Various forms of cracks, long seam weld anomalies and dents are known to be present in pipelines, which can become a safety concern over the operational life of the pipeline. The most typical forms for cracking are Environmentally Assisted, Manufacturing Related, and Operational Driven. Vintage and newer pipelines have the capacity to plastically deform allowing local formation that typically results in dents. In some cases, the local capacity of the pipeline is exceeded creating tearing or cracking in dents.
This course will cover in greater depth the formation and conditions that drive cracking and denting to growth until they become unstable, leading to leaks or ruptures. Appropriate assessment methods such as ILI tools, and pressure testing will be reviewed as well as traditional and current engineering methods for determining severity of these integrity threats 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 I gives an overview of fracture principles and analysis and then concentrates on inspection, assessment and repair options. Course E is an in-depth review of fracture characteristics and behavior, modeling, and analysis methods.
Who Should Attend
- Pipeline engineers and maintenance personnel who are involved or responsible for the maintenance, inspection, assessments and repair of pipeline systems.
- Non-Destructive Inspection personnel who wish to acquire or increase their knowledge of crack formation and growth on pipelines
What Will Be Learned
On completion of the course, the student will understand what factors contribute to the formation and growth of crack‐like features and seam-weld anomalies on pipelines. In addition, participants will be able to gather and analyze the type and extent of cracking found, key operational parameters, pipe material properties, full-scale testing data, and ILI crack tool data, and to apply industry-recognized engineering methods for developing and recommending appropriate remedial action.
Participants will receive a full set of course slides and notes in print and electronic form, in color throughout, as well as an Excel-based tool for calculating failure pressure due to the presence of cracks.
Sergio Limón has worked in the oil & gas pipeline industry for more than 15 years with emphasis on pipeline integrity threat analysis and response. He was employed for 10 years with a large owner and operator of natural gas gathering, processing and transportation services. He led for six years the Asset Integrity group for the western division responsible for the analysis, response and remediation of integrity threats as well as the implementation of the Gas Integrity Management Program. Sergio holds B Sc. and M Sc. degrees in Mechanical Engineering with emphasis in fracture mechanics and materials from the University of Utah. He is the founder of Elevara Partners.
On completion of the course, participants will be awarded 1.4 CEUs.
1. Formation and Growth of Cracks, Crack-like Features and Dents in Pipelines
- A review of line pipe making, with emphasis on vintage ERW, Flash and
Double Submerged Arch Welded pipelines
- A description of factors that contribute to the formation and growth of the following cracks and crack-like features
- 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 in the body of the pipe and weld toe)
- A description of the capacity of pipelines to plastically deform and their behavior during dent formation
- Deformation strain capacity and residual strength
- Formation of plain dents and dents with damage
- Restrained and unrestrained dent behavior
2. Foundations of Engineering Fracture Mechanics
- The deformation and fracture process of pipelines in the presence of cracks, cracks-like feature and dents
- The concept of Stress Intensity Factor (SIF) describing the relationship of failure
stress as a function of crack size and material properties
- Liner Elastic and Elastic-Plastic Engineering Fracture Mechanics
- Setting up a Fracture Mechanics based analysis applicable to pipelines
- Identify Fracture Process being modeled (fracture initiation, stable fracture/growing crack, fracture instability)
- Anticipated Fracture Behavior (brittle, ductile or mix behavior)
- Fracture Toughness values to use (should correspond the Fracture Process and Behavior being modeled)
- Failure Mode expected or being modeled (leak or rupture or mix mode)
- Engineering Fracture Models available (for cracks: NG-18/KAPA, API-579/ASME FFS-1, CorLAS, others; for dents: ASME B31.8 strain equations, Finite Element Analysis, Dent fatigue models)
- Fracture Toughness testing:
- Charpy V-Notch (CVN) and its relation to Ductile-to-Brittle transition curve
- Stress Intensity Factor resulting in KMAT & JMAT
- Relationships of CVN to KMAT & JMAT
3. Performing Engineering Evaluation of Cracks and Seam Weld Anomalies
- What to look for in any engineering method for determining the failure
pressure of pipelines in the presence of cracks
- Review of NG-18/KAPA, Newman-Raju, API-579 CorLAS, and MAT-8
- Are long seam weld anomalies cracks?
- Appropriate engineering models for evaluating seam weld anomalies
- In class demonstration with case studies for predicting the fracture stress of pipeline with cracks and seam weld anomalies
- Severity evaluation and the development of a prioritized dig list of cracks and seam weld anomalies reported by ILI tools
- Growing cracks: pressure cycle fatigue crack growth analysis and remaining fatigue life assessments
- Applicable fatigue crack growth relations (Paris-Erdogan, Walker, Forman, and NASGRO)
- Effects of fracture toughness on the final fatigue life
- In-class demonstration of fatigue crack growth analysis case studies and the simplification of variable cyclic pressure spectra
4. Performing Engineering Evaluation of Dents
- Evaluating dents and dents with damage in pipeline requires
- The analysis of how the dent was formed, its final shape and size, a determination if the dent resulted in local material tearing or cracking, potential growth mechanisms (cyclic pressure), the presence of gouging or any other damage and possible interacting threats
- Performing static dent strain analyses
- ASME B31.8 strain equations
- Finite Element Analysis and the concept of Stress Concentration Factor (SFC)
- Preforming pipe local material tearing or cracking formation analysis
- Ductile Failure Damage Indicator (DFDI)
- Minimum Specified Elongation Criteria
- Strain Limit Damage
- Evaluating and ranking dents for response using ILI data
- Modeling fatigue behavior of pipelines with dents and dents with damage
- The use of fatigue life S-N (stress) and ε -N (strain) curves
- Dent fatigue life prediction models
- Fowler, Alexander & Kiefner, Rosenfeld and EPRG
- Petrobras, API 579/ASME FFS-1 and PRCI MD4-9
- What we have learned from full scale dent fatigue testing
- Where cracks typically form in and around dents
- Relationship of cycles to failure to dent size and shape; constrained and unconstrained
- Relationship of cycles to failure to dent strain and cycles to failure to dent SCF
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 for cracks and Geometry and MFL tools for dents, 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?
- A framework for an Integrated Strategy for Managing Cracks, Seam Weld Anomalies and Dents
It will be necessary to bring a laptop to this course.