Valve packing optimization
While there is increasing demand from valve end-users for low emission sealing systems , it is essential that the valve stem continues to move smoothly and efficiently . The frictional load of the stem packing has a conflicting effect on these two requirements , so valve and valve packing manufacturers are challenged with respect to the prediction and improvement of packing behaviour in a valve .
The definition of a global design method for the optimization of packings with regard to sealing performance and friction forces is needed to meet both low emissions and energy efficiency requirements . But no standardized method for packing calculation nor packing full characterization ( mechanical , friction , sealing performance vs . packing load .) exists in Europe , in a similar manner to that for bolted flange joints and associated gasket detailed in EN1591-1 and EN13555 . Therefore , Cetim ( The Technical Center for the French Mechanical Industry ), in collaboration with the European Sealing Association ( ESA ) and the Fluid Sealing Association ( FSA ) has initi-
Figure 1 : Stuffing-box packing simplified geometry
ated the development of a tool to predict the initial packing tightening force required to reach certain characteristics in relation to friction and sealing performance .
Model and associated tool
A simplified 2-dimensional asymmetric stuffing box packing geometry is considered as shown
Figure 2 : Calculation sequence
By Hubert Lejeune
About the author :
Hubert is a mechanical engineer and Sealing Technologies senior expert at CETIM ( Technical Center for Mechanical Industry ), France . He is a member of the ESA Packings Division .
Figure 3 : Test rig structure π www . valve-world . net Valve World August 2022
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