What Is A Flange In Plumbing

What Is A Flange In Plumbing


What Is A Flange In Plumbing: Understanding the role and components of a plumbing system is essential for any homeowner or plumbing enthusiast. One crucial element commonly encountered in plumbing installations is a flange. A flange serves as a vital connecting piece that brings stability and reliability to various plumbing connections. 

Whether it’s connecting pipes, valves, or fixtures, a flange plays a crucial role in ensuring leak-free and secure joints. In this article, we will explore what a flange is in plumbing, its types, functions, and how it contributes to the overall efficiency and durability of a plumbing system. So, let’s dive into the world of plumbing flanges and unravel their significance in maintaining the smooth operation of our water and wastewater systems.

Flanges offer several advantages in plumbing systems. They provide a reliable and durable connection that can withstand high pressures and temperatures. The use of flanges allows for easier disassembly and maintenance of the plumbing system without the need for cutting or modifying the pipes. Flanges also facilitate flexibility in system design and allow for the connection of various components, such as valves, pumps, or fittings.

What Is A Flange In Plumbing

What Is A Pipe Flange?

What is a Pipe Flange? A pipe flange connects piping and components in a piping system by use of bolted connections and gaskets. Most commonly used flanges are weld neck flange, slip on flange, blind flange, socket weld flange, threaded flange and lap joint flange (RTJ Flange).

Pipe flanges are essential in plumbing and piping. A metal disc with a flat or raised rim connects pipes, valves, and other equipment. A pipe flange’s main purpose is to unite pipes securely and leak-free.

Pipe flanges come in various sizes, shapes, and materials to accommodate different system requirements. They are usually bolted or welded to the pipe ends, providing a secure connection. The flange’s flat or raised rim creates a sealing surface when compressed against a gasket, ensuring a tight seal that prevents leaks.

Flanges offer several advantages in plumbing systems. They simplify installation and allow for easy maintenance and repairs by providing an accessible connection point. Additionally, they enhance the structural integrity of the system by providing stability and support to the connected pipes.

What Is Flange And Types Of Flanges?

The key types of flanges are the welding neck, long welding neck, slip-on, socket weld, lap joint, threaded and blind flanges. In addition to these standard flanges, some special ones exist, called Weldoflange/Nipoflange and Elboflange, swivel flange, expander/reducer flange, and orifice flanges.

Flanges join pipes, valves, and other equipment in plumbing and other industries. The disc-shaped construction with a flat or raised rim secures joints and prevents leakage. Flanges come in many types for different applications.

Weld Neck Flange: A pipe-welded flange with a long tapered hub. Its structural robustness makes it appropriate for high-pressure and high-temperature applications.

Slip-On Flange: Slip-on flanges slide over pipes and are welded in place. They fit low-pressure systems and are easy to install.

Blind Flange: Blind flanges seal pipe ends. These boreless pipes are used to shut pipelines or provide inspection locations.

Socket Weld Flange: Their socket-like bore helps fluid to flow smoothly. They fit small-bore pipes and are welded.

Lap joints have stub end and slack backing flanges. Because they align and disassemble quickly, they are utilized in systems that require regular disassembly.

These are just a few examples of the types of flanges available. Each type has its unique features and applications, making it important to select the appropriate flange based on the specific requirements of the plumbing or industrial system.

What Is The Function Of Flange In Plumbing?

Flanges are helpful to connect pumps, valves, pipes, and other parts to form a piping system. Flanges are typically welded or thread screwed to connect. The use of flanges allows a person for maintenance and easy repair of the pipe system.

In plumbing, a flange serves several essential functions that contribute to the overall efficiency and reliability of the system.

Connection: The primary function of a flange is to provide a secure and leak-proof connection between pipes, valves, and other plumbing components. By creating a flat or raised rim, the flange allows for the attachment of various elements, ensuring a tight and dependable joint.

Support and Stability: Flanges offer stability and support to the connected pipes. They help distribute the weight and pressure evenly, preventing excessive stress on the joints. This is especially crucial in high-pressure or heavy-duty plumbing systems.

Easy Installation and Maintenance: Flanges simplify the installation process by providing accessible connection points. They allow for easy assembly and disassembly, making maintenance, repairs, and component replacements more convenient and efficient.

Leak Prevention: When used with gaskets, flanges create a sealing surface that helps prevent leaks. The compression of the gasket between two flanges creates a tight seal, ensuring that no fluids or gases escape from the joint.

Versatility: Flanges are available in different sizes, shapes, and materials, making them compatible with a wide range of plumbing applications. They can be used in various industries, including residential, commercial, and industrial plumbing systems.

Overall, the function of a flange in plumbing is to provide a secure connection, enhance stability, prevent leaks, and facilitate easy installation and maintenance. These functions make flanges indispensable components in ensuring the smooth operation and longevity of plumbing systems.

How Do You Identify A Flange?

You need to find the outer diameter, the inner diameter, the number of bolt holes, bolt hole diameter, and the bolt circle diameter. Bolt circle diameter (B.C.) is one of the most important measurements to make when identifying a flange.

Identifying a flange requires a basic understanding of its physical characteristics and visual cues. Here are some key factors to consider when identifying a flange:

Shape and Design: Flanges typically have a disc-like shape with a flat or raised rim around the outer edge. This distinctive design helps distinguish them from other plumbing components.

Bolt Holes: Around flanges, bolt holes are evenly spaced. Bolt or stud the flange to a pipe or valve using these holes.

Size and Measurements: Flanges come in various sizes, and their measurements are usually specified in terms of pipe diameter or nominal pipe size (NPS). Determining the size of a flange can help narrow down its identification.

Material and Finish: Flanges are commonly made of metal, such as stainless steel, carbon steel, or brass. The material may be evident through its appearance, texture, or the presence of manufacturer markings.

