GB/T 5018-2008 Test method for corrosion preventive properties of lubricating greases

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Card type: Test method

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

• Standard number: GB/T 5018-2008
• Chinese title: Test method for corrosion preventive properties of lubricating greases
• English title: Standard test method for determining corrosion preventive properties of lubricating greases
• Replacement relationship: replaces GB/T 5018-1985 "Test method for corrosion preventive properties of lubricating greases"; GB/T 5018-1985 was formulated with reference to ASTM D1743:1973 (81).
• Adoption relationship: This standard is a modified adoption of the American Society for Testing and Materials standard ASTM D1743-05a "Test method for corrosion preventive properties of lubricating greases"; this standard was redrafted according to ASTM D1743-05a.
• Main differences from ASTM D1743-05a (original text):
  • The referenced standards adopt China's current national standards and petrochemical industry standards.
  • The motor speed adds the optional speed of 1450 r/min±50 r/min.
  • The imperial units involved in the figures are converted to International System of Units units.
  • Deleted key clauses (original wording; the specific clause numbers are not provided in the available source).
• Main changes compared with GB/T 5018-1985 (original text):
  • The test procedure was modified according to ASTM D1743-05a.
  • The bearing was changed from a 7601 type bearing or Timken bearing (cone No.09074, cup No.09169) to a bearing with model LM11949 bearing cone and LM11910 bearing cup.
  • The evaluation of test results was modified according to ASTM D1743-05a.
  • The precision was modified according to ASTM D1743-05a.
  • Annex A of GB/T 5018-1985 was changed to Annex A (informative annex) "Version description", and Annex B (informative annex) "Alternative corrosion preventive test methods" was added.
• Publication/implementation: published on 2008-02-13, implemented on 2008-09-01.
• Proposal/administration/drafting: proposed by China Petrochemical Corporation; administered by the Petrochemical Research Institute of China Petroleum & Chemical Corporation; drafting organization is the Petrochemical Research Institute of China Petroleum & Chemical Corporation; main drafters Liu Zhongqi and Yao Zhishu (requires confirmation against the source standard (source-text extraction); the original text is "Yao Zhishu [name characters unverified]").
• Previous versions: GB/T 5018-1985.

2. Scope of application and non-application

• This standard specifies the determination of the corrosion preventive properties of lubricating greases under wet conditions using a tapered roller bearing coated with lubricating grease.
• This standard was formulated based on the CRC technical document L41, which can indicate the correspondence between laboratory evaluation results and actual service results of wheel bearings lubricated with lubricating grease.
• Note: The United States Cooperative Research Council (CRC) technical document L41-857 studied test methods for the corrosion preventive properties of lubricating greases in the presence of free water; the address of CRC is 219 Perimeter Center Parkway, Atlanta, CA 30345, USA (original text as such, requires confirmation against the source standard (source-text extraction)).
• This standard does not purport to address all safety problems; therefore, users should establish appropriate safety and protective measures and determine applicable management systems before using this standard.
• Non-application scope: not provided in the available source.

3. Method principle

A new, clean bearing coated with the lubricating grease sample is run under a slight thrust load for 60 s±3 s so that the lubricating grease is distributed as in actual use. The bearing is stored under conditions of 52 ℃±1 ℃ and 100% relative humidity for 48 h±0.5 h, then cleaned and inspected for corrosion marks on the bearing cup raceway.

4. Reagents and materials (purity / preparation)

• 7.1 Distilled water: meets the requirements for grade three water in GB/T 6682.
• 7.2 Isopropanol: chemically pure. Note: Isopropanol is flammable.
• 7.3 Ammonium hydroxide: chemically pure. Note: Toxic, flammable, vapor is extremely irritating, fatal if swallowed, harmful if inhaled.
• 7.4 Solvent rinse liquid, composition as follows:
  • 7.4.1 Isopropanol: 90% (volume fraction).
  • 7.4.2 Distilled water: 9% (volume fraction).
  • 7.4.3 Ammonium hydroxide: 1% (volume fraction).
• 7.5 Cleaning solvent: solvent naphtha meeting the requirements of SH 0005. Note: Flammable, vapor is toxic.

