SH/T 0565-2008 Determination of sludge and corrosion tendency of inhibited mineral oils

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Incomplete source card: Sections 13, 14 are absent from the available source. Only available content is translated; source completion is pending.

Card type: Test method

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

• Standard number: SH/T 0565—2008
• Chinese name: Determination of sludge and corrosion tendency of inhibited mineral oils
• English name: Standard test method for determination of the sludging and corrosion tendencies of inhibited mineral oils
• Replacement relationship: Replaces SH/T 0565—1993 "Determination of sludge tendency of inhibited mineral oils"; SH/T 0565—1993 was developed by reference adoption of ASTM D4310-83 (1991).
• Adoption relationship: This standard modifies and adopts ASTM D4310-06b "Determination of sludge and corrosion tendency of inhibited mineral oils", and was redrafted according to ASTM D4310-06b.
• Main differences from ASTM D4310-06b: The referenced standards adopt the corresponding current standards of our country; the cleaning agent is replaced with chromic acid cleaning solution.
• Editorial modifications: The expressions of repeatability and reproducibility are changed to the customary expressions of our country; the chapter on keywords in ASTM D4310-06b is deleted.
• Publication/implementation: Published on 2008-04-23, implemented on 2008-10-01.
• Issuing authority: National Development and Reform Commission of the People's Republic of China.
• Secretariat: Sinopec Research Institute of Petroleum Processing.
• Drafting organization: PetroChina Dalian Lubricant Research and Development Center.
• Participating drafting organization: Sinopec Lubricant Research and Development (Beijing) Center.
• Main drafters: Yu Bing, Su Jiang, Li Jianxin.
• Previous versions: SH/T 0565—1993.

2. Scope of application and non-applicability

• 1.1 This standard specifies the tendency of inhibited mineral oil-type turbine oils and mineral oil-type anti-wear hydraulic oils to corrode copper catalyst metal and form sludge at high temperature in the presence of oxygen, water, metallic copper and iron. This standard also applies to testing circulating oils with a relative density less than that of water and containing rust inhibitors and antioxidants.
• 1.1 Note: In comparative tests, the copper and iron contents in the oil, water and sludge phases were determined. However, it was found that the total iron content was too low (below 0.8mg) to be suitable for statistical analysis.
• 1.2 This standard is a modification of GB/T 12581, and GB/T 12581 determines the oxidation stability of oil products by tracking and measuring the acid value of similar oil products. The number of hours required for the acid value of the oil product to reach 2.0mgKOH/g is the oxidation life.
• 1.3 Procedure A of this standard requires the determination and reporting of the mass of sludge and the total amount of copper in the oil, water and sludge; procedure B only requires the determination of the mass of sludge. In both procedures, the determination of acid value is optional.
• 1.4 This standard uses (SI) International System of Units.
• 1.5 This standard involves certain safety issues related to the use of the standard. However, it is not intended to address all safety issues. Therefore, users should establish appropriate safety and protective measures and determine applicable management systems before using this standard.
• Non-applicability: No explicitly listed non-applicable clauses are provided in the available source (except for the note in 1.1 stating that the total iron content is too low for statistical analysis).

3. Method principle

• 4 Method summary: The sample is contacted with oxygen for 1000h at 95℃ in the presence of water and an iron-copper catalyst. The insoluble matter in the oxidation tube is filtered through a 5μm pore size filter membrane, and the mass of the insoluble matter is determined gravimetrically. The total amount of copper in the oil, water and sludge phases is also determined.
• 4 Note: Sometimes some testers may arbitrarily choose test contents: (a) evaluate the mass change of the catalyst coil, or (b) determine the acid value when the sample is oxidized for 1000h, or do both. The determination of acid value can serve as a basis for determining whether the insoluble matter determination is reliable. Usually, further testing is not recommended for highly oxidized oils (acid value greater than 2.0mgKOH/g). This method does not include guidelines for selecting these tests.
• 5 Significance and use:
  • 5.1 Oil products will form insoluble matter under oxidizing conditions.
  • 5.2 During this test, the tendency to obviously form insoluble matter and/or metal corrosion products can indicate that the oil product will produce insoluble matter and/or metal corrosion products in actual use. However, the correlation between this method and actual application has not been established.

