NB/SH/T 0031-2013 Diesel engine piston cleanliness rating method

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Card type: Test method

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

• Standard number: NB/SH/T 0031—2013
• Chinese name: Diesel engine piston cleanliness rating method
• English name: Rating method for diesel engine piston cleanliness
• Replacement relationship: replaces SH/T 0031—1990 "Diesel engine piston cleanliness rating method"
• Previous versions: SH/T 0031—1990
• Publication/implementation: published on 2013-06-08, implemented on 2013-10-01
• Issuing authority: National Energy Administration
• Custodian: Subcommittee on Petroleum Fuels and Lubricants of the National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280/SC1)
• Drafting organization: Sinopec Research Institute of Petroleum Processing
• Main drafters: Wei Caitian, Li Shaoyu, Lu Wentong, Wang Shanshan (the characters of the names require confirmation against the source standard (source-text extraction))
• Main changes compared with the 1990 version: some referenced standards were modified and deleted; because SH/T 0186, SH/T 0262, SH/T 0263, etc. have been abolished, the ratings of evaluation methods related to this standard such as SH/T 0782, SH/T 0786 were added; Annexes A, B, C are all informative annexes.

2. Scope of application and non-applicability

• 1.1 This standard specifies the methods for numerical rating of diesel engine piston cleanliness using the piston deposit rating A method and the piston deposit rating B method.
• 1.2 The piston deposit rating A method is applicable to the SH/T 0261 method; the piston deposit rating B method is applicable to methods such as GB/T 9932, GB/T 9933, SH/T 0782, SH/T 0786, etc. At the same time, this standard is also applicable to other engine piston cleanliness ratings that need to be carried out.
• Note: The relevant content of carbon deposit and lacquer film rating in this standard refers to CRC (Coordinating Research Council) Part 20 of the Coordinating Research Council Deposit Rating Manual, the carbon deposit/lacquer film rating scale section.
• Not applicable: the source text does not explicitly list the scope of non-applicability.

3. Method principle

• 4 Method summary: After the engine test run is completed, stop the engine—cool down—disassemble—take out the test piston. After the piston is treated according to the specified method, it is placed in a rating box for cleanliness rating of the piston surface. According to the requirements of each test method, the piston rating calculation is carried out by the piston rating A method or the piston rating B method, and the piston total weighted rating, first ring groove carbon filling percentage, first ring land heavy carbon rate, etc. are listed in the form of a report, with a color photograph of the piston attached.
• 3.2 Piston deposit rating A method: describes in numerical form the deposition status of various deposits on the piston surface, and uses the results calculated from these numerical values to evaluate the high-temperature cleanliness performance of diesel engine oil. The rating by this method represents the sum of the ratings for no deposition of any deposit in each specific area or the whole of the piston surface, and represents the degree of cleanliness of each specific area or the whole of the piston; the higher the score, the less deposit contamination.
• 3.3 Piston deposit rating B method: describes in numerical form the deposition status of various deposits on the piston surface, and uses the results calculated from these numerical values to evaluate the high-temperature cleanliness performance of diesel engine oil. The rating by this method represents the sum of the ratings of various deposits in each specific area or the whole of the piston surface, and represents the severity of deposit contamination in each specific area or the whole of the piston; the higher the score, the more severe the deposit contamination.

4. Reagents and materials (purity / preparation)

• 6.1 Cleaning solvent naphtha: low-aromatic solvent naphtha No. 5 conforming to GB 1922.
• 6.2 Lint-free cloth.
• Other reagents and materials: not provided in the available source.

