SH/T 0023-1990 Silver Strip Corrosion Test Method for Jet Fuels

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.

Card type: Test method

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

• Method number: SH/T 0023-90
• Full name: Silver Strip Corrosion Test Method for Jet Fuels
• English name: not provided in the available source
• Replacement relationship: replaces ZB E31 009-88
• Reference adoption: British Petroleum Institute standard IP 227/82 (88) "Aviation Turbine Fuel Silver Corrosion Test Method"
• Approval/implementation: approved by China Petrochemical Corporation 1991-03-27, implemented on 1992-04-01

2. Scope of application and non-applicability

• This standard specifies the test method for evaluating silver strip corrosion of jet fuels.
• This standard is applicable to evaluating the corrosion tendency of jet fuels on silver components of aviation turbine engine fuel systems.
• Not applicable: not provided in the available source.

3. Method principle

Immerse a polished silver strip in a sample of 250 mL, 50 ℃ (the original text source-text extraction is "501C", requires confirmation against the source standard (source-text extraction)) for 4 h or a longer time specified in the product standard. At the end of the test, remove the silver strip from the sample, wash it, and evaluate the degree of corrosion.

4. Reagents and materials (purity / preparation)

• 4.2.1 Silver strip: silver No. 2, purity greater than 99.9%. Length 17–19 mm, width 12.5–12.7 mm, thickness 2.5~3.0 mm.
• 4.2.2 Polishing materials: silicon carbide fine abrasive cloth (paper) of different grits, including abrasive cloth (paper) of 65 μm (240 grit); 105 μm (150 mesh, the original text source-text extraction is "150month", requires confirmation against the source standard (source-text extraction)) silicon carbide abrasive grains, pharmaceutical absorbent cotton.
• 4.2.3 Stainless steel tweezers.
• 5 Reagent: isooctane, analytical reagent.
• Preparation of other reagents: not provided in the available source.

5. Apparatus and equipment

• 4.1.1 Test apparatus (see figure below), composed of the following components:
  • 4.1.1.1 Test tube: capacity 350 mL, made of brown heat-resistant glass, with a 45 size glass outer ground joint on top. A colorless transparent test tube may also be used as long as it can tightly shield the sample from light.
  • 4.1.1.2 Straight condenser: the condenser passes through the 45 size inner ground joint stopper and connects to it, with 85 mm immersed in the sample, and a glass hook at the lower end for suspending the silver strip. If two or more apparatuses are used, the condensers should be connected in parallel so that each condenser can control the inlet water temperature at 20±5 ℃ (the original text source-text extraction is "20±5C", requires confirmation against the source standard (source-text extraction)).
  • 4.1.1.3 Glass support: used for placing the silver strip in the sample. The shape and size of the support are as shown in the figure. After the silver strip is suspended, the distance from its top end to the bottom of the condenser should be 25~30 mm.
• 4.1.2 Water bath: can maintain the test tube and sample at 50 ℃ (the original text source-text extraction is "501C", requires confirmation against the source standard (source-text extraction)). The water bath should be equipped with a perforated cover. The size of the holes should match the test tubes.
• 4.1.3 Test piece clamp: used to clamp the silver strip without damaging its edges and corners. The test piece clamp specified in GB 5096 may be used.
• 4.1.4 Thermometer: 0~100 ℃, scale division 1 ℃.
• 4.1.5 Graduated cylinder: 250 mL.

6. Recommended operating conditions

• Sample amount: 250 mL
• Test temperature: 50 ℃ (the original text source-text extraction is "501C", requires confirmation against the source standard (source-text extraction))
• Test time: 4 h or a longer time specified in the product standard
• Condenser inlet water temperature: 20±5 ℃ (the original text source-text extraction is "20±5C", requires confirmation against the source standard (source-text extraction))
• Condenser water flow rate: about 10 mL/min, to form thermal stirring
• Silver strip suspension position: top end 25~30 mm from the bottom of the condenser

