Studying Stress Corrosion Cracking Crack Initiation in Pipeline Steels in a Near-Neutral pH Environment: The Role of Hydrotesting

CORROSION ◽  
10.5006/3492 ◽  
2020 ◽  
Vol 76 (11) ◽  
Author(s):  
Zeynab Shirband ◽  
Jing-Li Luo ◽  
Reginald Eadie ◽  
Weixing Chen
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
High Pressures ◽  
Initial Study ◽  
Corrosion Cracking ◽  
Pressure Cycling ◽  
Small Cracks ◽  
Crack Transition ◽  
Operational Failures

Hydrostatic testing, or hydrotesting, has been widely used as a stress corrosion cracking management method in the pipeline industry, particularly in gas pipelines. Although the technique has been very useful in the prevention of operational failures, it is known that these high pressures can produce significant plastic deformation around stress concentrators, such as pits and other surface flaws, that might be present. This plasticity can temporarily retard long, well-developed cracks; however, the effect of this plasticity on growth of very small cracks has not previously been studied. In this work, a long-term test was conducted to simulate real pipeline pressure cycling conditions by the application of occasional hydrotesting loads on steel samples. Crack initiations from pits were compared between specimens undergoing no hydrotesting load (control specimens) and those that underwent three hydrotest cycles during the test. The results showed that pit-to-crack transition was enhanced by the application of three hydrotesting loads. Seventy percent more cracks were found to have grown beyond ferrite grain boundaries in the hydrotested specimens. This initial study indicated substantial differences between small crack formation with and without hydrotesting. These differences predict significantly higher short crack growth in the hydrotested samples. Further study is necessary to further delineate these effects.

On the role of intergranular nanocavities in long-term stress corrosion cracking of Alloy 690

2021 ◽  
pp. 117453
Author(s):  
Zhao Shen ◽  
Edward Roberts ◽  
Naganand Saravanan ◽  
Phani Karamched ◽  
Takumi Terachi ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Alloy 690

Methodology to Develop Fitness-for-Service Assessments for Crack Detection In-Line Inspection Data

2006 ◽  
Author(s):  
David Shanks ◽  
Rob Leeson ◽  
Corina Blaga ◽  
Rafael G. Mora
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Crack Detection ◽  
Corrosion Cracking ◽  
Life Extension ◽  
Remaining Life ◽  
Service Monitoring ◽  
Criticality Assessment ◽  
Inspection Data

Implementation of Integrity Management Programs (IMP) for pipelines has motivated the design of Fitness-For-Service methodologies to assess Stress Corrosion Cracking (SCC) and fatigue-dependent features reported by Ultrasonic Crack Detection (UTCD) In-Line Inspections. The philosophical approach defined by the API 579 [1] “Fitness-For-Service” from the petrochemical industry in conjunction with Risk-based standards and regulations (i.e. CSA-Z662-2003 [2] and US DOT 49 Parts 192 [3] and 195 [4]) and in-line inspection validation (i.e. API 1163 [5]) approaches from the pipeline industry have provided the engineering basis for ensuring the safety, reliability and continued service of the in-line inspected pipelines. This paper provides a methodology to develop short and long-term excavation and re-inspection programs through a four (4) phase-process: Pre-Assessment, Integrity Criticality Assessment, Remediation and Repair, Remaining Life Extension and In-Service Monitoring. In the first phase, Pre-assessment, areas susceptible to Stress Corrosion Cracking (SCC) and fatigue-dependent features are correlated to in-line inspection data, soil modeling, pipeline and operating conditions, and associated consequences in order to provide a risk-based prioritization of pipeline segments and technical understanding for performing the assessment. The second phase, Integrity Criticality Assessment, will develop a short-term maintenance program based on the remaining strength of the in-line inspection reported features previously correlated, overlaid and risk-ranked. In addition, sites may be identified in Phase 1 for further investigation. In the third phase, a Remediation and Repair program will undertake the field investigation in order to repair and mitigate the potential threats as well as validating the in-line inspection results and characterization made during the Pre-assessment and Integrity Criticality Assessment (Phases 1 & 2). With the acquired knowledge from the previous three (3) phases, a Remaining Life Extension and In-Service Monitoring program will be developed to outline the long-term excavation and re-inspection program through the use of SCC and Fatigue crack growth probabilistic modeling and cost benefit analysis. The support of multiple Canadian and US pipeline operating companies in the development, validation and implementation of this methodology made this contribution possible.

Effect of Long-Term Service Exposure on the Localized Corrosion and Stress Corrosion Cracking Susceptibility of Type 347 Stainless Steel

CORROSION ◽  
10.5006/2612 ◽  
2017 ◽  
Vol 74 (3) ◽  
pp. 350-361 ◽  
Author(s):  
K. Ravindranath ◽  
N. Tanoli ◽  
B. Al-Wakaa
Keyword(s):  
Stainless Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Localized Corrosion ◽  
X Ray Diffraction ◽  
Degree Of Sensitization ◽  
Corrosion Susceptibility ◽  
Service Exposure

The paper presents the results of a study conducted on the effects of long-term service exposure of Type 347 stainless steel (SS) on the microstructure and corrosion susceptibility. The material subjected to the study was in service in a petroleum refinery as heater tube at 620°C for 31 years. The microscopic and x-ray diffraction studies of the service-exposed specimen revealed the precipitation of chromium-rich carbides along the grain boundaries. The microstructural changes that occurred as a result of service exposure affected the ductility and toughness of the alloy. The sensitization of the alloy was assessed by scanning electron microscopy and double loop electrochemical potentiodynamic reactivation. The studies have indicated some degree of sensitization in the alloy. The service exposure resulted in a marginal increase in the susceptibility of Type 347 SS to pitting in environments containing NaCl and NaCl + H2S. Environments such as H2SO4 and K2S4O6 at the tested concentrations did not differentiate between service-exposed and solution annealed specimens for their corrosion susceptibility. Slow strain rate testing of Type 347 SS in both the service-exposed and solution annealed conditions showed susceptibility to stress corrosion cracking in environment containing NaCl + H2S, while the alloy did not show susceptibility to SCC in H2SO4 and K2S4O6. The long-term service exposure did not noticeably influence the SCC susceptibility of Type 347 SS under the tested conditions.

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.

Role of Cavity Formation on Long-Term Stress Corrosion Cracking Initiation: A Review

CORROSION ◽  
10.5006/3374 ◽  
2019 ◽  
Vol 76 (2) ◽  
pp. 142-175
Author(s):  
Koji Arioka
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Life Extension ◽  
Cavity Formation ◽  
Material Degradation ◽  
Term Operation ◽  
Fundamental Research

Plant life extension from the initial licensed life to beyond 60 years is now being discussed for light water cooled nuclear powered reactors (LWRs). Reliable prediction for material degradation is extremely important to keep the reliability of LWRs during such long-term operation. One of the specific perspectives for this prediction is to take into account the changes in material properties during long-term operation, such as cavity formation, even at the LWR operating temperature. The mechanism of cavity formation and the associated phenomena are closely intertwined with interdisciplinary technological and scientific knowledge. Therefore, historical key knowledge from both phenomenological and fundamental research studies related to cavity formation was first reviewed to understand the overall picture. Subsequently, current research results related to long-term stress corrosion cracking initiation in the LWR environment were summarized to explain what is known, what is still unknown, and what are the critical remaining subjects.

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