Hydrogen Permeation Behavior of X-70 Pipeline Steel in a Near-Neutral pH Soil Environment

2000 ◽  
Author(s):  
Weixing Chen ◽  
Sheng-Hui Wang ◽  
Fraser King ◽  
Tom R. Jack ◽  
Martyn J. Wilmott
Keyword(s):  
Boundary Conditions ◽  
Hydrogen Permeation ◽  
Pipeline Steel ◽  
Soil Environment ◽  
Diffusible Hydrogen ◽  
Concentration Boundary ◽  
Hydrogen Flux ◽  
Neutral Ph ◽  
Best Fit ◽  
Galvanostatic Conditions

This paper reports the hydrogen permeation behavior of an X-70 pipeline steel in a synthetic near neutral pH field solution under both galvanostatic and potentiostatic conditions. The hydrogen flux through the steel exposed to the solution is influenced by the chemical reactions at the steel surface on the charging side. Results from tests done under potentiostatic and galvanostatic conditions were compared to predictions based on different boundary conditions assumed in solving Fick’s diffusion equations. Constant concentration boundary conditions gave the best fit. It was also found that the diffusible hydrogen generated in a near neutral pH soil environment is likely to be 3 to 10 times lower than the minimum hydrogen concentration required to initiate hydrogen blistering in pipeline steels.

scholarly journals Analysis of Hydrogen Permeation Through Pipeline Steel in Near-Neutral pH SCC Environments

2000 ◽  
Author(s):  
Yufeng Cheng ◽  
Lin Yang ◽  
Fraser King
Keyword(s):  
Organic Material ◽  
Hydrogen Permeation ◽  
Pipeline Steel ◽  
Open Circuit ◽  
Permeation Flux ◽  
Concentration Boundary ◽  
Sulfate Reducing ◽  
Neutral Ph ◽  
Disulphonic Acid ◽  
Reducing Bacteria

The Devanathan-cell technique has been used to determine the permeation flux of hydrogen through X-65 steel at the open-circuit potential in solutions associated with near-neutral pH stress corrosion cracking. The effects of organic material and microbial activity were also simulated by suitable additions to the solution. A model based on a constant-concentration boundary condition was found to fit the experimental data better than one based on a constant flux condition. The addition of 9,10-anthroquinone-2,6-disulphonic acid to the solution to simulate the effect of organic material lowered the hydrogen permeation flux. Sulfide additions to simulate the action of sulfate-reducing bacteria initially increased the rate of hydrogen permeation, but subsequently resulted in a decrease in permeation current. The hydrogen permeation rate measured on the original oxide-covered surface is lower and more variable than that on polished surfaces. Corrosion rate measurements were also made, from which the fraction of atomic hydrogen diffusing through the specimens was estimated. The results are discussed in terms of the mechanism of hydrogen evolution and absorption.

Study of Electrochemical Behavior, Hydrogen Permeation and Diffusion in Pipeline Steel

2021 ◽  
Vol 1019 ◽  
pp. 145-156
Author(s):  
Swapna Dey ◽  
Seetharaman Sivaprasad ◽  
Nityananda Das ◽  
Indranil Chattoraj
Keyword(s):  
Corrosion Behavior ◽  
Hydrogen Permeation ◽  
Pipeline Steel ◽  
Electrochemical Corrosion ◽  
Hydrogen Distribution ◽  
X70 Pipeline Steel ◽  
Hydrogen Flux ◽  
Hydrogen Damage ◽  
Internal Surfaces ◽  
Neutral Soil

The pipeline steels which are used for transportation of natural gas and crude oil suffer from hydrogen damage at their internal as well as external surfaces. The internal surfaces of pipelines are generally affected due to hydrogen induced cracking and the external surfaces due to the soil environmental conditions which cause stress corrosion cracking. In the present investigation, the electrochemical corrosion behavior of X70 pipeline steel was studied in sour environment and near neutral soil environment. To assess the mechanism of hydrogen damage in steel, electrochemical hydrogen charging and permeation techniques were used to characterize the hydrogen distribution, trapping and its diffusion in X70 pipeline steel. It has been found that corrosion behavior of pipeline steel in the sour environment is higher than the near neutral soil solution. From the hydrogen permeation study it is established that the hydrogen permeation rate increases with the square root of the charging current density, and the increase of hydrogen flux is directly proportional to the subsurface hydrogen concentration.

