ELEVARA Partners

Evaluating Cracks and Dents with Damage in Pipelines

The course content as outlined below is being offered through Clarion Technical. Follow this link to the Clarion website for information on the next scheduled upcoming dates and locations and to register http://www.clarion.org/conferencesDate.php

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), Operational 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 crack
growth 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.

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 K MAT & J MAT

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 assessment models
  - Fowler, Alexander & Kiefner, Rosenfeld and EPRG
  - Petrobras, API 579/ASME FFS-1 and PRCI
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
- o Guidelines for buffing out cracks and linear indications
Review repair case studies: what would you recommend for repair?

FATIGUE AND FRACTURE PERFORMANCE OF PIPELINES

Fatigue analysis and fracture behavior evaluations are important considerations for predicting and demonstrating the future structural integrity of pipelines. Fatigue failures of energy pipelines are governed mainly by the magnitude and frequency of the operational cyclic pressures, fracture behavior (brittle or ductile), initial crack shape and size, fracture toughness and residual deformation stresses. In fatigue analysis, any deficiency in considering the interrelationship of these factors can result in unreliable predictions or overly conservative results.

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Chapter 1: Common Definitions and Concepts in Fatigue Analysis

Pressure cycle, maximum and minimum stress, pressure range, amplitude
Mean stress, stress ratio-R and frequency
The total fatigue life cycle of crack
The cumulative effects of cyclic loading on the performance of pipeline with cracks
Fatigue life S-N (stress) and ε -N (strain) curves

Chapter 2: Pipeline Fracture Behavior

Brittle and ductile fracture behaviors
The capacity of pipelines to allow plastic deformation
True stress-true strain and strain hardening exponent
Fracture behavior of vintage long seam welds
Fracture toughness testing
Foundational principles of engineering Fracture Mechanics
The concept of Stress Intensity Factor-K
Fatigue crack growth testing
Typical fatigue crack growth data behavior

Chapter 3: Characterization of Variable Cyclic Pressure Data

Review of methods for analyzing and simplifying variable cyclic pressure data sets
Rainflow Counting
Level-Crossing Counting
Peaking Counting
Simple-Range Counting
Palmgren-Miner’s rule of cumulative damage
Demonstration of an Excel based calculator for simplifying cyclic pressure spectra

Chapter 4: Performing Pressure Cycle Fatigue Crack Growth Analysis

Type of cracks, crack-like features and long seam weld defects susceptible to fatigue growth
SCC, hydrogen induced cracking, linear indications
Hook crack-like, lack of fusion, cold welds, selective seam corrosion
Setting the initial crack size
From ILI reported or NDE confirmed cracks and crack-like features
Cracks that survived a pressure test
Choosing material properties
Fracture toughness
Flow stress properties (yield and tensile) and strain hardening exponent
Applicable fatigue crack growth relations
Paris-Erdogan
Walker
Forman
NASGRO
Determination and use of fitting parameters
Fatigue as a function of fracture toughness
Determination of next assessment interval
Demonstration of an Excel based fatigue crack growth calculator
Case studies:
Fatigue life analysis of cracks in the base of the pipe and the long seam weld

Chapter 5: Evaluating Dent Fatigue Performance

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 test program – modern and vintage pipelines
PRCI- MD 4 program – modern and vintage pipelines
Dent fatigue life prediction models
Fowler (1994)
Alexander & Kiefner (1997)
Rosenfeld (1999)
EPRG (1999)
PRCI (2016)
Finite Element Analysis (FEA) fatigue modeling of dents
What to look for when setting up a FEA dent fatigue modeling
An integrated dent fatigue management approach

Chapter 6: Validating Fatigue Crack Growth Life Predictions

Measure + Analyze + Predict + Verify model
With emphasis on validation
The relationship between analytical and experimental evaluations
The importance of a physics based analytical foundation and derivation
Appropriate design of fatigue experiments and treatment of data scatter
Transfer function between actual fatigue crack growth and experimental testing and analytical modeling

Our Services

Crack & Long Seam Weld Integrity Management

Dent & Mechanical Damage Integrity Management

Fatigue Management

Fracture Mechanics Evaluations

Training Courses and Workshops

ELEVARA Partners is an internationally recognized consulting firm in the areas of measuring, analyzing, predicting and verifying the performance of energy pipelines with cracks, crack-like features and dents

Alliance Partners

When a multidisciplinary approach or complimentary expertise is needed, we associate with colleagues and companies at the top of their fields who possess extraordinary technical and operational expertise and ingenuity

Hill Engineering

When there is a need for advanced fatigue crack growth computational analysis and residual stresses measurements, we reach out to Hill Engineering. They are experts in fatigue and fracture experimental testing and Finite Element Analysis predictions

Anderson & Associates

Anderson and Associates performs high quality mechanical testing and metallurgical failure analysis services. We reach out to them for routine mechanical tensile tests and advanced fracture toughness and fatigue testing as well as for metallurgical failure analysis expertise

Integral Engineering

A probabilistic engineering analysis is a more rigorous approach but offers more meaningful results when evaluating defects and damage on pipelines. To stay up to date on the latest probabilistic techniques and methods and to elevate our probabilistic analyses, we team up with Integral Engineering

ADV Integrity

We team up with Chris Alexander when designing and executing full-scale experimental testing of pipeline samples with cracks and dents with damage. We collaborate in the review, evaluation and testing of emerging technologies for pipeline applications

RCS NDE

Ralf Weber ILI Consulting

We work with Ralf Weber ILI Consulting when performing independent ILI Crack tools data analysis and validation performance. Mr. Weber and his team are experienced in reviewing UTCD and EMAT data sets and proof ups of reported features

CONTACT US

Sergio Limon, Managing Partner