Development and Experiences of a Circumferential Stress Corrosion Crack Management Program

2018 ◽  
Author(s):  
Neil Bates ◽  
Mark Brimacombe ◽  
Steven Polasik
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Crack Detection ◽  
Circumferential Stress ◽  
Management Program ◽  
Corrosion Cracking ◽  
Pipeline System ◽  
Average Growth ◽  
Proactive Management ◽  
Inspection Data

A pipeline operator set out to assess the risk of circumferential stress corrosion cracking and to develop a proactive management program, which included an in-line inspection and repair program. The first step was to screen the total pipeline inventory based on pipe properties and environmental factors to develop a susceptibility assessment. When a pipeline was found to be susceptible, an inspection plan was developed which often included ultrasonic circumferential crack detection in-line inspection and geotechnical analysis of slopes. Next, a methodology was developed to prioritize the anomalies for investigation based on the likelihood of failure using the provided in-line inspection sizing data, crack severity analysis, and correlation to potential causes of axial or bending stress, combined with a consequence assessment. Excavation programs were then developed to target the anomalies that posed the greatest threat to the pipeline system or environment. This paper summarizes the experiences to date from the operator’s circumferential stress corrosion cracking program and describes how the pipeline properties, geotechnical program, and/or in-line inspection programs were combined to determine the susceptibility of each pipeline and develop excavation programs. In-line inspection reported crack types and sizes compared to field inspection data will be summarized, as well as how the population and severity of circumferential stress corrosion cracking found compares to the susceptible slopes found in the geotechnical program completed. Finally, how the circumferential SCC time-average growth rate distributions were calculated and were used to set future geohazard inspections, in-line inspections, or repair dates will be discussed.

Complex Circumferential Stress Corrosion Cracking: Identification, Sizing and Consequences for the Integrity Management Program

2018 ◽  
Author(s):  
Brett Johnson ◽  
Bereket Tesfaye ◽  
Cory Wargacki ◽  
Thomas Hennig ◽  
Ernesto Suarez
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Service Providers ◽  
Circumferential Stress ◽  
Management Program ◽  
Corrosion Cracking ◽  
Pipeline System ◽  
Mountain Areas ◽  
Circumferential Welds ◽  
Circumferential Crack

Since the late 1980’s Ultrasonic tools have been used for the detection and sizing of crack like indications. ILI service providers developed inspection technologies for liquid and gas lines that are widely used nowadays. In comparison to axial cracking, circumferential cracking is not a prevalent risk to most pipelines and therefore is not as well understood. Nevertheless, pipeline Operators observe from time to time circumferentially oriented defects, often in combination with circumferential welds or local stress/strain accumulations. These are often caused by pipeline movement, which may especially occur in mountain areas. With the introduction of Ultrasonic circumferential crack inspection tools in the late 2000’s the knowledge has steadily increased over time. Extensive data collected from in-ditch NDE validations has provided NDT Global with an increased knowledge of the morphology of single cracking and stress corrosion cracking defects both in the axial and circumferential orientations. Field verifications have shown that not all features have the same morphology. Some of the challenges with circumferential cracking are for features that fall outside of the industry standard specifications. These types of features can exhibit characteristics such as being sloped, skewed or tilted. In 2016 NDT Global was approached by Plains Midstream Canada to complete inspections utilizing the 10″ Ultrasonic Circumferential crack inspection technology. The pipeline system spans 188km within Canada and consists of 2 segments. The pipeline traverses several elevation changes and crosses several creeks and roads. Circumferential cracking was identified during dig campaigns performed for other threats, therefore the need to inspect each pipeline segment with the Ultrasonic circumferential technology was identified. Plains Midstream Canada and NDT Global formed a close collaboration to assess the severity of circumferential crack features in this line. This paper will discuss integrity aspects from an Operator and Vendor perspective. Challenges identified due to the morphology of the circumferential crack like indications and derived analysis rules and interpretation methodologies to optimize characterization and sizing are presented. Finally, potential opportunities to maintain the integrity of similar assets by applying some of the findings and enhance the management and decision making process are suggested.

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.

