Susceptibility of Stress Corrosion Cracking in Liquid and Gas Pipelines: A Saudi Aramco Study Using Statistical Approaches

2016 ◽  
Author(s):  
William Harper ◽  
Nader A. Al-Otaibi ◽  
Abdulaziz N. Ababtain ◽  
Thomas Bubenik ◽  
Husain M. Al-Muslim
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Crack Detection ◽  
Corrosion Cracking ◽  
Metal Loss ◽  
Electromagnetic Acoustic Transducer ◽  
Saudi Aramco ◽  
Processing Plants ◽  
Study Team ◽  
Crack Susceptibility

Owned by the Saudi Arabian Government, Saudi Aramco is a fully-integrated, global petroleum enterprise and a world leader in exploration and producing, refining, distribution, shipping and marketing. The company manages the largest proven reserves of conventional crude and the fourth-largest gas reserves in the world. The company runs a vast network of pipelines transporting oil, gas and refined products to processing plants, refineries, export terminals and other customers all over the Kingdom of Saudi Arabia. Saudi Aramco maintains its commitment to supply gas to the continuously growing local markets by implementing latest technologies and state of the art engineering solutions. Since 2009, and as a result of launching an Electromagnetic Acoustic Transducer (EMAT) In-Line Inspection (ILI) Program, Saudi Aramco has discovered Stress Corrosion Cracking (SCC) defects in a number of its pipelines. Saudi Aramco built on ASME B31.8S criteria for identifying SCC susceptible segments to prioritize its network to manage the utilization of the EMAT technology. The criteria were based on pipeline operating parameters, environment, age and condition. An Extensive Field Verification program was put in action that illustrated the capabilities of the EMAT ILI tools. (Saudi Aramco’s ILI program included a few additional runs of Ultrasound Crack Detection Tool, UTCD, as well). This paper discusses in more detail how the Study Team enhanced the ASME B31.8S prioritization criteria and the major findings and highlights realized from this activity. A statistical evaluation of the data compiled in the 1st phase of the comprehensive study was conducted along with the literature review. The Study Team used logistic regressions[1,2] to identify factors that increase or decrease the likelihood that cracking is present. The trends that were identified relate to coating type, pipe grade, pipeline age, diameter, thickness, metal loss, cathodic protection (CP) level, slope, and pipe type. The Study Team used the findings to profile crack susceptibility in the pipelines found with SCC and for the Saudi Aramco pipeline network as a whole to identify pipelines susceptible to cracking to include in the future ILI runs.

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.

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.

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.

SCC Inspection and Mitigation Program on Suncor OSPL Pipeline: Field Data Trends and Observations

2006 ◽  
Author(s):  
Robert Leeson ◽  
Derek K. Spitzmacher
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Field Data ◽  
Analysis Data ◽  
Corrosion Cracking ◽  
Metal Loss ◽  
Thin Wall ◽  
Neutral Ph ◽  
Pump Station ◽  
Short Period

This paper reviews a recent extensive Stress Corrosion Cracking (SCC) inspection and mitigation program on Suncor Energy’s NPS 16 Oilsands Pipeline (OSPL). The primary focus of the paper will be on the findings, trends, and observations obtained from the actual “as found” field data. Suncor’s SCC management philosophy will also be discussed, including in-line inspection, engineering analysis, data collection and defect mitigation. Suncor Energy owns and operates the 426 km NPS 16” (406.4 mm) OSPL system from the Suncor Oilsands site north of Fort McMurray to Edmonton, Alberta, Canada. The pipeline operates as a batched system and transports a range of products from heavy viscous crude oil, light synthetic crude, naptha and diesel to natural gas liquids (NGL). This pipeline experienced a rupture in August of 2004. The cause of failure was determined to be near-neutral pH Stress Corrosion Cracking (SCC). An extensive excavation and inspection program was undertaken following a comprehensive in-line inspection (ILI) program to detect any crack, metal loss and geometry features. A total of 282 crack field and crack-like features as well as 57 notch-like and non-decidable features were excavated and inspected. A number of trends and observations were identified during the inspection and assessment program. Most of the SCC occurred in an area immediately downstream of a newly commissioned pump station. Also, all SCC was detected in thin wall pipe sections and no SCC was identified in heavy wall pipe sections. Most of the SCC occurred in locations with moderate well to rapidly drained glaciofluvial sands and loamy sands. Field observations and findings along with post rupture metallurgical analysis agreed with recent published developments in the mechanism of near-neutral pH SCC. Suncor completed an extensive integrity program in a relatively short period of time (less than a year). All crack-field and crack-like defects as identified by the UltraScan CD tool were mitigated. Suncor plans to continue their integrity program to ensure the continued safety and integrity of their pipeline facilities.

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.

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.

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.

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