CORROSION-PREVENTING PROPERTIES OF LUBRICATING GREASES: ASTM D5969
EXPLANATION
This test method differentiates the relative corrosion-preventive capabilities of lubricating greases under the test conditions using grease lubricated tapered roller bearings exposed to various concentrations of dilute synthetic sea water stored under wet conditions. It is based on Test Method ASTM D1743, which is practiced using a similar procedure and distilled water. The reported result is a pass or fail rating as determined by at least two of three bearings.
TEST SUMMARY
New, cleaned, and lubricated bearings are run under a light thrust load for 60 +/- 3 s to distribute the lubricant in a pattern that might be found in service. The bearings are exposed to a solution of synthetic sea water at some percentages in distilled water, then stored for 24 +/- 0.5 h at 52 +/- 1 ° C and 100 % relative humidity. After cleaning, the bearing cups are examined for evidence of corrosion.
TEST PRECISION
Traditional ways of expressing precision are not available. However, in a round robin study, 92 % of the duplicate results were in agreement. Similarly 77 % of the six labs matched results. This exercise involved six laboratories and eight samples at four concentrations of synthetic sea water (0 %, 5 %, 10 %, and 100 %).
Since this is a pass-fail test, no bias statement regarding this method can be made.
