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Installation Locations of Dual-Plate Check Valves on Ships

August 8, 2025

Dual-plate check valves are mainly installed in pipelines where the medium flows in one direction, preventing backflow and reducing water hammer impact. On ships, typical installation locations include:

1. Engine Room Systems

Main Seawater Cooling System
Installed between the sea chest valve and the seawater pump, or between the pump outlet and the cooler, to prevent seawater from flowing back when the pump stops.

Freshwater Cooling System
Located at the outlet of the cooler to prevent backflow of cooling water to the equipment.

Fuel and Lube Oil Cooling Systems
Installed at the cooler or pump outlet to prevent oil from flowing back after the pump stops.

2. Ballast and Tank Systems

Ballast Water System
Between the ballast pump outlet and the ballast tanks to prevent water from flowing back, especially in systems with multiple pumps or tanks where each branch line needs a check valve.

Tank Drain Systems
To prevent liquid from one tank from flowing into another.

3. Firefighting and Emergency Systems

Firefighting System
At the outlet of the fire pump or branch lines to prevent backflow to the pump or other systems.

Emergency Pump Systems
To prevent cross-flow between the emergency pump and the main pump.

Installation Notes:

Can be installed horizontally (shaft vertical) or vertically (flow upward).

Should be located close to the pump outlet to minimize backflow and water hammer.

The arrow on the valve body must align with the flow direction of the pipeline.

Installation Locations of Concentric Butterfly Valves in Marine Applications

July 29, 2025

Concentric butterfly valves, also known as centerline butterfly valves, are widely used in marine piping systems due to their compact structure, light weight, quick operation, cost efficiency, and adaptability to various media. Below are the typical installation positions and application systems on ships:

Common Installation Locations & Applications

Ballast Water System

Installed between ballast tanks and ballast pumps.

Used to control seawater intake and discharge, adjusting ship stability and draft.

Cooling Water Systems (Seawater/Freshwater)

Installed on inlet/outlet pipes of engines, condensers, and heat exchangers.

Controls the flow of cooling water, ensuring efficient heat dissipation.

Bilge System

Located at the suction lines of bilge pumps or branch pipelines.

Manages bilge water discharge from different compartments.

Sanitary and Sewage Systems

Installed between sewage holding tanks and treatment units.

Ensures safe flow control and maintenance isolation.

Ventilation and HVAC Systems

Mounted in ventilation ducts to regulate or shut off airflow.

Ideal for confined spaces with limited installation clearance.

Fuel and Lubricating Oil Systems

Applied in low-pressure areas for oil flow control and emergency shut-off.

Suitable for non-critical and low-temperature locations.

Deck Service Lines (e.g., Fresh Water, Tank Washing Water)

Installed on deck piping systems to manage service fluid distribution.

Found under deck, in passageways, or utility corridors.

Installation Notes for Concentric Butterfly Valves

Recommended positions: Mid-pipeline or near the equipment inlet/outlet.

Shaft orientation: For horizontal pipelines, it’s advised to install with the shaft vertical (disc horizontal).

Ease of maintenance: Ensure installation allows for convenient access.

Suitable media: Seawater, freshwater, air, sewage, light oil, and other non-corrosive or mildly corrosive fluids.

Difference Between Low Temperature Valves and Normal Temperature Valves in Marine Applications

July 22, 2025

In marine valve applications, low temperature valves and normal temperature valves are designed for different working conditions. Their main differences are as follows:

Operating Temperature Range

normal temperature valves are designed for media with temperatures ≥ -29°C (e.g. seawater, freshwater, fuel oil, compressed air).

Low temperature valves are designed for extremely low temperatures ≤ -29°C, such as -46°C, -101°C, -196°C, used for LNG, LPG, liquid nitrogen, etc.

Material Selection

normal temperature valves use conventional materials like carbon steel (WCB), stainless steel (CF8/CF8M), or bronze.

