TY - JOUR
T1 - External corrosion of api-x100 pipeline steels in near-neutral ph soils of variable aeration and nitrate ion content
AU - Gadala, Ibrahim M.
AU - Alfantazi, Akram
AU - Farhat, Zoheir
AU - Mohamed, Adel M.A.
N1 - Funding Information:
This publication was made possible by NPRP Grant 6-027-2-010 from the Qatar National Research Fund (a Member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.
Publisher Copyright:
Copyright 2015, Brazilian Petroleum, Gas and Biofuels Institute - IBP.
PY - 2015
Y1 - 2015
N2 - The external corrosion and subsequent cracking of buried pipeline steels have been serious problems facing pipeline operators for many decades. The recently discovered near-neutral pH stress-corrosion cracking is often simulated in experimental tests by a soil solution containing dilute amounts of bicarbonate, chloride, and sulfate, deaerated with a gas mixture containing 5% carbon dioxide. However, noticeable differences in groundwater ion and oxygen content are observed between simulated and actual conditions, raising concerns about the real corrosion performance of buried pipeline steels. The present work aims to study the corrosion of a new pipeline steel grade (X100) in NS4 simulated soil solutions of different dissolved oxygen and nitrate concentrations. Variations in oxygen concentration are instigated through deaerating (5% carbon dioxide / 95% nitrogen), naturally aerating, or saturating (pure oxygen) the test solutions. Nitrate concentrations are varied between 0.005 and 0.015 M. Differential oxygen access and nitrate content promote corrosion, as deduced from open circuit potential, potentiodynamic polarization, and linear polarization resistance tests. Corrosion rates of the X100 steel are calculated using established electrochemical techniques, and a preliminary model is presented for predicting corrosion rates in solutions with oxygen and nitrate concentrations other than those tested.
AB - The external corrosion and subsequent cracking of buried pipeline steels have been serious problems facing pipeline operators for many decades. The recently discovered near-neutral pH stress-corrosion cracking is often simulated in experimental tests by a soil solution containing dilute amounts of bicarbonate, chloride, and sulfate, deaerated with a gas mixture containing 5% carbon dioxide. However, noticeable differences in groundwater ion and oxygen content are observed between simulated and actual conditions, raising concerns about the real corrosion performance of buried pipeline steels. The present work aims to study the corrosion of a new pipeline steel grade (X100) in NS4 simulated soil solutions of different dissolved oxygen and nitrate concentrations. Variations in oxygen concentration are instigated through deaerating (5% carbon dioxide / 95% nitrogen), naturally aerating, or saturating (pure oxygen) the test solutions. Nitrate concentrations are varied between 0.005 and 0.015 M. Differential oxygen access and nitrate content promote corrosion, as deduced from open circuit potential, potentiodynamic polarization, and linear polarization resistance tests. Corrosion rates of the X100 steel are calculated using established electrochemical techniques, and a preliminary model is presented for predicting corrosion rates in solutions with oxygen and nitrate concentrations other than those tested.
UR - http://www.scopus.com/inward/record.url?scp=85044629113&partnerID=8YFLogxK
M3 - Conference article
AN - SCOPUS:85044629113
SN - 2447-2069
VL - 2015-September
JO - Rio Pipeline Conference and Exposition, Technical Papers
JF - Rio Pipeline Conference and Exposition, Technical Papers
T2 - 2015 Rio Pipeline Conference and Exposition
Y2 - 22 September 2015 through 24 September 2015
ER -