4. Reagents and materials (purity / preparation)

• 7.1 Purity of reagents: The reagents used in this test are generally of analytical grade. Other grades of reagents are also allowed as long as the purity of the reagents can ensure that the measurement precision is not affected.
• 7.2 Purity of water: Unless otherwise specified, the water involved in this method shall meet the requirements of grade two water of GB/T 6682 specification.
• 7.3 Acetone: analytical grade. Warning: harmful to health, flammable.
• 7.4 Cleaning agent: chromic acid cleaning solution. Soak the apparatus to be cleaned in chromic acid cleaning solution at room temperature for 24h and then clean it. Warning: corrosive, harmful to health.
• 7.5 n-Heptane: analytical grade. Warning: harmful if inhaled, flammable.
• 7.6 Concentrated hydrochloric acid: concentration 36% (mass fraction), relative density 1.19. Warning: toxic, corrosive.
• 7.7 Isopropanol: analytical grade. Warning: flammable.
• 7.8 Catalyst coil:
  • 7.8.1 Iron wire: high-quality carbon structural steel, diameter 1.6mm (meets GB/T 699 specification 08 number). Note: If the above iron wire is not available, other iron wires that have been proven to meet the requirements in comparative tests with SH/T 0565 method are also allowed.
  • 7.8.2 Copper wire: electrical round copper wire, diameter 1.6mm, purity not less than 99.9%. Soft copper wire of equivalent grade may also be used. Note: Commercially available catalyst coils meeting the requirements may be purchased.
• 7.9 Detergent: water-soluble.
• 7.10 Oxygen: purity not less than 99.5%, with suitable pressure regulation to keep the oxygen flow rate through the apparatus constant. It is recommended to use a two-stage pressure regulator on the oxygen cylinder. Warning: oxygen can violently accelerate combustion.
• Appendix A Materials:
  • A.1.1 Test tube: borosilicate glass, length 250mm, outer diameter 25mm, inner diameter approximately 22mm.
  • A.1.2 Cap: for test tube, made of polyethylene, designed as a cylinder that can tightly fit the outer surface of the test tube.
  • A.1.3 Desiccant packet: silica gel particles.
  • A.1.4 Flushing tube: made of stainless steel or glass, outer diameter approximately 5mm, length 305mm, used to deliver nitrogen to the bottom of the test tube.
  • A.1.5 Nitrogen: minimum purity 99.7%. Warning: compressed gas. This gas can cause suffocation.

