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.

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.

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.

Using In-Line Inspection to Address Deformations Containing Near-Neutral pH Stress Corrosion Cracking

2002 ◽  
Author(s):  
Dennis C. Johnston ◽  
Thomas G. Hrncir
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Transverse Field ◽  
Corrosion Cracking ◽  
Slope Deformation ◽  
Pipeline System ◽  
Dissolved Carbon ◽  
Neutral Ph ◽  
Ph Stress ◽  
Pipe Line

Marathon Ashland Pipe Line LLC (MAPL) experienced a pipeline release on January 27, 2000 from cracking in a bottom-side shallow deformation. The crack that caused the release was determined to have propagated due to corrosion fatigue that progressed from an area of near-neutral pH stress corrosion cracks. A combination of a transverse field magnetic flux inspection (TFI) tool and a slope-deformation tool were used to inspect the entire pipeline segment for additional injurious deformations that could contain cracks. The TFI tool data were used to differentiate deformations that contained linear indications (typically cracks or corrosion) from deformations that did not. The slope-deformation tool data were used to measure the deformation magnitudes and shapes and to assist with locating the (TFI) deformations that were to be excavated. The pipe conditions necessary for these types of cracking to occur are discussed as well as the findings of the in-line inspection and remediation program. Prior to this release, it was perceived within the industry that constrained shallow deformations were not likely to fail catastrophically. The failure mechanism, particularly from constrained deformations, was normally as a leak. The near-neutral pH stress corrosion cracking phenomenon within deformations was first thought to be a unique event. Based on the investigation program conducted by MAPL, this phenomenon was identified elsewhere within the pipeline system. Based on MAPL’s investigation, pipelines susceptible to or containing slight deformations (typically high D/t ratios) in areas with groundwater containing high levels of dissolved carbon dioxide and coated with materials prone to shielding cathodic protection may be particularly susceptible to the deformation near-neutral pH stress corrosion cracking phenomenon.

scholarly journals Bounding Surface Flaw Configuration Susceptible to Stress Corrosion Cracking Under Welding Residual Stress in a Multiple-Purpose Canister

2017 ◽  
Author(s):  
Poh-Sang Lam ◽  
Robert L. Sindelar ◽  
Andrew J. Duncan ◽  
Joe T. Carter
Keyword(s):  
Residual Stress ◽  
Stress Intensity ◽  
Stress Corrosion ◽  
Nuclear Fuel ◽  
Stress Corrosion Cracking ◽  
Spent Nuclear Fuel ◽  
Management Program ◽  
Corrosion Cracking ◽  
Surface Flaw ◽  
Welding Residual Stress

The part-through-wall crack perpendicular to the circumferential weld on the outside surface of a spent nuclear fuel (SNF) multiple-purpose canister (MPC) can be shown to be the most limiting fracture configuration driven by the welding residual stress (WRS). A series of semi-elliptical cracks of various sizes is chosen to calculate the stress intensity factors (K) under a bounding residual stress (i.e., the stress distribution that bounds all WRS in a canister). The threshold stress intensity factor (KISCC) of the canister material in the storage environment is used to determine a critical flaw size, below which the stress corrosion cracking would be unlikely to take place. This result can be considered as the flaw disposition criterion should a surface flaw be detected during the inservice inspection as required by the aging management program (AMP), and can be proposed to American Society of Mechanical Engineers (ASME) Section XI Code Case N-860, “Examination Requirements and Acceptance Standards for Spent Nuclear Fuel Storage and Transportation Containment Systems.”

The CEPA Report on Circumferential Stress Corrosion Cracking

1998 ◽  
Author(s):  
Robert L. Sutherby
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Research Effort ◽  
Circumferential Stress ◽  
Corrosion Cracking ◽  
Soil Movement ◽  
Significant Research ◽  
Potential Risks ◽  
Management Approaches ◽  
Pipe Bending

According to the NEB Report of the recent inquiry on pipeline stress corrosion cracking (NEB Order No. MH-2-95), six of the Canadian failures to that time had been leaks resulting from circumferentially-oriented cracks. A review has been made of the five CEPA leaks; two leaks from non-CEPA companies; and a case of non-leaking circumferential SCC, also from CEPA. All of the Canadian cases occurred in regions of west and central Alberta. Circumferential stress corrosion cracking is a rare cause of pipeline leakage. Canadian cases have occurred in very specific conditions that exist in only a small proportion of the regions where pipelines operate. All cases of circumferential SCC, to date, have occurred under either polyethylene tape or a polyethylene backed shrink sleeve. The SCC appears to have been of the neutral-pH form and initiated and grew in response to high axial stresses generated by soil creep and/or localized pipe bending on slopes of 10° or greater. In this sense, circumferential SCC is a manifestation of a geotechnical instability in an area of SCC susceptibility. It would be prudent for operators of susceptible pipelines to consider the potential risks of such failures and to manage those risks accordingly. Management of circumferential SCC may be largely achieved by effective management of geotechnical concerns on slopes. Geotechnical programs directed toward preventing soil movement or pipe loading could have benefit with respect to preventing circumferential SCC in susceptible areas. Other management approaches, involving in-line inspection tools, may also be found to have benefit. Given that circumferential SCC (C-SCC) is driven by geotechnical instability, a significant research effort directed specifically toward C-SCC is not considered warranted at this time. Rather, geotechnical research will augment SCC research in progress to provide insight and capabilities to manage the concern. To assist pipeline operators, CEPA will issue, in 1998, a revision of the SCC Recommended Practices providing guidance to manage this concern.