5. Instruments and equipment

• 5.1 Piston rating box: a 20W cool white ring rating lamp and a spherical magnifier are installed in the rating box; the schematic diagram is shown in Figure 2.
• 5.2 Lacquer film rating pictures and rating color plates: the rating color plates are made from passivated aluminum plates and are divided into colors such as black, dark brown, brown, light brown, light yellow, and natural color. To prevent the rating color plates from changing color, they should be stored in a dry, dark place. Note: The lacquer film rating pictures and rating color plates can be obtained from CRC.
• 5.3 Piston surface zoning cover: use the piston surface zoning cover to evenly divide the piston surface, facilitating calculation of the area percentages of various deposits. For the schematic diagrams and dimensions of the piston surface zoning cover for each test method, see Annex A.
• Annex A Composition of the piston surface zoning cover: a) circular zoning cover plate; b) cover plate screws; c) φ1.6mm stainless steel wire.
  • A.1.1 The circular zoning cover plate has a thickness of 10mm; the side surface of the circular zoning cover plate is evenly divided into several equal parts, each equal part is engraved with a number in sequence; the center hole of the cover plate with height 5mm, φ10, the engraved line on the side of the cover plate, and the center line of the stainless steel wire hole are on the same tangent plane.
  • A.1.2 The zoning cover plate screws are M10 aluminum alloy screws, used for lifting the piston surface zoning cover.
  • A.1.3 Several steel wires of φ1.6mm are respectively inserted into the small holes around the zoning cover plate and fixed firmly with epoxy resin.
  • A.1.4 Detailed dimension table of the piston surface zoning cover for each test method A.1: SH/T 0261 zoning cover plate φ152mm, distance from the center of the upper outer zone cover plate to the center of the steel wire hole R73.5mm, steel wire length 180mm, number of equal parts on the side surface of the zoning cover plate 25; GB/T 9933 zoning cover plate φ142mm, R67mm, steel wire length 201mm, number of equal parts 20; SH/T 0786 zoning cover plate φ154mm, R79mm, steel wire length 201mm, number of equal parts 20; SH/T 0782 zoning cover plate φ154mm, R75mm, steel wire length 201mm, number of equal parts 20 (some values in Table A.1 require confirmation against the source standard (source-text extraction)).
• Other instruments and equipment: not provided in the available source.

6. Recommended operating conditions

• Rating environment: 7.4 Piston rating should be carried out in a piston rating box, and the entire rating environment should avoid natural light.
• Rating lamp: 20W cool white ring rating lamp (see 5.1, Figure 2).
• Other operating conditions: not provided in the available source.

7. Sampling and specimen preparation

• 7.1 After taking the piston out of the cylinder liner, allow it to cool naturally to room temperature. Then carefully observe the degree of freedom of the piston rings in the ring grooves and record the condition of the piston rings. When ring sticking occurs, record the sticking position and degree of sticking of the piston rings (expressed as a percentage).
• 7.2 Use a feeler gauge to measure the side clearance of the piston rings, but do not damage the ring groove deposits. Record the side clearance of the piston rings. After removing the piston rings, clean the piston in solvent naphtha, then carefully dry it with a lint-free cloth.
• 7.3 When it is necessary to stop the test midway to inspect the deposition status of deposits on the piston surface, the surface may be wiped with a lint-free cloth without rinsing with solvent naphtha.
• 7.5 Prepare various record sheets for piston rating.
• Other sampling and specimen preparation: not provided in the available source.

