A Statistical Predictive Model to Prioritize Site Selection for Stress Corrosion Cracking Direct Assessment

2006 ◽  
Author(s):  
Anthony Merle ◽  
P. F. Ehlers
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Environmental Parameters ◽  
Predictive Modelling ◽  
Corrosion Cracking ◽  
Direct Assessment ◽  
Degree Of Certainty ◽  
Regression Techniques ◽  
Selection For ◽  
High Degree

Pipeline stress-corrosion cracking (SCC) is an ongoing integrity concern for pipeline operators. A number of different strategies are currently employed to locate and mitigate SCC. Ultrasonic in-line inspection tools have proven capable of locating SCC, but reliability of these tools in gas pipelines remains in question. Rotating hydrotest programs are effectively employed by some companies but may not provide useful information as to the location of SCC along the pipeline. NACE Standard RP0204-2004 (SCC Direct Assessment Methodology) outlines factors to consider and methodologies to employ to predict where SCC is likely to occur, but even this document acknowledges that there are no well-established methods for predicting the presence of SCC with a high degree of certainty. Predictive modelling attempts to date have focused on establishing quantitative relationships between environmental factors and SCC formation and growth; these models have achieved varying degrees of success. A statistical approach to SCC predictive modelling has been developed. In contrast to previous models that attempted to determine direct correlations between environmental parameters and SCC, the new model statistically analyzed data from dig sites where SCC was and was not found. Regression techniques were used to create a multi-variable logistic regression model. The model was applied to the entire pipeline and verification digs were performed. The dig results indicated that the model was able to predict locations of SCC along the pipeline.

scholarly journals POTENTIAL MITIGATION STRATEGIES FOR PREVENTING STRESS CORROSION CRACKING FAILURES IN HIGH-BURNUP CANDU FUEL

2018 ◽  
Vol 7 (2) ◽  
pp. 127-146 ◽  
Author(s):  
Markus Piro ◽  
Dion Sunderland ◽  
Winston Revie ◽  
Steve Livingstone ◽  
Ike Dimayuga ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Lessons Learned ◽  
Mitigation Strategies ◽  
Nuclear Materials ◽  
Characterization Methods ◽  
Candu Reactors ◽  
High Degree ◽  
Fuel Doping

Potential mitigation strategies for preventing stress corrosion cracking (SCC) failures in CANDU fuel cladding that are based on lessons learned on both domestic and international fronts are discussed in this paper. Although SCC failures have not been a major concern in CANDU reactors in recent decades, they may resurface at higher burnup for conventional fuels or with nonconventional fuels that are currently being investigated, such as MOX or thoria-based fuels. The motivation of this work is to provide the foundation for considering possible remedies for SCC failures. Three candidate remedies are discussed, namely improved fabrication methods for fuel appendages, barrier-liner cladding, and fuel doping. In support of this effort, recent advances in experimental characterization methods are described—methods that have been successfully used in non-nuclear materials that can be used to further elucidate SCC behaviour in CANDU fuel. The overall objective is to outline a path forward for characterizing material behaviour as an essential part of investigating remedies to SCC failure. This will allow increased fuel discharge burnup, maximum linear power, and plant manoeuvrability, while maintaining a high degree of reliability.

Advanced Eddy Current Array Tools for Stress Corrosion Cracking Direct Assessment on Pipelines

2020 ◽  
Author(s):  
Michael Sirois ◽  
Mathieu Bouchard ◽  
Ahmed Sweedy
Keyword(s):  
Stress Corrosion ◽  
Eddy Current ◽  
Stress Corrosion Cracking ◽  
Human Factor ◽  
Corrosion Cracking ◽  
Probability Of Detection ◽  
Ease Of Use ◽  
Process Efficiency ◽  
Screening Process ◽  
Direct Assessment

Abstract Magnetic Particle Inspection (MPI) has been the main reference for Stress Corrosion Cracking (SCC) detection in pipeline integrity for years. Although this technique is relatively economical and easy to deploy — thanks to a large pool of certified technicians — it remains time consuming and highly user dependent. Some of the factors impacting results during SCC Direct Assessment (SCCDA) include the total surface area requiring examination, hard-to-reach positions underneath pipes during inspection, improper surface preparation due to poor sandblast or contrast, condensation on pipes, and operator fatigue. Recent trials have proved that Eddy Current Array (ECA) technology compares favorably against MPI on many aspects in the field, and that ECA has the potential to become the new standard for SCCDA on pipelines. Offering an impressive speed, combined with a particularly high Probability of Detection (PoD), ECA could transform the work of technicians in ditches and above all, offer greater control over the human factor. Besides detection, ECA has also proven its reliability for SCC characterization on real SCC colonies in both lab and field environments. Comparisons to metallography sections, grinding measurements and X-Ray Computed Tomography (XCT) data have greatly contributed to optimized depth sizing algorithms for this new solution, providing accurate SCC depth readings. Although ECA and Phased Array Ultrasonic Testing (PAUT) are often complementary techniques in the field, the main advantage of ECA over PAUT resides in the short amount of time required to locate and size the deepest cracks among colonies containing sometimes thousands of cracks. Within a few minutes, technicians and engineers know where to concentrate and how critical SCC really is so that decisions can be made instantly. Combining ease of use and repeatability (ways to control the human factor) is another key benefit of ECA technology. This paper provides information about a complete ECA solution for SCC detection and depth sizing on pipelines. It reveals results from the field, comparing ECA with MPI, covering several key points and demonstrating how ECA stands out as improving the overall screening process efficiency during examinations in digs. Furthermore, it also exposes and compares ECA data with both destructive and non-destructive testing performed on test pieces containing real SCC.

Determining the Number of Excavations Required to Confirm the Presence or Absence of SCC on a Pipeline Following an SCCDA Process

2016 ◽  
Author(s):  
Guy Desjardins ◽  
John MacKenzie ◽  
David Aguiar
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Research Council ◽  
Practical Method ◽  
Corrosion Cracking ◽  
Direct Assessment ◽  
Recommended Practices

The pipeline industry has been managing the threat of Stress Corrosion Cracking (SCC) for several years using the methods developed by NACE SCCDA [1] (Stress Corrosion Cracking Direct Assessment) and ASME B31.8S [2] standards. SCCDA is a widely accepted tool for assessing the threat of Stress Corrosion Cracking in pipelines. The process utilizes data from direct examinations at excavations to validate the process as well as to address existing SCC anomalies, if found. However, neither the recommended practices nor the literature provide a usable and practical method for determining the number of excavations necessary for the excavation program based on observed results. To address this question, the Pipeline Research Council International (PRCI) sponsored a project to develop a statistically defendable procedure to determine the number of excavations which would be required to validate the SCCDA process and confirm either the presence or absence of SCC.

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