GB/T 11138-1994 Copper Strip Corrosion Test Method for Industrial Aromatic Hydrocarbons

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 title / English name / replacement relationship

• Standard number: GB/T 11138-94
• Chinese title: Copper Strip Corrosion Test Method for Industrial Aromatic Hydrocarbons
• English title: Industrial aromatic hydrocarbons—Test method of copper corrosion
• Replacement relationship: replaces GB/T 11138-89
• Approval/implementation: approved by the State Bureau of Technical Supervision on 1994-08-23, implemented on 1995-06-01
• Reference adoption: American Society for Testing and Materials standard ASTM D849-98 (Copper Strip Corrosion Test Method for Industrial Aromatic Hydrocarbons) (unclear in the source text, year requires confirmation against the source standard (source-text extraction))

2. Scope of application and non-applicability

• This standard specifies a qualitative test method for the corrosiveness of a sample to a copper strip under heating and reflux conditions.
• This standard applies to industrial aromatic hydrocarbons.
• Note: The samples and solvents used in this standard are toxic, and inhalation and skin contact should be avoided; they are flammable, and corresponding safety and health measures should be followed during operation.
• Not applicable: not provided in the available source.

3. Method principle

Immerse a polished copper strip in a 200 mL sample in a flask equipped with a condenser. Place the flask in a constant-temperature bath at 100±1℃, remove the copper strip after 30 min, and compare it using the corrosion standard color plate.

4. Reagents and materials (purity / preparation)

• 5.2.1 Copper strip: the material meets the requirements of T2 in GB 5231. Dimensions are 75 mm × 12.5 mm × (1.5~3.0)mm; on the transverse centerline of the copper strip, about 3.0 mm from one end, there is a hole with a diameter of 3.0 mm. The copper strip may be reused, but it cannot be used if its surface is deformed after treatment.
• 5.2.2 Copper wire: soft copper wire meeting Cu2 in GB 466, with a diameter of about 0.3 mm and a length of about 150 mm.
• 5.2.3 Polishing materials: 65 μm (240 grit) silicon carbide (or aluminum oxide) abrasive paper (or abrasive cloth); 105 μm (150 mesh) silicon carbide (or aluminum oxide) abrasive grains, and pharmaceutical-grade absorbent cotton. Note: In case of dispute, polishing materials made of silicon carbide should be used.
• 5.2.4 Corrosion standard color plate: meets the requirements of GB/T 5096.
• 5.2.5 Washing solvent: any volatile sulfur-free hydrocarbon solvent that, when tested according to this standard at 100℃ for 1 h, does not corrode the copper strip. Suitable solvents include analytically pure isooctane, standard isooctane, and reference fuel isooctane; analytically pure petroleum ether (90~120℃) or rubber industry solvent naphtha meeting the requirements of SH 0004 may also be selected. Note: In case of dispute, reference fuel isooctane should be used.
• 5.2.6 Varnish: volatile varnish.

5. Apparatus and equipment

• 5.1.1 Flask: 250 mL, flat-bottomed, made of chemically resistant glass.
• 5.1.2 Glass condenser: length 300 mm, inner diameter of the condenser tube not less than 10 mm.
• 5.1.3 Constant-temperature bath: a water bath or oil bath of any suitable size and shape capable of maintaining the temperature at 100±1℃.
• 5.1.4 Polishing clamp: meets the requirements of GB/T 5096.

6. Recommended operating conditions

• Constant-temperature bath temperature: 100±1℃
• Heating reflux time: 30 min
• Sample amount: 200 mL
• Observation angle: observe the copper strip and corrosion standard color plate at an angle of about 45° to scattered daylight

