A socket weld flange, also known as an SW flange, is a type of forged flange designed with a recessed socket where the pipe is inserted before being fillet welded from the outside. The pipe does not pass through the entire flange thickness, creating a smooth internal flow passage.

Compared with slip-on flanges, socket weld flanges provide improved fatigue resistance and better internal flow performance, making them suitable for small diameter and higher-pressure piping systems.

DTC manufactures and supplies carbon steel socket weld flanges, stainless steel socket weld flanges, and alloy steel socket weld flanges according to international standards including ASME B16.5, EN 1092-1, and JIS B2220.

Key Features of Socket Weld Flange

Strong and Reliable Connection

The socket design provides accurate pipe positioning, while external fillet welding ensures a secure connection.

Suitable for High-Pressure Applications

Socket weld flanges are commonly used in applications where pressure resistance and leakage prevention are critical.

Easy Pipe Alignment

The recessed socket helps maintain proper pipe alignment before welding, reducing installation difficulty.

Smooth Internal Flow

The pipe is inserted into the socket without a full penetration weld, providing a relatively smooth internal passage.

Technical Specifications

Common Materials

Carbon Steel Socket Weld Flange

Typical grades:

• ASTM A105
• ASTM A350 LF2

Applications:

• Hydraulic systems
• Steam pipelines
• General industrial piping
• Oil & gas systems

Stainless Steel Socket Weld Flange

Typical grades:

• ASTM A182 F304
• ASTM A182 F316
• 304L / 316L

Applications:

• Chemical processing
• Food processing
• Pharmaceutical systems
• Corrosive fluid pipelines

Socket Weld Flange Applications

Socket weld flanges are widely used in:

• Oil & Gas Industry
• Petrochemical Plants
• Chemical Processing
• Hydraulic Systems
• Steam Systems
• Power Generation
• Water Treatment
• Industrial Equipment

They are especially suitable for:

• Small diameter pipelines
• High-pressure systems
• High-temperature applications
• Systems requiring frequent maintenance

Socket Weld Flange vs Slip-On Flange

Socket Weld Flange vs Threaded Flange

Advantages of DTC Socket Weld Flanges

Reliable Supply Chain

DTC provides stable sourcing of forged flanges with strict control over materials, dimensions, and quality requirements.

Wide Material Options

Available materials include:

• Carbon steel
• Stainless steel
• Alloy steel

Customized Solutions

DTC supports:

• Customized dimensions
• Special drilling patterns
• Surface treatment
• Customer logo marking
• OEM/private label production

Quality Documentation

Available inspection documents:

• EN10204 3.1 Material Certificate
• Chemical Composition Report
• Mechanical Property Test Report
• Dimensional Inspection Report

Frequently Asked Questions (FAQ)

What is a socket weld flange?

A socket weld flange is a forged flange where the pipe is inserted into a recessed socket and welded externally to create a strong connection.

What sizes are socket weld flanges commonly used for?

Socket weld flanges are mainly used for small diameter piping, typically from 1/2″ to 4″.

What is the difference between socket weld flange and slip-on flange?

Socket weld flanges have a socket design and are mainly used for higher-pressure small pipes, while slip-on flanges are more economical and suitable for general piping systems.

Are socket weld flanges suitable for high-pressure applications?

Yes. Socket weld flanges are commonly used in Class 300, 600, and higher pressure applications where reliable connections are required.

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