Application and Validation of Statistically Based Corrosion Growth Rates

2012 ◽  
Author(s):  
Clifford J. Maier ◽  
Pamela J. Moreno ◽  
William V. Harper ◽  
David J. Stucki ◽  
Steven J. Polasik ◽  
...  
Keyword(s):  
Growth Rates ◽  
Local Corrosion ◽  
Engineering Analysis ◽  
Local Conditions ◽  
Integrity Assessment ◽  
Field Verification ◽  
Combined Use ◽  
Close Interval ◽  
Integrity Assessments ◽  
Active Corrosion

When it comes to managing the integrity of corroded pipelines, operators are confronted with many difficult decisions — one of which is the level of conservatism that is used in pipeline integrity assessments. The financial implications associated with excavation, repair, rehabilitation, and inspection programs typically balance the level of conservatism that is adopted. More conservative approaches translate into more spending, so it is important that repair strategies developed based on the integrity assessment results are effective. As integrity assessment methodologies continue to evolve, so does the ability to account for local conditions. One development in recent years has been the ability to evaluate multiple MFL in-line inspections to determine areas of active corrosion growth, through the combined use of statistics, inspection signal comparisons, and engineering analysis. The authors have previously outlined one approach (commonly known as Statistically Active Corrosion (SAC)) that has been successfully used to identify areas of probable corrosion growth, predict local corrosion growth rates, and maximize the effectiveness of integrity assessments.[1] Validation of the SAC-predicted corrosion growth rates is important for establishing confidence in the process. This is achieved through inspection signal comparisons, integrating close interval survey (CIS) results, and (when possible) field verification. The means by which these methods are used for validating the SAC method are described in this paper.

INTEGRITY ASSESSMENT OF THICK WALLED INDUSTRIAL FURNACE TUBES

1993 ◽  
Vol 17 (2) ◽  
pp. 127-143
Author(s):  
R.K. Kizhatil ◽  
R. Seshadri
Keyword(s):  
Thermal Stresses ◽  
Furnace Operation ◽  
Remaining Life ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Firing Rates ◽  
Linear Finite Element ◽  
Core Method ◽  
Furnace Tube ◽  
Integrity Assessments

This paper examines various simplified methods proposed to analyze stresses and predict damage and remaining life in furnace tubes subjected to sustained primary pressure stresses and cyclic secondary thermal stresses resulting from a typical furnace operation. Operational effects such as tube fouling, firing rates, startup-shutdown cycles are considered. Component integrity assessments are carried out using some recently developed techniques. A numerical example of a furnace tube made of HK-40 material is presented, and results obtained using a non-linear finite element analysis are compared with predictions obtained using the elastic-core method.

Continuous Depth Sizing of ILI Ultrasonic Crack Detection

2016 ◽  
Author(s):  
Abdullahi Atto ◽  
Marius Grigat ◽  
Jens Voss
Keyword(s):  
Crack Detection ◽  
Performance Test ◽  
Crack Depth ◽  
Integrity Assessment ◽  
Depth Profiles ◽  
Field Verification ◽  
Large Populations ◽  
Continuous Crack ◽  
General Improvement ◽  
Inspection Data

Since the market launch of Ultrasonic crack detection tools, the conventional crack depth sizing is based on four depth classes or buckets. A more differentiated, continuous depth sizing is becoming increasingly relevant for the pipeline operators and especially for pipelines with large populations of planar anomalies (SCC colonies, lack-of-fusion in ERW seam-welds, etc.). The ILI industry is introducing a continuous crack depth sizing. Next to the better differentiation and the linearity of the depth reporting, the main advantage of the continuous depth sizing is the direct comparability to the results of the field verifications. The continuous depth sizing improves the ability to assess the performance validation of the depth sizing and thus, contributes to a general improvement of the crack depth sizing. This paper describes the development and implementation of a continuous crack depth sizing approach and shows its advantages in comparison to the conventional depth classes. A sizing model is introduced, making use of an empirically derived function, that relates the amplitude measurement to the defect depth. The continuous depth sizing applies to crack-like defects with depths ranging from 1mm to 4mm. The parameters of the model are derived from performance tests based on artificial flaws. In addition, the model is validated by means of field verification results. The depth sizing accuracy and confidence levels are obtained from the performance test data in accordance to API 1163 [1] and POF 2009 [2]. In addition, the paper discusses the extraction of the crack depth profiles from inspection data, making use of the newly developed continuous depth sizing model. In comparison to standard reporting of maximum depth and length, crack depth profiles deliver more accurate and more valuable input to the integrity assessment for pipeline operators. Examples of a direct comparison of these crack depth profiles to field verification data are included.