7. Sampling and sample preparation

• 7.1 If the sample contains free water, it must be removed by filtration with filter paper.
• Copper strip preparation:
  • 6.1 Preparation of copper wire: rub the copper wire (5.2.2) with 65 μm (240 grit) silicon carbide (or aluminum oxide) abrasive paper (or abrasive cloth), and remove metal powder with clean absorbent cotton.
  • 6.2 Preparation of the copper strip surface: first use silicon carbide (or aluminum oxide) abrasive paper (or abrasive cloth) of the required grit to remove stains from all six faces of the copper strip. Then use 65 μm (240 grit) silicon carbide (or aluminum oxide) abrasive paper (or abrasive cloth) to remove all traces left by previously used abrasive paper of other grits. Immediately immerse the copper strip in the washing solvent, and take it out at the time of final polishing or store it for later use. A practical manual polishing method is to place a sheet of abrasive paper (or abrasive cloth) on a flat surface, wet it with washing solvent, and rub the copper strip against the abrasive paper (or abrasive cloth) in a rotary motion, protecting the copper strip with ashless filter paper so that it cannot contact the fingers. Alternatively, the copper strip may also be prepared using dry abrasive paper (or abrasive cloth) of suitable grit driven by an electric motor.
  • 6.3 Final polishing of the copper strip: remove the copper strip from the washing solvent. Protect the copper strip with ashless filter paper and hold it with the fingers, wet a ball of absorbent cotton with one drop of washing solvent, pick up 105 μm (150 mesh) silicon carbide (or aluminum oxide) abrasive grains from a clean glass plate, first polish the two ends of the copper strip, then polish the sides. Then rub vigorously with a clean ball of absorbent cotton, and afterward only stainless steel tweezers are allowed for handling; the copper strip must not be touched by hand. Clamp the copper strip in the clamp, and polish the main surface with absorbent cotton dipped in silicon carbide (or aluminum oxide) abrasive grains. When polishing, move along the long axis of the copper strip, and before polishing in the reverse direction, the stroke should extend beyond the end of the copper strip. Then rub the copper strip vigorously with a clean ball of absorbent cotton to remove all metal powder until it remains clean when rubbed with a clean ball of absorbent cotton. When the copper strip is clean, immediately pass a prepared copper wire about 150 mm long through the copper strip, and then place the tied copper strip into the flask. Note: In order to obtain a copper strip with uniform color, it is important to polish the entire surface of the copper strip uniformly. If wear appears on the edges of the copper strip (the surface appears oval), these areas may corrode more severely than the center. Using a polishing clamp will help polish the copper strip uniformly.

8. Analytical procedure

• 7.2 Add 200 mL of sample to the flask, adjust the position of the copper strip with the copper wire so that the copper strip is completely immersed in the sample, placed as flat as possible and with only the two ends of the copper strip touching the flask wall. Insert the copper wire into the condenser tube, then connect the flask and the vertical reflux glass condenser with a suitable cork stopper; a matched apparatus of a ground-joint flask and glass condenser may also be used. Rubber stoppers are prohibited to avoid contamination of the sample by sulfur in the rubber stopper.
• 7.3 Place the flask in a constant-temperature bath at 100±1℃ so that the liquid level of the sample in the flask is entirely below the liquid level of the constant-temperature bath.
• 7.4 After heating under reflux for 30 min, remove the flask. Remove the glass condenser, take out the copper strip with the copper wire, and do not touch the copper strip with hands. Because water will cause severe local corrosion of the copper strip, contact between the copper strip and water must be avoided throughout the entire test.
• 7.5 To preserve the copper strip for future reference, the removed copper strip may be directly immersed in varnish and then taken out for storage.

9. Qualitative and quantitative determination and calculation formulas

• 8 Judgment of results: compare the removed copper strip using the corrosion standard color plate, observing the copper strip and corrosion standard color plate at an angle of about 45° to scattered daylight. If the copper strip shows slight tarnish or an appearance better than this (1b or 1a), it is considered non-corrosive (pass). All other changes are considered corrosive (fail).
• Calculation formula: not provided in the available source.

10. Precision

This standard only makes a qualitative judgment of whether the copper strip is corroded or not, and has no precision.

11. Report

If the copper strip is not corroded, report as "pass"; if the copper strip is corroded, report as "fail".

12. Referenced documents

• GB 466 Copper classification
• GB/T 5096 Copper Strip Corrosion Test Method for Petroleum Products
• GB 5231 Wrought copper — Chemical composition and product forms
• GB/T 11117.1 Knock test reference fuels — Reference fuel isooctane (unclear in the source text, name requires confirmation against the source standard (source-text extraction))
• SH 0004 Rubber industry solvent naphtha

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 questions and answers