CONSTRUCTION & DESIGN STYLES Selection of the optimum construction for fabric expansion joints depends on a number of factors which need to be considered for the application, generally speaking there are no “standard” designs. Fabric expansion joints are available in many configura- tions with single-layer or multi-layer fabric elements. The multilayer expansion joint is generally made from: 1. Internal material ; to avoid abrasion 2. Insulation material ; to resist high temperature 3. Sealing foil ; for gas tight con- struction 4. Outer cover ; against mechanical loads 5. R einforcement ; protection ensuring strong construction in the area where bolts are fixed. DESIGN STYLES Fabric expansion joints are usually supplied as a “belt” or with integral flanges, the preferred arrangement will depend on the conditions of the installation and system temperature. Simple flanged solutions are common for installing against flanges mounted onto the ductwork, an arrangement suitable for low temperature areas. Design styles Belt type expansion joint attached directly onto the outside of the duct using clamping bands normally used for: 1. Low temperatures (up to 300°C) 2. Low to medium velocity 3. Low to medium dust load i.e.: Clean air ducts Convoluted fabric expansion joints are attached directly onto the outside of the duct using clamping bands normally used for: 1. Large movements 2. Low velocity 3. Low dust content 4. Low temperature i.e.: Pulp and paper industry Fabric expansion joints mounted on vertical flanges, typically used in systems with: 1. Low flow velocity 2. Low dust content 3. Low temperature (up to 450°C) The design can be made both with and without sleeve. The sleeve primarily acts to protect the fabric expansion joint from the particles in the flow medium i.e.: Chemical industry (wet and dry)
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