5. Apparatus and equipment

• 6.1 Oxidation tube: includes test tube, condenser and oxygen inlet tube, made of borosilicate glass, as shown in Figure 1. The test tube is marked with a 300mL graduation line at 20℃ (maximum error 1mL).
• 6.2 Heating bath: capable of maintaining the temperature of the sample in the oxidation tube at 95℃±0.2℃, equipped with a suitable stirring device to maintain uniform temperature throughout the heating bath, with dimensions sufficient to accommodate the required number of oxidation tubes, and ensuring that the insertion depth of the oxidation tube in the heating bath is 390mm±10mm and the immersion depth in the heating medium is 355mm±10mm.
  • 6.2.1 Direct sunlight or artificial light can affect the results of this test. To minimize the effects caused by light exposure to the test samples, one or more of the following methods may be used to avoid light exposure to the samples:
    • 6.2.1.1 It is recommended to use a heating bath made of metal or a combination of metal and other opaque materials to prevent light from entering the test tube from the side. If a viewing window is designed on the heating bath, an opaque cover should be installed on the viewing window and kept closed when not observing.
    • 6.2.1.2 If a glass heating bath is used, the heating bath should be wrapped with aluminum foil or other opaque material.
    • 6.2.1.3 The use of an opaque shield can prevent bright light from entering the test tube from the top.
• 6.3 Flowmeter: capacity at least 3L/h, accuracy 0.1L/h.
• 6.4 Heating bath thermometer: oxidation characteristics 2 number thermometer, measurement range 72℃~126℃, meets the requirements of thermometer GB-58 in GB/T 514. Temperature measuring devices of equivalent or higher accuracy are allowed.
• 6.5 Oxidation tube thermometer: oxidation characteristics 1 number thermometer, measurement range 80℃~100℃, graduation value 0.1℃. Meets the requirements of thermometer GB-57 in GB/T 514.
• 6.6 Catalyst coil winding rod: as shown in Figure 2.
• 6.7 Thermometer holder: material is 1Cr18Ni9Ti stainless steel, used to fix the oxidation tube thermometer, dimensions as shown in Figure 3. The thermometer is fixed on the holder by two fluoroelastomer "O" type rings with an inner diameter of approximately 5mm. Fine stainless steel wire may also be used.
• 6.8 Emery cloth: silicon carbide emery cloth, grain size 100 number (basic grain size range 125μm~150μm).
• 6.9 Hose: polyvinyl chloride material, inner diameter approximately 6.4mm, wall thickness 2.4mm, used to introduce oxygen into the oxidation tube.
• 6.10 Filter membrane: white, flat, diameter 47mm; pore size 5μm.
• 6.11 Filter holder: 47mm, composed of a silicon glass funnel and a funnel base, the funnel base includes a sintered glass filter support of grain (40μm~60μm) or a stainless steel mesh support, and the filter membrane is clamped between the ground sealing surface of the glass funnel and its base with a metal clamp.
• 6.12 Weighing bottle: cylindrical, with ground stopper, capacity 60mL, inner diameter approximately 45mm, height approximately 65mm.
• 6.13 Vacuum source: capable of reducing absolute pressure to 13.3kPa±0.7kPa.
• 6.14 Cooler: desiccator or other type of container with a sealed cover, used to cool the weighing bottle before weighing. It is recommended not to use desiccant.
• 6.15 Drying oven: capable of maintaining temperature at 105℃±2℃.
• 6.16 Tweezers: toothless at the tip.
• 6.17 Syringe: 50mL, with 305mm needle.
• 6.18 Separatory funnel: capacity 1000mL.
• 6.19 Rubber policeman.
• 6.20 Rubber-tipped dropper.
• 6.21 Syringe: made of glass or plastic, volume 10mL, syringe with connector.
• 6.22 Syringe sampling tube: stainless steel tube, outer diameter 2.11mm, inner diameter 1.60mm, length 559mm±2mm, one end is machined to a 90° angle, and the other end has a well-sealed connector that can be connected to a syringe.
• Figure 5 oil level indicator strip: material 1Cr18Ni9Ti stainless steel (thickness 0.792mm), dimensions see figure (14.8±0.8, R2.4±0.8, 270±3.2, 254±3.2 etc., unit mm).

6. Recommended operating conditions

• Sample temperature: 95℃±0.2℃.
• Test duration: 1000h.
• Oxygen flow rate: 3L±0.1L/h, continuous aeration 30min (10.3).
• Heating bath liquid level: the depth to which the test tube is immersed in the liquid is 355mm±10mm (10.2).
• Condenser outlet water temperature: during the test it should not exceed 32℃ (10.2).
• Water addition: at the start of the test add 60mL distilled water (10.4); during the test add distilled water to the oxidation tube at least once every two weeks to restore the water level to the shoulder of the oxygen delivery tube (10.6).
• Bath temperature control: once adjusted to the required bath temperature, keep it within ±0.2℃ of that temperature (10.5).
• Thermometer reading correction: because the 76mm immersion line of the thermometer is at the oil surface, taking into account the heating of the thermometer stem above the immersion line, in order to obtain the true temperature, subtract 0.1℃ from the thermometer reading (10.5 note).
• Drying: dry in an oven 105℃ for at least 1h (12.1).
• Cooling: cool in a desiccator for at least 2h (12.1).
• Standing: the rinse liquids of oil, n-heptane and water are placed in the same beaker, briefly stir the mixture, cover with a glass cover, and store protected from light for 16h~20h (11.3).

