Various forms of cracks, crack-like indications and long seam weld anomalies are known to be present in pipelines, which can become a safety concern over the operational life of the pipeline. The most typical forms of cracking are manufacturing-related (such as lack of fusion, cold welds and hook-crack-like phenomena), operations-Driven (fatigue cracks initiating at imperfections or dents) and environmentally-assisted (stress corrosion cracking, hydrogen-induced cracking and corrosion fatigue cracking).

This course will cover in greater depth the formation and conditions that drive growth of cracks until they become unstable, leading to leaks or ruptures. The appropriate assessment methods such as ILI tools, pressure testing and direct assessments will be reviewed as well as traditional and current engineering methods for determining crack severity for response and remediation. Each attendee will receive a complimentary Excel-based crack assessment calculator which will be demonstrated in class using practical case studies.

It will be necessary to bring a laptop to this course.

Course Program

1. Characteristics and Behavior of Cracks in Pipelines
   • A review of line pipe making, with emphasis on vintage ERW, Flash and Direct Current Welded pipelines
   • A description of factors that formation and growth of
     • Environmentally Assisted Cracking (SCC, corrosion fatigue, hydrogen induced, sulfide stress cracking, selective seam corrosion) and
     • Manufacturing Related Anomalies (lack of fusion, cold welds, stitching, and hook crack-like features)
     • Operational Driven (fatigue cracks)
   • Review of current industry standards and recommended practices related to addressing cracking and seam weld integrity: ASME, API, CSA, and NACE
   • An approach for addressing cracks: Measure + Analyze + Predict + Verify
2. Foundations of Engineering Fracture Mechanics
   • The concept of Stress Intensity Factor-K describing the relationship of failure stress as a function of crack size and material properties
   • The influence of cracks on the fracture behavior of pipelines: brittle and ductile
   • Fracture Toughness testing: Impact Charpy V-Notch and Drop Weight and their relation to Ductile-to-Brittle transition curve
     • Stress Intensity Factor resulting in KMAT & JMAT
3. Performing Engineering Analyses of Cracks
   • What to look for in any engineering method for determining the failure pressure of pipelines in the presence of cracks or seam weld anomalies
     • Review of NG-18 Equation, Newman-Raju Equation, API-579, and CorLAS and in class demonstration with case studies
     • Predicting the fracture stress of pipeline with cracks while accounting for the expected fracture behavior (brittle or ductile or mix-mode)
   • Pressure cycle fatigue crack growth analysis and remaining safe life assessments
     • The total fatigue life of crack concept
     • Setting initial cracks sizes, choosing material properties, applicability of fatigue crack growth relation and fatigue as a function of toughness
     • Fatigue life S-N (stress) and ε -N (strain) curves and their application to pipeline fatigue analysis
     • In class demonstration of case studies and the analysis of cyclic pressure spectra
4. Evaluating Dent Fatigue Behavior
   • The capacity of pipelines to allow plastic deformation 
   • Dent strain analyses using ILI data or in-field measurements
   • Plain dents and dents with damage
   • Crack formation in dents 
   • Fatigue growth behavior of cracks in and around dents
     • Restrained and unrestrained 
   • Review of full-scale fatigue testing of pipeline samples with dents and dents with damage completed throughout the years 
     • Design of experiments and scope of applicability 
     • What we have learned from full scale dent fatigue testing so far 
       • DOT and PRCI- MD 4 programs –modern and vintage pipelines 
     • Dent fatigue life prediction models 
       • Fowler (1994), Alexander & Kiefner (1997) 
       • Rosenfeld (1999) and EPRG (1999) 
   • Managing the threat of dent fatigue failures
5. Integrity Assessments for Addressing Cracks and Dents
   • Factors to consider when evaluating and deciding on assessment methods
   • Hydrostatic Testing: setting up appropriate pressure test targets, hold times, the role of spike testing and determination of appropriate re-test intervals
   • In-line Inspection: description of the UT, EMAT and C-MFL technologies, their performance, industry experience, and development of response criteria
   • Direct Assessment methods: review and applicability of NACE SP0204 for SCCDA and CSA Z662 & CEPA Condition Monitoring for SCC
6. In-Ditch Non-Destructive Evaluation (NDE) and Repair Methods
   • Review of current NDE methods and technologies
   • In-class demonstration of NDE technologies and techniques
   • Review of repairs options in the industry: ASME B31.4 & B31.8 and PCC-2, API, PRCI Repair Manual, and applicable US and Canadian regulations
     • The basis for sleeve repairs, Type A and B sleeve repair systems
     • Guidelines for buffing out cracks and linear indications
   • Review repair case studies: what would you recommend for repair?

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