Low temperature valves require special low-temperature-toughness materials, such as:

Low-temperature carbon steel (LCB, LC2)

9% Nickel steel

Austenitic stainless steel (304, 316L)

Aluminum alloy, Monel alloy

These materials maintain ductility and toughness at Low termperature temperatures, preventing brittle failure.

Structural Design

Normal temperature valves have standard designs without special considerations for thermal contraction.

Low temperature valves incorporate:

Extended bonnet (to keep packing away from the cold zone)

Special low-friction sealing materials suitable for low temperatures

Designs that minimize leakage and avoid jamming due to thermal contraction

Testing Requirements

Normal temperature valves are tested according to standard marine class rules (e.g. API, ISO, CCS, LR).

Low temperature valves undergo additional tests, such as:

Impact test at Low temperature temperature

Low-temperature sealing and functional tests

Typical Applications

Item	Normal temperature Valves	Low temperature Valves
Medium	Seawater, freshwater, fuel oil, air	LNG, LPG, liquid nitrogen
Temperature	≥ -29°C	≤ -29°C
Typical Use	General ship piping systems	LNG carriers, LPG carriers, Low temperature storage

Low temperature valves are specifically engineered for ultra-low temperature service, with materials, design, and testing tailored to prevent cold brittleness and leakage. normal temperature valves are not suitable for Low temperature applications.

Installation Position and Function of Marine Butterfly Valves on Ships

July 11, 2025

A marine butterfly valve is a common type of ship valve, widely used in various piping systems onboard. Below are its installation positions and functions on a ship:

Installation Positions of Marine Butterfly Valves

Butterfly valves are mainly used in locations where the pipe diameter is large, quick opening/closing is required, and installation space is limited. They are commonly found in the following piping systems:

Ballast Water System
Installed on ballast water pipelines to control the intake, discharge, and distribution of ballast water between tanks.
For example, on ballast water mains, branch lines, and at tank inlets/outlets.

Bilge (Seawater/Wastewater) System
Installed in bilge suction and discharge systems to control the drainage of seawater or wastewater.

Cooling Water System
Installed in the seawater cooling circuits of the main engine and generators to open/close or regulate the flow of cooling water.

Firefighting System
Installed on the main and branch fire mains to enable quick opening and closing of firefighting water supply.

Ventilation/Compressed Air Pipelines
Some butterfly valves are also used in non-liquid media pipelines, such as compressed air or low-pressure gas.

In general, butterfly valves are installed horizontally or vertically on pipelines, close to the area requiring control, for easy operation.

Functions of Marine Butterfly Valves

The primary functions are shut-off and throttling. Key characteristics include compact structure, light weight, easy operation, and low fluid resistance. Specific functions are as follows:

Shut-off or Open the Flow
Quickly cut off or open the water (or gas) flow in the pipeline.

Regulate Flow
Capable of adjusting the flow to some extent, not limited to fully open or fully closed positions.

Prevent Backflow
In combination with pipeline design, it helps prevent backflow (note: the butterfly valve itself does not have a check function; a check valve is required for that purpose).

Save Space and Weight
Compared to gate valves and ball valves, butterfly valves are lighter and more suitable for the limited space onboard ships.

Why are butterfly valves preferred on ships?

More economical and practical than gate or ball valves on large-diameter pipelines.

Lightweight, low operating torque, and quick to open/close.

Resistant to seawater, freshwater, oil, and other corrosive media (commonly made of stainless steel, bronze, or with rubber sealing materials).

Marine butterfly valves are typically installed on the main and branch lines of various shipboard water systems to control and regulate the flow of liquids or gases. Due to their light weight, simple structure, and easy operation, they are widely used in marine engineering and are an indispensable valve type in modern ship piping systems.

LRS Certificates in Marine Butterfly Valve

July 1, 2025

LRS Certificates in the context of marine butterfly valves refer to certifications issued by Lloyd’s Register of Shipping (LRS), a well-known maritime classification society. These certificates verify that the valves meet the standards required for marine applications, particularly for safety, reliability, and regulatory compliance.