Integrity Assessment of Spherical Pressure Components With Local Corrosion and Hot Spots

2006 ◽  
Author(s):  
Pattaramon Tantichattanont ◽  
Seshu Adluri ◽  
Rangaswamy Seshadri
Keyword(s):  
Lower Bound ◽  
Hot Spots ◽  
Structural Integrity ◽  
Hot Spot ◽  
Corrosion Damage ◽  
Pressure Vessels ◽  
Operating Conditions ◽  
Local Corrosion ◽  
Integrity Assessment ◽  
Spherical Pressure

Corrosion damage and hot spots are typical of damages that can occur in ageing pressure vessels and pipelines used in industrial processes. Internal and external corrosion could be the result of corrosive products stored inside or harsh environmental conditions on the outside. Hot spots are caused by damage due to loss of refractory lining on the inside wall of pressure components or due to maldistribution of flow containing catalyst and reactive fluids. The structural integrity of such ageing components needs to be evaluated periodically to establish the continued suitability of the vessels under operating conditions. The present paper develops a method for Level 2 (as categorized by API 579) structural integrity evaluations of spherical pressure vessels containing local corrosion damage or hot spot. The decay lengths for spherical shells subject to local damages have been studied based on stretching and bending effects using elastic shell theories so as to identify the reference volume participating in plastic action. A limit for “local” corroded spot or hot spot is defined by the size of damage that an onset of pure membrane action occurs inside the damaged area. The size of damage indicating the crossover from dominance of stretching effects on the damage behavior to that of bending effects is also presented. The lower bound recommended “remaining strength factors” for spherical pressure vessels containing corrosion or hot spot are formulated by application of Mura’s integral mean of yield criterion and the improved lower bound mα-multiplier. Three alternative recommendations are proposed. The effectiveness of the proposed methods is evaluated and demonstrated through illustrative examples and comparison with inelastic finite element analyses.

Epitaxial silicon carbide simulations vs. experiments: etching, growth rates and aluminum/nitrogen doping

2002 ◽  
Vol 742 ◽  
Author(s):  
Jérôme Mézière ◽  
Elisabeth Blanquet ◽  
Michel Pons ◽  
Jean-Marc Dedulle ◽  
Pierre Ferret ◽  
...  
Keyword(s):  
Growth Rates ◽  
Nitrogen Doping ◽  
Epitaxial Silicon ◽  
Surface Deposition ◽  
Hydrogen Etching ◽  
Nitrogen Incorporation ◽  
Combined Use ◽  
Modeling And Experiments ◽  
Simulation Results ◽  
Main Growth

ABSTRACTThis paper summarizes recent experimental and simulation results on etching, growth rates and aluminum/nitrogen incorporation in SiC epitaxial layers grown in a horizontal LPCVD hotwall reactor commercialized by the Epigress company. The combined use of modeling and experiments allows to identify and to quantify the main growth phenomena. In this paper, a chemistry model including surface deposition and hydrogen etching is first described. It is found that the contribution of the etching of the susceptor to the SiC growth is not negligible. A simple model is used to describe nitrogen incorporation.

Revised Corrosion Management With Reliability Based Excavation Criteria

2008 ◽  
Author(s):  
Shahani Kariyawasam ◽  
Warren Peterson
Keyword(s):  
Case Studies ◽  
Pressure Ratio ◽  
Reliability Assessment ◽  
Assessment Method ◽  
Integrity Assessment ◽  
Reliability Based Design ◽  
Defect Growth ◽  
Rupture Pressure ◽  
Integrity Assessments ◽  
Growth Assessment

For decades, TransCanada Pipelines has used inline inspection (ILI) to manage the threat of corrosion on gas pipelines. Immediate integrity was addressed using rupture pressure ratio and leak criteria, and future integrity was addressed using a growth assessment. However, a review of excavations based on predictions of defect growth shows that few excavations actually lead to repairs. This study investigated the areas of undue conservatism in both the integrity assessments and the excavation criteria. All aspects of the immediate and future integrity assessment based on ILI were examined. All relevant uncertainties were accounted for in calculating the reliability of the pipeline. A new basis of defining excavation criterion was established based on a reliability assessment and calibration. This criterion was validated against previous ILI based excavations which reveal the features that actually required repair. The criterion was also compared to reliability based criteria recommended in Annex O of the CSA Z662 which gives guidelines for Reliability Based Design and Assessment. This paper addresses the practical limitation of data and presents methods for extracting best information from available data. Case studies that demonstrate the application of the revised assessment method and criterion are also discussed.

