatings and ensure material compatibility with seawater.

Maintenance Schedule:

Weekly: Visual inspections, operational testing, and cleaning of external surfaces.

Monthly: Internal cleaning, actuator system checks, and lubrication.

Annually: Comprehensive inspections, including seal, gasket, and bolt checks; perform leakage tests and replace worn-out components.

Maintaining concentric butterfly valves on ships is crucial for ensuring the reliability of fluid systems, preventing leaks, and extending the valve’s service life.

 

Tianjin Tanghai Valve Co., Ltd. is a professional marine valve manufacturer, including butterfly valve, check valve, gate /Knife gate valve. We have certificates: CE, ISO, BV, DNV foundry and products approval. Now we have our own independent R & D, manufacturing, assembly and warehousing workshops; we have professional pre-sale and after-sale technical support and perfect services. Below is our wafer butterfly valve of marine valves,if you need to check more information, please click here:   https://www.tanghaivalve.com/wafer-type-butterfly-valve-th-btv-aw/

Please contact us if you need more support, please contact us freely: info@tanghaivalve.com.We are committed to “Build a top valve enterprise; Be a reliable partner!”Friends from all over the world are welcome to visit us for evaluation, guidance, and orders!

Concentric type Butterfly Valve Installation Manual

  1. Safety Precautions

Isolate the system: Ensure the pipeline is depressurized and drained before installation to avoid hazards.

Wear protective equipment: Always use appropriate personal protective equipment (PPE) like gloves, safety goggles, and hard hats during installation.

Inspect the valve and pipeline: Confirm that both the valve and pipeline are free from debris or foreign material before installation.

  1. Tools and Equipment Required

Torque wrench (to the manufacturer’s specifications)

Gaskets compatible with the pipeline and fluid

Bolts, nuts, and washers (as specified by the valve manufacturer)

Flange alignment tools

Pipe support tools

Pipe cleaning tools (if necessary)

  1. Valve and System Preparation

3.1 Check Valve Condition

Inspect the Valve: Before installation, check the valve for any visible damage, defects, or signs of wear. Ensure the disc operates smoothly by manually rotating it.

Verify Specifications: Make sure that the valve’s pressure, temperature ratings, and material specifications match the system requirements.

3.2 Check Pipeline Compatibility

Flange Condition: Ensure that the flanges on the pipeline are clean, flat, and free of debris. Irregularities in flange surfaces can lead to leakage.

Pipe Alignment: Check that the pipes are correctly aligned. Misaligned pipes can cause the valve to be stressed or damaged during installation.

  1. Installation Steps

4.1 Positioning the Valve

Disc Positioning: Keep the butterfly valve disc in the partially open position (about 10%) during installation. This prevents damage to the seat or disc and ensures easy centering between the flanges.

Mounting Orientation: Ensure the valve is installed with the flow direction indicated by the arrow on the valve body, if applicable. The valve can be installed horizontally or vertically, but ensure enough clearance around the valve for maintenance and operation.

4.2 Placing the Valve Between Flanges

Gasket Installation: Place a gasket between the valve and the flange on both sides. Use gaskets that are suitable for the valve material and the media being handled.

Valve Centering: Carefully place the butterfly valve between the pipeline flanges. The valve must be centered between the flanges to prevent the disc from contacting the inside of the pipe when opening or closing.

4.3 Bolt Tightening Procedure

Insert Bolts: Insert the bolts through the flange holes and the valve’s lugs, if applicable. Hand-tighten all bolts evenly, starting from the center and moving outward in a crisscross pattern.

Cross Pattern Tightening: Use a torque wrench to gradually tighten the bolts in a crisscross pattern to ensure even pressure across the flange surface. Avoid over-tightening to prevent flange distortion or valve damage.

Final Torque: Tighten to the manufacturer’s specified torque value for the bolts. It is important to follow the recommended torque values to avoid leaks or damage to the valve or flanges.

  1. Post-Installation Checks

5.1 Operational Test

Check Valve Operation: Manually operate the valve to ensure that the disc rotates smoothly through its full open and closed positions. There should be no interference with the pipeline.

Leak Testing: After installation, test the valve for leaks by pressurizing the system gradually. Check the valve body, flanges, and gaskets for any signs of leakage.

5.2 Pipeline Support

Support Pipes: Ensure that the pipeline is adequately supported on both sides of the valve. The valve should not bear the weight of the piping, especially for larger installations.

  1. Valve Operation and Maintenance

6.1 Routine Operation

Slow Operation: When operating the valve, do so slowly to avoid water hammer or mechanical shock that could damage the valve or piping system.

Open/Close Position: Ensure the valve is fully closed or fully open during operation, unless being used for flow control.

6.2 Regular Maintenance

Inspection Frequency: Periodically inspect the valve for signs of wear or damage. Pay special attention to the disc, seat, and seals.

Cleaning: If necessary, clean the valve and piping system to remove any buildup that could impair valve performance.

Lubrication: Lubricate moving parts if specified by the manufacturer to ensure smooth operation over time.

  1. Troubleshooting

7.1 Valve Leakage

Potential Causes: Misalignment of the valve, improper torque of the flange bolts, or a damaged gasket.

Solution: Recheck alignment, adjust the bolts according to torque specs, and replace any damaged gaskets.

7.2 Difficulty in Operation

Potential Causes: The valve may have been installed with the disc in contact with the flange or pipe, or debris may be obstructing the disc’s movement.

Solution: Check the installation for alignment issues and clean the pipeline if debris is suspected.

  1. Decommissioning and Removal

Isolate the Valve: Before removing the valve, ensure that the pipeline is depressurized and that the valve is fully closed.

Support the Valve: Ensure the valve is adequately supported during removal, especially for large valves, to prevent injury or damage.