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Anti-Corrosion Technology for Marine Concentric Butterfly Valves

March 20, 2025

Body Coating: Epoxy coating, thermal zinc spray, FBE coating.

Disc Protection: Stainless steel or copper alloy with surface treatment.

Seat Protection: Modified rubber for seawater resistance.

Shaft Sealing and Corrosion Prevention: Special coating in shaft sealing chamber + corrosion-resistant O-rings.

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!

Factors Affecting Sealing Performance of Concentric Soft Seal Butterfly Valves

March 13, 2025

Key Factors

Seat Material Selection: EPDM for seawater, NBR for oil, VITON for high temperature.
Machining Precision: Concentricity between valve body, disc, and seat.
Installation Position: Horizontal installation is preferred over vertical to avoid self-weight affecting sealing.
Torque Control: Excessive or insufficient torque may damage the seat.

Key Technical Points

Ensure concentricityamong body, disc, and seat.
Select suitable sealing materials.
Prevent high-temperature aging of the seat.
Apply anti-corrosion coatingsor linings to enhance seawater corrosion resistance.

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!

Comparison Between Concentric and Double Offset Marine Butterfly Valves

March 7, 2025

Item	Concentric Butterfly Valve	Double Offset Butterfly Valve
Structure	Disc center aligned with body centerline	Disc center offset from body centerline
Sealing Type	Mainly soft seal	Soft+hard seal available
Operation Torque	Low	Slightly higher
ApplicationPressure	Low to medium pressure(PN6-PN16)	High pressure(PN25-PN40)
Cost	Lower	Higher
Typical Application	General ship pipelines,ballast water systems	High-ressure fire system,deck wash system

Centerline butterfly valves are more economical and suitable for general marine pipelines, while double offset valves are better for high pressure, high temperature, or special media.

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.

The Processing of Butterfly Valve Fittings

February 21, 2025

The processing of butterfly valve accessories generally involves multiple steps, with the main goal of ensuring the precision and compatibility of each component. As a common type of regulating valve widely used in industrial pipelines, the processing accuracy of butterfly valve components directly affects the valve’s performance and lifespan. The main components of a butterfly valve include the valve body, valve disc, shaft, sealing ring, and actuator. Below are the typical processing methods for these components:

Valve Body Processing
The valve body is generally made from cast steel or cast iron. During the processing, the body is first cast and then trimmed. Afterward, machining operations such as turning and milling are performed to ensure the geometric precision and surface roughness of the valve body.

Valve Disc Processing
The valve disc is typically made from stainless steel or corrosion-resistant alloys. The disc is primarily processed by turning and milling to achieve the required shape. The sealing surface of the valve disc must be extremely smooth, often requiring grinding or fine turning to ensure a proper seal.

Shaft Processing
The shaft of the butterfly valve is the key component connecting the valve disc and the actuator. Shaft processing requires high precision, typically involving turning, grinding, and other processes to ensure the shaft’s straightness, coaxiality, and surface hardness.

Sealing Ring Processing
Sealing rings are typically made from rubber, PTFE, or metal materials, and they effectively prevent leakage of the medium. The manufacturing process for sealing rings includes molding, precision cutting, etc., to ensure their sealing performance and prevent leakage.

Actuator Accessories Processing
The actuator is the power source for the butterfly valve. Common types of actuators include electric, pneumatic, and hydraulic drive units. The processing of actuator components generally includes precision casting, machining, and assembly to ensure smooth operation of the actuator in driving the valve’s opening and closing.

When processing butterfly valve components, it is necessary to consider factors such as material selection, machining precision, surface treatment, etc., to ensure stable performance and durability of the valve. In some special working conditions, additional heat treatment or surface coating processes (such as nitriding, chromium plating, etc.) may be required to improve corrosion resistance and wear resistance.

Connection Standard of Dual Plate Check Valve

January 6, 2025

The connection standard of a Dual Plate Check Valve primarily refers to the standards governing the face-to-face dimensions, flange compatibility, and pressure ratings. These standards ensure that the valve can be installed easily in various pipeline systems with flanged connections.