Stress Corrosion Cracking “Like-in-Kind” Reliability Approach for Pipelines Without Crack Tool In-Line Inspection

2020 ◽  
Author(s):  
Amal Elsisi ◽  
Winston Y. W. Lee ◽  
Pushpendra Tomar ◽  
Dan Williams
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Direct Limit ◽  
Limit State ◽  
Corrosion Cracking ◽  
Pipeline System ◽  
Acoustic Transducer ◽  
Threat Level ◽  
Transmission Pipeline ◽  
Electro Magnetic

Abstract Gas transmission pipeline operators increasingly rely on Electro-Magnetic Acoustic Transducer (EMAT) technology to reliably detect, identify and size stress corrosion cracking (SCC) anomalies in their pipeline system. However, scheduling EMAT in-line inspection (ILI) on every pipeline in the system is not always practicable or achievable in an expeditious manner. A means of conducting a preliminary assessment of the SCC threat on pipelines without EMAT ILI data in an objective and quantifiable manner is useful for understanding the threat level and for prioritizing or deciding on outstanding EMAT inspections. A wealth of system-specific SCC field data from historical integrity excavations across the pipeline system typically exists in a pipeline operator’s dataset and can be readily leveraged for quantitatively estimating the SCC threat reliability in other, similar (“like-in-kind”) parts of the pipeline system. This system-specific data, based on actual SCC findings from integrity excavations, is an improved and more granular alternative to applying industry-wide SCC statistics to estimates of SCC reliability levels on pipelines without EMAT ILI data. This paper presents a robust and direct limit state approach for estimating the SCC reliability level in pipelines that have not yet had an EMAT ILI completed by leveraging system-wide SCC field findings from historical integrity excavations.

Now You SCC Me, Now You Don’t: Using Machine Learning to Find Stress Corrosion Cracking

2020 ◽  
Author(s):  
Michael Smith ◽  
Aidan Blenkinsop ◽  
Matthew Capewell ◽  
Brian Kerrigan
Keyword(s):  
Machine Learning ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Acoustic Waves ◽  
Good Practice ◽  
Metal Structure ◽  
Corrosion Cracking ◽  
Supervised Machine Learning ◽  
Pipeline System ◽  
Electromagnetic Acoustic Transducer

Abstract Electromagnetic Acoustic Transducer (EMAT) is a non-destructive inspection technology that uses guided acoustic waves to detect planar flaws in a metal structure. When deployed via in-line inspection (ILI), it is an effective way to detect cracks in a pipeline. EMAT has thus become a staple of crack management programs throughout the world since its introduction to the market over a decade ago. As with all technologies, challenges remain with the inspection process. One such challenge with EMAT is classification. While it is possible to determine that a defect is “crack-like” (a property determined by its tendency to reflect incident waves), it is difficult to determine the nature of the defect from the EMAT measurement alone. Indeed, similar reflections are obtained for many different types of defects, from relatively benign manufacturing and construction abnormalities, to more concerning anomalies such as stress corrosion cracking (SCC). To compensate for the difficulties in classification, it is good practice to follow up an EMAT inspection with a number of in-field verifications. These investigations allow for a more direct observation of classification and size, and provide valuable information about the nature of cracks. They are, however, expensive — meaning that avoiding unnecessary digs is a top priority. In this paper, we document a developing approach to post-ILI crack management, whereby the results of an EMAT run are combined with those from field verifications to maximize the amount of information gained from costly field work. This approach — which relies on supervised machine learning — leads to a marked improvement in the classification of crack-like indications from EMAT, and allows future investigations to be prioritized according to the likelihood of finding a concerning defect. The method was trialed on a pipeline system with extensive SCC, leading to an improved success rate in finding SCC, and a more cost effective crack management plan.

AMBRONZE 413

Alloy Digest ◽  
1969 ◽  
Vol 18 (6) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Surface Treatment ◽  
Stress Corrosion ◽  
Tensile Properties ◽  
Stress Corrosion Cracking ◽  
Electrical Contact ◽  
Heat Treating ◽  
Corrosion Cracking ◽  
Tin Bronze

Abstract AMBRONZE 413 is a copper-tin bronze recommended for plater's plates and electrical contact springs. It is relatively immune to stress-corrosion cracking. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cu-201. Producer or source: Anaconda American Brass Company.

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