5. Apparatus and equipment

• 6.1 Bearing: composed of LM11949 bearing cone and LM11910 bearing cup.
• 6.2 Motor: speed is 1150 r/min±50 r/min or 1450 r/min±50 r/min, 50 W (minimum).
• 6.3 Bearing holder (see Figure 1): composed of a stainless steel block with a mass of 1 kg±0.10 kg, upper and lower plastic flanges set according to the bearing cone, a metal screw, an O type ring for the bearing cup, and a threaded plastic container.
• 6.4 Running table: as shown in Figure 3.
• 6.5 Thrust loading drive shaft: as shown in Figure 4.
• 6.6 Bearing greaser: as shown in Figure 5 and Figure 6.
• 6.7 Pump stand: as shown in Figure 7.
• 6.8 Syringe: capacity at least 100 mL, with a needle of length not less than 100 mm and not smaller than gauge 16.
• 6.9 Stopwatch: capable of reading to 60 s±3 s.
• 6.10 Oven: laboratory oven, capable of maintaining 52 ℃±1 ℃.
• 6.11 Embedded type (original text incomplete, requires confirmation against the source standard (source-text extraction)).

6. Recommended operating conditions

• Running time: 60 s±3 s.
• Running speed: 1150 r/min±50 r/min or 1450 r/min±50 r/min (optional).
• Motor power: 50 W (minimum).
• Test temperature: 52 ℃±1 ℃.
• Relative humidity: 100%.
• Storage time: 48 h±0.5 h.
• Thrust loading: about 29 N load, giving a total load on the bearing of 89 N (provided by the force of the spring on the thrust loading shaft and the sum of the 1 kg stainless steel block and spring force; this total load is approximate; the accuracy of the 1 kg stainless steel block is 0.010 kg).
• Bearing drying conditions: maintain at 70 ℃±5 ℃ for 15 min～30 min.
• Cleaning solvent temperature: 52 ℃～66 ℃.
• Solvent rinse liquid temperature: 66 ℃～68 ℃ (original text is "66C-SC", requires confirmation against the source standard (source-text extraction)).

7. Sampling and specimen preparation

• 9.1 Carefully inspect the test bearing and select a bearing whose cup raceway and rollers are completely free of corrosion. During preparation of the bearing, handle it with tweezers or wear rubber gloves or plastic gloves; never touch the bearing directly with hands at any time.
• 9.2 Clean the selected bearing with hot cleaning solvent (52 ℃～66 ℃) to remove rust preventive, scrub the bearing rollers and bearing cup with cotton yarn in the solvent to completely remove residues, and repeat rinsing the bearing with fresh hot cleaning solvent. Note: The specified cleaning temperature is higher than the flash point of the cleaning solvent, so cleaning operations should be carried out in a well-ventilated fume hood where there is no open flame or other ignition source.
• 9.3 Transfer the bearing from the cleaning solvent to the solvent rinse liquid to remove cleaning solvent and any possible fingerprints; when rinsing in freshly prepared hot solvent rinse liquid (66 ℃～68 ℃), rotate the bearing slowly. Note: Freshly prepared solvent rinse liquid is used to avoid selective evaporation of components at the rinsing temperature.
• 9.4 Remove the bearing from the solvent rinse liquid and place it on filter paper to blot thoroughly, then place the bearing in an oven and maintain at 70 ℃±5 ℃ for 15 min～30 min.
• 9.5 Allow the bearing to cool to room temperature and re-inspect to ensure that the selected bearing is free of corrosion and rotates freely (after cleaning and drying, take care not to rotate the bearing when removing it).
• 9.6 Clean and dry the bearing greaser in the same manner as the bearing preparation.