The Role, Limitations, and Value of Hydrotesting vs In-Line Inspection in Pipeline Integrity Management

2014 ◽  
Author(s):  
Joshua Johnson ◽  
Steve Nannay
Keyword(s):  
Growth Rates ◽  
Management Plan ◽  
Comprehensive Assessment ◽  
Case Histories ◽  
The Public ◽  
Integrity Assessment ◽  
Failure Pressure ◽  
High Profile ◽  
First Choice ◽  
Integrity Management

In-Line Inspection has become the first choice for integrity assessment for most pipeline operators. The data generated from modern ILI tools allows operators a comprehensive assessment of the condition of their pipelines so they can plan out integrity actions based on the condition of the line. In-line inspection vendors continue to upgrade their tools and provide new services to pipeline operators to enhance integrity management programs. The data provided by these tools is relied upon by operators, regulators, and the public to be correct and complete and in most instances it is, but when near critical features are missed or data is used improperly, the results can be catastrophic. Hydrostatic testing has fallen out of favor with many pipeline operators due to the operational headaches, costs, difficult logistics, and lack of data generated during a hydrotest to conduct future integrity work. However, in light of a number of high profile accidents on pipelines that failed after an ILI run was performed, it may be time to reassess the role that hydrostatic testing plays in modern pipeline integrity management programs. This paper will explore failures and other case histories that have occurred on lines regulated by PHMSA where ILI results alone have failed to provide all of the necessary information to maintain pipeline integrity and how hydrostatic testing may provide value to integrity management programs. Limitations and misconceptions of ILI and hydrostatic testing will be discussed, particularly for seam defects and similar types of defects. Based on these analyses and observations, the roles of hydrostatic testing and ILI tools in a successful integrity management plan will be discussed along with flaw growth rates, predicted failure pressure calculations, re-inspection intervals, and other elements of successful integrity management programs.

scholarly journals Natural selection drives population divergence for local adaptation in a wheat pathogen

2019 ◽  
Author(s):  
Danilo Pereira ◽  
Daniel Croll ◽  
Patrick C. Brunner ◽  
Bruce A. McDonald
Keyword(s):  
Growth Rates ◽  
Common Garden ◽  
High Temperature Stress ◽  
Population Divergence ◽  
Stabilizing Selection ◽  
Evolutionary Potential ◽  
Local Conditions ◽  
Evolutionary Forces ◽  
Different Temperatures ◽  
Parastagonospora Nodorum

AbstractEvolution favors the emergence of locally-adapted optimum phenotypes that are likely to differ across a wide array of environmental conditions. The emergence of favorable adaptive characteristics is accelerated in agricultural pathogens due to the unique properties of agro-ecosystems. We performed a QST - FST comparison using 164 strains of Parastagonospora nodorum sampled from eight global field populations to disentangle the predominant evolutionary forces driving population divergence in a wheat pathogen. We used digital image analysis to obtain quantitative measurements of growth rate and melanization at different temperatures and under different fungicide concentrations in a common garden experiment. FST measures were based on complete genome sequences obtained for all 164 isolates. Our analyses indicated that all measured traits were under selection. Growth rates at 18°C and 24°C were under stabilizing selection (QST < FST), while diversifying selection (QST > FST) was the predominant evolutionary force affecting growth under fungicide and high temperature stress. Stabilizing selection (QST < FST) was the predominant force affecting melanization across the different environments. Melanin production increased at 30°C but was negatively correlated with higher growth rates, consistent with a trade-off under heat stress. Our results demonstrate that global populations of P. nodorum possess significant evolutionary potential to adapt to changing local conditions, including warmer temperatures and applications of fungicides.