8. Analysis procedure

• 8 Piston deposit rating A method:
  • The piston deposit rating A method follows formula (1): T = Σ(S)i × K (the typesetting of the original formula (1) requires confirmation against the source standard (source-text extraction)).
  • 8.1 Calculation of the rating of a specific piston area (taking the SH/T 0261 test method as an example): the rating of parts such as piston ring grooves, ring lands, skirt, and inner cavity top equals the area percentage of each type of deposit in each specific area multiplied by its respective deposit severity coefficient; the resulting products are added to obtain the deposit rating of each specific area, and then the difference obtained by subtracting from 10 is used, see formula (2): S = 10 − Σ(A)j × (Ks)j.
  • 8.1.1 Deposit severity coefficients are shown in Table 1: black lacquer film (including carbon deposit) 10.0; dark brown lacquer film 7.5; brown lacquer film 5.0; light brown lacquer film 2.5; light yellow lacquer film 1.0; natural color 0.
  • 8.1.2 Calculation of the area percentage of various deposits in each specific area of the piston: first place the piston surface zoning cover on the piston at the specified position, dividing each specific area of the piston into a certain number of equal zones. Respectively calculate the number of points occupied by various deposits in a certain equal zone and record them in the corresponding deposit type cells in the record sheet. Finally, add the points of deposits of the same nature, then divide by the total points of each specific area of the piston specified in 8.1.2.1, to obtain the area percentage of the deposit in that area (expressed as a decimal, retaining two decimal places).
  • 8.1.2.1 Total points of specific piston areas are shown in Table 2 (SH/T 0261): first ring groove 100; second ring groove 100; third ring groove 100; fourth ring groove 100; second ring land 100; third ring land 100; fourth ring land 100; skirt 260; inner cavity top 24.
  • 8.1.2.2 Calculate the deposit area percentages; taking the first piston ring groove as an example to calculate the area percentages of various deposits, see Table 3 (black lacquer film m=38, A=0.38, A×Ks=3.80; dark brown lacquer film m=19, A=0.19, A×Ks=0.98 (in the original Table 3, 0.98 and 0.19×7.5=1.425 are inconsistent, requires confirmation against the source standard (source-text extraction)); brown lacquer film m=11, A=0.11, A×Ks=0.55; light brown lacquer film m=12, A=0.12, A×Ks=0.30; light yellow lacquer film m=15, A=0.15, A×Ks=0.15; natural color m=5, A=0.05, A×Ks=0.05; M=100).
  • 8.1.3 Taking the first piston ring groove as an example, the calculation of the score for a specific area is shown in Table 4: S = 10 − Σ(A)j × (Ks)j = 10 − (3.80 + 0.98 + 0.55 + 0.30 + 0.15) = 4.22 (the value of the dark brown lacquer film item in the original Table 4 requires confirmation against the source standard (source-text extraction)).
  • 8.2 Piston cleanliness rating adjustment coefficient: different test methods have different piston cleanliness rating adjustment coefficients. For example, the SH/T 0261 method specifies that the piston cleanliness rating adjustment coefficient is 10/9.
  • 8.3 SH/T 0261 method piston rating is equal to the sum of the scores of nine specific areas of the piston—first ring groove, second ring groove, third ring groove, fourth ring groove, second ring land, third ring land, fourth ring land, skirt, and inner cavity top—multiplied by the piston cleanliness rating adjustment coefficient 10/9, see formula (3): T = Σ(S)i × 10/9.
  • 8.4 The piston deposit rating table is shown in Table 5 (SH/T 0261 piston rating table).
• 9 Piston deposit rating B method:
  • Piston deposit rating B method according to formula (4): T = Σ(Sw)i.
  • 9.1 The weighted rating of specific areas such as piston ring grooves and ring lands is equal to the area percentage of each type of deposit in each specific area multiplied by its respective deposit severity coefficient; the resulting products are added together to obtain the rating of each specific area; the rating of each specific area is multiplied by the specific area weighting coefficient of the respective area to obtain the weighted rating of each specific area, see formula (5) and formula (6): S = Σ(A)j × (Ks)j; Sw = Σ(S)i × (Ka)i.
  • 9.1.1 The deposit severity coefficients are shown in Table 6 and Table 7. Among them, Table 6 applies to test methods such as GB/T 9932 and GB/T 9933, and Table 7 applies to test methods such as SH/T 0782 and SH/T 0786.
    • Table 6 (GB/T 9932, GB/T 9933) deposit severity coefficients: heavy carbon 1.00; medium carbon 0.50; light carbon 0.25; black lacquer film 0.10; dark brown lacquer film 0.075; brown lacquer film 0.050; light brown lacquer film 0.025; light yellow lacquer film 0.010; natural color 0.