Key Connection Standards for Dual Plate Check Valves:

1. API 594 – Check Valve Face-to-Face and End Connection Dimensions

Specifies the face-to-face dimensions of wafer, lug, and double-flanged check valves.
Ensures interchangeability between different manufacturers’ valves.
Widely used in industries such as oil & gas, petrochemical, and water treatment.
Applicable pressure classes:
- Class 150, 300, 600, 900, 1500, 2500

2. ASME B16.5 – Pipe Flanges and Flanged Fittings

Defines the dimensions, materials, and pressure ratings for flanges up to 24 inches.
Used to ensure flange compatibility when installing the valve.
Flange pressure classes:
- Class 150, 300, 600, 900, 1500, 2500

3. ASME B16.47 – Large Diameter Steel Flanges

Covers flange sizes from 26 inches to 60 inches.
Used in large-diameter piping systems.

4. EN 558 / ISO 5752 / DIN 3202 – Face-to-Face Dimensions of Valves

European and international standards defining face-to-face dimensions for valves.
These standards ensure compatibility with flanged connections under PN-rated systems.
Pressure ratings: PN 10, 16, 25, 40.

5. EN 1092-1 – Steel Flanges

European standard for flange dimensions, materials, and pressure ratings.
Common pressure ratings: PN 10, 16, 25, 40, 63, 100.

End Connection Types:

Wafer Type:

Designed to fit between two flanges with bolts passing through.
Compatible with multiple flange standards (ASME, EN, JIS, etc.).
Most compact and lightweight connection type.

Lug Type:

Equipped with threaded lugs around the circumference.
Allows the valve to be bolted directly to the flanges, enabling installation at the end of a pipeline.

Double Flanged Type:

Designed with integral flanges for bolted connections on both sides.
Provides more rigid support compared to wafer and lug types.

Summary of Pressure Ratings:

Standard	Pressure Class	Typical Notation
ASME B16.5	150 – 2500	Class 150, 300, etc.
EN 1092-1	PN 10 – PN 100	PN 10, PN 16, etc.
API 594	150 – 2500	Class 150, 300, etc.
JIS B2220	5K – 63K	JIS 10K, 16K, etc.

Butterfly Valve Connection Standard

December 27, 2024

Butterfly valves are widely used in industrial applications for regulating flow and are manufactured according to several connection standards. These standards ensure compatibility, safety, and reliability. Below are the common connection standards for butterfly valves:

1. Flanged Connections

Butterfly valves with flanged ends are designed to mate with standard pipe flanges. The key standards for flanged connections include:

ASME B16.5: Pipe Flanges and Flanged Fittings (covers sizes from ½ inch to 24 inches, pressure classes 150 to 2500).
EN 1092-1: Flanges and their joints for PN-designated pressure systems.
ISO 7005-1: Metallic flanges for general purposes.
JIS B2220: Japanese flange standard.

2. Wafer Type Connections

Wafer butterfly valves are designed to fit between two pipe flanges using bolts or studs.

They are typically compatible with flange drilling patterns as per:
- ASME B16.5
- EN 1092
- ISO 7005

3. Lug Type Connections

Lug butterfly valves have threaded inserts that allow them to be bolted to a pipe flange. Standards include:

ASME B16.5
EN 1092
ISO 7005

4. Grooved End Connections

For quick installation and connection to grooved piping systems.

AWWA C606: Grooved and shouldered joints.

5. Butt-Weld Connections

Less common for butterfly valves but occasionally used in specific applications.

ASME B16.25: Butt-welding ends.
ISO 9692: Welding preparation standards.

6. Standards for Specialized Applications

AWWA C504: For waterworks applications, especially large-diameter valves.
API 609: Butterfly valves for general-purpose applications.
MSS SP-67: Covers butterfly valves, general-purpose and high-performance types.

