Case story


Power plant



Back in 2021 Belman engineered some precision engineered Flexible Joints for Coal Dust for a power plant in the US. Now, the client has returned to Belman with a wish to install the same solution in another part of its pipeline in the same power plant. This has led to Belman engineering and manufacturing a further two Flexible Joints for the client.


The client first approached Belman in 2021 as its pre-existing Expansion Joint solution was not performing optimally and presented a health and safety risk due to unwanted coal emissions. Based on an on-site inspection, troubleshooting and analysis, Belman engineered some Tied Double Bellow Coal Dust Expansion Joints. After some time in operation, the client was so happy with the solution that it decided to order two more Expansion Joints for another part of its pipeline.


BELMAN SOLUTION – another unique Flexible Joint solution for coal dust
Belman engineered a number of same-design Coal Dust Expansion Flexible Joints for the power plant which incorporated a flanged pipe section between two Tied Expansion Joints. Two Tied Flexible Joints acting together can work in the same way as a Universal Expansion Joint by absorbing multi-plane movements in combination. This solution ensured optimum absorption of the movements generated by the boilers, which tended towards movement in all three planes. The Flexible Joints will absorb large movements in combination, which are AX +/-187 mm (range 374 mm), LA +137 mm/-0 mm and AN +/- 3°. The Expansion Joints are equipped with tie rods to control the large movements. The Flexible Joints were designed in accordance with their position in the system to increase the working efficiency and extend their life cycles. This unique design prevents the emission of unwanted coal dust. The media in the fuel ducts is a mixture of air with pulverised coal dust, which is why special refractory lined insulation of the Flexible Joints is needed. Coal dust is extremely abrasive and can backfill in the Bellows of the Flexible Joints. The refractory lining prevents erosion of the inner lining. Additionally, ceramic wool was installed around the bellow. A special braided hose was used as additional insulation in order to provide further protection against the aggressive medium. The Flexible Joints for Coal Dust were coated with a two-ingredient zinc-rich ethyl silicate grey paint and further coated with a grey single ingredient matrix paint. This special coating provides improved protection against corrosion to the Coal Dust Flexible Joints for many years.


Belman – Expertise on Expansion Joints for Coal Dust
Belman first invented this state-of-the-art Expansion Joint type for a European Power plant. Since then, Belman has further developed and customised the solution for other power plants as well. This is what Belman does: troubleshoots, analyses and engineers optimum solutions to the needs of the client and the application – also for coal-fired power plants.