Sealing characteristics of gland packing (1streport, A testing method of the mechanical properties of packing and some experimental results in asbestoid and graphitic packings)

Abstract

The leakage rate of fluid is strongly affected by the magnitude of the contact pressure between packing and the stem or stuffing-box. If the packing is tightened by a high gland load to prevent leakage, the friction between the stem and the packing becomes larger. From the practical viewpoint. the distribution of the contact pressure and the friction at any given gland pressure or at any given compressive displacement of the packing are required in order to make an analytical prediction. In making the first step toward analyzing the contact pressure and the friction for various combinations of packing, this paper describes the mechanical properties of various asbestoid and graphitic packing. A testing method to determine the normal to axial pressure ratio K, the coefficient of friction μ and the axial pressure-strain relation Pz-|ez| is presented. The experimental equations for these values, K, μ and ez, are found as functions of the axial pressure Pz K=KoPaz, μ=μoPbz, |ez|=EoPcz, where Ko, a, μ0, b, Eo and c are material constants.