Key Considerations

Always ensure that the valve and mating components meet the same flange drilling patterns and pressure ratings.
Verify that the material of construction and dimensions meet the system’s operational requirements (temperature, pressure, medium compatibility).

Let us know if you’d like details on a specific standard!

The Valve Disc Material of Concentric Type Butterfly Valve

December 19, 2024

The common valve disc materials for middle-line butterfly valves are as follows, with each material suitable for different working environments and media:

Ductile Iron: Known for its good strength, toughness, and impact resistance, ductile iron is commonly used in general industrial applications involving media such as water and gas. It is cost-effective, but its corrosion resistance is relatively poor.

304 Stainless Steel: A widely used stainless steel material, 304 offers good corrosion resistance and is suitable for less aggressive corrosive media, such as water, air, and oil.

316 Stainless Steel: Compared to 304, 316 stainless steel offers better corrosion resistance, especially in environments with more aggressive media like seawater, acidic substances, or saltwater.

C95400 Aluminum Bronze: This material provides excellent corrosion resistance, wear resistance, and mechanical strength, and is widely used in marine, shipbuilding, and chemical industries. It is suitable for highly corrosive media such as seawater and saltwater.

C95800 Aluminum Bronze: With higher strength and enhanced corrosion resistance, C95800 is particularly suitable for marine environments and applications involving corrosive media like acids and chlorides.

These materials are selected based on specific application requirements such as temperature, pressure, and the corrosiveness of the media, ensuring the most suitable valve disc material for optimal performance.

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!

Electroplating of Single Plate Check Valves

December 11, 2024

Electroplating is a surface treatment process for single-plate check valves that aims to enhance their corrosion resistance, wear resistance, and aesthetic appeal. This process is particularly suited for valves operating in corrosive environments for extended periods. Below is an overview of the electroplating process and key considerations for single-plate check valves:

Common Electroplating Types

Zinc Plating

Features: Economical and practical; suitable for low-corrosion environments.
Applications: Commonly used in indoor or mildly corrosive conditions.

Nickel Plating

Features: Excellent corrosion resistance and decorative finish with a smooth surface.
Applications: Ideal for medium-corrosion environments with higher demands.

Chrome Plating

Features: High wear resistance, hardness, and surface gloss.
Applications: Used in industrial environments with high wear and corrosion.

Zinc-Aluminum Alloy Plating

Features: Combines the advantages of zinc and aluminum for superior corrosion resistance.
Applications: Suitable for harsh environments, such as marine climates or chemical plants.

Multilayer Composite Plating

Features: Combines multiple metal layers to enhance overall performance.
Applications: High-demand scenarios, such as aerospace and marine industries.

Electroplating Process

Pre-treatment

Degreasing: Cleans oil and grease from the surface using an alkaline solution.
Rust Removal: Removes surface rust via acid pickling or mechanical methods.
Surface Activation: Improves plating adhesion.

Electroplating Stage

Primary Electroplating: The valve is placed in an electrolyte solution, where a chemical reaction deposits the metal layer.
Post-Plating Treatment: Includes passivation to enhance corrosion resistance.

Inspection and Post-Treatment

Plating Thickness Check: Ensures the layer meets design specifications.
Appearance Check: Inspects for defects such as bubbles or cracks.
Sealing Treatment: Seals the plating layer to improve corrosion resistance.

Key Considerations

Material Selection
The substrate material of the single-plate check valve must be identified before electroplating. Common materials include cast iron, stainless steel, and carbon steel, which may require different plating processes.

Plating Thickness
Determine the plating thickness based on the operating environment, typically ranging from 5 to 25 microns.

Environmental Compliance
Some electroplating processes involve hazardous substances (e.g., hexavalent chromium). Compliance with environmental regulations is essential, and eco-friendly plating options should be prioritized.

Adhesion Testing
Ensure strong adhesion between the plating and substrate to prevent peeling or flaking.

Corrosion Resistance Testing
Validate the plating’s corrosion resistance through salt spray tests and other methods.

