November 14, 2012
Both scientific research and industrial experience have determined that bitumen-derived crude oil is no more corrosive in transmission pipelines than other crudes.
ASTM International — an internationally recognized agency that develops standards tests — recently published a guide (Guide G205) for measuring the corrosivity of crude oil under pipeline conditions, based on research conducted by several organizations including the CANMET Laboratories of Natural Resources Canada.
Guide G205 is an important step toward the creation of an industry-wide standard test to measure the corrosivity of different crude oils under pipeline conditions, since it describes test methods that enable a direct comparison of the corrosivity of crude oils from various sources.
Measurements obtained from these tests indicate that the corrosivity of oil sands-derived crudes is no different than that of other crudes.
The low corrosivity of all crude oils — including bitumen-derived crude in transmission pipelines regulated by the National Energy Board — is due to the fact that corrosive (water) and erosive (mud, sand) constituents are largely removed upstream of the pipelines as part of achieving transport quality specifications. For transport in transmission pipelines, the sand and water content of the oil is controlled, and the combined basic sediment and water content must be less than 0.5% by volume.
Crude oils, including bitumen-derived crudes, contain little or no carbon dioxide (CO2) or hydrogen sulphide (H2S). Furthermore, these transmission pipelines operate at temperatures below 60°C. Consequently, naphthenic acid and sulphur compounds that can cause corrosion under refinery conditions (>200°C) do not cause corrosion in pipelines.
Pipelines carrying bitumen-derived crude oil operate at approximately the same pressure levels as pipelines carrying other crude oils.
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