EXPANSION JOINTS FOR A CONCRETE SHAFT Belman has just executed a two-part delivery of a total of 16 axial expansion joints with guide pipes and movement restrictors to be installed at the entry of a concrete shaft in a district heating pipe system in Korea.
Complex construction The district heating pipe system is a sturdy and complex construction. In the core there is the actual district heating pipe, which is surrounded by insulation. Around this insulation the expansion joints from Belman are installed. In turn, the expansion joints are surrounded by insulation and finally the outer pipe is installed around the insulation. There is a vacuum in the expansion joints to insulate against heat loss from the inner pipe. The expansion joints from Belman are therefore so-called vacuum shutters. Together, the large movement coming from the long pipeline and the temperature result in large movements in the pipe system.
Four bellows Due to the immense movements caused by the district heating pipe it was necessary to use a construction with four bellows in the expansion joint in order to be able to absorb this large axial movement. A rule-of-thumb is that the more flexibility in the expansion joint, the less stability. Movement restrictors have been installed to ensure an even absorption of movement across the four bellows. Thus the movement acting on each bellow is controlled so that the individual bellows of the expansion joint only have to absorb a certain area of movement.
Insulation The construction is insulated with a rockwool material, which means that the expansion joints from Belman are insulated both on the inner and the outer side.
No medium In this district heating pipe system the expansion joints from Belman actually do not come into contact with a medium. However, should the pipe running through our expansion joints break, the medium contained herein would leak and come into contact with the expansion joints from Belman. This medium is steam and the choice of material as well as the design of the expansion joints are therefore based on a steam medium.
Technical data The expansion joints have the following technical data: Dimension: NB 450 to NB 1300. Installation length: 1630 mm to 2370 mm. Medium: Steam. Design temperature: From 120ºC to 180ºC. Design pressure: Up to 7.5 bar. Movements: Axial movements: Up to +/- 580 mm.
