The Difference Between WNF and LWNF: A Quick Application Guide

Contents

• Introduction
• What is a WNF
• Detailed Explanation of Weld Neck Flanges
  • Main Types of Weld Neck Flanges
  • Standards for Weld Neck Flanges
  • Structural Characteristics of Weld Neck Flanges
  • Applications of Weld Neck Flanges
• Advantages of Weld Neck Flanges
• What is a LWNF
• Features of Long-Warm-Neck Flanges
  • Classifications of Long-Warm-Neck Flanges
  • Applications of Long-Warm-Neck Flanges
  • Installation of Long-Warm-Neck Flanges
  • How to Choose a Long-Warm-Neck Flange
  • Is a Long-Warm-Neck Flange a Narrow-Face or Wide-Face Flange?
• Advantages of Long-Warm-Neck Flange Welding
• FAQ
• Summary

Introduction

There are many different types of flanges, and in industrial applications, there are over a dozen different types, each suitable for different industrial environments.

Today, we’ll focus on two very similar flanges: WNF and LWNF. We hope this will help you better understand these two types.

If you’d like to learn more about flange manufacturing, you can follow Metleader’s YouTube and LinkedIn channels.

What is a WNF

WNF stands for Weld Neck Flange, a type of flange used for welding. It features a tapered neck, which significantly improves strength and sealing when welded to the pipe. Unlike long-neck weld neck flanges, weld neck flanges have a shorter neck.

Detailed Explanation of Weld Neck Flanges

Weld neck flanges are an essential component of industrial piping systems.

They are typically welded to the piping system to connect, seal, and support the pipes. Understanding the characteristics of weld neck flanges in detail will help you better select the right flange.

Main Types of Weld Neck Flanges

• Slip-on flange (SO): Features a lower neck height and is suitable for low-pressure applications (≤2.5 MPa).
• Weld-neck flange (WN): The neck is butt-welded to the pipe, offering high pressure resistance (up to 42 MPa) and complying with ASME B16.5 standards.
• Blind flange (BL): Used to seal the end of a pipe, with the same pressure rating as the WN flange.

Standards for Weld Neck Flanges

• ASME B16.5: American standard, pressure ratings 150#, 300#, to 2500#.
• EN 1092-1: European standard, PN6 to PN100 (1 MPa = 10 bar).
• GB/T 9119: National standard, pressure range 0.25 MPa to 16 MPa.

Structural Characteristics of Weld Neck Flanges

The most notable feature of weld neck flanges is their connection method – welding to the pipeline.

This connection method gives weld neck flanges extremely high strength and sealing properties, allowing them to withstand large pressure and temperature fluctuations, ensuring the safe and stable operation of the pipeline system.

Applications of Weld Neck Flanges

Weld neck flanges are widely used in various piping systems, especially in situations where they need to withstand high pressure, high temperature, or corrosive media.

In addition, weld neck flanges are also commonly used in civil piping systems such as fire protection and water supply, providing safe and reliable protection for people’s lives.

Advantages of Weld Neck Flanges

Excellent Sealing Performance: Weld neck flanges offer excellent sealing performance, effectively preventing media leakage and ensuring a safe and stable production process.

Strong Load-bearing Capacity: Weld neck flanges can withstand significant pressure and tension, maintaining stable connections even in high-pressure and high-temperature environments.

Long Lifespan: Weld neck flanges are generally made of high-strength materials and specialized welding processes, resulting in a long lifespan and reducing equipment maintenance and replacement costs.

Strong Adaptability: Weld neck flanges can connect pipes and equipment of varying materials and specifications.

What is a LWNF

LWNF, short for long-neck weld neck flange, is an important pipe connection component.

Its design features a longer neck, which provides additional support and reduces the torque caused by the pipe, thereby reducing stress concentration and improving overall structural stability.

This feature enables long-neck weld neck flanges to perform excellently under high-temperature and high-pressure conditions.

Features of Long-Warm-Neck Flanges

The characteristics of the long neck butt welding flange are versatility and interchangeability, which means that it can be connected to various types of pipes and equipment, greatly improving the efficiency and flexibility of engineering installation.

Classifications of Long-Warm-Neck Flanges

According to the material, there are carbon steel long neck flanges, stainless steel long neck flanges, etc.; according to the connection method, there are flat welding long neck flanges, butt welding long neck flanges, etc.; according to the purpose, there are pipeline connection long neck flanges, equipment connection long neck flanges, etc.

Applications of Long-Warm-Neck Flanges

Long-neck butt-weld flanges are widely used in industries such as petroleum, chemical, natural gas, and shipbuilding.

Due to their high load-bearing capacity, long-neck flange welded joints are often used to connect large equipment and pipelines. Furthermore, their high-temperature and high-pressure performance make them a top choice for high-end applications.

Installation of Long-Warm-Neck Flanges

When installing long-neck butt-weld flanges, special precautions are required:

• First, ensure the concentricity of the flange and the pipe to prevent leakage caused by installation deviation.
• Second, strictly control the welding quality and temperature during the welding process to ensure the strength and sealing of the weld joint.
• Finally, after installation, the flange connection should be rigorously pressure and leak-tightened to ensure safe operation of the piping system.

How to Choose a Long-Warm-Neck Flange

1. Select the appropriate long-neck weld flange based on the pipe material and design requirements.
2. Choose the appropriate material and specifications based on the specific operating conditions, such as temperature and pressure.
3. When purchasing, pay attention to the flange’s surface smoothness and specification compatibility.
4. When selecting a flange, consider the specific operating environment and process characteristics to ensure flange stability and service life.

Is a Long-Warm-Neck Flange a Narrow-Face or Wide-Face Flange?

The neck length of the long neck butt welding flange is longer than that of the ordinary flange, and the area of ​​the supporting flange is also larger, which is similar to the wide face flange.

Therefore, the long neck butt welding flange is classified as a wide face flange.

Advantages of Long-Warm-Neck Flange Welding

Higher-quality welded joints: The long-neck flange’s structural design provides higher-quality welds during welding, resulting in a stronger weld.

Faster welding speed: Long-neck flange welding is faster than traditional welding methods because it eliminates the need to wait for the weld surface to cool.

Higher technical requirements: Long-neck flange welding requires more precise control of wire heating and pressurization.

FAQ

Q: What is the neck height of a DN100 flange?

A: According to ASME B16.5, the neck height of a DN100 WN flange is 56mm (±1.5mm).

Q: How should the flange material be matched to the pipe?

A: The “equal strength principle” must be followed. For example, 304 pipe should be matched with a 304 flange to avoid electrochemical corrosion.

Summary

Through the above content, I believe everyone has a deeper understanding of these two flanges. If your project requires these flanges, you can consult Metleader’s professional engineers.

We will provide free and professional guidance and provide complete flange solutions.