ISO 2160 Petroleum products - Corrosiveness to copper - Copper strip test
4 Reagents and materials
4.1 Wash solvent
2,2,4-trimethylpentane (isooctane) of minimum 99.75 % purity is the referee solvent, but any volatile sulfur-free hydrocarbon solvent that shows no tarnish when tested by the procedure of this International Standard for 3 h at 50 °C is suitable.

4.2 Polishing materials
4.2.1 Silicon-carbide paper or cloth, of varying degrees of fineness, including 65 µm (240 grit) grade.

4.2.2 Silicon-carbide powder, of 105 µm (150 mesh) size.

4.2.3 Absorbent cotton (cotton wool).

NOTE - Commercial grade is suitable, but pharmaceutical grade is most commonly available.

5 Apparatus
5.1 Copper strips, cut from smooth-surfaced, hard temper, cold-finished electrolytic-type copper of more than 99.9 % purity; electrical busbar stock is generally suitable.

The strips shall be 75 mm +/- 5 mm in length, 12.5 mm +/- 2 mm in width, and 1.5 mm to 3.0 mm in thickness.

When the strips show pitting or deep scratches that cannot be removed by the specified polishing procedure, or when the surfaces become deformed on handling, they shall be discarded.

5.2 Pressure vessel, constructed of stainless steel and of the dimensions shown in figure 1.

The vessel shall be capable of withstanding a test pressure of 700 kPa gauge.

NOTE - Alternative designs for the vessel cap and synthetic rubber gasket may be used, provided that the internal dimensions of the vessel are the same as those shown in figure 1.

5.3 Test tubes, of borosilicate glass, of nominal 25 mm x 150 mm.

The internal dimensions shall be checked with a metal strip of the maximum length given in 5.1 and not more than the median dimensions for width and thickness. When 30 ml of liquid is added, a minimum of 5 mm shall be above the top surface of the strip.

5.4 Test baths
5.4.1 General
All test baths shall have sufficient heat capacity to raise the product temperature to within +/- 1 °C of the test temperature within 15 min.

5.4.2 Liquid bath for pressure vessel, capable of maintaining the product at the specified test temperature +/- 1 °C.

The bath shall be constructed of non-transparent material and shall be deep enough to submerge one or more pressure vessels (5.2) completely during the test. It shall be fitted with suitable supports to hold each pressure vessel in a vertical position when submerged.

5.4.3 Bath for test tubes, capable of maintaining the product at the specified test temperature +/- 1 °C.

Liquid baths shall be constructed of non-transparent material, and shall be fitted with suitable supports to hold each test tube (5.3) in a vertical position to a depth of 100 mm +/- 5 mm. Solid block baths shall meet the same temperature control and immersion conditions, and shall be checked for temperature measurement (heat transfer) for each product class, by running tests on tubes filled with 30 ml of product plus a metal strip of the nominal dimensions given in 5.1, plus a temperature sensor.

5.5 Temperature sensor, for indicating the test temperature.

For liquid baths, a total immersion liquid-in-glass thermometer is suitable, with graduations of 1 °C or less. It shall be submerged in the liquid such that not more than 25 mm of the thread extends above the liquid surface.

NOTE - The ASTM 12C/IP 64C thermometer is suitable.

5.6 Polishing vice or holder, for holding copper strips firmly without marring the edges while polishing.

The strip shall be held tightly, and the surfaces of the strip that is being polished shall be supported above the surface of the holder.

NOTE - A suitable apparatus is illustrated in figure 2.

5.7 Viewing test tubes, for protecting corroded copper strips during close inspection or during storage, of such dimensions to allow the introduction of a copper strip (5.1) and made of glass which is free of striae or similar defects.

NOTE - A suitable "flat" tube is illustrated in figure 3.

5.8 Forceps, spade-ended, with either stainless steel or polytetrafluoroethylene (PTFE) tips.

5.9 Corrosion standards, for the evaluation of tarnish at the end of the test.

Further details on the composition and maintenance of these standards are given for information in annex A.

5.10 Timing device, electronic or manual, accurate to 1.0 s.