Application of ECA Procedures in Integrity Assessments of Ductile Pipes With Axial Flaws

2006 ◽  
Author(s):  
Roberto Ferraboli ◽  
Claudio Ruggieri
Keyword(s):  
Structural Integrity ◽  
Steel Pipes ◽  
Integrity Assessment ◽  
Ductile Materials ◽  
Axial Crack ◽  
Open Issue ◽  
Failure Predictions ◽  
Low Constraint ◽  
Assessment Problems ◽  
Integrity Assessments

ECA procedures of crack-like defects based upon the FAD philosophy have undergone extensive developments in the past decade to form the basis for industrial codes and guidelines for structural integrity assessments. However, the application (and validation) of these procedures in defect assessments of structural components made of ductile materials under low constraint conditions remains a potential open issue. A central objective of this work is to assess the capability of the failure assessment diagram methodology to predict the failure pressure of ductile pipes with planar defects having different geometries. Specifically, the present work compares the burst pressure predictions for austenitic steel pipes with axial flaws derived from two widely used FAD procedures: BS7910 and API579. Such an application serves as a prototype for a wide class of integrity assessment problems involving the effects of strain hardening properties and ductility while, at the same time, assessing the robustness of FAD procedures in failure predictions. The direct application of BS 7910 procedure indicate rather large margins between the predicted and the actual (measured) failure pressures. In contrast, the API 579 procedure appears to provide better agreement with experimental data. Overall, the results validate the use of FAD-based methodologies for defect assessments of ductile pipes with axial crack-like flaws.

Application of Probabilistic Fracture Mechanics to Reactor Pressure Vessel Using PASCAL4 Code

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Kai Lu ◽  
Jinya Katsuyama ◽  
Yinsheng Li ◽  
Shinobu Yoshimura
Keyword(s):  
Fracture Mechanics ◽  
Power Plants ◽  
Structural Integrity ◽  
Pressure Vessels ◽  
Pressurized Water ◽  
Integrity Assessment ◽  
Thermal Transients ◽  
Probabilistic Fracture Mechanics ◽  
Integrity Assessments ◽  
Reactor Pressure

Abstract Probabilistic fracture mechanics (PFM) is considered to be a promising methodology in structural integrity assessments of pressure-boundary components in nuclear power plants since it can rationally represent the inherent probabilistic distributions for influence parameters without over-conservativeness. To strengthen the applicability of PFM methodology in Japan, Japan Atomic Energy Agency has developed a PFM analysis code PASCAL4 which enables the failure frequency evaluation of reactor pressure vessels (RPVs) considering neutron irradiation embrittlement and thermal transients. PASCAL4 is expected to make a significant contribution to the probabilistic integrity assessment of Japanese RPVs. In this study, PFM analysis for a Japanese model RPV in a pressurized water reactor (PWR) was conducted using PASCAL4, and the effects of nondestructive examination (NDE) and neutron flux reduction on failure frequencies of the RPV were quantitatively evaluated. From the analysis results, it is concluded that PASCAL4 is useful for probabilistic integrity assessments of embrittled RPVs and can enhance the applicability of PFM methodology.

Dealing With Low-Frequency-Welded ERW Pipe and Flash-Welded Pipe With Respect to HCA-Related Integrity Assessments

2002 ◽  
Author(s):  
John F. Kiefner
Keyword(s):  
Low Frequency ◽  
Metal Loss ◽  
Electric Resistance ◽  
Integrity Assessment ◽  
Systematic Procedure ◽  
Pipe Line ◽  
Welded Pipe ◽  
Integrity Assessments ◽  
Pipe Materials

The new regulations, Part 195 Section 195.452, require that special integrity assessments be made to address potential seam-defect problems in low-frequency-welded ERW (electric-resistance-welded) pipe materials where a failure of such materials could have an impact on a high-consequence area (HCA). The spirit of this requirement appears to require action if, and only if, significant seam-related deficiencies are in evidence or if they can be reasonably anticipated. This leaves open the option of categorizing these types of pipelines by performance such that potentially problematic pipeline segments can be subjected to special (i.e., seam-quality) inspections while those that show little or no propensity for such problems can be subjected to metal loss and deformation inspections only. This document is intended to establish a systematic procedure to permit an operator to characterize the relevant ERW pipe segments as to the likelihood of significant seam-related deficiencies. The author is particularly grateful to Rich Turley of Marathon Ashland Pipe Line LLC for helping to formulate the essential steps in deciding when an integrity assessment is needed. Rich made significant inputs to Figure 1 of this document.

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