What Is an LRS Certificate?

An LRS Certificate demonstrates that a product—like a butterfly valve—has been:

Inspected and tested by Lloyd’s Register or an authorized party.

Compliant with Lloyd’s marine classification rules.

Suitable for use on ships and offshore platforms.

What It Means for Marine Butterfly Valves

A butterfly valve with an LRS certificate has typically passed tests related to:

Criteria	Typical Requirements
Pressure rating	Confirmed for marine system pressures
Material quality	Approved corrosion-resistant materials
Fire safety	Fire-safe design (if required)
Functionality	Reliable operation under marine conditions
Leakage tests	Zero or acceptable leakage rates

Types of LRS Certificates

There are different types depending on what’s being certified:

Certificate Type	Description
Type Approval Certificate	Confirms a valve design meets LR rules. Valid for multiple units of the same design.
Inspection Certificate (3.2)	Confirms that each valve is individually tested and inspected (often project-specific).
Works Certificate	Provided by the manufacturer, verified by LR or its representative.

Why Is It Important?

Regulatory Compliance: Required for equipment used on LR-classed vessels.

Insurance and Safety: Helps in securing vessel insurance and ensuring safe operations.

Global Acceptance: LRS is recognized by maritime authorities worldwide.

How to Verify an LRS Certificate

Check the certificate number on the LRS website.

Request the Type Approval Certificate from the valve supplier.

Ensure the stamp or signature of Lloyd’s Register is present on the physical certificate.

ABS Certification in Marine Butterfly Valves

June 17, 2025

In the field of marine butterfly valves, ABS certification is a crucial qualification for entering the international shipbuilding and offshore markets. Here’s a detailed overview of how ABS certification applies to marine butterfly valves:

1. What is ABS Certification?

ABS (American Bureau of Shipping) is a globally recognized classification society that sets technical standards for the design, construction, and maintenance of ships and offshore structures.
An ABS certificate confirms that a product complies with ABS rules in terms of design, material selection, manufacturing process, and performance, making it suitable for harsh marine environments.

2. Types of ABS Certification for Butterfly Valves

Certification Type	Description	Typical Application
Type Approval Certificate (TAC)	Confirms that a valve model meets ABS standards	For batch production of standard models
Product Design Assessment (PDA)	A detailed review of the valve’s design and intended service	For customized or critical-use products
Manufacturing Assessment (MA)	Assesses factory quality management and production capability	Usually combined with TAC or PDA
Individual Product Certification	Each valve is individually tested and inspected by ABS	Required for critical shipboard systems (e.g., fire-fighting, ballast)

3. Common Marine Applications of ABS-Certified Butterfly ValvesBallast Water Systems

Cooling Water Circuits

Firefighting Systems

Fuel and Oil Lines

Sea Water Inlet/Outlet Systems

4. ABS Requirements for Marine Butterfly Valves

Item	Requirement
Materials	Must meet ASTM or marine-grade standards (e.g., CF8M, Bronze, Ductile Iron)
Design	In accordance with ANSI/API or ISO standards and marine conditions (corrosion, vibration resistance)
Pressure Rating	Commonly PN10, PN16, or 150 PSI
Tests	Includes pressure, sealing, and performance testing
Documentation	Material certificates, test reports, drawings, and QA documents are required for ABS review

DNV Certification in Marine Butterfly Valves

June 4, 2025

DNV certification plays a vital role in marine butterfly valves, signifying that the product complies with the standards set by Det Norske Veritas (DNV, formerly DNV-GL). It is a key requirement for entering the international shipbuilding and offshore engineering markets.

1. What is DNV Certification?

DNV (Det Norske Veritas) is a world-leading classification society and risk management organization.
DNV certification is a third-party verification that a product meets DNV’s classification standards in terms of design, materials, manufacturing, testing, and quality control.
It is widely applied to ships, offshore structures, and energy equipment that demand high reliability and safety.