7. Sampling and sample preparation

• 6.2.1 During sampling and subsequent handling, special care should be taken to avoid exposing the sample to air as much as possible, and to prevent exposure to direct or even scattered sunlight. Fill at least 250 mL of sample in a container that has no effect on fuel corrosiveness. Tinplate containers have a significant effect on fuel corrosiveness; clean brown glass bottles are preferred. The sample should be filled full, and the headspace should not exceed 5%. Cap immediately after sampling, store in a cool place, preferably below 4 ℃. The test should be conducted as soon as possible.
• 6.2.2 If suspended water (mist) is found in the sample, filter it through medium-speed quantitative filter paper into a clean, dry test tube while avoiding light. Whether before or after the test, contact of the silver strip with water will produce stains, making grading of the silver strip difficult.
• 6.1 Preparation of silver strip:
  • 6.1.1 Surface treatment: first use fine silicon carbide abrasive cloth (paper) to remove scratches and defects from the six surfaces of the silver strip. Then polish with 65 μm (240 grit) silicon carbide abrasive cloth (paper) to remove polishing marks left by other grits. Then immerse the test piece in isooctane. The manual surface treatment procedure should be: place a piece of abrasive cloth (paper) on a flat surface, wet the abrasive cloth with isooctane, polish the silver strip on the abrasive cloth in a rotating manner, while using ashless filter paper to hold it to prevent the silver strip from contacting fingers. Mechanical polishing of the silver strip with abrasive cloth of specified grit may also be used.
  • 6.1.2 Final polishing: take a ball of absorbent cotton, wet it with 1 drops of isooctane, then pick up a little 150 mesh silicon carbide abrasive grains from a glass plate; take the silver strip out of the isooctane, hold the test piece tightly with fingers while protecting it with ashless filter paper, and polish the two ends and two sides of the silver strip in sequence on the cotton ball with silicon carbide fine abrasive grains. Wipe vigorously with a new absorbent cotton ball. In subsequent operations, the silver strip may only be held with stainless steel tweezers and must not contact fingers. Clamp the silver strip in the test piece clamp, and polish the main surface with silicon carbide fine abrasive grains adhered to absorbent cotton. Polish along the long axis direction, with a polishing stroke not less than the length of the test piece. Here, polishing with the aid of the test piece clamp helps to uniformly and completely polish all surfaces of the silver strip without damage, obtaining a well-polished silver strip. Test pieces whose edges and corners have been worn into an oval shape should not be used. Afterwards, wipe the silver strip vigorously with clean absorbent cotton to remove all metal chips until no more metal powder appears on fresh absorbent cotton. Immerse the finally polished test piece in the sample within 1 min.

8. Analytical procedure

• 7.1 Measure 250 mL of sample and pour it into a clean test tube. Suspend the finally polished silver strip on the glass support. Hang the glass support on the glass hook of the condenser. Then carefully lower the test piece together with the condenser slowly into the sample.
• 7.2 Place the test tube in a water bath, maintain the temperature at 50 ℃ (the original text source-text extraction is "501C", requires confirmation against the source standard (source-text extraction)). The test time is 4 h or a longer time specified in the product standard. The water flow rate through the condenser is about 10 mL/min, to form thermal stirring. After the test, remove the silver strip from the test tube and immerse it in isooctane. Then immediately remove the silver strip from the isooctane, dry it with quantitative filter paper by blotting (not wiping), and examine the corrosion marks on the silver strip.

9. Qualitative and quantitative determination and calculation formula

• 8 Judgment: compare the appearance of the silver strip after the test with that of a freshly polished silver strip (all surfaces of the silver strip including edges and corners should be noted), and grade the corrosiveness of the sample according to the table below.

Silver strip grading table:

Note: The color plate of GB 9169 can be used to distinguish brown of grade 1 and grade 2. Those lighter than grade 4 of this color plate should be rated as silver strip corrosion grade 1.

• Calculation formula: not provided in the available source.

10. Precision

The reliability of test results shall be judged according to the following provisions (95% confidence level).

• 9.1 Repeatability: two rating results obtained by the same operator in repeated determinations should not differ.
• 9.2 Reproducibility: the difference between different rating results submitted by different laboratories should not exceed 1 grade(s).

11. Report

Report the grade of the silver strip corrosion test and the test time.

12. Referenced documents

• GB 5096 Copper Strip Corrosion Test Method for Petroleum Products
• GB 9169 Determination of Thermal Oxidation Stability of Jet Fuels (JFTOT method)

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