Inhibitive effectiveness of hydrazine oxygen scavenger on low-Alloy steel in near-neutral ph underground conditions

I. M. Gadala, H. Jefri, A. Alfantazi

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Buried pipeline steels are susceptible to external corrosion from corrosive soil agents present in the trapped electrolyte in contact with exposed surfaces beneath disbonded coatings. Corrosion of these surfaces is often simulated with electrolytes categorized based on pH. A representative near-neutral pH dilute bicarbonate electrolyte with chlorides and sulphate represents one such environment. Although normally deaerated with a 5% carbon dioxide/ 95% nitrogen gas mixture, in practice soil aeration can support oxygen presence in this environment, accelerating corrosion mechanisms. Temperature influences and shielding of the cathodic protection (CP) current further exacerbate this problem. This paper investigates the effectiveness of oxygen scavenger injections on corrosion inhibition of a modern pipeline steel alloy (API-X100) in near-neutral pH conditions which may simulate trapped water environments. The influence of the pipeline's operating temperature on inhibition is studied at 50 and 25 °C. Polarization and Electrochemical Impedance Spectroscopy (EIS) results are highly dependent on temperature, dissolved oxygen, hydrazine, and CP levels. Current shielding effects on corrosion and inhibition process are analysed at field-relevant cathodic potentials (around the-0.85 VSCE NACE CP criterion), yielding unique insights into the applicability of this established standard.

Original languageBritish English
Title of host publicationCorrosion and Prevention 2016
ISBN (Electronic)9781510858541
StatePublished - 2016
EventAnnual ACA Conference on Corrosion and Prevention 2016 - Auckland, New Zealand
Duration: 13 Nov 201616 Nov 2016

Publication series

NameCorrosion and Prevention 2016


ConferenceAnnual ACA Conference on Corrosion and Prevention 2016
Country/TerritoryNew Zealand


  • Cathodic protection
  • Corrosion modeling
  • Inhibitor
  • Oxygen
  • Pipeline steel


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