Microstructure Dependence of Stress Corrosion Cracking Initiation in X-65 Pipeline Steel Exposed to a Near-Neutral pH Soil Environment

CORROSION ◽  
2004 ◽  
Vol 60 (3) ◽  
pp. 275-283 ◽  
Author(s):  
R. Chu ◽  
W. Chen ◽  
S.-H. Wang ◽  
F. King ◽  
T. R. Jack ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Stress Corrosion ◽  
Soil Solution ◽  
Open Circuit Potential ◽  
Pipeline Steel ◽  
Open Circuit ◽  
Polished Surface ◽  
Soil Environment ◽  
Neutral Ph

Abstract A study was carried out to understand mechanisms of stress corrosion crack initiation in an X-65 pipeline steel exposed to a near-neutral pH soil environment under a mechanical loading condition typical of a pipeline operating in the field. Microcracks initiated on the polished surface of the X-65 pipeline steel after long-term exposure at open-circuit potential in a near-neutral pH synthetic soil solution. It was found that these microcracks were initiated mostly from pits at metallurgical discontinuities such as grain boundaries, pearlitic colonies, and banded phases in the steel. Strong preferential dissolution was observed along planes of the banded structures in the steel. Selective corrosion at these metallurgical discontinuities is attributed to the anodic nature of those areas relative to the neighboring steel surface. Consistent with previous observations, no increased susceptibility to crack initiation was found at physical discontinuities mechanically introduced into the surface of steel exposed to synthetic soil solution at open-circuit potential.

scholarly journals Effect of Sulfate-Reducing Bacteria (SRB) on the Corrosion of Buried Pipe Steel in Acidic Soil Solution

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 625
Author(s):  
Lijuan Chen ◽  
Bo Wei ◽  
Xianghong Xu
Keyword(s):  
Soil Solution ◽  
Steel Surface ◽  
Pipeline Steel ◽  
Electrochemical Techniques ◽  
Sulfate Reducing Bacteria ◽  
Acidic Soil ◽  
Microbiologically Influenced Corrosion ◽  
Soil Environment ◽  
Sulfate Reducing ◽  
Reducing Bacteria

The influence of sulfate-reducing bacteria (SRB) on the corrosion behaviors of X80 pipeline steel was investigated in a soil environment by electrochemical techniques and surface analysis. It was found that SRB grew well in the acidic soil environment and further attached to the coupon surface, resulting in microbiologically influenced corrosion (MIC) of the steel. The corrosion process of X80 steel was significantly affected by the SRB biofilm on the steel surface. Steel corrosion was inhibited by the highly bioactive SRB biofilm at the early stage of the experiment, while SRB can accelerate the corrosion of steel at the later stage of the experiment. The steel surface suffered severe pitting corrosion in the SRB-containing soil solution.

scholarly journals Influence of the ultrasonic surface rolling process on stress corrosion cracking susceptibility of high strength pipeline steel in neutral pH environment

RSC Advances ◽  
2017 ◽  
Vol 7 (59) ◽  
pp. 36876-36885 ◽  
Author(s):  
Bingying Wang ◽  
Yu Yin ◽  
Zhiwei Gao ◽  
Zhenbo Hou ◽  
Wenchun Jiang
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Pipeline Steel ◽  
High Strength ◽  
Rolling Process ◽  
Corrosion Cracking ◽  
X80 Pipeline Steel ◽  
Enhancement Technique ◽  
Neutral Ph ◽  
Developed Surface

A developed surface enhancement technique, USRP, was applied on X80 pipeline steel and the stress corrosion cracking susceptibility was studied.

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