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White Papers
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Technical Belleville Spring Information in PDF Format!
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Decrease probability of joint failure. Using Belleville springs can improve retained bolt preloading and increase the elasticity of the fastening system.
The paper discusses:
- Principles of Belleville springs movement in joints
- Theories described through joint diagrams & test data
- Using Belleville springs to maintain bolt preload
- Tests demonstrating differences between an ordinary and a live loaded joint
- How to design a live loading joint system
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This paper discusses the main factors that cause bolted flange joints to leak due to various forms of relaxation, such as bolt and gasket creep, vibration, embedment and differential thermal expansion. Tests and data illustrate how the use of specially engineered Belleville Springs and Flange Washers can prevent leaks and reduce fugitive emissions by improving retained preload.
Live loading of packing on valves is simply the process of stacking Belleville Springs on the gland follower fasteners to maintain load on the packing set. This is done when the stretch in the fasteners is not sufficient to compensate for losses due to cycling the valve, differential thermal expansion, packing creep, etc. Since using Bellevilles decreases the spring rate of the fastening system, the loss of force on the packing set will be lower if it is live loaded.
The paper discusses the phenomena that cause valves to leak. It then describes the theory and use of Bellevilles for live loading. A brief explanation of how to design a live loaded system is also given.
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Keeping Electrical Connections tight after Differential Thermal Expansion
Electrical connections are often made up of materials that have various coefficients of thermal expansion. In addition, the joint materials also carry more current than the bolts. This causes the joint to heat up more than the bolts. This resultant differential thermal expansion (DTE) results in an increase in bolt load, possibly causing the joint material to yield.
Solon Belleville Springs are commonly used on electrical connections because they counteract the effects of differential thermal expansion by maintaining sufficient load on bolted electrical connections during and after temperature cycles.
The paper discusses:
- Bolt stretch and bolt preload loss
- Joint deflection, illustrated through diagrams
- Preventing "hot spots" during & after temperature cycles
- Belleville Springs Application
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