Date of Graduation

Spring 2015

Document Type

Honors Research Project

Degree Name

Bachelor of Science

Major

Chemical Engineering - Cooperative Education

Research Sponsor

Dr.Homero Castenada-Lopez

First Reader

Dr.Homero Castenada-Lopez

Second Reader

Dr.Hongbo Cong

Abstract

Through the analysis of materials and environments seen in industry a better understanding of the fundamentals behind degradation mechanisms can be observed. The scope of this project was to better understand the fundamentals behind the degradation of high strength pipeline steels in a lab setting to simulate an environment seen in industry. Specifically the degradation mechanisms of high and nearly neutral pH stress corrosion cracking were examined in environments that simulated oil and gas pipelines buried in soil. Experimentation was carried out utilizing X65 carbon steel specimen, a Gamry potentiostat, a CORTEST proof ring, a CORTEST slow strain rate machine, and NS4 standard solution. Performance of the steel was characterized utilizing electrochemical impedance spectroscopy, SEM/EDS technology, and loading versus failure curves. The stress induced (extension rate) on the specimen was controlled utilizing the CORTEST equipment and the amount potential induced on the specimen was controlled using the potentiostat. It is reasonable to believe that the high pH SCC cracking mechanism is accelerated when large amounts of cathodic over potential (~-1200 mV vs. SCE) are induced on the specimen. It is observed that better equipment should be used to simulate the environment to draw broader based conclusions at varied over potentials.

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