NB/SH/T 0865-2013 Determination of Wear Metals and Contaminant Elements in In-Service Lubricating Oils by Rotating Disc Electrode Atomic Emission Spectrometry

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Card type: Test method

1. Method number / full title / English title / replacement relationship

• Standard number: NB/SH/T 0865—2013
• Chinese full title: Determination of Wear Metals and Contaminant Elements in In-Service Lubricating Oils by Rotating Disc Electrode Atomic Emission Spectrometry
• English title: Standard test method for determination of wear metals and contaminants in used lubricating oils by rotating disc electrode atomic emission spectrometry
• Replacement relationship: This standard is first published (original text: This standard is first published)
• Adoption relationship: Modified adoption of ASTM D6595-00 (2005), and redrafted according to ASTM D6595-00 (2005)
• Main differences from ASTM D6595-00 (2005) (original text):
  • The standard title is changed to "Determination of Wear Metals and Contaminant Elements in In-Service Lubricating Oils by Rotating Disc Electrode Atomic Emission Spectrometry"
  • The referenced standards of this standard adopt the corresponding national standards of our country
  • The content of the significance and application of Chapter 5 is adjusted to the introduction
  • The keywords of Chapter 16 are deleted
• Editorial modifications (original text): The expressions of repeatability and reproducibility are modified to the customary expression forms of our country; ASTM D6595-00 (2005) has been editorially modified according to the drafting format of our country's standards
• Publication/implementation: published on 2013-06-08, implemented on 2013-10-01; issued by the National Energy Administration
• Secretariat: Subcommittee on Lubricating Oil Change Intervals of the National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC280/SC6)
• Drafting organization: Dalian Lubricating Oil Research and Development Center of PetroChina Company Limited
• Participating organizations: Marine Engineering College of Dalian Maritime University, Shanghai Runkai Oil Monitoring Co., Ltd.
• Main drafters: Xie Pingping, Ding Donghai, Liu Honghui, Wei Haijun, Zhou Hongshu

2. Scope of application and non-applicability

• 1.1 This standard specifies a test method for the determination of wear metals and contaminant elements in in-service lubricating oils by rotating disc electrode atomic emission spectrometry (RED-AES).
• 1.2 It can quickly provide information on abnormal wear and contaminants in in-service oils, and is also applicable to the determination of new oils.
• 1.3 This standard uses oil-soluble metals for calibration, but the test results of oil samples containing insoluble particles cannot be taken as the content of dissolved metals. The analysis results are related to the particle size. When the element particles in the in-service oil are relatively large, the test results will be low.
• 1.4 The wear metals and contaminant elements that can be detected and quantitatively determined cover particles ranging from dissolved components to 10pm (requires confirmation against the source standard (source-text extraction), suspected to be 10μm) in size.
• 1.5 The International System of Units [SI] units are used. The values given in parentheses are for reference only. The preferred unit is mg/kg.
• 1.6 This standard involves certain hazardous materials, operations, and equipment, but it is not intended to address all safety issues associated with them. Therefore, users should establish appropriate safety and protective measures and formulate corresponding management systems before using this standard.

3. Method principle

• Chapter 4 Method summary: The wear metals and contaminant elements in the in-service oil are evaporated and excited by a controlled arc discharge generated by the rotating disc technique. The selected characteristic spectral lines and reference spectral line signals are collected and stored in photomultiplier tubes, charge-coupled devices, or other suitable detectors. By comparing the signal intensity of the elements in the in-service oil sample with the signal intensity of the calibration standard sample, the concentration of the test elements in the oil sample can be calculated, and the test results can also be input into a database for post-processing.
• Introduction (significance and application): The determination of wear elements in in-service oil is an important diagnostic method for implementing equipment condition monitoring. Compared with baseline concentration data, early wear can be predicted when wear metals appear or their concentration increases abnormally. A significant increase in the concentration of contaminant elements may indicate that foreign substances, such as antifreeze or sand particles, have entered the lubricating oil, which can cause equipment wear or degradation of the lubricating oil. Using this standard, the trend of metal and contaminant element contents over time and driving distance can be obtained, and corresponding measures can be taken when necessary to avoid more serious or catastrophic accidents.

