The Bellevilles valve washers are known under different names: spring washers, belleville washers, disc spring, conical washers, Bellevilles…
These Bellevilles or elastic conical washers, offer unique performance characteristics as a spring, which are extremely beneficial when used for valves:
1. High forces for small deflections
2. Minimum fatigue and long service life under normal working conditions
3. Simple adjustment of the spring stack, by varying the number and arrangement of the washers, as well as its thickness.
The function of these washers inside the valve is to maintain a sufficient contact pressure on the joint. For this purpose, Belleville springs, are used in stacks, either in series or parallel, of several washers, looking to achieve the force and stroke required, depending on the needs of each valve. This stacking exerts a pressure and absorbs contraction and expansion that may occur due to changes in pressure, temperature, or due to the relaxation.
The most common material used for these washers is17-7 PH (cryogenic material).
This is due to its good ability to work in harsh conditions and temperature corrosion, while providing a competitive cost.
However it is also common, as required, the use of other materials as the AISI-301 and Inconel 718.
If your valve is in any of the above, this means that, due to dynamic loads which already support its environment, it is advisable to use Belleville washers to ensure proper operation.
Symbols and Nomenclature:
|De: External (outside) diameter
Di: Internal (inside) diameter
t: Material thickness for Belleville spring
ho: Dish or maximum deflection
lo: Unloaded free height of the single Belleville spring (lo = t + ho)