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

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.

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Acoustic detection of stress-corrosion cracking of nitrogen austenitic steels

The Physics of Metals and Metallography ◽

10.1134/s0031918x14060076 ◽

2014 ◽

Vol 115 (6) ◽

pp. 586-599 ◽

Cited By ~ 13

Author(s):

Yu. I. Filippov ◽

V. V. Sagaradze ◽

V. A. Zavalishin ◽

N. L. Pecherkina ◽

N. V. Kataeva ◽

...

Keyword(s):

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Corrosion Cracking ◽

Austenitic Steels ◽

Acoustic Detection ◽

Detection Of Stress

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Development and Experiences of a Circumferential Stress Corrosion Crack Management Program

Volume 1: Pipeline and Facilities Integrity ◽

10.1115/ipc2018-78315 ◽

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.

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Getting to Know Your Bends to Support SCC Management

Volume 1: Pipeline and Facilities Integrity ◽

10.1115/ipc2020-9578 ◽

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.

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Detection of Stress Corrosion Cracking by Direct-Current Potential Difference Method

ASME 2011 Pressure Vessels and Piping Conference: Volume 5 ◽

10.1115/pvp2011-57913 ◽

2011 ◽

Author(s):

Naoya Tada ◽

Makoto Uchida ◽

Hiroki Maeda ◽

Atsushi Hozuki

Keyword(s):

Stress Corrosion ◽

Direct Current ◽

Stress Corrosion Cracking ◽

Difference Method ◽

Corrosion Cracking ◽

Potential Difference ◽

Measurement Results ◽

Detection Of Stress ◽

Metal Weld ◽

Current Potential

Stress corrosion cracking (SCC) is one of serious damages occurred in power generating plants, petrochemical plants, and gas pipelines. However, it is not easy to detect and evaluate SCCs because their shapes are complex and they are usually initiated in the weldment composed of base metal, weld metal, and heat-affected zone. In this study, the direct-current potential difference method (DC-PDM) was applied to SCCs artificially introduced in plate specimens and the applicability of DC-PDM to their detection was discussed. It was found from the measurement results that the potential differences near SCC were higher than those away from SCC. This fact suggests that SCC is detectable by DC-PDM.

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Detection and Verification of SCC in a Gas Transmission Pipeline

Volume 2: Integrity and Corrosion; Offshore Issues; Pipeline Automation and Measurement; Rotating Equipment ◽

10.1115/ipc2000-184 ◽

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.

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Crack Detection Using Acoustic Emission Methods – Fundamentals and Applications

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.293-294.33 ◽

2005 ◽

Vol 293-294 ◽

pp. 33-48 ◽

Cited By ~ 6

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.

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