2. DNV Requirements for Marine Butterfly Valves

In the field of marine butterfly valves, DNV certification involves the following aspects:

1. Product Design and Drawing Approval

Valve designs must be submitted for review by DNV, including:

Structural drawings

Material specifications

Working pressure

Temperature range

Sealing structure and configuration

2. Material Certification

All pressure-bearing parts must use DNV-approved materials.
Material certificates conforming to EN 10204 3.1 or 3.2 are usually required.

3. Inspection of Castings or Forgings

DNV requires NDT (non-destructive testing) on valve bodies and discs, including:

Ultrasonic testing (UT)

Radiographic testing (RT)

Magnetic particle testing (MT) or dye penetrant testing (PT)
These inspections must be witnessed or reviewed by a DNV surveyor.

4. Performance Testing

Valves must undergo:

Shell pressure tests

Leakage/sealing tests
Typically carried out under the supervision of a DNV inspector.

For specific applications, additional tests may be required:

Low-temperature impact test

Fire safety test

Corrosion resistance tests (e.g., NACE standards)

5. Manufacturing Supervision and Final Acceptance

DNV monitors the manufacturing process.
A DNV-signed Product Certificate must be issued upon final acceptance.

3. Common Applications of DNV-Certified Marine Butterfly Valves

Onboard Ship Systems:

Seawater cooling systems

Ballast water systems

Fire-fighting pipelines

Offshore Platforms:

Living quarters

Oil & gas transfer pipelines

LNG and Liquid Cargo Ships:

Cryogenic butterfly valves

Bi-directional sealing butterfly valves

4. Importance of DNV Certification for Export

DNV certification is a passport to major global markets such as:

Europe, Norway, Germany, the Netherlands, Singapore, Japan, etc.

Many renowned shipyards (e.g., Hyundai, Samsung Heavy Industries, Fincantieri) require valves to be certified by DNV or other major classification societies such as ABS, BV, or LR.

5. Recommended Information for Your Promotion

If you are involved in the casting of valve bodies, discs, or shafts, you can include the following statement in your promotional materials:

Our marine butterfly valve parts (valve body, disc, and shaft) are made from DNV-approved materials and produced under ISO 9001 quality control. We support our clients to pass DNV product certification through strict casting quality and mechanical property assurance.

Application of 2205 and 2507 in Marine Valves

May 16, 2025

2205 and 2507 are two types of duplex stainless steel that are widely used in marine valves (such as butterfly valves, gate valves, and check valves), particularly in environments where excellent corrosion resistance is required. Below is a comparison of their applications and key characteristics in marine valve usage:

I. Comparison of Basic Material Properties

Property	2205 (UNS S31803/S32205)	2507 (UNS S32750)
Type	Duplex Stainless Steel	Super Duplex Stainless Steel
Corrosion Resistance	Excellent, suitable for most marine environments	Superior, suitable for extreme marine and chemical environments
Pitting/Crevice Resistance	Good	Excellent
Chloride Stress Corrosion Resistance	Strong	Very strong
Yield Strength	Higher than austenitic stainless steel (e.g., 316L)	Even higher
Operating Temperature Range	-50℃ to +300℃	-50℃ to +250℃ (recommended)
Cost	Moderate	High

II. Specific Applications in Marine Valves

1. Applications of 2205:

Seawater piping systems: Valves used in ballast water and cooling water systems

Desalination systems: Butterfly and gate valves

Liquid transportation systems on oil tankers and cargo vessels

Auxiliary systems in ships with moderate corrosion exposure, such as wastewater treatment systems

Cost-effective option for general-purpose marine valves

2. Applications of 2507:

Critical valves in high-corrosion, high-pressure environments such as deep-sea operation vessels and subsea equipment

LNG carriers and chemical tankers with extremely high corrosion resistance requirements

