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Hub Flange vs Ring Flange – What’s the Difference

Hub Flange vs Ring Flange

When it comes to mechanical engineering, flanges play a crucial role, connecting various parts of a machine or system to ensure seamless functioning. Two popular types of flanges are hub flange and ring flange, and in this blog post, we will discuss their differences, advantages, and use cases. Understanding the unique properties of each type can help you make better design and application decisions.

What is Hub Flanges?

Hub flanges are components that join multiple pipe or tubing sections in a pipeline system. They are often made from machined metal components that contain holes for bolts, studs, or screws. A hub flange allows two different sized pipes or tubes to be connected together with one fastener set, creating a leak-proof joint. The hub portion of the flange is designed to provide additional support for the assemblies and help reduce stress on the connection joints when they are pressurized. It also makes it easier to separate these parts if needed for maintenance purposes.

What is Ring Flanges?

Ring Flanges are a type of pipe flange that features an interior or exterior raised lip, providing excellent sealing capabilities and strength. Oil, gas, and water transfer piping systems typically use them to connect components such as pumps, valves and pipes. Ring flanges come in different sizes with varying numbers of bolt holes depending on their application. When handling higher pressures, these flanges can also be ordered with additional rings for more stability. Ultimately, ring flanges provide a reliable method of connecting pipes, ensuring maximum system performance under pressure conditions.

Difference Between Hub Flange and Ring Flange


A hub flange has a slight bulge on the male face, while a ring flange is flat across the entire face. This difference in design affects how the flanges connect to other parts. A hub flange uses bolts to attach to a flat surface and is commonly used in automotive and machinery parts. On the other hand, a ring flange uses welds to attach to pipes and is commonly found in pipelines, heat exchangers, and pressure vessels.


Another significant difference between a hub flange and a ring flange is their location on the machine or system. A hub flange is typically located at the end of a shaft, connecting to another rotating component like a wheel or gear. In contrast, a ring flange is typically located at the end of a pipe, where it joins with another pipe or pressure vessel.

Size and Shape:

The size and shape of flanges directly impact their strength, load-bearing capacity, and sealing ability. Hub flanges are generally smaller in diameter and have a round shape, which helps them accommodate the inherently circular shape of the shaft. In contrast, ring flanges come in various shapes, like square, oval, and rectangular, and are larger in diameter to better accommodate the larger pipes or vessels they connect.


Both ring flanges and hub flanges come in different strengths depending on their material, size, and shape. However, ring flanges tend to be stronger and able to withstand higher pressures and stresses, making them the preferred option for critical applications like oil and gas pipelines. On the other hand, hub flanges are more commonly used in lighter-duty applications, like automotive or motorized equipment.

Cost and Availability:

Finally, the cost and availability of hub flanges and ring flanges can vary based on their demand and supply in the market. Hub flanges tend to be more readily available and less expensive than ring flanges, making them a more cost-effective option for some applications. However, ring flanges often come with more rigorous industry certifications, like ASME or ASTM, and are preferred in some industries, which can make them more expensive.


Both hub flanges and ring flanges are essential components of mechanical systems and have distinct features that make them ideal for different applications. Understanding the differences between these types of flanges can help you make informed decisions about design, application, and cost. Whether you are designing automotive parts, pipelines, or pressure vessels, choosing the right type of flange can make all the difference in ensuring smooth and safe functioning.

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