Lubricant acceptance management

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As we all know, lubricants are liquid substances used in various types of machinery to reduce friction and protect the machinery as well as the components being processed. They serve multiple functions, including lubrication, cooling, rust prevention, cleaning, sealing, and cushioning. The equipment that currently uses oil in our company’s projects includes the air compressors in the air separation plant, oil for expansion units, lubricating oil for synthesis units, as well as lubricating oil for gasification and utility processes. These are mostly large-scale, critical compression units, steam turbines, and pump systems, and a large quantity of oil is used in these applications. Therefore, lubricant management is a very important issue for our company. Only by managing lubricants properly can we ensure their correct use, utilize their technical properties to the fullest, maintain the proper operation of equipment, extend its lifespan, save on lubricant costs, conserve energy, and improve economic efficiency. The acceptance of oil products upon entry is also one of the important tasks in lubricant management. It is essential to conduct acceptance inspections on the oil upon its arrival, using various testing methods to assess both the visual quality and internal performance parameters of the oil, thereby ensuring that it is a qualified product. This prevents substandard or counterfeit products from reaching the departments that use it and causing damage to the company’s important equipment without anyone being aware of it. The main oils used by our company are compressor oils, such as L-DAB100# and L-DAB150# ； Turbine turbine oil, such as L-TSA46# Great Wall Lubricants ； Gear oil, such as CKC-150# and CKC-220# Great Wall Lubricants ； Anti-wear hydraulic oils, such as L-HM32# and L-HM46#; in addition, there are transformer oils, various types of greases, and many other products that can be used. The specific types of oils and their quantities that I have been responsible for inspecting recently are as follows: Name, Specification/Model, Quantity – High-quality lithium-based grease SKF LGLT2: 1 kg per bucket; 13 buckets. L-TSA46# turbine oil: 170 kg per bucket; 230 buckets. High-performance extreme-pressure turbine oil X-EP46#: 209 liters per bucket; 125 buckets. High-quality lithium-based grease SKF LGLT2: 1 kg per bucket; 14 buckets. 7008 aviation grease: 30 buckets. Compressor oil for LPG stations L-DBA100#: 2 buckets. Anti-wear hydraulic oil L-HM46: 170 kg per bucket; 6 buckets. Anti-wear hydraulic oil L-HM68: 170 kg per bucket; 2 buckets. Industrial closed-gear oil CKC-150#: 170 kg per bucket; 58 buckets. Industrial closed-gear oil CKC-220#: 170 kg per bucket; 75 buckets. The inspection process for oils arriving at the facility is the same as that for other materials entering the facility. The main steps in the inspection process are as follows: 1. For oil inspections, the procurement department first notifies the equipment department that the oil has arrived. The equipment department then organizes a team consisting of its own staff, the process department, the site supervisor, the warehouse department, and the quality control department to conduct an on-site visual inspection at the designated location. 2. The Equipment Department, together with the Process Department, the boundary supervision team, the Warehouse Department, and the Quality Inspection Department, must sequentially verify and fill in in detail the name and specification model of the incoming oil products, the date of arrival, the production date, the name of the manufacturer, the production batch number, etc., in accordance with the company’s acceptance form for equipment received at the plant. 3. Carefully inspect and verify the packaging, appearance quality, quantity, volume, etc., and fill in the corresponding details on the acceptance form. 4. The supplier is required to immediately provide the certificate of conformity for the delivered oil products and indicate this on the acceptance form. 5. After the above tasks are completed, the Quality Control Department will conduct sampling and analysis in accordance with the corresponding oil quality standards specified on the product quality certificate, as well as the indicators for the quality assessment of the oil, using a random sampling ratio. 6. Once the results of the quality inspection are available, and if all the analysis indicators meet the requirements, an analysis report will be issued. Subsequently, the department heads can be asked to sign off on it, after which the goods can be processed for storage. If the quality inspection results show that the product is not up to standard, even if just one indicator fails to meet the requirements, it is necessary to immediately inform the department head and the procurement department to request a return or other corrective actions; no warehousing procedures shall be carried out. In special cases, if a certain analytical parameter does not meet the requirements, there may be interfering factors in the analysis process; it is necessary to take new samples and conduct multiple analysis tests before deciding to return the product. After several inspection processes, I believe the main points to note when inspecting oil products are: 1. The oil entering the plant must come with a product certificate of conformity. The product certificate must include the relevant applicable standards, data on the oil composition, that is, the factory inspection report, and it must bear the inspection seal of the manufacturing unit. 2. Pay special attention to the production date; it must be a new or recently produced product, and it must be within the warranty period. 3. Pay special attention to ensure that the packaging is intact; the waterproof seal at the oil outlet must not be damaged. 4. The main analytical parameters to pay attention to during oil analysis are as follows: (1) Color – The color of lubricating oil is related to the degree of oxidation and deterioration of the oil during storage. If it is milky white, there is water or bubbles present ； A darker color indicates oxidation, deterioration, or contamination. The determination of lubricant color can be carried out in accordance with B/T6540-86. (2) Viscosity Viscosity is the most important and fundamental performance parameter of lubricating oils. Most lubricants are classified by their dynamic viscosity. The higher the viscosity of the lubricating oil, the thicker the oil film that is formed, which helps to withstand high loads. However, its poor fluidity increases the resistance to mechanical movement, or it may not reach the areas that need lubrication in time, resulting in a loss of lubrication effect. Therefore, the viscosity of the lubricating oil used in each type of equipment must be appropriate. (3) Viscosity-temperature characteristics: As the temperature changes, the viscosity of the lubricating oil also changes. As the temperature rises, the viscosity decreases, and vice versa. The characteristic of lubricant viscosity changing with temperature is known as the viscosity-temperature behavior of the lubricant, and it is one of the important