Mecatheque
Results of collective works
Additional leak testing of valve packings
When designing valve packings, manufacturers are faced with a tightness dilemma. High tightening force ensures sealing performance, but causes friction; conversely, low tightening force reduces friction, but leads to insufficient sealing. There currently is no standardised method for striking the right balance between these two opposing requirements. During previous studies commissioned by its Valve & Sealing Products Trade Committee, Cetim defined tools for designing valve packings and developed a set of procedures and experimental facility for characterising them. The purpose of this new study was to conduct leak tests on two graphite rings under various configurations, i.e. two stem movement types, four helium pressure levels, and one sequence of stress applied to the stacked packing. The results obtained made it possible to define the amount of contact pressure to be applied to stacked packings during tightening and the amount to be maintained during pressurisation in order to achieve the desired level of sealing performance.
Auteur : Hubert LEJEUNE, Cetim
