PLTL-136 – U.S. Steel Method, Static Heat Test
An idle grease, such as under storage conditions or in inactive machinery, exposed to elevated temperatures may undergo physical and chemical changes. These changes may alter the properties of the grease. This test determines the change of penetration values of a grease exposed to high temperatures for extended periods of time under static conditions.
An unworked penetration is performed on the test grease (ASTM D1403). The grease is then carefully placed in a wire gauze cone so as to eliminate any air pockets. The cone is placed over a beaker and the assembly is brought to the test temperature for the test time. A second penetration is then determined. The remaining sample is placed back in the oven and the process is repeated giving a third penetration value. Reported are the all three penetration values. The changes observed in penetration are a relative indicator of heat stability.
Related tests: ASTM D403, ASTM D217, ASTM D6185