Getting to Know Your Bends to Support SCC Management

2020 ◽  
Author(s):  
Chris Wood ◽  
Fernando Merotto ◽  
Brian Kerrigan ◽  
Ramon Loback ◽  
Pedro Gea
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Crack Detection ◽  
Axial Stress ◽  
Corrosion Cracking ◽  
Inspection System ◽  
Pipe Material ◽  
Baseline Assessment ◽  
Limited Information ◽  
Metallographic Examination

Abstract Nova Transportadora do Sudeste (NTS) own and operate a gas transmission system in Brazil constructed in 1996. One of the confirmed primary integrity threats to this system is axial stress corrosion cracking. The pipelines vary in diameter, weld type, manufacturer and age. One of the pipelines failed in 2015 due to an axial stress corrosion crack. Since the failure, NTS have executed an intense inspection campaign to detect and size axial cracking within their network. The 2015 failure occurred on a field bend. The inspection campaign and following dig campaign has confirmed that cracking (both axial and circumferential) within field bends is the primary integrity threat. Brazil has a challenging terrain and approximately 40% of joints within the network were subject to cold field bending. The influences of the pipeline geometry within these areas have resulted in localised elevated stresses where the axial stress corrosion cracking colonies are initiating and growing. To date, no cracking (axial or circumferential) has been verified within their straight pipe joints. NTS initially took a conservative baseline assessment approach using API 579 Part 9, due to the limited information regarding the pipe material and complex stress state. In addition to the hoop stress from internal pressure, the baseline assessment also considered weld residual stress and bending stress due to ovalization to determine immediate and future integrity. An intensive dig campaign is underway following a crack detection in-line inspection campaign using electromagnetic acoustic transducer technology. A large number of deep cracks were reported by the in-line inspection system, these were verified to be deep and repaired with a type B sleeve. However, at one site an entire joint was removed for further analysis, to investigate the crack morphology, confirm material properties and refine the predictive failure pressure modelling. This paper outlines how NTS have combined a burst test, mechanical testing, FEA modelling, fractography and metallographic examination to further understand the feature morphology and stresses within these areas and how they have been able to reduce conservatism from their baseline assessment with confidence and adopt a plastic collapse approach to accurately predict failure.

Statistical Predictive Modelling: A Methodology to Prioritize Site Selection for Near-Neutral pH Stress Corrosion Cracking

2010 ◽  
Author(s):  
Edgar I. Cote ◽  
James Ferguson ◽  
Nauman Tehsin
Keyword(s):  
Tensile Stress ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Probability Of Detection ◽  
Predictor Variables ◽  
Neutral Ph ◽  
Proactive Management ◽  
Ph Stress ◽  
Axial Defects

Pipelines are subjected to both residual and applied tensile stresses, and can form near-neutral pH SCC (transgranular stress corrosion cracking) if the pipeline is exposed to a conducive environment and is made from a material that is susceptible to SCC. This transgranular SCC is an ongoing integrity concern for pipeline operators. As part of an SCC Integrity Management Program (IMP), it is necessary to perform integrity assessments and prioritize segments of the pipelines to manage the SCC threat. Ultrasonic crack detection in-line inspection tools have proven capable of locating SCC, but reliability of these tools is not absolute and the reduced probability of detection of subcritical flaws limits options for proactive management. Hydrostatic retesting is a very effective program for removing near-critical axial defects, such as SCC, but does not provide useful information as to the location of SCC along the pipeline. NACE Standard RP0204-2004 (SCC Direct Assessment Methodology or SCCDA) outlines factors to consider and methodologies to employ to predict where the SCC is likely to occur, but the standard acknowledges that there are no well-established methods for predicting the presence of SCC with a high degree of certainty. The trend in probabilistic modelling has been to focus on establishing deterministic relationships between environmental factors, tensile stress and SCC formation, and growth; these models have achieved varying degrees of success. The Statistical Predictive Model (SPM) was previously developed to predict the likelihood of occurrence of near-neutral pH Stress Corrosion Cracking (SCC) for the NPS 10 Alberta Products Pipeline (APPL). SPM Phase 5 uses selected predictor variables representing tensile stress, environmental, pipe-related, corrosion control and operational relevant factors to determine the Probability of Occurrence of SCC. Regression techniques were used to create multi-variable logistic regression models. The results for each model are checked at locations where SCC is known to be present or absent to assess predictive accuracy, then used to prioritize susceptible segments for field excavation. The relative strength of individual predictor variables provides insight into the mechanism of near-neutral pH SCC crack initiation.

