NB/SH/T 0450-2019 Determination of Oxidation Corrosion of Synthetic Oil

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Card type: Test method

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

• Standard number: NB/SH/T 0450—2019 (the file name is NBSHT-0450-2019, the header of the main text is NB/SH/T 0450—2019; the cover source-text extraction is written as "NB/SE/T 0450—2019", requires confirmation against the source standard (source-text extraction))
• Chinese name: Determination of Oxidation Corrosion of Synthetic Oil
• English name: Test method for the determination of oxidation corrosion of synthetic oil
• Replacement relationship: replaces SH/T 0450—1992 "Determination of Oxidation Corrosion of Synthetic Oil"
• Issued/implemented: issued on 2019-11-04, implemented on 2020-05-01
• Issuing authority: National Energy Administration
• Secretariat: Subcommittee on Synthetic Lubricants of the National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC280/SC.5)
• Drafting organization: Sinopec Research Institute of Petroleum Processing
• Main drafters: Li Hongyan, Hu Haibao
• Previous versions: SH/T 0450—1992

2. Scope of application and non-applicability

• This standard specifies the determination method for oxidation corrosion of synthetic oil.
• This standard is applicable to the determination of the oxidation corrosion characteristics of synthetic oil.
• Non-applicable scope: not provided in the available source.

3. Method principle

Under specified conditions, the sample is oxidized, and the oxidation stability of the sample is evaluated by the rate of change of kinematic viscosity before and after oxidation, the change in acid value, and the mass change of metal sheets.

4. Reagents and materials (purity / preparation)

• 5.1 Benzene: analytical reagent.
• 5.2 Anhydrous ethanol: analytical reagent.
• 5.3 Petroleum ether: boiling range 60℃~90℃, analytical reagent.
• 5.4 Hydrochloric acid: concentration about 36%~38%, chemical reagent.
• 5.5 Water: meets the requirements for grade three water in GB/T 6682—2008.
• 5.6 Metal sheet: a small hole with a diameter of 2.5mm is drilled in the center at a position 5mm above the metal sheet, with the following requirements:
  • a) Steel sheet (steel No. 45): 20mm×10mm×2mm;
  • b) Copper sheet (copper No. T1): 20mm×10mm×2mm;
  • c) Aluminum sheet (aluminum No. LY11): 20mm×10mm×2mm;
  • d) Magnesium sheet (magnesium No. MB8): 20mm×10mm×2mm;
  • e) Lead sheet (lead No. Pb1 or Pb2, containing lead 99.99%): 20mm×10mm×2mm.
• 5.7 Brush.
• 5.8 Tweezers.
• 5.9 Sandpaper or abrasive cloth: P180~P240, P400.
• 5.10 Absorbent cotton.
• 5.11 Chamois leather.
• Other preparations: 10% dilute hydrochloric acid (mass fraction 10%), used for soaking lead sheets (see 6.1.2); benzene-ethanol solvent (4:1), used for cleaning metal sheets when there is a dispute (see the foreword and note in 6.2.4).

5. Apparatus and equipment

• 4.1 Oxidation tube: type A with a glass stopper (standard ground stopper No. 24); type B with a reflux condenser. Hard round-bottom glass test tube with length 260mm±5mm, inner diameter 23mm±1mm, wall thickness 1.4mm±0.2mm, with a graduation line at a capacity of 25mL (see Figure 1). Note 1: type B oxidation tube is suitable for determining the oxidation stability of hydraulic oil.
• 4.2 Gas inlet tube: type A length 400mm±5mm, type B length 535mm±5mm, outer diameter 7mm±0.5mm. The inner diameter of the outlet at the tail end is 2.5mm±0.3mm, and there is a protrusion at a height of 35mm±1mm from the outlet for fixing a small aluminum hook (see Figure 2).
• 4.3 Constant-temperature bath: a constant-temperature bath capable of controlling 200℃±1℃.
• 4.4 Air flowmeter: 0mL/min~100mL/min, controlled to ±3 mL/min.
• 4.5 Metal sheet suspension hook: aluminum hook or glass hook, fitted over the protruding part of the gas inlet tube (see Figure 3).
• 4.6 Thermometer: rod-type mercury thermometer and platinum resistance thermometer 0℃~250℃, with a scale division of 1℃.
• 4.7 Caliper: minimum reading 0.02mm.
• 4.8 Analytical balance: sensitivity 0.1mg.

