ASTM D1838 Test Method for Copper Strip Corrosion by Liquefied Petroleum (LP) Gases
11. Interpretation of Results
11.1 Interpret the corrosiveness of the sample in accordance with one of the classifications listed in Table 1.
11.1.1 When a strip is in the obvious transition state between that indicated by any two adjacent classifications, rate the sample at the more tarnished classification, unless a strip appears to have a darker orange color than Classification 1, in which case, consider the observed strip as still belonging in Classification 1; however, if any evidence of red color is observed, the observed strip belongs in Classification 2.
11.1.2 A Classification 2 strip (Claret red) can be mistaken for a Classification 3 strip (Magenta overcast on brassy strip) if the brassy underlay of the Classification 3 strip is completely masked by a magenta overtone. If needed to distinguish between the two, immerse the strip in wash solvent; a Classification 2 (Claret red) strip will appear as a Classification 1 strip (Dark orange), while a Classification 3 strip (Magenta overcast on brassy strip) will not change.
11.1.3 If needed to distinguish a Classification 2 strip (Multicolored with lavender blue or silver, or both, overlaid on claret red) from a Classification 3 strip (multicolored with red and green showing (peacock), but no gray), one may place a test strip in a 25 mm by 150 mm test tube and bring to a temperature of 340 °C +/- 30 °C in 4 min to 6 min with the tube lying on a hot plate and adjusted to temperature as appropriate using a temperature sensing device in a second test tube. A Classification 2 strip will assume a silvery color or successive stages of tarnish that is also within Classification 2, whereas a Classification 3 strip will take on the appearance of a Classification 4 strip (transparent black, dark gray or brown with peacock green barely showing).
12. Report
12.1 Report the results in accordance with one of the classifications listed in Table 1, and reference this test method. State the duration of the test and the test temperature.
13. Precision and Bias
13.1 In the case of ordinal classification data, no generally accepted method for determining precision or bias is currently available.
14. Keywords
14.1 copper corrosion; copper strip; liquefied petroleum gases
