Case story


Chemical plant


EN 13445

Belman engineered and manufactured a special Pressure Balanced Pipe Expansion Bellow for installation in the compressor lines at a chemical facility in Europe.


The client first contacted Belman in 2021 as they had a broken Pressure Balanced Expansion Joint in their piping system. Belman not only delivered a new Pressure Balanced Expansion Joint solution but also studied the photos and specifications and recommended some design improvements to avoid the problem reoccurring. Now, the client was reaching out to Belman again, as they were looking for a spare Expansion Joint to keep in stock. This will eliminate the need to wait for a new unit once the existing Expansion Joint reaches the end of its service life.


BELMAN SOLUTION – Pressure Balanced Pipe Expansion Bellow with special design
As the Expansion Joint had to absorb both axial and lateral movements in combination, Belman designed the Inline Pressure Balanced Pipe Expansion Joint with two flow bellows at one end. This special design allows the first flow bellow and the balance bellow (the largest bellow) to take up the axial movement together with the flow bellow on the other side of the balance bellow. The flow bellow in the middle then takes up both axial and lateral movement. For lateral movement absorption, it works together with the second working bellow placed at the very end of the Expansion Joint. You can see how this works and looks in detail in this film: Animation

The Pressure Balanced Pipe Expansion Joint was designed with external limiters to control the Expansion Joint movements. Thus, the tie rods are responsible for transmitting the movements from the flow bellows to the balance bellow and vice-versa.

Due to high flow velocity, the Pressure Balanced Pipe Expansion Bellow was designed with an inner sleeve to protect the bellows. High flow velocity can result in flow-induced vibrations in the bellow, which can considerably shorten lifetime or, in worst-case scenarios, cause damage to the Expansion Joint. An inner sleeve can help solve this problem.


Expansion Joint kept under pressure during storage
As per client request, the Pressure Balanced Pipe Expansion Joint was delivered with blind flanges at each end of the Expansion Joint. Furthermore, it was delivered with seals, bolts, a pressure gauge monitor and a ball valve. Due to the client’s critical need of the unit, they wanted to make sure this spare replacement Expansion Bellow could be used immediately when necessary. The client therefore wanted to keep the Expansion Joint under pressure during storage. The Expansion Joint was delivered with inert gas at a pressure of 0.5 barg. By keeping it under pressure, the intention was to reduce the risk of corrosion on the carbon flanges. By creating a controlled atmosphere inside the unit, the client could also prevent the inside of the Expansion Bellow from corroding. The ball valve was included in the design to release overpressure. In addition, when the client is ready to insert and use the spare Expansion Joint, they can open the ball valve to release the 0,5 barg pressure. They can then simply remove the blind flanges and the Expansion Joint is ready for installation in the pipeline gap intended for it.


Belman – expertise on highly customised Expansion Joints
Belman has engineered special Pressure Balanced Expansion Joint solutions for clients across different industries worldwide since 1994. Throughout the years, Belman has supplied Pressure Balanced Expansion Bellows with hidden balance chambers designed to fit into limited spaces in the piping system as well as Pressure Balanced Expansion Joints formed with wide open angles to avoid media build-up inside the bellows. Belman has also designed many large-diameter Pressure Balanced Expansion Joints as well as Ring Reinforced Pressure Balanced Expansion Bellows. Highly customised solutions are what Belman do best.