Application and Context: Consider where the flange is located and its role within the plumbing system. Flanges are often found at the connection points of pipes, valves, or equipment.

By considering these factors, one can identify a flange based on its shape, bolt holes, size, material, and context within the plumbing system.

What Is A Flange In Plumbing

How Many Flange Sizes Are There?

Some breast pumps have five pump flange sizes. Refer to your manual. For two sizes, measure both breasts.

Flanges are available in many sizes to fit pipe diameters and systems. The wide range of flange diameters available suits many industries and applications. However, plumbing and pipe systems use some standard flange sizes.

NPS or OD are used to measure flange sizes. Flange diameters typically range from ½ inch to 24 inches, with smaller sizes in between. These diameters match ANSI/ASME B16.5 and DIN pipe and flange specifications.

For smaller pipes, such as those used in residential plumbing, flange sizes usually start from ½ inch or ¾ inch and increase in increments of 1/8 or 1/4 inch. As the pipe diameter increases, so does the corresponding flange size. Larger industrial applications may require flanges in sizes ranging from 10 inches up to 24 inches or more.

It is important to note that specific projects or industries may require custom or non-standard flange sizes to meet specific requirements. Flanges can be made or machined to size.

Overall, the number of flange sizes available is vast, with common sizes ranging from ½ inch to 24 inches. Consulting relevant standards and specifications can provide further guidance in selecting the appropriate flange size for a specific plumbing or piping application.

What Is The Function Of Flange In Ball Valve?

Industries that pipe water or other liquids at low to high pressures and temperatures employ flanged ball valves. A flanged ball valve can start and halt liquid flow and swap pipes without disturbing the line.

Flanges play a crucial role in ball valve applications, enhancing their functionality and reliability. The function of a flange in a ball valve can be summarized as follows:


Ball valves are connected to pipes by flanges. Fastening the valve and pipe flanges creates a leak-proof union.

Alignment and Support:

Flanges help align the ball valve with the pipeline, ensuring a proper flow path. They provide stability and support to the valve, minimizing stress on the valve body and internal components.

Easy Installation and Maintenance:

Flanges simplify ball valve removal and installation. Bolted flange connections allow valve maintenance, repair, and replacement without pipe cutting or welding.

Pressure Resistance:

Flanges in ball valves are designed to withstand high pressure conditions. The flange connection ensures that the valve remains securely in place even under high operating pressures, preventing leaks and maintaining system integrity.


Flanges allow for flexibility in system design and modification. They enable versatile and adaptable ball valve installation and replacement in the pipe system without major alterations.

Overall, the function of a flange in a ball valve is to provide a strong and reliable connection, align and support the valve, facilitate easy installation and maintenance, withstand high pressures, and offer flexibility in system design. These functions contribute to the overall efficiency, safety, and longevity of ball valve applications in various industries.

What Is The Difference Between A Coupling And A Flange?

Flanges have many advantages over couplings. They attach better than couplings. Flanges can link pipes of different sizes, but couplings can only connect shafts of the same diameter.

Couplers and flanges are two types of plumbing and piping fittings with different functions. Their main differences are:


Couplers join two pipes directly. Screws, nuts, or compression rings secure two socket-like ends to the pipe ends. Mechanical couplings link pipe ends.


A flange is a flat or raised rim attached to the end of a pipe, valve, or equipment. Flanges require bolts or welding to connect them to another flange or component. They create a strong and secure connection by compressing a gasket between two flanges, forming a sealed joint.


Jointing pipes of the same material and size is common. They make installation, repair, and modification easy. Low-pressure or frequent-disassembly systems use couplings.


High-pressure, high-temperature systems use flanges. Suitable for connecting pipes, valves, equipment, or plumbing access points. Industrial, commercial, and large-scale plumbing employ flanges.


Couplings provide a reliable connection between pipes but may have limitations in terms of pressure and structural integrity.


Flanges offer robust strength and stability due to their bolted or welded connections. They can handle higher pressures and provide greater structural integrity, making them suitable for demanding plumbing systems.


Couplings allow for easy disassembly and reassembly of pipes, facilitating maintenance, repairs, or modifications.


While flanges provide a more secure connection, they may be harder to install and disassemble. They are used in low-maintenance applications.

Flanges seal joints, couplings link pipes. Couplings are flexible and easy to install for minor applications, whereas flanges are for high-pressure and permanent plumbing connections.

Is Flange A Type Of Fitting?

Pipe flanges are typical pipe fittings. Flanges mechanically join pipes. Additionally, it can mechanically connect a pipe to a tee, valve, choke, or other device.

Flat- or raised-rimmed flanges are discs. Flanged pipes, valves, and equipment are secure. Bolting or welding them to pipe or equipment ends provides stability and leak resistance.

Different plumbing applications require different flange sizes, shapes, and materials. Residential, commercial, and industrial contexts use them to connect pipes, valves, and other components.

Besides flanges, plumbing systems use elbows, tees, couplings, reducers, and adapters. These fittings accommodate pipe size, direction, and configuration variations. Each fitting is essential to a working plumbing system.

What Is A Flange In Plumbing


The flanges support pipes, seal leaks, and make installation and maintenance easier. Flanges work for residential and industrial plumbing. They accommodate different plumbing needs with sizes, shapes, and materials. Slip-on for quick connections and weld neck for high-pressure applications, flanges give plumbing systems strength and reliability.

Understanding the role and importance of flanges in plumbing empowers piping system homeowners, plumbers, and industry professionals to make informed decisions when it comes to selecting and installing these critical fittings. With their ability to create secure connections and ensure system integrity, flanges contribute significantly to the overall durability and functionality of plumbing systems.