Test method for copper sheet corrosion of petroleum products

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The copper sheet corrosion tester produced by Delit Beijing Technology Co., Ltd. is developed in accordance with GB/T5096, and is suitable for determining the degree of corrosion of copper sheets caused by aviation gasoline, jet fuel, automotive gasoline, natural gas, other hydrocarbons with a Red vapor pressure not exceeding 124 kPa (930 mm Hg), solvent oils, diesel, distillate fuels, lubricating oils, and other petroleum products. Why is it necessary to measure copper sheet corrosion in petroleum products? Since crude oil contains acids, the vast majority of products derived from it have a certain degree of acidity (corrosivity), and the corrosion of copper sheets is used to measure the corrosivity of petroleum products ； Different indicators are applicable to terminals of different levels. For example, liquefied gas is corrosive; it causes slight corrosion to steel equipment and melts rubber. All terminals used for filling liquefied gas incorporate plastic pipes, and due to its high corrosiveness, it certainly poses a danger. The testing method for the copper sheet corrosion tester is described in detail below: This equipment is used to determine the degree of corrosiveness of diesel, gasoline, lubricants, or other petroleum products on copper. Since this method involves flammable materials, it is necessary to pay attention to the ignition point and flash point of the samples before operation, as well as to ensure safety during use. Preparation of the copper sheet: 1. Clamp the copper sheet vertically using fixtures. First, use coarse sandpaper (the lower the grit number, the coarser the sandpaper) to remove any imperfections on the copper sheet. The direction of the sheet in the fixtures can be changed back and forth to ensure that all imperfections and traces from previous grinding are removed from all six sides of the sheet. After grinding, metal shavings can be removed from the sheet using filter paper. At this point, the sheet can be cleaned in a cleaning solvent, dried, and then given a final polish; it is also possible to proceed directly to the final polishing step. The polished copper sheets should always be handled using forceps or filter paper, and must not be touched with bare hands. 2. Sand the copper sheet with sandpaper of high grit, or use degreased cotton dipped in sand particles to polish the surface of the copper; try to sand along the long axis of the copper sheet. 3. After polishing the copper sheet until it is shiny, use absorbent cotton to remove any metal shavings; once the sheet is clean, place it in the prepared sample. Test procedure for copper sheet corrosion tester: 1. Sampling: Pour 30 milliliters of the sample into a test tube; the sample should be stored in a clean, dark-colored glass bottle, and the test tube must be dry and clean. 2. Different test procedures are used for different samples: A. For lubricating oils, solvent oils, and kerosene: Measure 30 milliliters of a completely clear sample free from suspended water or internal moisture, pour it into a clean, dry test tube equipped with a test tube holder. Place the freshly polished and clean copper sheet into the sample in the test tube, then place the test tube with its holder in a bath maintained at 100±1°C. After leaving it in the bath for 3±5 hours, remove the test tube and inspect the copper sheet. B. Aviation gasoline, jet fuel: Measure 30 milliliters of a completely clear sample free from suspended water or internal moisture, pour it into a clean, dry test tube, carefully insert this tube into the test cartridge, tighten the cartridge lid, and place the entire cartridge in a bath maintained at 100±1°C. After leaving it in the bath for 2±5 hours, remove the cartridge, rinse it with tap water for a few minutes, open the cartridge, take out the test tube, and inspect the copper sheet. C. Natural gasoline: Measure 30 milliliters of a completely clear sample, free from any suspended water or internal moisture, and pour it into a clean, dry test tube. Carefully place this test tube into the testing chamber, tighten the lid of the chamber, and submerge the entire chamber in a bath maintained at 40±1°C. After leaving it in the bath for 2±5 hours, remove the chamber, rinse it with tap water for a few minutes, open the chamber, take out the test tube, and inspect the copper sheet.

D. Diesel, fuel oil, automotive gasoline: Measure 30 milliliters of a completely clear sample, free from any suspended water or internal moisture, and pour it into a clean, dry test tube equipped with a test tube holder. Place a freshly polished and clean copper sheet into the sample in the test tube. Then, place the test tube with its holder in a bath maintained at 50±1°C. After leaving it in the bath for 3±5 hours, remove the test tube and inspect the copper sheet.

Inspection of the copper sheet using a copper corrosion detector:
1. Use forceps to remove the copper sheet. The sample can be washed away using a cleaning solvent, or the sample on the copper sheet can be wiped clean with filter paper. Do not touch the copper sheet with your hands.
2. Place the copper sheet in a flat observation test tube, so as to prevent any marks or contamination from occurring during inspection and comparison.
3. Compare the copper sheet with the corrosion standard color plates. When comparing, hold both the copper sheet and the color plates at an angle of 45° to the light for better observation.
4. Determine the degree of corrosion of the sample based on the grading of the corrosion standard color plates.

Grading of corrosion standard color plates:
1. Mild discoloration:
a. Light orange, almost identical to that of a freshly polished copper sheet.
b. Dark orange.
2. Moderate discoloration:
a. Purplish-red.
b. Light purple.
c. Multicolored with light purplish-blue or silver tones, or both, covering the purplish-red color.
d. Silver.
e. Brass-colored or golden-yellow.
3. Severe discoloration:
a. Multicolored with magenta covering the brass-colored surface.
b. Multicolored with red and green tones, without gray.
4. Corrosion:
a. Transparent black, dark gray, or brown with only peacock green tones.
b. Graphite black or dull black.
c. Glossy black or very shiny black.

Guidelines for determining corrosion level:
1. If the copper sheet falls between two adjacent standard color plates, determine the corrosion level based on the more severe discoloration.
2. If the copper sheet shows an orange color deeper than that of 1b in the standard color plates, it is still considered grade 1. However, if red is observed, it is classified as grade 2.
3. In grade 2, a purple-colored copper sheet might be mistaken for grade 3, where the brass color is completely covered by magenta. To distinguish between these two grades, soak the copper sheet in a cleaning solvent; grade 2 will show a dark orange color, while grade 3 will remain unchanged in color.
4. If the copper sheet becomes contaminated during heating or extraction, the test must be repeated.
5. If there are areas along the edges of the copper sheet where the corrosion level is higher than that of the rest of the surface, the test must be repeated.
6. If the results of two repeated tests differ, repeat the test again. If the results of the repeated tests still differ, determine the corrosion level based on the more severe discoloration. Automation of chemical process instruments