Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D6138-23 – Standard Test Method Technical Guide
ASTM D6138-23, known as the Emcor Test, standardizes the evaluation of corrosion-preventive properties in lubricating greases under dynamic wet conditions. It is essential for greases used in ball bearings exposed to water contamination.
📐 Scope and Key Definitions
According to Section 1, this test method determines the corrosion-preventive properties of greases using grease-lubricated ball bearings under dynamic wet conditions. All values are stated in SI units per scope 1.2. The following definitions from Section 3 are critical for understanding the method:
| 🟦 Term | 📏 Definition |
|---|---|
| Corrosion | The chemical or electrochemical reaction between a material and its environment that produces deterioration of the material and its properties. |
| Lubricating Grease | A semifluid to solid product of a thickener in a liquid lubricant. |
| Thickener | Finely-divided particles dispersed in a liquid lubricant to form the product’s structure. |
Per Section 3.1.2.1, corrosion in this test is manifested by red rust or black stains on the bearing race, but stains through which the underlying metal surface remains visible are not considered corrosion.
⚙️ Test Procedure and Referenced Standards
The test uses grease-lubricated ball bearings conforming to ISO 15, operated dynamically in the presence of water. Water quality must meet ASTM D1193 or ISO 3696 specifications for reagent water. The test references the following standards for methodology and terminology:
| 🟦 Standard | 📐 Application |
|---|---|
| ASTM D665 | Rust-preventing characteristics of inhibited mineral oil in the presence of water |
| ASTM D1193 | Specification for reagent water |
| ASTM D4175 | Terminology relating to petroleum products, liquid fuels, and lubricants |
| ISO 15 | Rolling bearings — radial bearings — boundary dimensions |
| ISO 3696 | Water for analytical laboratory use — specifications and test methods |
| ISO 7120 | Petroleum products — determination of rust-preventing characteristics in the presence of water |
| IP 530 | Determination of the density of grease — density cup method |
These referenced documents ensure consistency and reliability across testing procedures.
📊 Corrosion Evaluation and Reporting
After the dynamic wet test, the bearing is examined for signs of corrosion. Red rust or black stains indicate deterioration, while stains that do not obscure the metal surface are ignored per Section 3.1.2.1. This evaluation directly reflects the grease’s ability to prevent corrosion under wet, dynamic conditions.
⚠️ Safety Notice: This standard (scope 1.3) does not address all safety concerns. Users must establish appropriate safety, health, and environmental practices prior to use.
💡 Evaluation Tip: Only red rust or black stains that cover the underlying metal are considered corrosion; surface-level stains are excluded from scoring.
❓ Frequently Asked Questions
🔍 What is the primary application of ASTM D6138?
It is used to evaluate the corrosion-preventive properties of lubricating greases in ball bearings under dynamic wet conditions.
💡 How is corrosion assessed in the Emcor test?
Corrosion is identified by red rust or black stains on the bearing race, excluding stains where the metal surface remains visible.
⚡ What water specifications are required for the test?
The test requires reagent water meeting ASTM D1193 or ISO 3696 standards.
📌 Which key ISO standards are referenced in D6138?
ISO 15 for bearing dimensions, ISO 3696 for water quality, and ISO 7120 for rust-prevention characteristics are referenced.