7. Sampling and sample preparation

• 8.1 Samples for this method may be taken from tanks, drums, small containers or even equipment in operation. Sampling is carried out in accordance with GB/T 4756.
• 8.2 The minimum sample amount required for a single test is 300mL.
• 9 Apparatus preparation:
  • 9.1 Cleaning the catalyst: before winding the catalyst coil, use absorbent cotton dipped in n-heptane to clean one piece each of iron wire and copper wire of length 3.00m±0.01m, then rub with emery cloth until a fresh metal surface is exposed. Use dry absorbent cotton to wipe off all metal filings and emery cloth debris. Wear clean gloves (cotton, rubber or plastic) when handling the catalyst coil to avoid contact with skin.
  • 9.2 Preparation of the catalyst coil: twist one end of the prepared iron wire and copper wire tightly together for three turns, then wind the two metal wires side by side simultaneously onto the threaded catalyst coil winding rod (see Figure 2), with the iron wire placed in the deeper thread. Remove the coil from the winding rod, twist the free ends of the iron wire and copper wire together for three turns, then bend the two twisted ends into a shape that meets the requirements of the spiral coil. The total length of the wound coil is 225mm±5mm. If necessary, the coil may be stretched to the required length.
    • Note: The prepared catalyst coil is a double helix of copper wire and iron wire, total length 225mm±5mm, inner diameter 15.9mm–16.5mm. The spacing between coils is uniform, and the center-to-center distance between two adjacent turns of the same metal wire is 3.96mm–4.22mm. The winding rod shown in Figure 2 is designed for making such a coil. When using this winding rod, the iron wire is wound on a thread of diameter 14.98mm, and the copper wire is wound on a thread of diameter 15.9mm. The smaller diameter is to allow for the springback of the iron wire after winding, so as to obtain a coil with a uniform inner diameter of 15.9mm. If very soft annealed steel wire is used, both metal wires can be wound using equal thread diameters. Other schemes that can make the wound coil structure meet the above requirements may also be used.
  • 9.3 Catalyst storage: before use, the catalyst coil may be stored in dry inert gas. Appendix A gives a suitable procedure for storing the catalyst. Before use, inspect the catalyst coil to ensure there are no corrosion products or contaminants. For overnight storage (less than 24h), the coil may be stored in n-heptane.
    • 9.3.1 The n-heptane used for storing the catalyst must not contain traces of water and corrosive substances. n-heptane redistilled as required in clause 7.5 and stored in a sealed bottle may be used.
  • 9.4 Cleaning of new glassware: clean new oxygen delivery tubes, condensers and test tubes with hot detergent solution, then rinse with tap water. Clean the inside of the test tube, the outside of the condenser, and the inside and outside of the oxygen delivery tube with cleaning agent. Thoroughly wash off the cleaning agent solution with tap water. Rinse all parts with distilled water and allow them to dry at room temperature or in an oven. After rinsing with distilled water, they may be rinsed with isopropanol or acetone, or purged with dry air, to speed up drying at room temperature.
  • 9.5 Cleaning of used glassware: immediately after a test is completed, pour out all the oil in the test tube. Rinse the glassware with n-heptane to remove oil stains, pour in hot detergent solution, clean with a long-handled brush, then rinse with tap water. If deposits still adhere to the glassware, the test tube may be filled with detergent solution, the oxygen delivery tube and condenser inserted, and the test tube placed in a heating bath controlled at the test temperature. Soaking in this way for several hours can remove all adhering matter except iron oxide. Then clean with hot (50℃) hydrochloric acid to remove iron oxide. After removing all deposits, rinse all glassware with cleaning solution. Then rinse thoroughly with tap water until all acid is removed. Rinse all parts with distilled water and allow them to dry at room temperature or in an oven. After the final rinse with distilled water, they may be rinsed with isopropanol or acetone, or purged with dry air, to speed up drying at room temperature. Before ready for use, the glassware should be stored in a dry, dust-free place.