Shipboard systems exposed to high concentrations of chlorides or acidic gases (e.g., H₂S)

Ideal for scenarios requiring long-term, maintenance-free operation or extended service life

III. Material Selection Recommendations

Application Requirement	Recommended Material
General seawater corrosion with cost-effectiveness priority	2205
Extreme corrosion (high chloride, high temperature, high pressure)	2507
Good weldability and high mechanical strength needed	2205 preferred
High safety margin and sufficient project budget	2507

In the marine valve industry, 2205 offers a cost-effective and corrosion-resistant solution suitable for wide application. 2507, on the other hand, delivers higher safety and durability in extremely harsh environments.

SS316 Wafer Type Single Disc Check Valve

May 7, 2025

Reliable Backflow Protection – Built for Harsh Marine and Industrial Environments

Product Overview

Our SS316 Single Disc Check Valve is designed for high-performance backflow prevention in demanding environments such as marine systems, chemical plants, and water treatment facilities. Made from 316 stainless steel, it offers exceptional resistance to corrosion, even in seawater and aggressive media.

With its compact wafer-type body and single disc design, it ensures fast response, minimal pressure drop, and easy installation between flanges.

Key Features

Material: SS316 Body & Disc – excellent corrosion resistance

Design: Compact wafer type, single disc for fast shut-off

Seal Options: EPDM / NBR / PTFE – compatible with various media

Installation: Horizontal or vertical (upward flow)

Pressure Rating: PN10 / PN16 / ANSI150 available

Sizes: DN40 to DN600 (larger sizes customizable)

Applications

Marine pipelines (ballast systems, cooling water, bilge lines)

Offshore platforms

Chemical and pharmaceutical industries

Water treatment & desalination systems

Pump discharge lines

Why Choose Us

Over 15 years in precision casting and valve component manufacturing

OEM/ODM services available

Fast lead times, reliable quality

Export-ready with international shipping & documentation support

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!

Selection Standard and Application Analysis for Marine Valve

April 15, 2025

Choosing the right valves for marine systems is crucial to ensure safety, reliability, and long-term performance in harsh offshore environments. Key selection criteria include:

1.1 Material Selection

Preferred Material: SS316, Duplex Stainless Steel, Bronze

Reason: High corrosion resistance in seawater, brine, and aggressive chemicals

Tip: Avoid carbon steel for exposed or submerged applications

1.2 Valve Type Selection

Valve Type	Typical Marine Application
Butterfly Valve	Ballast systems, cooling water lines
Check Valve	Pump discharge, bilge lines, fire systems
Gate Valve	Seawater intake, cargo pipelines
Globe Valve	Flow regulation in steam or fuel systems
Ball Valve	Quick shut-off for fuel, oil, or air lines

1.3 Standards & Classification

Ensure compliance with IMO, IACS, and classification societies such as:

DNV, ABS, LR, BV, CCS

Check for Fire-Safe, DNV-GL approved, or ISO/ANSI certified valves where required

1.4 Functional Requirements

Operating pressure & temperature

Flow direction and velocity

Manual, pneumatic, or electric actuation

End connection (flanged, wafer, threaded)

2. Application Analysis – Where Marine Valves Are Used

2.1 Engine Room Systems

Seawater cooling lines

Fuel oil, lubricating oil pipelines

Steam and condensate systems

Bilge and ballast systems

2.2 Deck Systems

Cargo handling valves

Firefighting systems

Air vent check valves for tanks

2.3 Underwater / Hull Applications

Seachests

Overboard discharge valves

Bottom inlet valves

Note: Corrosion resistance and class approval are critical here

3. Additional Recommendations

Use soft-sealing valves (e.g., EPDM-lined butterfly valves) for low-pressure, non-critical lines

Use metal-seated valves for high-temperature or abrasive media

Choose compact wafer-type valves to save space in narrow engine rooms

Plan for easy maintenance access, especially in engine room clusters

Ensure spare part availability for long-term operation at sea

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/.