What is a weld neck flange used for?

Weld neck flange

What is a weld neck flange used for?

A weld neck flange is one of the most common types of flanges used in piping applications. In this blog, we will cover the basic definitions of weld neck flange, how many types of weld neck flanges are there and how is weld neck flange made, etc.

So what is a weld neck flange used for? Weld neck flanges are commonly used to connect with pipes in high-pressure applications where extra strength and stability can be critical. They are also often used in situations where welds need to be inspected regularly, as the exposed weld makes it easy to check for signs of defects. In addition, weld neck flanges can be used as an alternative to threaded or slip-on flanges in some cases.

So here is some more information about weld neck flange that is also important.

weld neck flange

What is a weld neck flange?

Weld neck flange, also called a high-hub flange or a tapered hub flange is a type of pipe flange that is attached to a pipe by welding. The neck of the flange is welded to the pipe, providing extra support and preventing the flange from coming loose.  

Weld neck flanges are designed to transfer stress from the point where the pipe meets the flange to the body of the pipe. This allows for a decrease in high-stress concentration at the bottom of the flange. Weld neck flanges are often used in high-pressure applications, such as oil and gas pipelines.

They are also used in corrosive environments, such as chemical plants. One advantage of weld neck flanges is that they can be easily disassembled and reused. However, they are more expensive than other types of flanges and require more time to install.

What are the main types of weld neck flanges?

In fact, there are two types of weld neck flanges. One is a standard weld neck flange and the other one is a long weld neck flange.

The standard or regular weld neck flange is always used with pipes and typically is butt welded to them. Butt welded joints are one of the most widely used methods for joining metal components. The process involves pressing two pieces of metal together and welding them. Butt welds are typically less visible than other types of welds, making them ideal for use in applications where aesthetics are essential.

The long weld neck flanges are not suitable for pipes and they are used more with vessel nozzles and process plants. Long weld neck flanges, as the name implies, have longer necks than standard flanges. This allows for a greater degree of adjustability and flexibility in their applications.

Long weld neck flanges are often used as nozzles for columns or barrels. This is because the long neck gives the operator more control over the flow of material through the nozzle. Another advantage of the long neck also provides a better seal against leakage. So long weld neck flanges are ideal for applications where precision and control are essential.

weld neck flange

Materials of weld neck flanges

As one of the most popular types of flanges used in piping systems, weld neck flanges are available in a variety of materials, including stainless steel, carbon steel, and alloy steel. Each material has its own advantages and disadvantages, so selecting the right material for the application is important.

For example, stainless steel weld neck flanges are resistant to corrosion and can be used in both high-temperature and low-temperature applications. Carbon steel weld neck flanges are more economical but may not be suitable for use in high-temperature applications.

Alloy steel weld neck flanges offer the best combination of strength, durability, and resistance to corrosion and are often used in critical applications such as chemical processing and power generation. When selecting a material for weld neck flanges, it is important to consider the piping system’s operating conditions and the connection’s required strength and durability.

How is a weld neck flange made?

Three primary techniques are used to manufacture flanges: casting, forging, and cutting from rolled plate material. Each method has unique benefits and drawbacks, so the appropriate manufacturing technique must be carefully selected to meet the application’s specific needs.

Casting is the most versatile of the three manufacturing methods, as it can be used to produce flanges of nearly any size and shape. However, cast flanges are often less accurate than those produced using other methods, and they may require additional machining to meet dimensional tolerances.

Forging, on the other hand, produces extremely strong and durable flanges. But because forging involves shaping molten metal using dies or molds, it is generally limited to producing flanges with standard dimensions and shapes.

Cutting from rolled plate material is the most efficient way to produce large quantities of identical flanges. However, this method requires high precision and well-maintained equipment, which can drive up costs.

Weld neck flanges are manufactured by cutting a pipe to the desired length. The end of the pipe is then beveled to create a smooth transition for welding. Next, a ring-shaped plate called a hub is welded onto the end of the pipe.

The hub provides extra support for the weld and gives the flange a place to connect to another pipe or fitting. Finally, the entire assembly is welded together to create a strong, leak-resistant connection.

weld neck flange

What is the difference between a weld neck flange and a slip on flange?

Both weld neck and slip on flanges are used to connect pipes and other fittings together. Weld neck flanges are one of the most common types of flanges used in pipe fittings. They consist of a circular plate with a raised neck that is welded to the pipe.

Slip on flanges are similar, but they have a recess instead of a raised neck. This allows them to be slipped over the end of the pipe before being welded in place. Normally speaking, there are 3 main differences between a weld neck flange and a slip on flange: the connection structure, application situation, and welding form.

1. The connection structure

The major difference between a weld neck flange and a slip on flange the way that they connect to pipes. A slip-on flange is connected to a pipe at an angle, while a butt welding neck flange can be connected to a pipe directly.

Slip-on flanges can only be connected to pipes, while welding neck flanges can be connected to both pipes and other welding neck flanges. This means that welding neck flanges are more versatile in the ways that they can be used. However, slip-on flanges are typically easier to install, making them a popular choice for many applications.

2. Application situation

Slip-on flanges are commonly used in low-pressure piping applications. A big advantage of this type of flange is that it can be easily attached to the pipe without welding. This is because the slip-on flange slips over the end of the pipe and is then secured with bolts.

Welding neck flanges are used in high-pressure applications. They are welded to the pipe, which provides extra reinforcement. According to the test, slip on flange’s nominal pressure is 0.6 – 4.0 MPa and that of the welding neck flange is 1-25 MPa.

weld neck flange

3. Welding form

Another huge difference between a weld neck flange and a slip on flange is that welding neck flanges have a tapered hub, which aligns itself with the pipe’s inside diameter once welded in place. This creates less turbulence and stress on the weld, making it ideal for high-pressure situations.

Slip-on flanges, on the other hand, have a flat face that butts up against the pipe. They’re secured with fillet welds at both hubs and around the circumference of the flange. This mounting method is perfectly adequate for most low to moderate-pressure applications.

Actually, welding neck flanges can be attached to the pipe before welding, while slip-on flanges must be slid over the end of the pipe before welding can begin. This makes welding neck flanges more convenient to work with in many situations.


Overall, the main benefit of using a weld neck flange is that it helps reinforce the connection between the pipe and the flange, which can help prevent leaks.

The downside of weld neck flanges is that they are generally more expensive than other flanges, requiring more time and effort to install. However, weld neck flanges are excellent for applications requiring a strong, leak-proof connection.


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