Influence of roughness on the tribological behavior of a steel- steel couple lubricated with thread compound

Abstract

The purpose of this study is to determinate the influence of surface roughness on the tribological behavior of a lubricated steel against steel tribosystem. Tests were carried out at high pressure and slow sliding speed, in order to simulate at small scale, the contact conditions found in the seal of the threaded joints used in oil & gas casing and tubing strings. Tests were carried out with a simplified block-onring test, varying the surface roughness of rings between 1.3 to 3 m Ra values. A thread compound lubricant containing lead, copper, zinc and graphite was used. During each cycle of test, the normal load was varied linearly between 250 N and 7000 N. An exponential correlation between Ra and Rt roughness values with the wear damage was found and the wear damage of the blocks decreases about 40 percent with the increasing of initial Ra roughness parameter in the movil surface.