ASTM D6138-19 Standard Test Method for Determining the Anti-Corrosion Properties of Lubricating Greases in Dynamic Wet Conditions (Emcor Test)

The ASTM D6138-19 standard, developed by the American Society for Testing and Materials (ASTM), defines a test method (Emcor test method) for determining the anti-corrosion properties of greases using grease-lubricated ball bearings under dynamic wet conditions. This test method is used to evaluate the ability of grease to prevent corrosion in rolling bearings operated in the presence of distilled water, sodium chloride solution or synthetic seawater. In addition, this test method is applied for development and specification purposes.

The Emcor test, described in the ASTM D6138-19 standard, subjects a series of new, cleaned, and lubricated bearings to partial submersion in water under applied load at 80 rpm during a predetermined start and stop cycle for approximately one week . The results are evaluated as follows:

0 No corrosion: No corrosion
1 Trace: No more than three corrosion spots, none greater than 1 mm in diameter
2 Lightweight: Small areas of corrosion covering 1 percent of the surface
3 Medium: Areas of corrosion covering 1 percent to 5 percent of the surface
4 Heavy: Areas of corrosion covering 5 to 10 percent of the surface
5 Severe: Areas of corrosion covering more than 10 percent of the surface than traces of corrosion

In order to maximize the number of bearing operating hours, it is very important to prevent the formation of rust on the bearings. Most bearings are exposed to moisture or temperature differences between day and night due to outdoor use. This causes the bearings to rust. Therefore, a good quality grease is also expected to protect the bearing against corrosion in extreme cases.

The Emcor tester measures the ability of a grease to protect the bearing from corrosion in the presence of water. During testing, two sets of grease-coated bearings per station are partially submerged and rotated at 80 rpm for a series of run and rest periods. At the end of the test, the raceways of the bearing outer rings are checked for corrosion.

Among the numerous tests, measurements, analyses, and evaluations our organization provides for businesses in various sectors, we also offer standard testing services under the ASTM D6138-19 standard to determine the corrosion-inhibitory properties of lubricating greases under dynamic wet conditions, utilizing a trained and expert staff and advanced technological equipment.