Overview
ASTM D6138-23a - Standard Test Method for Determination of Corrosion-Preventive Properties of Lubricating Greases Under Dynamic Wet Conditions (Emcor Test) is a crucial method for evaluating the ability of lubricating greases to prevent corrosion in rolling bearings operating under dynamic wet environments. Developed by ASTM International, this standard helps manufacturers, formulators, and users to assess the anti-corrosion performance of greases in the presence of distilled water, sodium chloride solution, or synthetic sea water. This Emcor Test is widely referenced in lubricant specification and quality control processes, supporting the development and selection of greases suitable for challenging industrial conditions.
Key Topics
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Scope and Significance:
- Assesses the corrosion-preventive properties of lubricating greases in ball bearings under conditions simulating real-world wet environments.
- Supports formulation, specification, and quality assurance of industrial and automotive lubricants.
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Test Method Overview:
- Uses grease-lubricated, double row self-aligning ball bearings partially immersed in water-based solutions during dynamic operation.
- Bearings are examined and rated for corrosion after exposure, following a controlled sequence of running and stopping.
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Corrosion Evaluation:
- Degree of corrosion is visually inspected and classified from 0 (no corrosion) to 5 (severe corrosion).
- Only rust or black stains are considered corrosion; superficial stains revealing visible metal are ignored.
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Standardized Conditions:
- The procedure is performed with specific water types (distilled, sodium chloride solution, or synthetic sea water) and under defined temperatures and operational profiles.
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Safety and Compliance:
- Users must implement appropriate safety, health, and environmental practices and comply with applicable regulatory requirements.
Applications
ASTM D6138-23a finds practical use in numerous industries where lubricated bearings are exposed to moisture, including:
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Industrial Machinery:
- Ensures that greases employed in equipment such as pumps, conveyors, and electric motors offer durable protection against corrosion in humid processes or washdown environments.
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Automotive & Transportation:
- Specifies or verifies bearing greases for vehicles operating in wet or marine climates, minimizing bearing failure and improving reliability.
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Marine & Offshore Equipment:
- Certifies that marine-grade greases can effectively protect critical rotating components from saltwater-induced corrosion.
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Quality Control & Product Development:
- Integrates into routine laboratory screening during formulation or batch testing to maintain performance standards required by end users.
Utilizing this test method reduces the risk of equipment downtime, maintenance costs, and potential failures caused by bearing corrosion, driving higher operational efficiency across industries.
Related Standards
Organizations often use ASTM D6138-23a alongside related standards to ensure comprehensive lubricant performance evaluation. Important references include:
- ASTM D217: Test Methods for Cone Penetration of Lubricating Grease.
- ASTM D665: Test Method for 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 and lubricants - Determination of rust-preventing characteristics in the presence of water.
- IP 530: Determination of the density of grease by density cup method.
By following ASTM D6138-23a in conjunction with these related standards, lubricant producers and end users can ensure that products meet rigorous international corrosion-preventive performance requirements.