indicators of lubricants. There are two methods to represent the viscosity-temperature characteristics of lubricants: one is the viscosity ratio, and the other is the viscosity index VI. The viscosity index is calculated from the assumed viscosity indices of two standard oils. The higher the VI value of an oil, the less its viscosity changes with temperature; generally, this indicates that the oil has better viscosity-temperature properties. (4) Freezing point and pour point: The freezing point is the highest temperature at which the oil stops flowing under specified cooling conditions; generally, the operating temperature of lubricants should be 5–7°C higher than their freezing point. The freezing point can be determined using the method specified in GB/T510-83. The pour point is the lowest temperature at which an oil can be cooled under specified conditions while still remaining fluid; it represents the limit temperature for the flow of the oil. Therefore, it provides a better indication of the oil’s flowability at low temperatures, and its practical value as a parameter is greater than that of the freezing point. The minimum operating temperature of the lubricating oil should be 30°C above its pour point. The pour point can be determined using the method specified in GB/T3535-83. (5) Flash point The flash point is an indicator of the volatility of oils. The greater the volatility of a fuel, the lower its flash point. At the same time, the flash point is an indicator of the fire hazard of petroleum products. When selecting lubricating oil, it should be determined based on the operating temperature and the working conditions of the lubricant. It is generally believed that a flash point 20–30°C higher than the operating temperature ensures safe use. The flash point can be determined using the methods specified in GB/T267-88 or GB/T261-83. (6) Acid value: The acid value refers to the number of milligrams of potassium hydroxide required to neutralize all acidic substances in 1 gram of the oil sample, expressed in mgKOH/g. For new oils, the acid value indicates the degree of refining of the oil or the amount of additives used (when acidic additives are added) ； For used oil, the acid value indicates the degree of oxidation and deterioration. During storage and use, ordinary lubricants experience changes in their acid value due to reactions with oxygen in the air at certain temperatures, which result in the formation of organic acids, or as a result of the consumption of basic additives. Therefore, a high acid value indicates severe oxidation and deterioration, and oil change should be considered. The acid value can be determined using the method specified in GB/T264-83. (7) Water-soluble acids and bases (also known as reactions), which are mainly used to determine whether inorganic acids and bases have been thoroughly washed away during the refining process of oils ； During storage and use, has it been contaminated by inorganic acids and bases, or has the oil oxidized and decomposed due to improper packaging or storage, resulting in the formation of organic acids and thus water-soluble acids and bases in the oil? Generally speaking, water-soluble acids and bases are not allowed to be present in oils; otherwise, oils that come into contact with water and steam are prone to corroding mechanical equipment. This is a qualitative test that can be carried out according to the method specified in GB/T259-88. (8) Mechanical impurities: Mechanical impurities refer to the content of precipitates or colloidal suspensions in lubricating oil that are insoluble in solvents. Most of them are sand, gravel, iron filings, or some organometallic salts that are insoluble in solvents and brought in by additives. Mechanical impurities will accelerate the normal wear of mechanical equipment; in severe cases, they can block oil passages, nozzles, and filters, disrupting proper lubrication. Furthermore, metal shavings act as a catalyst for oil at certain temperatures, accelerating the oxidation and deterioration of the oil. Mechanical impurities can be determined using the method specified in GB/T511-88. (9) Moisture Moisture refers to the weight percentage of water contained in the lubricant. Water in lubricating oil generally exists in three states: ① free water ； ②Emulsified water ； ③Dissolve in water. The presence of water in lubricating oil can damage the lubrication film, reducing its effectiveness. It also accelerates the corrosion of metals by organic acids. Furthermore, it causes additives (especially metal salts) to undergo hydrolysis and become ineffective, resulting in precipitates that block the oil passages and hinder the circulation and supply of lubricating oil. Furthermore, when the operating temperature is close to the freezing point, it reduces the fluidity of the lubricant and deteriorates its viscosity-temperature properties. At high operating temperatures, water vaporizes, which not only destroys the oil film but also creates air resistance, affecting the circulation of the lubricating oil. Moisture determination can be carried out in accordance with the provisions of GB/T260-88. (10) Ash: Ash refers to the non-combustible substances remaining after burning under specified conditions, expressed as a weight percentage. Its determination can be carried out according to the method specified in GB/T508-85. Ash generally consists of various metal elements and their salts. For base oils or oils without additives, ash content can be used to determine the degree of refining of the oil. For oils to which metal salt additives have been added (new oils), ash content serves as a reference for quantitatively controlling the amount of additives used. In this case, it’s not the case that the lower the ash content, the better; rather, it must be above a certain threshold. For example, the product standards for internal combustion engine oils specify both a maximum and a minimum ash content for the base oil. (11) Emulsification resistance: The emulsification resistance of lubricating oil refers to its ability to prevent emulsification, or to allow for temporary emulsification followed by rapid separation of oil and water upon standing. It can generally be determined using the methods specified in GB/T7305-86 or GB/T8022-87. Industrial lubricants such as hydraulic oil, gear oil, and turbine oil often inevitably become mixed with some cooling water during use. If their resistance to emulsification is poor, they will form an emulsion with the water that has mixed in, which reduces their lubricating properties, damages mechanical components, and facilitates the formation of sludge. The above are the main performance indicators of oils. At present, our company’s quality control department analyzes six parameters: moisture content, flash point, kinematic viscosity, acid value, emulsification resistance, and mechanical impurities. An oil is considered qualified if it meets these six requirements. Does anyone know if there are any other suggestions or experiences? The above are merely my personal and superficial insights from work, provided for everyone’s reference only. There are inevitably some inaccuracies in this summary, and I welcome any criticism and suggestions from others.