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| By combining different materials and taking into account their thermal,
chemical and mechanical resistance as well as their fatigue properties,
we ensure the optimum solution both in technical and economical respect. Basically, the design of multi-layer expansion joints comprise four groups of materials; |
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Outer cover material Protects the expansion joint from pressure and temperature and guarantees form stability. In most cases the material is coated and may also function as gas sealing barrier. Stainless steel wire mesh and steel bands are further used for special designs to give added mechanical protection and dimension stability. |
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Gas sealing foil The gas sealing foil is the actual sealing element, usually imbedded between fabric layers. Impermeable and chemically resistant. |
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Temperature-resistant fabrics Very strong and temperature resistant fabrics are used to protect the gas sealing foil and/or the insulation materials. |
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Insulation materials Protect both the gas sealing foil and the other expansion joint materials from high temperature of the medium. |
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The following considerations will influence the design and the choice of the right expansion joint type. |
■Medium The choice of expansion joint type is determined, among other things, by possible chemical influences. Abrasion from solid matters is largely prevented by using a sleeve/baffle construction. |
■Temperature A specific number of insulating materials are required for reducing the temperature, We determine the insulating effect by calculating and measuring the temperatures in a complete expansion joint. The exact temperature flow is found by means of probes and recorders. Temperature range : -60～+1400℃（depend on design） |
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■Pressure Will the expansion joint be used in a positive pressure or negative pressure area? This will have influence on both type and design of the expansion joint. The main application area covers the pressure range of ±400mbar（±40kPa）.(Fabric expansion joints will resist pressureup to approx. 3 bars.) |
■Tightness (sealing) The requirement for tightness have influence on the design and especially the configuration of the flange area. If the sealing rate must be documented ( Nekal tightness or specific leakage rates), the expansion joints are built with special flange designs. We are able to determine leakage rates for various materials and complete expansion joint structure on our test rigs. |
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