4. Reagents and materials (purity / preparation)

• 7.1 Blank standard oil: 75mm²/s blank standard oil that does not contain the elements to be determined (requires confirmation against the source standard (source-text extraction), original text is "75mm'/s"), used as calibration blank or to dilute calibration standard samples.
• 7.2 Check sample: A standard oil or oil sample of known concentration is tested periodically, and whether standardization is required is judged by whether the test results meet the tolerance range of ±10%.
• 7.3 Cleaning solvent: A safe and environmentally friendly, chlorine-free, fast-evaporating, and non-film-forming solvent, such as petroleum ether, used to clean oil samples spilled or splashed onto the sample stage.
• 7.4 Disc electrode: A graphite disc electrode made of high-purity graphite (spectral purity). The dimensions of the electrode meet those shown in Figure 1 (Figure 1: φ12.5±0.03, φ3.18±0.03, 5.08±0.08, unit mm, material is high-purity graphite (spectral purity)).
• 7.5 Cleaning glass solvent: A solvent capable of cleaning and removing oil samples splashed onto the quartz window (protecting the incident lens and optical fiber), either isopropanol or an amino glass cleaner is acceptable.
• 7.6 Organometallic standard oil: A high-concentration single standard or multi-element mixed standard used for instrument standardization (requires confirmation against the source standard (source-text extraction), suspected to be "multi-element mixed standard"), or a check sample for calibration confirmation. The typical concentration at the high point of the calibration curve for wear metals and contaminant elements in in-service oil is 100mg/kg, and the typical concentration at the high point of the calibration curve for additive elements is 900mg/kg.
  • 7.6.1 Standard oils all have a shelf life. Standard oils beyond the specified validity period shall not be used for standardizing instruments.
• 7.7 Counter electrode: The counter electrode is a rod electrode or a disc electrode, and the material must be high-purity graphite (spectral purity). The dimensions meet those shown in Figure 2 (Figure 2: φ12.5±0.03, φ3.18±0.03, φ6.15±0.03, 10°±0.1°, 152.4±1.57, unit mm, material is high-purity graphite (spectral purity)).
• 7.8 Sample container: There are many types of sample containers used for analyzing in-service oil. Disposable sample containers can only be used once, and reusable sample containers must be cleaned thoroughly after one determination. All sample containers must be ensured to be free of contamination and stored accordingly. When analyzing light flammable samples such as hydraulic oil, a sample container cover is required.

5. Instruments and equipment

• 6.1 Electrode sharpener (requires confirmation against the source standard (source-text extraction), original text is "electrode sharpener with the curvature of 160%"): The electrode sharpener is used to remove contaminants remaining on the rod electrode from the previous test, and at the same time form a (requires confirmation against the source standard (source-text extraction), the original text is incomplete here) at the end of the electrode. If a preformed disc electrode is used as the counter electrode, an electrode sharpener is not required.
• 6.2 Rotating disc electrode atomic emission spectrometer: Composed of an excitation source, a spectroscopic system, and a data readout system. The elements to be determined and their recommended wavelengths are shown in Table 1 (where multiple wavelengths appear in the table, they are ordered according to priority recommendation or determination range).
• 6.3 Heatable ultrasonic homogenizer (recommended): For samples containing large particles or transported and stored for more than 48h, use a heatable ultrasonic homogenizer to heat the sample so that the particles in the sample are uniformly suspended in the oil (requires confirmation against the source standard (source-text extraction), original text is "the sample particles are uniformly suspended in the oil").

Table 1 Elements and recommended wavelengths (the original text source-text extraction contains noise; the following is the identifiable content, marked as requiring confirmation against the source standard (source-text extraction))

6. Recommended operating conditions

• 10.1 Preheating: After the instrument has been idle for several hours, it is necessary to perform at least three pre-burns to stabilize the excitation source before starting sample measurement. Any sample or standard oil can be used. For specific pre-burn procedure requirements, refer to the manufacturer's operation manual.
• 10.2 Optical path scanning: Perform the daily optical path scanning procedure according to the instrument operation manual. Optical path scanning is required when the instrument has been shut down and left for a certain period of time or when the ambient temperature deviates from the last calibration temperature by more than 10°.
• 10.3 Validity check: Before performing daily sample analysis, the validity of the calibration can be confirmed through a pass/fail standardization check using one or several check samples. The check sample can be the standard oil used for calibration or a sample of known concentration. When the test result of the element to be determined exceeds the precision requirement of ±10%, the optical path scanning and standardization procedures recommended by the instrument manufacturer are required.
• 9.2 Ultrasonic conditions: The ultrasonic temperature is not lower than 60℃ (requires confirmation against the source standard (source-text extraction), original text is "604"), and the ultrasonic time is not less than 2min.
• 9.4 Sample stage: adjust the position of the sample stage until it is fully raised, so that at least one third of the disc electrode is immersed in the sample.
• 12.2 Analysis of flammable samples: when analyzing light flammable samples such as hydraulic oil, a non-plastic sample cup lid should be used, which can retard flame and reduce smoking, avoiding attenuation of the response signal. Most lids can be matched with reusable or disposable sample cups.

7. Sampling and specimen preparation

• 8 Sampling: in-service oil samples must be representative. A standardized sampling procedure is the key to ensuring accurate analysis results; the sampling procedure shall follow the standard requirements of GB/T 4756.
• 9.1 Shaking: in-service oil contains particulate matter; to ensure it is representative, the sample must be shaken before sampling.
• 9.2 Ultrasonic homogenization: if the sample has been transported for several days, stored for a long time, or has high viscosity, before sampling it must first be placed in a heatable ultrasonic bath for ultrasonication, so that aggregated particles are uniformly dispersed in the sample. The ultrasonic temperature shall not be lower than 60℃ (requires confirmation against the source standard (source-text extraction)), and the ultrasonic time shall not be less than 2min.
• 9.3 Sample cup: before measurement, pour the in-service oil sample or standard oil into a sample cup with a capacity of not less than 1mL (requires confirmation against the source standard (source-text extraction), original text is “1ml.”). To obtain good analytical repeatability, it is necessary to ensure that the amount of sample poured into the sample cup is consistent each time.
• 9.4 Sample stage: adjust the position of the sample stage until it is fully raised, so that at least one third of the disc electrode is immersed in the sample.

