All you want to know about threaded flanges

Threaded flanges

All you want to know about threaded flanges

Threaded flanges are an important part of any plumbing system, whether they are used in residential applications or large industrial facilities. Threaded connections are highly reliable and often the only choice in areas where welding isn’t practical. They enable easy assembly and disassembly by hand and provide a secure seal for piping systems.

These flanges come in various sizes, materials, and pressure classes, allowing them to be used for a broad range of applications. Each one is designed to securely connect two pipes together, providing a liquid-tight connection that can stand up to long-term use without degrading or leaking.

The variety available makes it easy to find the perfect threaded flange for the needs, making them essential for redirecting plumbing directions or sealing off ends where needed. Whether working with PVC, polyethylene pipe, steel tube fittings, valves, or other components, threaded flanges will help ensure long-term performance.

Easy installation combined with reliability has made them hugely popular and widely adopted around the world. So in this blog, we will make an in-depth and all-around introduction to threaded flanges.

threaded flanges

What is a threaded flange?

A threaded flange(also called a ‘screwed flange’) is a part used in high-pressure piping systems, designed to provide a safe and secure connection between two pieces of equipment or piping.

As its name suggests, the threaded flange is to connect the flange to a pipe with external or internal threads which are attached to the outer wall of the pipe, allowing them to be tightly screwed together while creating an air and water-tight seal. Threaded flanges come in standard sizes from 1/2″ up to 8″.

They are available in multiple materials such as stainless steel, brass, and plastic for various applications. They can also be fitted with safety mechanisms such as antistatic ground circuit protection, back pressure prevention valves, and leak detectors to ensure maximum safety for operators using the connection. In simpler terms, a threaded flange is essentially a large bolt that is used to connect pipes.

What types are there of threaded flanges?

Threaded flanges come in two varieties. The first is to use a lens pad and a specific sealing surface to seal the two pipe ends and it’s also called The other type has two flange sealing faces and functions similarly to conventional flanges. But more often, people divide the types of threaded flanges according to the forms of facing. The threaded flange has two facing types, one is raised face flange and the other is ring joint flange.

threaded flanges

Raised face flange

The raised face threaded flange has been used in many industries since it was developed in the late nineteenth century. It is composed of two components: the flange section, which provides support and stability; and the body, where bolts are installed to hold the joints together.

This flange type is widely recognized in various industries due to its ease of installation as well as its interaction with gaskets. When laid down on a flat surface, this flange’s gasket surface area lies above the bolted line, making it easy for even amateur installers to spot when properly aligned.

Furthermore, the range of compatible gaskets for a raised face threaded flange is quite wide, from flat types all the way to semi-metallic and metallic gaskets in either ring or full form. Every single one of these different varieties can be used interchangeably with this particular flange without any additional work or modifications.

threaded flanges

Ring joint flange

RTJ Flanges, or Ring Joint Threaded Flanges, are essential components of many high-pressure and high-temperature systems. It’s easy to recognize this type of flange because it has a circular groove with a concrete circumference for accommodating a ring joint gasket.

These are used when metal-to-metal seals are required in extreme conditions, ensuring that all connections remain secure and tight. RTJ Flanges come in both pressure classes as well as types such as slip-on, blind, weld neck, and socket weld. The grooves of the flange itself provide added security for use with more demanding applications like power generation, petrochemical processing, and oil refining.

Additionally, the design of an RTJ Flange ring allows for easier dismantling since no special tools are necessary. Despite the fact that they offer additional sealing capabilities compared to ordinary raised face flanges or cut gasket joints, RTJ Flanges can also be reworked and reused easily as long as it is not depreciated or damaged., making maintenance much more cost-effective in the long run.

All in all, RTJ Flanges provide excellent sealing protection required during intense operating conditions and can be reworked with ease whenever necessary which makes them the perfect choice when strength is essential.  Overall, their versatility makes them one of the most reliable industrial components available today.

Where can I use threaded flange?

Threaded flanges are an essential component for many industrial, commercial, and residential applications.

Threaded flange products are used in a remarkably wide array of applications, from providing pipes and other components with secure connections in manufacturing, to helping plumbers and contractors in the installation and maintenance of various mechanical systems.

In construction, they can be used as bridges between two pieces of equipment or other flat surfaces; in water pumps, they are frequently used to establish a connection between pipes and pressure tanks.

Additionally, threaded flanges can also act as key components in heat exchangers. Whatever application threaded flanges are being used for, the demand for reliability to assure safety is paramount; that is why these fittings must always be carefully chosen for each particular project’s needs.

Thanks to their versatile use cases, threaded flange products remain an integral element across different industries. This kind of reliable connector ensures tight strength and structural integrity so every job runs without fail no matter the environment it’s being used in.

threaded flanges

How is a threaded flange measured?

When it comes to measuring threaded pipe flanges, precision is key in order to obtain the right results. The amount of data that must be collected can seem overwhelming at first, but it ensures that all dimensions are within specified tolerances.

This includes measuring the outside diameter of the flange (O), along with its thickness (C). The diameter of the raised face (R) and hub diameter at base (X) also needs to be determined, as well as the length through the hub (Y), minimum thread length (T), and minimum diameter of the bolt circle (Q). In a time where accuracy and safety are essential for success, it is important for these values to be measured accurately in order to guarantee that all parts fit together properly. With the right know-how and reliable methods, undoubtedly a high degree of accuracy can be achieved in measuring threaded pipe flanges.

  • Q-Outside Diameter
  • C-Thickness
  • R-Diameter of the raised face
  • X-Hub Diameter
  • Y–Length through the hub
  • T–Minimum thread length
  • Q–Minimum diameter of the bolt circle

Can you weld a threaded flange?

Welding a threaded flange is not recommended and may not even be possible in many cases. Threaded flanges prevent access to the weld area, and once welded, any failure of the connection could cause significant problems due to the confined space. Additionally, materials such as plastic flanges cannot be welded due to their reduced melting point.

Furthermore, threaded flanges are often used in pipes that are galvanized or subject to temperature fluctuations — both of which can have a negative effect on welding results. In these situations, it is generally much safer to use a fastener such as a bolt instead of welding the threaded flange in order to keep the pipe secure.

Ultimately, it is important to fully assess the application before attempting any kind of welding and determine whether welding a threaded flange is safe and viable. Otherwise, disaster could ensue if done improperly!  All these factors considered, it’s usually best practice to avoid welding when working with threaded flanges.


When creating certain types of industrial machinery, threaded flanges can prove to be an indispensable tool. By creating a great degree of support and protection for pipes, wires, and other components, threaded flanges greatly increase the safety and longevity of these machines.

Highly heat-resistant fibers contribute toward their superior performance making threaded flange an obvious choice for anyone needing extra security in their machinery construction projects.

If you need more information about threaded flanges, please don’t hesitate to contact us!


Some other related articles:

What is a blind flange in plumbing?

All you need to know about lap joint flange in this blog

What is a weld neck flange used for?