Case story


Steel plant


EN 14917

Belman has designed, manufactured and supplied two specially configured Inline pressure balanced expansion joints for installation in a Swedish steel plant. One of the expansion joints was specially designed with one of the bellows being partly hidden within the balance chamber. This remarkable Expansion Joint solution is an excellent solution when limited space in the pipeline is an issue.


Limited space

The choice of inline pressure balanced expansion joints was due to the challenging piping layout, which prevented the use of standard hinged expansion joints. The DN 1200 inline pressure balanced expansion joint, weighing 3 tons, represented a standard solution and was later installed against the silencer. In contrast, the DN 1000, weighing in at 2 tons, was installed against the compressor nozzle where the available space was limited. This space limitation in the pipe system resulted in a limited gap in the pipeline for the DN 1000 pressure balanced expansion joint. Further, the client had a requested spring rate which the expansion joint had to meet. In order to comply with the clients wishes Belman designed a customer specific special solution.


The special design of the DN 1000

The special design concerned an Inline pressure balanced expansion joint with one of the bellows partly hidden within the balance chamber. This was a natural choice in order to ensure the best absorption of movements, while meeting the required spring rates and built-in length. Typically, all of the bellows of an inline pressure balanced expansion joint would be fully visible. The selection of this partly hidden bellow was the result of a more complex calculation of the pressure bearing parts and a requirement for a well-planned line through production.


Additional 3 expansion joints supplied

Two further DN 1000 hinged expansion joints were supplied to the same steel plant and installed in the pipeline after the DN 1000 inline pressure balanced expansion joint. There was sufficient space in these locations and the pipeline layout permitted the installation of hinged expansion joints. One of the DN 2200 expansion joint was supplied with customized transport devices, including a lifting device and installed against the compressor.


The specially designed Inline Pressure Balanced Expansion Joints have the following design parameters:

Dimension: DN 1000 • Length: 1729 mm • Medium: Air • Design temperature: -40/260°C • Design pressure: 6 barG • AX: +/-10 mm • LA: +/-3 mm • Bellows: 1.4541 • Pipe ends: 1.0565 • Flanges: 1.0565 • Design code: EN 14917

Dimension: DN 1200 • Length: 1945 mm • Medium: Air • Design temperature: -40/260°C • Design pressure: 4,4 barG • AX: +10/-40 mm • LA: +/-38 mm • Bellows: 1.4541 • Pipe ends: 1.0565 • Flanges: 1.0565 • Design code: EN 14917


  • Short on-time delivery
  • A space saving solution that meets both the demands for low spring rates and the short build-in lenght
  • Reliability of the Expansion Joint designed to work under the operating parameters
  • Reduces the complexity and size of fix points
  • Benefit from the considerable know-how of an experienced manufacturer
  • Guaranteed to deliver safe, reliable and smooth operation.

TECHNICAL information

  • Technical information on Pressure Balanced Expansion Joints with compact design is available in the Expansion Joint Catalogue
    page 361
  • Technical information on spring rates is available in the Expansion Joint Catalogue
    page 416


Thyssenkrupp • Severstal • TATA • ArcelorMittal • SSI (CORUS) •
SSAB • Salzgitter • NLMK Group • Nornickel • Ruukki •
AET Technologies • ISD Dunaferr • Gerdau •
Salzgitter Flachstahl GmbH • TRIMET • Voestalpine • Steel dynamics • Usiminas • Hüttenwerke Krupp Mannesmann (HKM) • Al Ezz Dekheila •  FENI • Steel – EZDK • Evraz • Paul Wurth • Siemens VAI • Corus •
Aurubis • SMS Group • Kalugin •




This 4-meter long DN 2500 Inline Pressure Balanced Expansion Joint having a balancing bellow of an amazing DN 3800.


To avoid closed spaces were the media could pack up and restrict the correct functioning of the bellows this unique design was made.


This Finger Type Inline Pressure Balanced Expansion Joint has ring reinforcement due to high pressure ensuring both pressure integrity and service life.