8. Analysis procedure

• 11.1 Factory calibration: the analytical range of each element is determined by measuring organometallic standard oils of known concentration. A calibration curve and corresponding correction factor for each element were established to obtain a linear response. The concentrations of tested samples shall all be within the linear response range. Table 1 lists typical elements and recommended wavelengths for the determination of in-service oils.
• 11.2 Daily standardization: when the instrument validity check fails or each time the work is switched, a daily standardization with at least two points is required, and at least three blank and working standard oil measurements are required.
• 12.1 Sample analysis: during sample analysis, the same calibration curve procedure and manner as for the standardization standard oils shall be used. Each analysis shall use a new disc electrode, a polished rod electrode, or a new counter disc electrode. When installing the disc electrode, to prevent finger contamination, laboratory-grade paper towels or installation tools shall be used. The cleaning procedure shall follow the manufacturer's recommendations to avoid cross-contamination and contamination from residual or spilled samples.
• 12.2 Analysis of flammable samples: when analyzing light flammable samples such as hydraulic oil, a non-plastic sample cup lid should be used, which can retard flame and reduce smoking, avoiding attenuation of the response signal. Most lids can be matched with reusable or disposable sample cups.
• 12.3 Quality control: during continuous measurement, a check sample shall be measured at least every hour; under intermittent operation, one check sample shall be measured for every 25 samples analyzed, to confirm that the instrument's measurement results for the elements to be determined meet the precision requirements of ±10%.

9. Qualitative and quantitative determination and calculation formulas

• Chapter 4 Method summary: by comparing the signal intensity of elements in the in-service oil sample with the signal intensity of the calibration standard, the concentration of the test element in the oil sample can be calculated.
• 11.1: the analytical range of each element is determined by measuring organometallic standard oils of known concentration. A calibration curve and corresponding correction factor for each element were established to obtain a linear response.
• 13 Report: the units of reported results are all mg/kg. For wear metals and contaminant elements with concentrations below 10mg/kg, results are reported to one decimal place; for concentrations above 10mg/kg, report as integers. The analysis results for additive elements are reported to three significant figures. In-service oil samples need only be measured once.
• The precision formulas (Table 2, Table 4) are expressed as the average concentration (mg/kg) of X=; for the specific formulas see Section 10 (the original formula source-text extraction has high noise, marked as requires confirmation against the source standard (source-text extraction)).

10. Precision

• 14 Precision and bias: the precision of this standard is determined through statistical analysis results among multiple laboratories, and the reliability of test results is judged according to the following provisions (confidence level of 95%).
• 14.1 Repeatability: in the same laboratory, by the same operator using the same instrument, using the same method, the difference between two consecutive test results on the same test specimen shall not be greater than the values in Table 2 and Table 3.
• 14.2 Reproducibility: in different laboratories, by different operators using different instruments, using the same method, the difference between two independent results on the same test specimen shall not be greater than the values in Table 4 and Table 5.
• 14.3 Bias: the bias was calculated from the determination of three calibration standards 30mg/kg, 50mg/kg, and 100mg/kg. Except for the barium content of 30mg/kg, the nickel content of 50mg/kg, and the titanium content of 100mg/kg, the bias of other elements is not significant. The bias values have no important effect on the trend analysis of in-service oils.

Table 2 Repeatability (mg/kg) (original text source-text extraction has high noise; the following is the identifiable content; formula requires confirmation against the source standard (source-text extraction))

Table 3 Repeatability at selected concentrations (mg/kg) (original text source-text extraction has high noise; the following is the identifiable content; requires confirmation against the source standard (source-text extraction))

Table 4 Reproducibility (mg/kg) (the source text at source-text extraction is noisy; the following is the recognizable content; formula requires confirmation against the source standard (source-text extraction))

Table 5 Reproducibility at selected concentrations (mg/kg) (the source text at source-text extraction is noisy; the following is the recognizable content; requires confirmation against the source standard (source-text extraction))

11. Report

• 13 Report: the units for all reported results are mg/kg. For wear metals and contaminant elements with concentrations below 10mg/kg, report results to one decimal place; for concentrations above 10mg/kg, report as integers. Report the analysis results for additive elements to three significant figures. In-service oil samples need only be measured once.

12. Normative references

• GB/T 4756 Petroleum liquids—Manual sampling (GB/T 4756-1998, eqv ISO 3170:1988)
• ASTM D6595-00 (2005) (modified adoption)

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick reference for questions and answers