8 TECHNICAL INFORMATION District Heating Expansion Joints are designed to absorb mainly axial movements caused by temperature expansions of the pipeline. The Expansion Joints are suitable for both trenched/trenchless pipelines. They are reliable in operation and do not require any maintenance. Highly flexible Bellows is a main component of the Expansion Joint, ensuring absorption of large axial movements. The solid cover and guides mounted on the Expansion Joints perform multiple functions e.g. the protection of the Bellows from mechani- cal damage, providing higher Bellow stability and helping to absorb eventual misalignments in the pipeline. An inner sleeve protects the Bellows against internal abrasives as sand and dirt particles often carried by district heating water. These particles settle between the convolutions preventing the Bellows from functioning as intended. Further- more, the Expansion Joints have a safeguard preventing torsion of the Bellows and other unintended loads, thus ensuring a longer service life. The basis design (AXDH) is represented by two types: short or long (for bigger axial movements). Additionally, we offer a reinforced design (type AXTDH) with built-in guide support, which doesn’t require utilization of the first guides, normally installed at 2÷4 DN distance. Pre-stressing The District Heating Expansion Joints are usually available as pre-stressed. Pre-stressing is often required in order to utilize the complete range of compensa- ting ability of the Expansion Joint. The optimum value of pre-stressing is 50% of the total movement. It comes ready to install with a pre-tensioning device that unfastens itself automatically when the system is started-up. www.belman.com BG2024 – Subject to changes and misprints
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