Stainless steel bellows as a flexible pressure pipe fittings installed in the liquid delivery system to compensate for pipeline or machine, equipment, mutual displacement of the connection end, absorbing vibration energy, can play a vibration, silencer and other effects, with good flexibility, light weight , Corrosion-resistant, anti-fatigue, high and low temperature resistance, and many other features. Metal bellows stiffness to the metal bellows or other elastic elements to produce the required displacement of the unit load is called the stiffness of the element, generally "K" said. If the elastic properties of the element are non-linear, the stiffness is no longer constant but changes as the load increases. Nominal stiffness Elastic element design calculations given the stiffness known as the nominal (or nominal) stiffness. It has an error with the measured stiffness of the element, especially the elastic element with non-linear elastic properties. Nominal stiffness represents the stiffness of the point on the curve, and careful consideration is required. In general, the nominal stiffness is best not to directly use the calculated value, but should be tested with the product prototype after the correction value. Stiffness Tolerance The range of allowable stiffness for a batch of elastomeric components. On the same batch of flexible components, stainless steel metal hose each element of the stiffness are not the same, there is a dispersion range. In order to ensure the use of components performance, it is necessary to have a limited range of stiffness dispersion. For elastomeric components, the stiffness tolerance is limited to within +/- 5% of the nominal value; for bellows-like resilient elements for general engineering applications, the stiffness tolerance can be limited to +/- 50%.