6. Recommended operating conditions

• Constant-temperature bath temperature: capable of controlling 200℃±1℃ (4.3); the specific test temperature is "determined according to the product standard" (6.1.4 with respect to the viscosity measurement temperature).
• Air flow rate: adjusted by the flowmeter to the specified air flow rate (6.2.2); flowmeter range 0mL/min~100mL/min, controlled to ±3 mL/min (4.4); the specific specified value is not provided in the available source.
• Oxidation time: oxidation proceeds to the specified time (6.2.3); the specific specified value is not provided in the available source.
• Sample amount: 25mL (6.2.1).
• Distance from the outlet of the gas inlet tube to the bottom of the oxidation tube: 3mm~5mm (6.2.2).
• Order of hanging metal sheets: steel (or lead), copper, aluminum, magnesium (6.2.2).

7. Sampling and sample preparation

• 6.1.1 Sampling and sample handling: sample according to the requirements of GB/T 4756 or GB/T 27867, and ensure the sample is uniform before sampling.
• 6.1.2 Treatment of metal sheets: polish all surfaces of the metal sheets required for the test (first grind with P180~P240 sandpaper or abrasive cloth, then polish with P400 sandpaper or abrasive cloth); the treatment method for lead sheets is to first soak in 10% dilute hydrochloric acid (mass fraction 10%) for 2min, then remove, wash the acid off the surface of the lead sheet with water, and then polish with chamois leather so that all surfaces are smooth and bright with no obvious processing marks. After polishing the metal sheets, clean the test pieces with petroleum ether, air-dry, classify, and place in a desiccator for later use. According to the test requirements, number the metal sheets as a set, and weigh to an accuracy of 0.1mg.
• 6.1.3 Preparation of oxidation tubes: number clean oxidation tubes as a set, insert the gas inlet tube with a suspension hook, and fix it to the oxidation tube stopper with a rubber tube. If an oxidation tube with a condenser is used, insert the gas inlet tube from the upper end of the condenser and connect it with a notched cork stopper.
• 6.1.4 Determine the kinematic viscosity of the sample before oxidation according to GB/T 265 or GB/T 30515 (temperature determined according to the product standard); determine the acid value of the sample according to GB/T 7304.

8. Analysis procedure

• 6.2.1 Inject 25mL sample into the oxidation tube.
• 6.2.2 Hang the weighed metal sheets in the order of steel (or lead), copper, aluminum, magnesium with tweezers on the small hook at the lower end of the gas inlet tube, and place them into the sample in the tube. The distance from the outlet of the gas inlet tube to the bottom of the oxidation tube is 3mm~5mm. Place the oxidation tube into a constant-temperature bath that has reached the specified temperature, connect the upper end of the gas inlet tube to the outlet of the flowmeter, and adjust the flowmeter to the specified air flow rate. Start timing after the bath temperature reaches the specified temperature.
• 6.2.3 When oxidation proceeds to the specified time, turn off the power and cut off the gas flow, and remove the oxidation tube from the constant-temperature bath. After slight cooling, pour the sample into a conical flask for determination of viscosity and acid value.
• 6.2.4 Remove the metal sheets from the oxidation tube, place them in a small dish containing petroleum ether, and brush them twice with a soft brush until the oil film and attached matter are cleaned off. After cleaning, blot the metal sheets dry with filter paper, and immediately weigh with an analytical balance to an accuracy of 0.1mg. If there is a mass change in the metal sheets (a mass change of the metal sheet within 0.4mg is defined as no corrosion), measure the dimensions of the metal sheets with a caliper and calculate their surface area. Note: if there is a dispute about the test results, use benzene-ethanol solvent as the washing solvent to clean the metal sheets after the test.
• 6.2.5 Determine the kinematic viscosity and acid value of the sample after oxidation.