8. Analytical procedure

• 10 Oil oxidation procedure:
  • 10.1 Adjust the heating bath to a sufficiently high temperature so that the oil temperature in the oxidation tube is maintained at the specified 95℃±0.2℃.
  • 10.2 Add the oil sample to the empty oxidation tube up to the 300mL mark. Slide the catalyst coil in from the upper part of the oxygen delivery tube. If the wires at one end of the coil are uneven, place that end downward. Place the oxygen delivery tube together with the catalyst coil into the test tube. Place the condenser on the upper part of the oxygen delivery tube and test tube. Immerse the test tube in the heating bath. Adjust the liquid level height of the heating bath so that the depth to which the test tube is immersed in the liquid is 355mm±10mm. Connect the condenser to cooling water; during the test, the condenser outlet water temperature should not exceed 32℃.
  • 10.3 Using a new polyvinyl chloride hose of length not exceeding 600mm, connect the oxygen delivery tube through a flow meter to the oxygen source (see 6.9). Before use, the new polyvinyl chloride hose should be cleaned on the inner wall with n-heptane and blown dry with air. Adjust the flow rate to 3L±0.1L and aerate continuously for 30min.
  • 10.4 Lift the condenser from the oxidation tube, add 60mL distilled water to the test tube, and start timing the test.
  • 10.5 Under the condition of oxygen flow, ensure that the temperature of the oil-water mixture in the oxidation tube (sample temperature) is maintained at 95℃±0.2℃ throughout the test. To meet this requirement, it is necessary to ensure the bath temperature that must be controlled when the sample temperature is 95℃±0.2℃. The bath temperature is always higher than the sample temperature; this is due to the cooling effect of the oxygen flow and is related to the heating bath medium, capacity, circulation rate and the number of oxidation tubes in the bath. As shown in Figure 4, use a thermometer holder to place the thermometer in the oxidation tube for sample temperature measurement. Only new, unoxidized oil samples may be used for temperature measurement. It is best to use a dedicated simulated oxidation tube for temperature measurement. When using an actual sample, remove the thermometer immediately after the temperature measurement is completed; in this way measure the temperature at different positions of the heating bath to check the uniformity of temperature control. Once adjusted to the required bath temperature, keep it within ±0.2℃ of that temperature.
    • Note: The installation is as shown in Figure 4. Because the 76mm immersion line of the thermometer is at the oil surface, taking into account the heating of the thermometer stem above the immersion line, in order to obtain the true temperature, subtract 0.1℃ from the thermometer reading.
  • 10.6 During the test, add distilled water to the oxidation tube at least once every two weeks to restore the water level to the shoulder of the oxygen delivery tube. Use a sampling tube and a 50mL syringe to add water.
    • Note: In some cases, the water level cannot be observed due to the formation of sediment and emulsification. A suitable method may be used to mark the upper liquid level of the oil in the filled oxidation tube, and water is replenished periodically to maintain this level, thereby ensuring the proper amount of water in the oxidation tube. If necessary, a movable metal strip (Figure 5) may be used to indicate the corrected level for water replenishment. For example, use an adjustable ring-shaped clamp to clamp the metal strip to the outside of the oxidation tube. When using this indicator, at the start of the test adjust the lower end of the metal strip to the upper oil level. As the test proceeds and water evaporates causing the oil level to drop, especially before sampling, sufficient make-up water must be added to return the oil level to the position marked by the metal strip.
• 11 Procedure for treating the oil after oxidation:
  • 11.1 When the test time reaches 1000h, remove the oxidation tube from the heating bath and remove the condenser.
  • 11.2 If the acid value needs to be determined after the test, sample according to the following procedure.
    • 11.2.1 While the oxidation tube and sample are still hot, lift the oxygen delivery tube together with the catalyst coil out of the liquid and drain for 5min–10min. Then lower the oxygen delivery tube together with the catalyst coil so that the end of the oxygen delivery tube is approximately in the middle of the oil layer, then lift the oxygen delivery tube together with the catalyst coil out of the liquid again and drain in the oxidation tube for 5min. Finally, carefully lift the oxygen delivery tube out of the oxidation tube, use a rubber-bulb dropper to take 3mL of sample and place it in a suitable sample bottle. Immediately place the oxygen delivery tube above the sample in the oxidation tube and continue draining for 25min–30min.
    • 11.2.2 If a syringe sampling tube is used to take a sample for acid value determination, insert the sampling tube through the center hole of the condenser to the middle of the oil layer. Draw 6mL of sample, place the sampling tube at the bottom of the test tube for 5min to allow water to settle to the bottom of the sampling tube. After 5min, adjust the sample volume to 3mL and remove the sampling tube from the oxidation tube. This method allows most of the water taken out together with the sample to return to the oxidation tube. Then inject 3mL of the sample into a sample bottle, and determine the acid value using GB/T 7304 or SH/T 0163. Shake the sample thoroughly before taking a portion from the sample bottle.
  • 11.3 If acid value determination is not required after the test, lift the oxygen delivery tube together with the catalyst coil out of the liquid and drain for 30min, then fix and suspend it above a 1000mL beaker. Pour the contents of the test tube into the beaker. Place a thermometer in the beaker; when the sample temperature drops to 50℃, rinse the catalyst coil and the test tube wall several times with 250mL n-heptane in a wash bottle, allowing the rinse liquid to flow into the beaker; care must be taken to thoroughly wash off the oil stains on the coil. Then rinse with 100mL distilled water in a wash bottle. Keep the rinse liquids of oil, n-heptane and water in the same beaker, briefly stir the mixture, cover with a glass cover, and store protected from light for 16h~20h.
    • Note 1: Sometimes solid substances may adhere to the test tube wall, catalyst coil, oxygen delivery tube or condenser and cannot be washed off with n-heptane and distilled water. In this case, scrape manually with a rubber policeman and rinse with n-heptane; collect the scraped substances and the n-heptane rinse liquid together into the beaker containing the mixture of oil, n-heptane and water.
