Methanol-Induced Axial Stress Corrosion Cracking in a Northern Canadian Liquids Pipeline

2014 ◽  
Author(s):  
Barbara N. Padgett ◽  
Mohamed R. Chebaro ◽  
David M. Norfleet ◽  
John A. Beavers ◽  
Scott D. Ironside
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Axial Stress ◽  
Internal Surface ◽  
Corrosion Cracking ◽  
Laboratory Research ◽  
Published Data ◽  
Contributing Factors ◽  
Pipeline Steels ◽  
Oil Pipeline

Three in-service leaks on a crude oil pipeline operating in Canada were investigated to identify their metallurgical cause(s). The releases were found to be associated with cracks originating from the internal surface of the pipeline. Further similarities between the releases included: (1) the axial directionality of the cracks, (2) the short crack length, (3) the crack location adjacent to girth welds, (4) the circumferential location of the cracks and (5) the intergranular crack morphologies. A comprehensive metallurgical investigation concluded that the likely crack-initiating mechanism was methanol-induced stress corrosion cracking (SCC). While this SCC mechanism is extremely rare in buried petroleum pipelines, all other plausible causes were considered and eliminated. Methanol-induced SCC, similar to other forms of SCC, requires three contributing factors: (1) a susceptible material, (2) a corrosive environment and (3) sufficient tensile stresses. Although much research has been performed on the effects of ethanol on pipeline steels, published data on the effects of methanol is very scarce. A laboratory research program using slow strain rate (SSR) testing was initiated to determine if pipeline steels are susceptible to methanol-induced SCC and identify the conditions necessary to reproduce it in a laboratory environment. This paper outlines the major findings from this program.

Hydrogen Facilitated Anodic Dissolution Type Stress Corrosion Cracking of Pipeline Steels in Coating Disbondment Chemistry

1998 ◽  
Author(s):  
Scott X. Mao ◽  
J. L. Luo ◽  
B. Gu ◽  
W. Yu
Keyword(s):  
Stress Corrosion ◽  
Anodic Dissolution ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Strain Rates ◽  
Pipeline Steels ◽  
Dilute Aqueous Solution ◽  
Sims Analysis ◽  
Cracking Process ◽  
Secondary Ion

The stress corrosion cracking (SCC) of pipeline steels in coating disbondment chemistry (near neutral pH solution) was studied by using slow strain rate tests (SSRT), polarization techniques, SEM and SIMS (secondary ion mass spectroscope). It was found that SCC susceptibility increased as the applied electrochemical potential and strain rates decreased. Hydrogen (H) precharging or addition of CO2 facilitated the process of SCC, suggesting that dissolution and hydrogen ingress are involved in the cracking process. SIMS analysis showed that hydrogen could diffuse into steels around the crack tip during the SCC process, which would facilitate the dissolution rate of the steel and increase SCC susceptibility. A mechanism was proposed which shows that hydrogen enhances anodic dissolution type of SCC in dilute aqueous solution. A thermodynamic analysis of the SCC process was carried out, and was found to be consistent with the experimental results.

Hydrogen in stress corrosion cracking of X-70 pipeline steels in near-neutral pH solutions

2006 ◽  
Vol 41 (6) ◽  
pp. 1797-1803 ◽  
Author(s):  
Bingyan Fang ◽  
En-Hou Han ◽  
Jianqiu Wang ◽  
Ziyong Zhu ◽  
We Ke
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Pipeline Steels ◽  
Neutral Ph

The Canadian Energy Pipeline Association Stress Corrosion Cracking Database

1998 ◽  
Author(s):  
Bruce R. Dupuis
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Data Entry ◽  
Corrosion Cracking ◽  
Laboratory Research ◽  
Data Repository ◽  
Detailed Data ◽  
Current Version ◽  
Industry Standard ◽  
Operational Failures

The SCC (stress corrosion cracking) database was initiated by the CEPA (Canadian Energy Pipeline Association) SCC Working. The current generation of the database has a broad scope, containing detailed data for each and every colony and its associated environmental conditions. The database also includes corrosion and dents amongst other integrity concerns to identify any correlation with SCC and provide a common industry data format to investigate these other integrity issues. The intent of the current version of the database is to provide for the most detailed data entry that one could typically capture at an investigative dig. With the wide acceptance of the current version the CEPA database it is evolving into the industry standard for investigative excavation data. The initial trending results are based on the dataset generated by CEPA member companies, which represents over a thousand investigative excavations. The trend results should only be interpreted broadly at this time, although they do generally support industry’s understanding of SCC. The development and implementation of the CEPA SCC database is premised on the belief, developed through extensive field investigations and laboratory research, that SCC is not a random development, but it initiates and grows at specific locations susceptible to SCC. It is further premised on the belief that such susceptible sites can be generally located by appropriate prioritization techniques. Thus, the objective of the database is to explore correlation among the various operational and environmental variables to improve the current understanding of how to locate SCC, and in particular ‘significant’ SCC, in order that measures can be taken to prevent operational failures and enhance the safety of Canadian pipelines. The need for an industry database regarding SCC was identified by the CEPA SCC working group shortly after its formation 1994. It was apparent that the various companies were collecting the field data from investigative excavations in significantly different formats, only some of which were electronic. The need for a common data structure and data repository to facilitate trending was reinforced numerous times at the Banff Conferences and by the NEB during its inquiry into SCC in 1995/96.

Stress corrosion cracking of X-70 pipeline steels by eletropulsing treatment in near-neutral pH solution

2005 ◽  
Vol 40 (24) ◽  
pp. 6545-6552 ◽  
Author(s):  
Bingyan Fang ◽  
Jianqiu Wang ◽  
Suhong Xiao ◽  
En-Hou Han ◽  
Ziyong Zhu ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Pipeline Steels ◽  
Neutral Ph
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