Surface analyses of corrosion products formed on API X-70 steel in sour brine after testing in a pipe loop

Abstract

Flow assisted corrosion (FAC) is a problem of pipeline systems that handle high flow rates and strong direction changes. In the present investigation, FAC was tested on carbon steel exposed to the NACE 1D-196 environment by means an experimental pipe loop. As the exposure time increased, corrosion products formed a mixture of oxides, sulfides, and an apparent sulfate (rhombohedral mikasaite Fe _2 (SO _4 ) _3 ), which was found in greater proportion and appeared to have a significant effect on decreasing corrosion rate. Transmission electron microscopy and x ray diffraction patterns seemed to confirm the presence of a sulfate and some oxides as the major chemical species contained in the corrosion products.

Keywords

• flow assisted corrosion
• API 5L X-70 steel
• corrosion products
• rhombohedral mikasaite
• hydrogen sulfide