    • Note 2: The placement of 16h~20h is to allow sufficient equilibration time between the insoluble matter and the oil-n-heptane and aqueous phases. It also allows the insoluble matter time to coalesce into a form that is easy to filter, thereby making the sludge easy to filter.
• 12 Determination of sludge mass:
  • 12.1 Before filtering the oil-water mixture, weigh one filter membrane in each of two weighing bottles, to the nearest 1mg (A₁ and B₁) (see Note 1, Note 2). Install filters with filter membranes on two 1000mL suction flasks; the filter membranes may only be handled with toothless tweezers. Under an absolute pressure of 13.3kPa±0.7kPa (100mmHg±5mmHg), carefully pour approximately two equal portions of the oil-n-heptane layer into two filter funnels (the aqueous layer must not be carried over) (see Note 3), and vacuum filter. After the oil layer has filtered through, rinse the suction filter funnel with n-heptane, allow air to pass briefly through the suction filter, then begin adding the aqueous layer in approximately two equal portions into the two suction filter funnels. First with water, then with n-heptane, thoroughly rinse the walls of the beaker and the walls of the funnel. During rinsing, a rubber policeman may be used to scrape the walls of the beaker. In the first rinsing step, the amounts of water and n-heptane used shall be no less than 50mL and 250mL, respectively. In the second step, rinse again with 100mL n-heptane until the n-heptane passing through the filter is colorless.
    • Note 1: Weigh the bottles, watch glasses (one used as a container, one used as a cover), glass culture dishes, or aluminum foil dishes to be used in this test.
    • Note 2: If there is too much sludge, more than two filter membranes may be used for filtration.
    • Note 3: To increase the filtration speed, do not introduce the aqueous phase into the filter during the filtration of the oil and n-heptane phases. For this purpose, a separatory funnel should be used to separate the aqueous phase from the oil phase before filtration begins. Sometimes, despite the above measures, the filtration speed is still very slow. In this case, extending the filtration time may be considered. If filtration is left unattended for a long time, it should be stopped and the filter returned to atmospheric pressure. Before resuming vacuum filtration, cover the filter funnel with a tight-fitting lid.
  • 12.2 While maintaining vacuum, remove the clamp and funnel from the filter membrane and funnel base. Gently rinse the surface of the filter membrane with n-heptane, rinsing from the edge of the filter membrane toward the center, to wash away the last traces of oil on the filter membrane. Continue applying vacuum for a period, and finally remove residual n-heptane. Place the filter membrane with insoluble matter into a constant-weight weighing bottle and dry in an oven at 105℃ for at least 1h. Then place the weighing bottle in a desiccator near the balance, cool for at least 2h, and weigh (to the nearest 1mg). Repeat drying, cooling, and weighing until the difference between two consecutive weighings does not exceed 2mg or 5% of its mass, and report the last weighed mass (A₂ and B₂).
• 13 Determination of copper in the oil, water, and sludge from step A:
  • 13.1 Preparation for determination of copper content in the oil layer and aqueous layer: After filtration is complete, transfer the oil-n-heptane and water filtrates from the two 1000mL suction flasks to a separatory funnel. Separate the oil-n-heptane layer from the aqueous layer. Weigh two suitably sized beakers (to the nearest 1g). Into one beaker weigh all of the separated oil-n-heptane mixture (W_O-H), and into the other beaker weigh all of the separated water (W_W) (to the nearest 1g).
  • 13.2 Analysis of copper:
    • 13.2.1 Direct method (homogeneous sample): Determine the copper content in the oil-n-heptane mixture and aqueous solution by a suitable method, such as atomic absorption spectrometry (AAS), direct current plasma emission spectrometry (DCP-AES), inductively coupled plasma emission spectrometry (ICP-AES), or X ray fluorescence spectrometry (XRF). If the result is less than 0.100%, express as mg/kg; if the result is equal to or greater than 0.100%, express as % (mass fraction).
    • 13.2.2 Ashing method (non-homogeneous sample): For insoluble matter and in cases where the oil-n-heptane mixture and aqueous solution are not homogeneous, the ashing method shall be used. After the final weighing of the filter membranes, ash the two filter membranes with insoluble matter using GB/T 2433.
    • 13.2.3 If the ashing method is used for the oil-n-heptane mixture or aqueous solution, the solvent or water may first be evaporated to dryness, and the residue ashed using GB/T 2433, without the need to weigh and calculate the ash content. Rinse the inner wall of the crucible with 5mL concentrated hydrochloric acid and dissolve the ash. Digest on a hot plate for 15min to completely dissolve the copper. Cool the sample to room temperature and transfer to a 50mL volumetric flask, dilute to the mark with distilled water. Determine the copper content in the aqueous solution by any suitable method such as AAS, DCP-AES, ICP-AES, or XRF.
• Appendix A Method for sealing and storing catalyst coils:
  • A.2 Procedure: Use a purge tube to pass nitrogen into a new test tube to blow out loose dust. The test tube must be clean and dry in appearance. Tilt the test tube at a certain angle and gently slide the catalyst coil into the test tube. Add a desiccant packet folded longitudinally to fit the test tube. Insert the nitrogen purge tube into the middle of the test tube, then to the bottom, and purge the test tube with nitrogen for a few seconds. Immediately after withdrawing the purge tube, seal the test tube with a polyethylene cap.
• Appendix B Reference representation of coil corrosion levels:
  • B.1 Some studies require rating the catalyst coil as a qualitative indicator of the corrosive characteristics of the oil. The iron wire and copper wire phenomenon tables (see Table B.1, Table B.2) are attached below for reference only.
  • B.1.1 Rate only the outer surface of the coil.
  • Table B.1 Corrosion phenomena of iron wire: Ratings are divided into bright, discolored, light rust, moderate rust, heavy rust, coated. Description: bright—appearance like newly polished; discolored—no red-brown corrosion rust spots, but overall discolored; light rust—limited rusting, no more than six rust spots; moderate rust—7 to 12 rust spots; heavy rust—more than 13 rust spots; coated—deposits on the iron wire prevent evaluation of the surface.
  • Table B.2 Corrosion phenomena of copper wire: Ratings are divided into bright, discolored, green, black, coated. Description: bright—appearance like newly polished; discolored—moderate discoloration; green—obvious green; black—very black color; coated—deposits on the copper wire prevent evaluation of the surface.

