Corrosion mitigation with pH stabilisation in slightly sour gas/condensate pipelines
Kvarekvål, J.
,
Dugstad, A.
Corrosion 2006, San Diego, Calif., 2006-03-12--03-16. Paper 06646
- Publ. year
- 2006
- Publ. type
- paper
- Abstract
- An experimental study focused on the applicability of pH-stabilisation for corrosion control in sour environments with hydrate preventer has been carried out, consisting of flow loop experiments with 50 % diethylene glycol, 0.02 bar H2S and 2 bar CO2. pH values in the range of 6.0-7.0 were investigated. The experiments were run at flow velocities between 1 and 3 m/s and temperatures of 20, 60 and 120oC. It has been shown that pH-stabilisation at a target pH of 7.0 seems to give sufficient corrosion protection under these conditions. The steady state uniform corrosion rates were 10 times less at pH 7 (0.01 mm/y) than at pH 6.5 (0.1-0.2 mm/y). While a few cases of pitting and edge corrosion were found on the specimens exposed at pH 6.5, no localised attacks occurred at pH 7.0. The intensity of corrosion attacks was similar for the three types of carbon steel (St52, X65 and Cr0.5) used in the tests. The findings have contributed to increased confidence in pH stabilisation as a viable corrosion control method for natural gas pipelines with low H2S levels. ©NACE International. All rights reserved. Paper reproduced with permission from CORROSION/2006 Annual Conference and Exhibition, San Diego, California. <A HREF="http://www.nace.org" target=_blank>www.nace.org</A>
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