Characteristics, Causes, and Management of Circumferential Stress-Corrosion Cracking

2014 ◽  
Author(s):  
Raymond R. Fessler ◽  
Millan Sen
Keyword(s):  
Residual Stresses ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Axial Stress ◽  
Circumferential Stress ◽  
The United States ◽  
Maximum Tensile Stress ◽  
Corrosion Cracking ◽  
Poisson Effect ◽  
Bent Pipe

While much more rare than axial stress-corrosion cracking (SCC), circumferential SCC (CSCC) has been observed in pipelines in Canada, the United States, and two European countries. In some cases, the CSCC has been of sufficient size to cause in-service leaks. Because the orientation of stress-corrosion cracks invariably is perpendicular to the maximum tensile stress, the axial stresses at the locations of the cracks must have been greater than the hoop stress. The Poisson effect and thermal effects can account for about half of the axial stresses. Evidence from the field suggests that there are three probable sources of additional axial stresses that can promote CSCC: residual stresses in bent pipe, axial stresses caused by movement of unstable soil on slopes, and residual stresses opposite rock dents. CSCC can be managed by one or a combination of the following procedures: direct assessment (DA), in-line inspection (ILI), or hydrostatic testing. Guidance for selection of sites for DA is derived from industry experience, which was determined from responses to a questionnaire and published reports. The capabilities of ILI to detect circumferential stress-corrosion cracks or the conditions that promote them are summarized. The benefits and limitations of hydrostatic testing also are described. A method for calculating the size of circumferential flaws that can cause ruptures is presented and compared with service experience. That information can provide useful guidance for ILI requirements and decisions about which flaws need to be removed immediately.

scholarly journals Remote detection of stress corrosion cracking: Surface composition and crack detection

2018 ◽  
Author(s):  
Cliff J. Lissenden ◽  
Igor Jovanovic ◽  
Arthur T. Motta ◽  
Xuan Xiao ◽  
Samuel Le Berre ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Crack Detection ◽  
Surface Composition ◽  
Corrosion Cracking ◽  
Remote Detection ◽  
Detection Of Stress

scholarly journals Detection and Verification of SCC in a Gas Transmission Pipeline

2000 ◽  
Author(s):  
B. Ashworth ◽  
Neb Uzelac ◽  
H. Willems ◽  
O. A. Barbian
Keyword(s):  
Stress Corrosion ◽  
Wall Thickness ◽  
Stress Corrosion Cracking ◽  
Confidence Level ◽  
Crack Detection ◽  
Corrosion Cracking ◽  
Inspection Method ◽  
Transmission Pipeline ◽  
History Of ◽  
Location Type

Two sections of a 914mm OD (36 in.) TransCanada (TCPL) gas transmission pipeline (predominantly with 9.14 mm wall thickness) were inspected using an ultrasonic liquid coupled crack detection In-Line Inspection (ILI) tool. One of the objectives of the inspection was to establish the condition of the pipeline sections with a known history of stress-corrosion cracking (SCC). Under test was the practicability of inspecting a gas line using a liquid coupled ILI tool, specifically its ability to detect and size defects deeper than 1 mm and distinguish cracks and crack-like defects from other types of anomalies, such as inclusions and laminations. In order to assess the confidence level of the tool, both sections were inspected in two independent runs and the repeatability of inspection was assessed. Cracks and crack-like defects with depths greater than 12.5% of the wall thickness from both runs were compared and correlation was established to assess repeatability. The accuracy of tool predictions was verified in excavations in both sections. 40 reported features, varying in depths up to over 40% were examined with respect to location, type, and size. Examples of defect patterns are shown to demonstrate the accuracy of the inspection method.