9. Qualitative and quantitative and calculation formulas

• 14 Calculation:
  • 14.1 Calculate the mass of insoluble matter (sludge) using formula (1):
    • W = (A₂ - A₁) + (B₂ - B₁) …(1)
    • Where: W—— mass of insoluble matter, mg; A₁, B₁—initial mass of filter membrane plus weighing bottle or watch glass, mg; A₂, B₂—final mass of filter membrane plus weighing bottle or watch glass, mg.
  • 14.2 Calculate the mass of copper in the oil, water, and insoluble matter, mg.
    • 14.2.1 Direct method: Calculate the mass of copper in the oil, water, and insoluble matter using formula (2), formula (3), formula (4), formula (5).
      • W₁ = 10 W_O-H P₁O-H or W₁ = W_O-H P₂O-H / 1000 …(2)
      • W₂ = 10 W_W P₁W or W₂ = W_W P₂W / 1000 …(3)
      • (Formula 4, Formula 5 original text source-text extraction displayed as numbers (4)(5), corresponding content is related to the calculation of copper mass in oil and water, specific symbols require confirmation against the source standard (source-text extraction))
      • Where: W₁—mass of copper in oil, mg; W_O-H—— mass of oil-n-heptane mixture, g; P₁O-H—— copper content of oil-n-heptane mixture, % (mass fraction); P₂O-H—— copper content of oil-n-heptane mixture, mg/kg; W₂—mass of copper in water, mg; W_W—— mass of aqueous solution, g; P₁W—— copper content of aqueous solution, % (mass fraction); P₂W—— copper content of aqueous solution, mg/kg.
    • 14.2.2 Ashing method: Calculate the mass of copper in the oil, water, and insoluble matter using formula (6), formula (7), formula (8), formula (9), formula (10), formula (11).
      • W₃ = 500 P₃I or W₃ = 0.05 P₄I …(6)(7)
      • W₁ = 500 P₃O-H or W₁ = 0.05 P₄O-H …(8)(9)
      • W₂ = 500 P₃W or W₂ = 0.05 P₄W …(10)(11)
      • Where: W₃—mass of copper in insoluble matter, mg; P represents the copper content of water in the 50mL volumetric flask, from: P₃I—— insoluble matter, % (mass fraction); P₄I—— insoluble matter, mg/kg; P₃O-H—— oil-n-heptane mixture, % (mass fraction); P₄O-H—— oil-n-heptane mixture, mg/kg; P₃W—— aqueous solution, % (mass fraction); P₄W—— aqueous solution, mg/kg.
    • 14.2.3 Calculate the total mass of copper in the oil, water, and insoluble matter using formula (12), mg:
      • W = W₁ + W₂ + W₃ …(12)
• 15 Reporting of results:
  • 15.1 Report the test method number used for the test (step A or step B).
  • 15.2 Step A:
    • 15.2.1 Mass of insoluble matter, mg;
    • 15.2.2 Total mass of copper in oil, water, and insoluble matter, mg;
    • 15.2.3 If the corrosion grade of the catalyst metal is also required, the method provided in Appendix B may be used.
    • 15.2.4 The acid value of the test sample at the end of the test, mgKOH/g, and the determination method used (optional).
  • 15.3 Procedure B:
    • 15.3.1 Mass of insolubles, mg;
    • 15.3.2 The acid value of the test sample at the end of the test, mgKOH/g, and the determination method used (optional).

