Axial Steel Bellows

Axial Steel Bellows

Stainless steel axial bellows, axial expansion joints or axial compensators are specialised components used in piping systems to accommodate axial or lateral movement caused by thermal expansion, contraction, or mechanical vibration. To absorb and compensate for changes in length along the pipe’s axis while maintaining the system’s integrity.

Construction: 

Axial expansion bellows typically consist of convolutions from thin-walled stainless steel tubing. The convolutions allow the bellows to elongate and compress in response to axial movement. The convoluted design provides flexibility while maintaining structural strength to withstand pressure and external loads.

Materials: 

Stainless steel is the most common material used in constructing axial bellows due to its excellent corrosion, durability, and temperature resistance. The specific grade of stainless steel chosen depends on factors such as the operating environment, temperature range, and compatibility with the fluid in the piping system.

Design Considerations: 

The design of stainless-steel axial bellows is a meticulous process, considering several factors to ensure their optimal performance and longevity:

1. Operating Conditions: The design must account for the temperature range, pressure levels, and fluid properties encountered in the application to select the appropriate material and configuration.
2. Movement Requirements: The expected axial movement, both expansion and contraction, dictates the number of convolutions and the overall length of the bellows. The design must accommodate the maximum expected movement while preventing over-extension or compression.
3. Pressure Rating: Engineered to withstand internal pressure without failure. The design considers wall thickness, convolution geometry, and reinforcement to ensure the bellows can withstand the maximum operating pressure.
4. End Connections: The axial bellows typically have flanged, welded end connections or BSP Threaded Ends. These connections are crucial in facilitating the bellows’ installation and connection to the piping system. They must be compatible with the system components and provide a secure seal to prevent leaks. More information on end fittings is below.

Axial Steel Bellows Benefits:

• Absorption of thermal expansion and contraction: Axial bellows prevent damage to piping and equipment by absorbing the linear movement resulting from temperature changes.
• Vibration and noise reduction: By absorbing mechanical vibrations and movement, axial bellows contribute to smoother operation and reduced noise levels in the piping system.
• Longevity and reliability: Axial bellows offer durability and resistance to corrosion, ensuring a long service life with minimal maintenance requirements.

In summary, stainless steel axial bellows are critical in accommodating axial movement in piping systems, providing flexibility, reliability, and longevity in diverse industrial applications.

End fittings in more detail.

Fixed Flange

Fixed flanges are welded at each end of the bellows unit with the holes in line as standard.

Swivel Flange (Vanstone)

Use swivel flanges when flange hole alignment is an issue or where all wetted parts are in stainless steel, but the flanges can be mild steel to reduce cost.

Weld Prepped Ends

Weld prep ends have a chamfered edge to weld directly to on-site pipework.

BSPT Male Ended

BSPT threaded ends can be screwed directly into a female threaded connection where installed on site.

Copper Pipe Ended

Copper pipe ends are for low-temperature hot water (LTHW) and can be fitted with compression or solder.

Union Ended

Union-ended bellows come as a 3-part fitting manufactured from malleable iron.