Evaluation of Inhibitor for Galvanic Corrosion of I625 and CS1018 Couple Under Flowing Conditions

Inconel clad tubulars are increasingly used for riser applications where concerns about carbon steel integrity and life expectancy exist. Here galvanic corrosion is one of possible problems.

The objective of this paper is to investigate the performance of corrosion inhibitor on the galvanic corrosion of Inconel 625 and Carbon steel X65. Multiphase flow loop tests were conducted to evaluate the effect of incline angles, flowing conditions, and inhibitor performance on possible detrimental influence of galvanic coupling between carbon steel and Inconel 625. To determine the galvanic coupling effect, a series of pipe spool pieces made of Inconel 625 and carbon steel X65 were used into the multiphase flow loop. The sections were made such that the interior exposed surface ratio was 10:1 (Inconel 625 to X65 carbon steel). Two commercial corrosion inhibitors were evaluated.

Results showed that severe galvanic corrosion was observed on carbon steel pipe sections coupled with inconel 625 in the absence of inhibitors. The galvanic corrosion attack was significantly decreased on the carbon steel pipe sections with the presence of corrosion inhibitor.