10. Precision

• 16 Precision and bias: judge the reliability of the test results according to the following rules (95% confidence level).
• 16.1 Precision: The precision of this test method for the mass of insolubles (sludge) and the total mass of copper in oil, water, and insolubles (sludge) was obtained from interlaboratory test results.
  • 16.1.1 Repeatability r: For the same operator, using the same apparatus, following the same test method, the difference between two consecutive test results obtained on the same test sample shall not exceed the values of equations (13), (14):
    • Mass of insolubles (sludge), mg: r = 4.68 X^0.5 …(13) (the original source-text extraction is shown as 4.6823, requires confirmation against the source standard (source-text extraction))
    • Total mass of copper, mg: r_Cu = 1.2 X^0.5 …(14)
    • Where: X—— the average of two replicate determination results.
  • 16.1.2 Reproducibility R: For different operators, in different laboratories, using different apparatus, with the same method, the difference between two single, independent test results obtained on the same test sample shall not exceed the values of equations (15), (16):
    • Mass of insolubles (sludge), mg: R = 6.3 X^0.5 …(15) (the original source-text extraction is shown as 6.3.82, requires confirmation against the source standard (source-text extraction))
    • Total mass of copper, mg: R_Cu = 3.3 X^0.5 …(16) (the original source-text extraction is shown as 3.380, requires confirmation against the source standard (source-text extraction))
    • Where: X—— the average of two determination results.
• 16.2 This precision expression was derived from test data for four new mineral oil-type turbine oils and four new mineral oil-type anti-wear hydraulic oils. These oil samples gave the following range of results:
  • 16.2.1 Insolubles (sludge): 4.6mg~250mg.
  • 16.2.2 Total mass of copper: 0.9mg~390mg.
• 16.3 Bias: Because the values for the mass of insolubles and the total mass of copper in oil, water, and insolubles are determined solely by the test method, this standard has no bias.

11. Report

• See the result reporting content of 15 in Clause 9.
• 15.1 Report the test method number used for the test (Procedure A or Procedure B).
• 15.2 Procedure A: Mass of insolubles (mg); total mass of copper in oil, water, and insolubles (mg); if the corrosion grade of the catalyst metal is required, Appendix B may be used; the acid value of the test sample at the end of the test (mgKOH/g) and the determination method (optional).
• 15.3 Procedure B: Mass of insolubles (mg); the acid value of the test sample at the end of the test (mgKOH/g) and the determination method (optional).

12. Normative References

• GB/T 514 Specification for glass liquid thermometers for petroleum product testing
• GB/T 699 High-quality carbon structural steel
• GB/T 2433 Determination of sulfated ash from additives and additive-containing lubricating oils (GB/T 2433-2001, eqv ISO 3987:1994)
• GB/T 3953 Round copper wire for electrical purposes
• GB/T 4756 Manual sampling of petroleum liquids (GB/T 4756—1998, eqv ISO 3170:1988)
• GB/T 6682 Specifications and test methods for water for analytical laboratory use (GB/T 6682-1992, neq ISO 369