CORROSIVENESS TO COPPER FROM PETROLEUM PRODUCTS: ASTM D7095
EXPLANATION
Crude petroleum contains sulfur compounds, most of which are removed during refining. However, of the remaining sulfur compounds can have a corroding action on various metals, including copper, and this corrosivity is not necessarily related to the sulfur content. The effect can vary according to the chemical types of sulfur compounds present. This copper strip corrosion test is designed to assess the relative degree of corrosivity of a petroleum product towards copper and copper-containing alloys using a shorter test duration than that specified in Test Method ASTM D130. Some sulfur species may become corrosive to copper only at higher temperatures. Thus, higher test temperatures, particularly 100° C, may be used to test some products by the pressure vessel procedure.

This test method is applicable to aviation gasoline, aviation turbine fuel, automotive gasoline, natural gasoline, or other hydrocarbons having a vapor pressure not greater than 124 kPa, cleaners such as Stoddard solvent, kerosene, diesel fuel, distillate fuel oil, lubricating oil, and other petroleum products.

This test method is similar to Test Method ASTM D130, but involves three major differences: (1) A single-use copper foil strip is used in place of Test Method ASTM D1340 multi-use copper strip. (2) A different polishing technique is used in preparing the copper foil strip. (3) This test method involves a shorter analysis time of 45 minutes for all product types versus two to three hours required in Test Method ASTM D130.

TEST SUMMARY
A polished copper strip is immersed in a specific volume of the sample being tested and heated under conditions of temperature and time that are specific to the class of material being tested. At the end of the heating period, the copper foil strip is removed, washed, and the color and tarnish level are assessed against the ASTM copper strip corrosion standard.

TEST PRECISION
In the case of pass/fail data, no generally accepted method for determining precision or bias is currently available.