Conclusion

Electroplating significantly improves the service life and performance of single-plate check valves. Selecting the appropriate plating process and ensuring stringent quality control are critical. For customized electroplating solutions, consult a professional surface treatment provider or manufacturer.

Corrosion Prevention Methods for WCB Material Valve Bodies in Marine Valves

December 4, 2024

WCB material (carbon steel castings) is prone to corrosion in certain environments, especially in marine applications. To enhance the service life of WCB valves, effective corrosion prevention methods are necessary. Here are some common approaches:

1. Cathodic Protection

Principle:Install sacrificial anodes (e.g., zinc or magnesium blocks) on the valve body to protect it from corrosion through electrochemical reactions.
Application:Commonly used in seawater pipelines on ships to prevent salt-induced corrosion.

2. Surface Coating Protection

Anti-corrosion Coatings:Apply protective coatings, such as epoxy resin or polyurethane, to the valve surface to create a barrier against corrosive media.
Metallic Coatings:Use thermal spraying to apply a corrosion-resistant metal layer (e.g., aluminum or zinc alloys) on the surface.
Key Requirement:The coating should be uniform, durable, and provide strong adhesion, especially in areas like threads and internal surfaces.

3. Internal Lining with Corrosion-resistant Materials

Method:Line the internal surfaces of the valve with corrosion-resistant materials, such as rubber, fluoroplastics (PTFE), or lead.
Advantages:Directly protects the valve from contact with corrosive media, significantly extending its service life.
Application:Ideal for systems handling highly acidic or alkaline fluids.

4. Application of Anti-rust Oil or Lubricants

Regular Maintenance:Apply anti-rust oil or lubricants to the valve surface, especially for valves that are not in regular use.
Application:Effective in humid or salt-laden environments typical in marine settings.

5. Material Modification or Upgrades

If the environment involves severe corrosion (e.g., sulfur gases, acidic water), WCB material can be treated or upgraded:

Chromium or Nickel Surface Treatment:Enhances oxidation and corrosion resistance.
Use of Alloy Materials:Opt for higher-grade materials like CF8 or CF8M (stainless steel valve bodies) for better performance.

6. Electroplating

Methods:Apply zinc, nickel, or chromium plating to the WCB valve body using electroplating techniques.
Advantages:Provides a dense, wear-resistant, and corrosion-resistant surface with a polished appearance.

7. Environmental Control

Reduce Exposure:Minimize direct contact with high-salinity air or water.
Cleaning and Maintenance:Regularly clean salt, dirt, or corrosive deposits from the valve surface to keep it in optimal condition.

8. Combination of Methods

Coating + Cathodic Protection:Combining surface coatings with cathodic protection can effectively address different types of corrosion and provide comprehensive protection.

Selection Criteria for Corrosion Prevention

Environmental Conditions:Whether the valve is exposed to seawater or acidic/alkaline environments.
Media Type:The corrosiveness of the fluids being handled.
Valve Type and Parts:Different requirements for internal passages and external valve body protection.
Cost-effectiveness:Balancing the cost of corrosion prevention with the expected service life.

In the marine industry, a combination of coatings and cathodic protection is widely used to ensure the durability of WCB material valves. If you have specific application scenarios, the prevention strategy can be further optimized.

Corrosion Resistance of Marine Butterfly Valves

November 28, 2024

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.

Anti-Corrosion Technology for Marine Concentric Butterfly Valves

Factors Affecting Sealing Performance of Concentric Soft Seal Butterfly Valves

Comparison Between Concentric and Double Offset Marine Butterfly Valves

The Processing of Butterfly Valve Fittings

Connection Standard of Dual Plate Check Valve

Butterfly Valve Connection Standard

The Valve Disc Material of Concentric Type Butterfly Valve

Electroplating of Single Plate Check Valves

Corrosion Prevention Methods for WCB Material Valve Bodies in Marine Valves

Corrosion Resistance of Marine Butterfly Valves

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