9. Qualitative and quantitative determination and calculation formulas

• 7.1 Mass change of metal sheet G (mg/cm²) is calculated according to formula (1): G = (m₁ − m₂) / S × 1000 Where:
  • m₁——mass of the metal sheet before oxidation, in grams (g);
  • m₂——mass of the metal sheet after oxidation, in grams (g);
  • S—— surface area of the metal sheet (not counting the small hole), in square centimeters (cm²). (Note: the symbols in the original source-text extraction formula are noisy, the numerator is suspected to be m₁−m₂, requires confirmation against the source standard (source-text extraction))
• 7.2 Rate of change of kinematic viscosity before and after oxidation X (%) is calculated according to formula (2): X = (ν₂ − ν₁) / ν₁ × 100 Where:
  • ν₁——kinematic viscosity before oxidation, in square millimeters per second (mm²/s);
  • ν₂——kinematic viscosity after oxidation, in square millimeters per second (mm²/s). (Note: the symbols in the original source-text extraction formula are noisy, requires confirmation against the source standard (source-text extraction))
• 7.3 Change in acid value before and after oxidation ΔAN is calculated according to formula (3): ΔAN = AN₂ − AN₁ Where:
  • AN₁——acid value before oxidation, in milligrams per gram (mg/g);
  • AN₂——acid value after oxidation, in milligrams per gram (mg/g). (Note: the symbols in the original source-text extraction formula are noisy, requires confirmation against the source standard (source-text extraction))
• 8 The test results shall include the following: a) kinematic viscosity before oxidation; b) kinematic viscosity after oxidation; c) rate of change of kinematic viscosity before and after oxidation; d) acid value before oxidation; e) acid value after oxidation; f) change in acid value before and after oxidation; g) mass change of each metal sheet after oxidation; a mass change of the metal sheet within 0.4mg is defined as no corrosion.

10. Precision

Judge the reliability of the test results according to the following provisions (95% confidence level):

• 9.1 Repeatability: within the same laboratory, by the same operator, using the same apparatus and equipment, under the same experimental conditions, the difference between two determination results for the same sample shall not exceed the data in Table 1.
• 9.2 Reproducibility: in different laboratories, by different operators, using different apparatus, the difference between two independent determination results for the same sample shall not exceed the data in Table 1.

Table 1 Precision requirements

(Note: The correspondence between "Result item" and "Repeatability/Reproducibility" in Table 1 is organized according to the source-text extraction layout, requires confirmation against the source standard (source-text extraction))

11. Report

No independent "Report" chapter is provided in the available source; Chapter 8 "Test Results" specifies the content that the results should include (see Section 9).

12. Normative references

• GB/T 265 Petroleum products—Determination of kinematic viscosity and calculation of dynamic viscosity
• GB/T 4756 Petroleum liquids—Manual sampling
• GB/T 6682—2008 Water for analytical laboratory use—Specification and test methods
• GB/T 7304 Determination of acid number of petroleum products—Potentiometric titration method
• GB/T 27867 Petroleum liquids—Automatic pipeline sampling
• GB/T 30515 Transparent and opaque liquids—Determination of kinematic viscosity and calculation of dynamic viscosity of petroleum products
• GB/T 1.1—2009 (mentioned in the foreword, as the basis for drafting rules) (Note: In Chapter 2 of the source text, the code source-text extraction for GB/T 265 and GB/T 27867 is written as "CB/T", requires confirmation against the source standard (source-text extraction))

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 Q&A