BS ISO 22479:2019 pdf download – Corrosion of metals and alloys — Sulfur dioxide test in a humid atmosphere (fixed gas method)
5.4 Conditioning of a new cabinet. In order to minimize the effect from the material of the cabinet by sulfur dioxide, a new cabinet shall be operated at least one test cycle in accordance with the procedures given in 8.2 to
8.5 without test specimens. The conditioning shall conform to Table 1, with 2,0 l of sulfur dioxide.
6 Test specimens
6.1 General The number, type, surface roughness, thickness of coatings, shape and dimensions of test specimens shall be selected according to the specification for the materials or product being tested. When not specified, details concerning the test specimens shall be agreed between the interested parties.
6.2 Dimensions A typical specimen size is 150 mm × 100 mm by 0,75 mm to 1,25 mm thickness.
6.3.1 Metals and alloys
Thoroughly clean the test specimens before testing. The cleaning method depends on the nature of the surface and the contaminants. Abrasives shall not include the use of any abrasives or solvents that may attack the surface of the test specimens. Take care that the test specimens are not recontaminated after cleaning, by excessive or careless handling. If test specimens are cut from a large coated article, the cutting shall be carried out in such a way that the coating is not damaged, especially in the area adjacent to the cut. Unless otherwise specified, the cut edges should be adequately protected by coating with a suitable medium that is stable under the conditions of test, such as wax or adhesive tape.
6.3.2 Paints and varnishes
Unless otherwise specified or agreed, the test specimens shall be prepared in accordance with ISO 1514 and then coated by the specified method with the product or system under test. The back and edges of the test specimens should be coated with the product or system under test. Dry (or cure) and age (if applicable) each coated test specimen for the specified time and under the specified conditions and, unless otherwise specified, condition them at a temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) % for at least 16 h, with free circulation of air and not exposed to direct sunlight. The test procedure shall then be carried out as soon as possible.
Determine the thickness, in micrometres, of the dried coating by one of the non-destructive procedures described in ISO 2808.
6.4 Arrangement of the test specimens
The distance between test specimens shall be not less than 20 mm. The distance between the edge of the test specimens and a wall of the test cabinet shall be not less than 100 mm. The test specimens shall be arranged in such a way that they cannot protect each other from the influence of the environment. The distance between the lowest edge of the test specimens and the surface of the water shall be greater than 200 mm. The contact area between test specimens and their supports shall be as small as possible. The orientation of the exposed test surface in the test cabinet is critical. Unless otherwise specified, test specimen shall be mounted at an angle between vertical and (15 ± 2)° to the vertical, with the area of primary interest facing up.
NOTE This is common practice for testing metallic specimens and measures to protect them from corrosion. When testing assemblies or enclosures, it is preferable to mount the specimen at the same angle as in typical use.
The total exposed surface area of the test specimens for one test shall be (0,5 ± 0,1) m 2 for each (300 ± 10) l of the test cabinet. For different volumes of the test cabinet, the total exposed surface area is to be adjusted proportionally. When the total exposed surface area is less than 0,5 m 2 for 300 l of the cabinet, substitute specimens shall be added to obtain a total surface area of 0,5 m 2 . The materials of the substitute specimens shall be the same as of the test specimens. Otherwise, test results may be different, since the influence (absorbance) of sulfur dioxide differs by materials.