Comment by Kate Stuart on 28 Dec 2009 at 15:35:59
Unfortunately I don't have access to the article, can you attach it?
Secondly, there is few work on X steels in CO2 environment that really contains hard and rigorous figure. The most rigorous statements I found so far are as follows:
Corrosion of pipelines is an important issue. Dry CO2 does not corrode the carbon-manganese steels generally used for pipelines, as long as the relative humidity is less than 60 per cent; this conclusion continues to apply in the presence of O2, N2, NOx and SOx contaminants, which would probably be components of any CO2 produced by a CCS process. CO2 that contains CO as a contaminant can induce corrosion. Seiersten wrote:
â€œThe corrosion rate of carbon steel in dry supercritical CO2 is low. For AISI 1080
values around 0.01 mm/y have been measured at 90-120 bar [9-12 MPa] and 160-
180Â°C during 200 days. Short-term tests confirm this. In a test conducted at 3 and
22Â°C at 140 bar CO2, 800 to 1000 ppm H2S, the corrosion rate for X-60 carbon
steel was measured to less than 0.5 micrometer/y [0.0005 mm/y]. Field experience also
indicates very few problems with transportation of high-pressure dry CO2 in
carbon steel pipelines. During 12 years, the corrosion rate in an operating pipeline
amounts to 0.25-2.5 micrometer/y [0.00025 to 0.0025 mm/y]â€
The water solubility limit in high-pressure CO2 (50 MPa) is 2000 ppm at 30Â°C.
Methane lowers the solubility limit, and H2S O2 and N2 may have the same effect.
Corrosion is much faster if free water is present. Seiersten measured a 0.7 mm/y
corrosion rate in 150 to 300 hours exposure at 40Â°C in water equilibrated with CO2 at 95
bars, and higher rates at lower pressures, and she found little difference between carbonmanganese steel (API grade X65) and 0.5 chromium corrosion-resistant alloy.
It follows that a CCS scheme ought to dry the CO2 as far upstream as possible, with no
liquid and a vapour phase water content below 4.8Ã—10-4 kg/m3, the level allowed in a
current specification for pipeline quality CO2.
Hope this helps,