    • Table 7 (SH/T 0782, SH/T 0786) deposit severity coefficients: carbon deposit heavy carbon 9, medium carbon 8, light carbon 7 (the correspondence between the values 9, 8, 7 corresponding to carbon deposits in the original Table 7 and the lacquer film grades 6, 5, 4, 3, 2, 1 and the coefficients 1.00, 0.50, 0.25, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, 0 requires confirmation against the source standard (source-text extraction)).
  • 9.1.2 Calculation method for the area percentage of various deposits in a specific area of the piston: use a piston surface zoning cover to divide the specific area of the piston into equal partitions such as 20, each partition accounting for 5% of the specific area, that is, the total value of each specific area is 100. Then, find the area percentage of each type of deposit deposited in each equal partition of each specific area, and record them separately in the respective deposit type cells. Then, add the deposition area percentages of deposits of the same nature to obtain the deposit area percentage of each type of deposit in each specific area (expressed as the numerical value of the area percentage). Examples are shown in Table 8 and Table 9.
  • 9.1.3 The weighting coefficients for each specific area of the piston are shown in Table 10 and Table 11; among them, Table 10 applies to test methods such as GB/T 9932, GB/T 9933, and SH/T 0786, and Table 11 applies to test methods such as SH/T 0782.
    • Table 10 (GB/T 9932, GB/T 9933, SH/T 0786) weighting coefficients for each specific area of the piston: first ring groove 10; second ring groove 35; third ring groove 70; fourth ring groove 3.5; second ring land 20; third ring land 20; fourth ring land 35 (the value 20 for the third ring land in the original Table 10 requires confirmation against the source standard (source-text extraction)).
    • Table 11 (SH/T 0782) weighting coefficients for each specific area of the piston: first ring groove 1.5; second ring groove 1.5; third ring groove 25; first ring land 1; second ring land 25; third ring land 20; inner cavity top 50; upper skirt 0; pin hole 0 (some values in the original Table 11 require confirmation against the source standard (source-text extraction)).
  • 9.2 The calculation of the weighted rating for each specific area of the piston is shown in Table 12 and Table 13.
  • 9.3 The calculation method for the ratings of the piston skirt and the piston inner cavity top is the same as the calculation method for the ratings of the piston ring lands and piston ring grooves. SH/T 0782 For the piston inner cavity top rating area, see Appendix B.
  • 9.4 The piston rating is equal to the sum of the weighted ratings of each specific area of the piston.
  • 9.5 Taking GB/T 9932 as an example, the piston rating calculation is shown in Table 14. Taking SH/T 0782 as an example, the piston rating calculation is shown in Table 15 and Table 16.
• 10 Calculation of the carbon deposit filling percentage of the piston first ring groove:
  • The piston deposit rating A method and the piston deposit rating B method use the same calculation method for the carbon deposit filling percentage of the piston first ring groove.
  • The carbon deposit filling percentage of the piston first ring groove is equal to the area percentage of each type of carbon deposit multiplied by its respective severity coefficient, and the above products are added together and then multiplied by 100, see formula (7): F = Σ(A)j × (Ks)j × 100 (the typesetting of the original formula (7) requires confirmation against the source standard (source-text extraction)).
  • 10.1 According to the deposition state of carbon deposits between the outer wall of the piston ring groove and the inner wall of the piston ring, carbon deposits are divided into 5 types, see schematic diagram 3. The carbon deposit severity coefficients are shown in Table 17: severe carbon deposit 1.00; heavy carbon deposit 0.75; medium carbon deposit 0.50; light carbon deposit 0.25; slight carbon deposit 0.10; no carbon deposit 0.
  • 10.2 The calculation of the area percentage of various carbon deposits in the piston first ring groove for each test method is the same as 8.1.2, 8.1.2.1 and 8.1.2.2.
  • 10.3 The calculation of the carbon deposit filling percentage of the piston first ring groove is shown in Table 18 (GB/T 9932 example: severe carbon deposit A=20, A×Ks=20.0; heavy carbon deposit A=10, A×Ks=7.5; medium carbon deposit A=20, A×Ks=10.0; light carbon deposit A=30, A×Ks=7.5; slight carbon deposit A=10, A×Ks=1.0; no carbon deposit A=10, A×Ks=0; F=20.0+7.5+10.0+7.5+1.0=46.0).

