Flange Faces

As you start to consider purchasing flanges or gaskets, you’ll see a variety of terms used that you may not have come across before. Flange faces are the surface area that will receive the gasket, allowing them to come together to create a seal when put under...

Octagonal Ring Type Joints

A ring-type joint is a metallic ring that is machined to sit between two mating surfaces, where it will be compressed to provide a high-quality and reliable seal. Ring-type joints are vital components in various applications across multiple industry sectors,...

Blind Flange vs Blank Flange

Small pieces of mechanical equipment flanges continually play a vital role across numerous industries and applications. In essence, we use flanges to connect pipes to each other, with flanges also found in valves and specific application fittings too. Due to the...

Types of Flanges

Businesses in a variety of industries rely on flanges to join pipes or components together or to keep equipment secured to a surface. When it comes to choosing the best types of flange for your processes, you’ll want to take the time to research the different options...

Threaded Flange

Threaded flanges are probably the most recognisable of all flanges due to their screw thread design that is used to connect it to the pipe. Threaded flanges, also known as screwed flanges (for obvious reasons), require a male and female thread to create a connection...

Weld Neck Flange

Also known as tapered hub flanges or high hub flanges, weld neck flanges are a specific type of gasket with a protruding ridge and long neck used to connect pipework and provide you with a high-quality seal. Weld neck flanges, in particular, are a popular choice when...

Nitrile vs Viton® – What is the Difference?

As you start to make a decision about what type of O-rings to purchase for your business, you might wonder what material is the most suitable for your unique needs. Every business operation has different requirements for their O-rings, such as the temperature,...

Aflas vs Viton

When it comes to choosing O ring suppliers in the UK, you’ll find that there are a wide range of materials on offer for you to choose from. Many people find that the options can seem quite overwhelming, with some materials having similar properties but offering...

EPDM Gasket

Both the automotive and construction industries have started to use EPDM gaskets more frequently in recent times. This rubber material is UV light resistant and has many fantastic properties that make this part highly effective for a wide range of processes. Keep...

Metal Gaskets

When comparing gaskets for use within your business processes, you’ll find that these can be made from a variety of materials. Metal gaskets are a very popular option, offering many advantages over other materials. When looking at sealing product options, make sure...

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Slip On Flange

A slip-on flange can also be known as a hubbed flange, which, as the name suggests, has a hub with a very low profile.

Why is this important?

Because this type of ring type joint gasket has an internal diameter larger than the connecting pipe, allowing you to slide it onto the pipe with ease and speed.

Sliding over the pipe, these types of RTJs can be directly connected to the equipment or pipe in question using a fillet weld in two locations on the flange.

This particular type of flange is typically found in low-pressure, medium-temperature piping systems.

To learn more about this flange and fillet welding type, read on.

Introduction to slip on flange

Slip on Flange Welding

Hubbed flanges can be connected to pipes with one or, in some instances, two fillet welds (one outside the flange and the other inside). This is, of course, dependent on the

application and the specifications of the piping system.

However, it’s important to be aware that because there is no full penetration weld (unlike the counterpart weld neck flanges), their use is limited as they offer lower weld integrity.

(Make sure to also check out our post on `Threaded Flanges` to find out the advantages and disadvantages and how these compare to slip on flanges.)

Slip-on flanges are also available in various sizes, making them suitable for a range of pipe diameters. And this type of ring type joint is ideal for low pressure applications and great if you’re limited on space.

Slip-on flanges in higher-pressure classes are often made with the height of a lap joint, allowing you to achieve a better connection.

However, if the hub height is not a concern, and you don’t need a specific lap joint, you can opt for a slip-on flange made to a lap joint style with a machined hub.

Two varying slip on flange types which have mechanical differences include:

  • Welding flange plate
  • Welding flange – hubbed steel pipe

Face types include:

Raised face slip-on flange – this type of flange sees a slight protrusion of the seal at the bottom, which is designed for gasket placement during installation. During installation, the benefit of this extrusion is that it allows for a gasket set to be inserted, enhancing and providing exceptional sealing performance. In addition, as pressure ratings increase, the raised face height will also increase, continuing to provide a secure seal – enforcing the seal.

RTJ slip-on flange – this type of flange requires a small precision groove to be expertly engineered on the face element of the flange. The groove created is then used to insert the gasket ring required for sealing. This particular type of slip-on flange then allows this type of flange to be suitable (short-term) for high-pressure applications due to its superior sealing ability.

Benefits of slip-on flanges

A simple and excellent alternative when looking for a quick sealing solution, slip on flanges offer:

  • Low procurement costs
  • Easy installation and disassembly
  • No weld preparation requirements
  • A great alternative if you’re limited on space
  • An integral ingredient to pipe connections
  • Looping systems
  • A simple structure
  • A convenient process
  • Cost-effective solutions

Disadvantages of a slip-on flange

  • You may need to use two welds to secure instead of just one
  • It has a reduced mechanical strength compared to weld neck flanges
  • It is not suitable for cyclic loading
  • Generally not used above ASME class 600
  • Durability life is one-third of a weld neck flange


Slip on flanges, slip over the pipe, where you will then align the bolt holes appropriately, followed by inserting the bolts and tightening to the correct torque levels.

Ring Type Joints

There are numerous requirements that still must be met for the installation, maintenance, and testing of these flanges – and this is where the experts at Specialist Sealing Products come in.

Used in various fluid applications to connect equipment, slip-on flanges offer low installation costs, are easy to align with other parts, and can provide a better seal in low-pressure applications.

However, we know that it’s vital to consider a range of factors and understand all of the advantages and disadvantages of a range of flanges before choosing the right one for your piping system.

Let us help.

With years of experience and expertise with various gaskets, seals, flanges, and more, we know what works with specific applications and what can provide you with the best sealing solution around.

Put us to the test.

Speak to a member of our team today about your specific requirements.

If you would like any further information on our slip-on flanges, please call 01535 274 776 or email us at



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