8. Analysis procedure

• 10.1 Place the reservoir of the bearing greaser on a clean workbench, put on gloves, place the bearing cup with the smaller-diameter end facing down into the base of the bearing greaser, place the bearing cone into the bearing cup, and while keeping the bearing in the bearing greaser, lift and invert the assembly as a whole to return it to the original workbench.
• 10.2 Fill the reservoir with the lubricating grease sample, press the sample into the bearing with the greasing piston, carefully remove the piston from the reservoir to prevent air from entering the bearing, slide the bearing greaser to the edge of the workbench, keep the bearing fixed in the reservoir, and invert it on the workbench back to its original state.
• 10.3 Using a small square scraper, scrape off excess lubricating grease from the bearing inner ring and the outside of the bearing sleeve and from the bearing greaser at the same thread. Remove the bearing from the bearing greaser with pliers or gloved fingers. Remove excess lubricating grease from the outside of the bearing with a scraper; this operation is to ensure that approximately the same amount of lubricating grease is used each time.
• 10.4 According to Figure 1, hold the grease-filled bearing with gloved fingers, with the larger inner-diameter end of the bearing cup facing down, insert the small-diameter plastic flange from the top of the bearing, insert the large-diameter plastic flange from the bottom of the bearing, slide the bearing onto the 1 kg stainless steel block so that the large-diameter flange fits exactly into the top groove of the stainless steel block, insert the screw through the flange and tighten the screw firmly into the stainless steel block, place the plastic bearing holder (see Figure 1 part 8) on the bearing (on the O type ring), and press down the bearing holder so that the bearing fits properly into the bearing holder.
• 10.5 Place the plastic container upside down on the bearing support, slide the plastic container to the edge of the operating table, and press the stainless steel weight with a finger against the inner bottom of the plastic container, invert the plastic container and keep all parts inside the plastic container from coming apart.
• 10.6 Place the plastic container on the base of the drive device so that it is centered under the drive pointer; start the motor so that the drive pointer enters the center of the 1 kg stainless steel weight, load until the nut reaches the bottom, run for 60 s, turn off the motor and let the bearing rotate by inertia until it stops; in this and the following steps, be especially careful not to damage the contact between the bearing outer ring and the rollers.
  • 10.6.1 During operation or after running for 60 s, grease should be added again to correct the inside of the bearing (original text incomplete, requires confirmation against the source standard (source-text extraction)).
• 10.7 Add distilled water (original text incomplete, requires confirmation against the source standard (source-text extraction)).
• 10.8 Use a clean (original text incomplete, requires confirmation against the source standard (source-text extraction)) to fill with 100 mL distilled water prepared according to 10.7, through the special small hole on the bearing support into the plastic container (original text incomplete, requires confirmation against the source standard (source-text extraction)) 50 mL (original text incomplete, requires confirmation against the source standard (source-text extraction)), open (original text incomplete, requires confirmation against the source standard (source-text extraction)) drip water, when the time is up (original text incomplete, requires confirmation against the source standard (source-text extraction)), use 10 mL water, leave 80 mL±1 mL water in the plastic container; ensure (original text incomplete, requires confirmation against the source standard (source-text extraction)) mL±1 mL water oil (original text incomplete, requires confirmation against the source standard (source-text extraction)), the remaining water will (original text incomplete, requires confirmation against the source standard (source-text extraction)) enter the bearing, in 5 s use 16 gauge needle to extract 70 mL±1 mL (original text incomplete, requires confirmation against the source standard (source-text extraction)) there is a certain degree of difficulty; therefore, a larger syringe needle can be used.
• 10.9 Tighten the plastic container lid, place it in a vibration-free oven at 52 ℃±1 ℃ for 48 h.
• 10.10 Each grease sample requires three bearings for testing.

9. Qualitative and Quantitative and Calculation Formulas

• 11.1 Remove the bearing from the plastic container, place it in a mixture of hot (original text is “[garbled heated-mixture description and ratio: 50358]”, requires confirmation against the source standard (source-text extraction)) isopropanol (note: flammable) and cleaning solvent (note: flammable, vapor toxic); the mixture can be heated to more easily remove grease from the bearing, shake vigorously to remove grease; repeat cleaning with fresh mixture or wipe the bearing with clean cotton yarn or silk cloth to ensure removal of trace grease.
• 11.2 Move the bearing outer ring from the rollers onto clean filter paper and air dry.
• 11.3 Do not magnify, inspect the bearing outer ring raceway for signs of corrosion, evaluate as pass or fail. The failure criterion should be the appearance of any 1.0 mm corrosion spots or larger spots, measured by the longest dimension, regardless of the number of spots.
  • 11.3.1 Stains that can be removed by lightly wiping with soft cotton yarn (dry or wetted at room temperature with a solvent that does not react with rust or corrosion) should not be considered corrosion in the rating.
• Calculation formula: not provided in the available source.

10. Precision

• 13.1 Precision: The precision of this standard is determined by statistical analysis of interlaboratory test results as follows:
  • 13.1.1 Repeatability can be judged from the following fact: in 9 laboratories, duplicate results obtained from 6 samples have 94% in agreement.
  • 13.1.2 Reproducibility can be judged from the following fact: in 9 laboratories, from 6 samples with good or poor corrosion resistance, at least 96% of the results are in agreement.
• 13.2 Bias: Since the test results only indicate whether they are consistent with the acceptance criteria specified in the method, this method does not specify bias.

11. Report

• 12.1 Evaluate as pass or fail, and report the result that at least two of the three bearing tests agree.

12. Referenced Documents

• GB/T 6682 Analytical laboratory water specifications and test methods (GB/T 6682-1992, eqv ISO 3696:1987) (original text is “GB/T 6682-1932,zcg ISO 3898:1987”, requires confirmation against the source standard (source-text extraction)).
• SH 0005 Solvent naphtha for the paint industry (original text is “SH 0005 solvent liquid for the paint industry [wording uncertain]”, 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 Reference Q&A