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What is Companion Flanges? Uses, Properties, and Dimensions

Companion Flanges

If you’re looking for a reliable way to connect two pieces of pipe, then companion flanges are your best bet. They use welding to create a secure seal and come in various types to suit your needs. In this blog post, we’ll take an in-depth look at companion flanges and explain why they are such an effective solution for connecting pipes.

What is Companion Flanges?

A companion flange is a type of pipe fitting that allows you to securely connect two sections of piping without the need for additional supports or welds. Companion flanges consist of two identical pieces with bolt holes, designed to align with each other. They are typically welded onto the ends of pipes, forming a solid connection. These flanges are commonly used in industries such as plumbing, oil and gas, and construction for their durability and reliability. With their ability to withstand high pressure and temperature conditions, companion flanges ensure a secure and long-lasting pipe connection.

Companion Flanges Uses

Companion flanges are most commonly used in constructing pipelines and other large-scale piping systems. They allow piping sections to be connected securely while allowing easy maintenance and repairs if necessary. They can also be used to construct boilers, tanks, and other vessels where it would be difficult or impossible to achieve a secure connection without welding.

Companion Flange Types

Several types of companion flange are available, each designed to meet specific needs depending on the application they’re being used for. The most common types include slip-on, lap joint, threaded, socket welded, blind lap joint, and weld neck companion flanges. Each type has its own unique advantages and disadvantages, so it’s essential to choose the right type for your project.

Companion Flange Welding

Companion flange welding is a great way to join two pipes together. It requires an experienced welder and heat source that can reach the proper temperature for the type of steel being joined. The process involves carefully preparing both pipes, ensuring they are free from rust or debris, and then aligning them perfectly. Once the pipes are in place, the welder will apply heat along the edges of each pipe until they meld into one piece. It’s essential to monitor the weld temperature very closely to get a successful joint with optimal strength. This method makes pipe connections incredibly durable and reliable for long-term use.

Companion Flange Sizes

Companion flanges come in various sizes to accommodate different pipe dimensions and requirements. They are available in standard sizes ranging from small to large, addressing various applications. Choosing the right size companion flange ensures a proper fit and secure connection between pipes, minimizing the risk of leaks or structural issues.

Companion Flange Dimensions

Companion Flange Dimensions

Flange A mm 90 100 120 150 180-8 180-10 225 250 285 315 350 390 435
Bolt Circle B mm 74.5 84 101.5 130 155.5 155.5 196 218 245 280 310 345 385
Pilot C mm 47 57 75 90 110 110 140 140 175 175 220 250 280
Pilot Height D mm 2.2 2.2 2.2 2.5 2.7 2.7 4 5 6 6 7 7 9
Hardware mm M8 M8 M10 M12 M14 M16 M16 M18 M20 M22 M22 M24 M27
# Bolts 4 6 8 8 8 10 8 8 8 8 10 10 10


In conclusion, companion flanges efficiently connect pipes without requiring additional support or welding processes. Depending on your specific needs, they come in several different types and can be used in various applications, including pipeline construction and vessel fabrication. No matter what type you choose or what application you’re using it for, you can trust that a companion flange will provide a secure connection every time!

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