9. Qualitative and Quantitative and Calculation Formulas

• Piston deposit rating A method: T = Σ(S)i × K (formula (1)); S = 10 − Σ(A)j × (Ks)j (formula (2)); SH/T 0261 method T = Σ(S)i × 10/9 (formula (3)).
• Piston deposit rating B method: T = Σ(Sw)i (formula (4)); S = Σ(A)j × (Ks)j (formula (5)); Sw = Σ(S)i × (Ka)i (formula (6)).
• Carbon deposit filling percentage of the piston first ring groove: F = Σ(A)j × (Ks)j × 100 (formula (7)).
• Symbol description:
  • T— piston rating;
  • S— piston specific area rating;
  • K— piston cleanliness rating adjustment coefficient;
  • i— a specific area of the piston;
  • A— deposit area percentage;
  • Ks— deposit severity coefficient;
  • j— deposit type;
  • Sw— weighted rating of a specific area of the piston;
  • Ka— specific area weighting coefficient;
  • F— carbon deposit filling percentage of the piston first ring groove.
• Term definitions:
  • 3.1 Piston specific area: different rating positions divided on the piston, see Figure 1.
  • 3.4 Lacquer film: a thin, glossy deposit that is insoluble in oil and not easily wiped off, composed of organic residues from the sample, appearing in various colors from light yellow to black, insoluble in certain solvents such as gasoline, but soluble in benzene, chloroform, ketones, and solvents with a structure similar to that of the lacquer film.
  • 3.5 Carbon deposit: a hard, black deposit of a certain thickness that is extremely difficult to dissolve, composed of residues from the sample. Carbon deposits are usually lusterless, but when carbon deposits on adjacent parts rub against each other, they may also appear bright or as gray spots. Carbon deposits are generally classified into heavy carbon, medium carbon, and light carbon grades. If carbon deposit 100% fills the space it occupies and its surface appears rubbed or polished, it is called heavy carbon; if the carbon deposit has a certain thickness but is less than 1/4 of the volume and its surface appears granular and not smooth, it is called light carbon; carbon deposit between heavy carbon and light carbon is called medium carbon.
  • 3.6 Free ring: when the piston is turned from a vertical position to a horizontal position, the piston ring can fall by its own gravity.
  • 3.7 Loose ring: when the piston is turned from a vertical position to a horizontal position, the piston ring cannot fall by its own gravity, but can be made to fall by light finger pressure.
  • 3.8 Stuck ring: a piston ring that is partially or completely seized in the ring groove and cannot be moved with moderate finger force.
  • 3.9 Deposit severity coefficient: a numerical value describing the severity of various deposits, such as color, strength, and degree of oxidation state. The deposit severity coefficients determined by different test methods are different.
  • 3.10 Specific area weighting coefficient: For certain specific areas of the piston, different doubling methods are used for the deduction score and the merit score to indicate the relative importance of these areas; these different doubling coefficients are the specific area weighting coefficients. These coefficients are determined through driving tests and statistical analysis of the test data.
  • 3.11 Deposit area percentage: Within each specific area of the piston, the percentage of area occupied by each type of deposit. When calculating the area percentage occupied by each type of deposit by the statistical method, it is obtained by dividing the number of points covered by each type of deposit by the total number of points in that specific area.
  • 3.12 Point: The basic unit of the area covered by each type of deposit within each specific area of the piston.
  • 3.13 Total points: The sum of points in each specific area, i.e., the total area of each specific area of the piston.
  • 3.14 Piston cleanliness rating adjustment coefficient: In the process of piston cleanliness rating, the piston cleanliness rating is expressed on a hundred-point scale by multiplying by certain coefficients; these coefficients are called piston cleanliness rating adjustment coefficients.

10. Precision

• Not provided in the available source.

11. Report

• 11.1 The diesel engine piston cleanliness rating shall be reported according to the following three items:
  • a) Piston rating;
  • b) Percentage of carbon deposit filling in the first piston ring groove;
  • c) Color photographs of the piston pressure-bearing surface, non-pressure-bearing surface, etc.
• The piston rating and the percentage of carbon deposit filling in the first piston ring groove shall be retained to one decimal place according to the numerical rounding rules.
• 11.2 For the piston cleanliness rating record forms of each test method, see Appendix C.

12. Normative references

• GB 1922 Solvent naphtha for paints and cleaning
• GB/T 9932 Performance evaluation method for internal combustion engine oils (Caterpillar 1H method)
• GB/T 9933 Performance evaluation method for internal combustion engine oils (Caterpillar 1G method)
• SH/T 0261 CD grade diesel engine oil high-temperature cleanliness evaluation method (1135D method)
• SH/T 0782 Performance evaluation method for diesel engine oils (Caterpillar 1K/1N method)
• SH/T 0786 High-temperature cleanliness evaluation method for internal combustion engine oils (Caterpillar 1M-PC method)
• Coordinating Research Council Deposit Rating Manual No. 20 CRC Manual No. 20

13. Source and verification

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