Determining Corrosive Properties of Insoluble Petroleum Product Pipeline Cargoes
|Publication Date:||1 January 2015|
This standard provides a test method to determine the corrosive properties of liquid petroleum products (e.g., gasoline and distillate fuels), and other liquid hydrocarbon products that are not water soluble, for transport through a steel pipeline. Information on the test specimen, test apparatus, test procedure, and rating of the exposed test specimen is included.
In this test method, the surface of a cylindrical steel test specimen is prepared and then immersed in the test liquid to be evaluated. The test liquid is stirred and maintained at a prescribed temperature. After a 3.5 h exposure, the test specimen is removed and rated by the percentage of the test specimen surface area that has corroded.
This test method is commonly performed in three standard variants.
First test liquid variation-original product The test liquid is the liquid petroleum or other hydrocarbon product itself, which is used to determine the corrosiveness of that original product. This test liquid variation is appropriate when the product is stable (no expected compositional, thermal, or other physical changes are expected during pipeline transport and/or storage) and when the pipeline transport and storage system is sealed from possible outside contamination.
Second test liquid variation-original product plus distilled water addition The test liquid is the liquid petroleum or other hydrocarbon product itself plus an addition of distilled water. A 10% distilled water addition has been shown to be adequately conservative for evaluating the impact of possible contamination on the corrosiveness of the liquid product in all but the most extreme cases. This test liquid variation is used when it is believed that the original product may undergo compositional or physical changes (such as cooling that causes water to condense out of the product) or when outside contaminants may enter the liquid product during transport or storage (such as when stored in tanks under atmospheric conditions).
Third test liquid variation-original product or original product with distilled water addition plus corrosion inhibitor addition The test liquid is the liquid petroleum or other hydrocarbon product, or the liquid petroleum or other hydrocarbon product that has been artificially contaminated with distilled water, plus the addition of a corrosion inhibitor. Both the corrosion inhibitor formulation and concentration can be tested to determine the adequacy of a proposed or ongoing treatment program.
This test method does not predict corrosiveness in a standing aqueous phase, nor does it predict microbiologically influenced corrosion (MIC) or underdeposit corrosion (UDC).
This test method is not appropriate for evaluating the corrosiveness of liquid hydrocarbons that are water soluble.