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In the valve industry, there is combined demand from the end-users for fugitive emissions reduction and energy efficiency improvement through the reduction of stem/packing friction forces. These two different goals will involve opposite trends on the load to be applied on the packing i.e. high load for good tightness and low load for low friction. Thus, the ability to define optimal ranges of packing tightening is important. Nevertheless, no standardized method for packing calculation nor packing full characterization (mechanical, friction, sealing performance vs. packing load,..) exists in Europe, as for bolted flange joints and associated gasket with EN1591-1 [1] and EN13555 [2]. In collaboration with ESA (European Sealing Association, www.europeansealing.com) and FSA (Fluid Sealing Association, www.fluidsealing.com), the Fluid Equipment Committee of CETIM has developed a tool for the optimization of packing. A set of tests enables to get the packing characteristics needed for the calculation. These tests can also be used for the comparison of packing materials and/or installation procedures performances in defined test conditions. This paper details the proposed calculation method and describes the associated test rigs and procedures. First test results and a calculation example are also given to show how the method works. |
