Introduction

Swivel flanges are unusual in industrial piping. Unlike conventional flanges, swivel flanges are designed to rotate during installation, making installation much easier. What other features does a swivel flange have? How do its operating principles, mechanical properties, and product specifications compare to conventional flanges? Let’s read the following article to find the answers.

What is a swivel flange?

A swivel flange consists of a heavy-duty hub and a rotatable outer ring. Installation of this type of flange is primarily accomplished by welding the inner hub to the pipe, then aligning the outer ring with the bolt holes in the other flange. The rotatable outer ring simplifies installation, making this type of flange particularly advantageous for installation in confined or underwater environments.

What is a swivel flange used for?

A key feature of swivel flanges is their ease of installation.

Thus, they are often used in the following types of pipelines:

• Submarine pipelines require installation to be performed underwater, but this type of flange simplifies alignment. Offshore platforms: These locations have limited safety and operating space for
• installers, requiring flanges that are easy to align.
• Floating production systems: Frequent adjustments are required.
• High-pressure pipelines: Efficient and safe flange installation is essential.

How Does a Swivel Flange Work?

Because a swivel flange consists of two parts: a welded-neck hub and a swivel ring, they must be installed separately.
Welded-neck hub: This part is welded directly to the pipeline.

Swivel ring: It rotates around the hub, facilitating nut connection with the flange on the other end. The swivel ring easily aligns with the bolt holes, even at different angles.

Advantages of Swivel Flanges

Compared to fixed flanges, swivel flanges offer the following advantages:

1. Simple Installation: Bolt holes are more easily aligned, making installation simpler.
2. Time Savings: Time is saved on aligning flange holes, especially in underwater environments.
3. Economical and Efficient: For offshore projects, this reduces the installer’s diving time.
4. Safe Operation: No more angular adjustments are required during alignment.

These advantages make it the flange of choice for offshore projects.

Swivel Flange vs. Lap Joint Flange

While the appearance may seem similar, swivel flanges and lap joint flanges are actually different.

• Swivel flanges consist of a welded hub and a swivel outer ring. Their characteristic is the rotatable outer ring, resulting in high strength and suitable for high-pressure systems.
• Lap joint flanges consist of a short pipe end and a lap joint, which cannot be rotated. They offer medium strength and are primarily used in medium- and low-pressure piping systems.

Swivel Flange Standards and Dimensions

Common production standards for swivel flanges include ASME B16.5 and API 17D (for subsea equipment).

The appropriate pressure rating is selected based on project requirements, but generally, flanges suitable for high pressure are selected.

For detailed standard dimensions, please contact the supplier.

Swivel Flange vs. Fixed Flange

Fixed flanges generally refer to common flanges such as butt-weld flanges, slip-on flanges, and blind flanges. These flanges are fixed after welding, making alignment more difficult and requiring pipe rotation. Swivel flanges effectively solve the aforementioned problem of rotating steel pipes. Their outer ring can rotate to adjust to different angles.

Applications Beyond Offshore

Swivel flanges are primarily used in subsea or offshore oil and gas applications, but they can also be used in other applications:

Pipe systems in large chemical plants.

Ship systems where frequent adjustments are required.

Other piping systems where frequent disassembly is required.

Summary

Swivel flanges are a special type of weld-neck flange. Compared to butt-weld flanges, they feature a swivel outer ring that allows for quick and easy alignment with the bolt holes on the other flange.

• They are primarily used in subsea and offshore projects.
• They are used in compact installation environments, allowing for more efficient installation.
• Swivel flanges differ in strength and functionality from lap joint and fixed flanges, but they must also be manufactured according to standards.

The above is a brief introduction to swivel flanges, which we hope will be helpful for those new to this industry.