Crack Detection Using Acoustic Emission Methods – Fundamentals and Applications

2005 ◽  
Vol 293-294 ◽  
pp. 33-48 ◽  
Author(s):  
Leonard M. Rogers
Keyword(s):  
Acoustic Emission ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Wave ◽  
Stress Corrosion Cracking ◽  
Crack Detection ◽  
Signal Amplitude ◽  
Offshore Structures ◽  
Corrosion Cracking ◽  
Measured Signal

This paper addresses the fundamentals of the acoustic emission effect associated with fatigue and stress corrosion cracking in metals. It considers the microstructure of cracks and the magnitude of the different types of physical event that can occur at the crack tip during plastic deformation and stable crack growth. Expressions are given for the threshold plastic zone size ‘Dl’ at which local fracture instability occurs and the stress-wave displacement amplitude as a function of distance ‘ui(r)’ for the different wave types ‘i’ produced during crack extension. Dispersion of the stress-wave and its convolution into an electrical burst signal at the sensor is considered together with the choice of appropriate sensing frequency. A methodology is described for correcting the measured signal amplitude for attenuation in the structure and for determining the maximum sensor spacing for the detection and location of events of a specified magnitude ‘Mae’ similar to the Richter scale. Case studies are presented to illustrate the extensive database now available on acoustic emission from crack growth in metallic structures and the technical and commercial benefits to be gained from an acoustic emission based inspection strategy. The applications considered are: • Fatigue crack growth in the node joints of offshore structures, • Stress corrosion cracking in platform flow lines.

Analysis of Emerging NDE Techniques: Methods for Evaluating and Implementing Continuous Online Monitoring

2009 ◽  
Author(s):  
Stephen E. Cumblidge ◽  
Steven R. Doctor ◽  
Leonard J. Bond ◽  
Tom T. Taylor ◽  
Timothy R. Lupold ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Online Monitoring ◽  
The United States ◽  
Corrosion Cracking ◽  
Review Section ◽  
The Past ◽  
Proactive Management ◽  
License Renewal

There are approximately 440 operating reactors in the global nuclear power plant (NPP) fleet with an average age greater than 20 years and original design lives of 30 or 40 years. The United States is currently implementing license extensions of 20 years on many plants, and consideration is now being given to the concept of “life-beyond-60”, license extension from 60 to 80 years and potentially longer. In almost all countries with NPPs, authorities are looking at some form of license renewal program. In support of NPP license renewal over the past decade, various national and international programs have been initiated. One of the goals of the program for the proactive management of materials degradation (PMMD) is to manage proactively the in-service degradation of metallic components in aging NPPs. As some forms of degradation, such as stress corrosion cracking, are characterized by a long initiation time followed by a rapid growth phase, new inspection or monitoring technologies may be required. New nondestructive evaluation (NDE) techniques that may be needed include techniques to find stress corrosion cracking (SCC) precursors, on-line monitoring techniques to detect cracks as they initiate and grow, as well as advances in NDE technologies. This paper reports on the first part of the development of a methodology to determine the effectiveness of these emerging NDE techniques for managing metallic degradation. This methodology will draw from experience derived from evaluating techniques that have “emerged” in the past. The methodology will follow five stages: a definition of inspection parameters, a technical evaluation, laboratory testing, round robin testing, and the design of a performance demonstration program. This methodology will document the path taken for previous techniques and set a standardized course for future NDE techniques. This paper then applies the expert review section of the methodology to the acoustic emission technique to evaluate the use of acoustic emission in performing continuous online monitoring of reactor components.

An Automated ACFM Peak Detection Algorithm With Potential for Locating SCC Clusters on Transmission Pipelines

1998 ◽  
Author(s):  
L. Blair Carroll ◽  
Craig C. Monahan ◽  
Raymond G. Gosine
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Liquid Fuel ◽  
Crack Detection ◽  
Alternating Current ◽  
Detection Algorithm ◽  
Peak Detection ◽  
Corrosion Cracking ◽  
Peak Detection Algorithm ◽  
Memorial University Of Newfoundland

The Alternating Current Reid Measurement (ACFM) crack detection and sizing technique has demonstrated its potential as a stress corrosion cracking (SCC) characterization tool in studies conducted at Memorial University of Newfoundland (MUN). It’s ability to detect and size cracks through non-conductive coating thicknesses of 5 mm or more can have a significant impact on the costs associated with the current SCC investigation practices of many gas and liquid fuel transmission companies. This paper outlines work conducted at MUN in automating the detection of SCC within ACFM signals. The technique may be refined and incorporated into SCC characterization procedures.

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