Methodology for Identifying Blunt Flaws Using Ultrasonic In-Service Inspection Data

2018 ◽  
Author(s):  
M. I. Jyrkama ◽  
M. D. Pandey ◽  
M. Li
Keyword(s):  
Structural Integrity ◽  
Search Algorithm ◽  
Ultrasonic Inspection ◽  
Three Dimensional ◽  
Signal Loss ◽  
Integrity Assessment ◽  
Coverage Error ◽  
Flat Profile ◽  
Inspection Data ◽  
Service Data

This paper presents a methodology for identifying blunt flaws in piping using in-service data from ultrasonic inspection tools. The method is applicable to data obtained from predetermined inspection grids, or directly from bracelet or array type inspection tools. The flaw edge and size are identified by calculating the three-dimensional slope vector (i.e., magnitude and direction) of each point in the kriging interpolated wall thickness profile. The transition from a steeper slope to a relatively flat profile is then used by a search algorithm to determine the flaw edge. The method is applied to the flaw assessment of feeder piping in CANDU nuclear reactors. The results show that in addition to identifying blunt flaws, the developed methodology also provides a convenient way for characterizing the flaw dimensions for structural integrity assessment. The uncertainty in the results is mainly attributed to the signal loss and coverage error associated with the inspection data.

French RPV PTS Assessment: An Overview of EDF Research and Development in Progress on Thermalhydraulic, Materials and Mechanical Aspects

2003 ◽  
Author(s):  
Dominique Moinereau ◽  
Jean-Michel Frund ◽  
Henriette Churier-Bossennec ◽  
Georges Bezdikian ◽  
Alain Martin
Keyword(s):  
Structural Integrity ◽  
Three Dimensional ◽  
Crack Arrest ◽  
Pressure Vessels ◽  
Short Description ◽  
Constraint Effect ◽  
Materials Properties ◽  
Integrity Assessment ◽  
Pressurized Thermal Shock ◽  
Reactor Pressure

A significant extensive Research & Development work is conducted by Electricite´ de France (EDF) related to the structural integrity re-assessment of the French 900 and 1300 MWe reactor pressure vessels in order to increase their lifetime. Within the framework of this programme, numerous developments have been implemented or are in progress related to the methodology to assess flaws during a pressurized thermal shock (PTS) event. The paper contains three aspects: a short description of the specific French approach for RPV PTS assessment, a presentation of recent improvements on thermalhydraulic, materials and mechanical aspects, and finally an overview of the present R&D programme on thermalhydraulic, materials and mechanical aspects. Regarding the last aspect on present R&D programme, several projects in progress will be shortly described. This overview includes the redefinition of some significant thermalhydraulic transients based on some new three-dimensional CFD computations (focused at the present time on small break LOCA transient), the assessment of vessel materials properties, and the improvement of the RPV PTS structural integrity assessment including several themes such as warm pre-stress (WPS), crack arrest, constraint effect ....

Preliminary Failure Assessment for Spiral Welded Defects of Pipeline

2008 ◽  
Author(s):  
Qingshan Feng ◽  
Yi-Han Lin ◽  
Fuxiang Wang ◽  
Bin Li
Keyword(s):  
Ultrasonic Inspection ◽  
Western China ◽  
Practical Significance ◽  
Oil Pipeline ◽  
Integrity Assessment ◽  
Failure Assessment ◽  
Transmission Pipeline ◽  
Collapse Failure ◽  
Inspection Data ◽  
Grade Assessment

The spiral welded defect of steel oil transmission pipeline is one of the main causes resulting in pipeline leakage accident. Hence the failure assessment for known-size spiral welded defects is an important step to ensure the safety of defected pipeline. Lack of suitable criterion for assessing the spiral welded manufacture defects of pipeline network in China, is a difficult technology problem to be solved desirably. This paper first summarized the basic idea of preliminary failure assessment (Grade 1A of code BS 7910:2005) with some insight of our own understanding, and then applied the preliminary failure assessment to the spiral welded defects of oil pipeline, with the use of ultrasonic inspection data of Daqing-Tieling old pipeline from LingYuan to XinMiao, Northeastern China. The calculation of both fracture and plastic collapse failure for spiral welded defects indicates some detected flaws of pipeline are not safe as the internal pressure is greater than 4.5 MPa. A leakage accident of spiral welded pipeline in Western China is also assessed through fractography analyses and failure calculations. This paper concludes that the preliminary failure assessment provides useful outcome for reference in making decision of inspection, integrity assessment and repair of spiral welded pipeline, and hence is a step of fundamental importance and practical significance before more accurate data becomes available for higher grade assessment.

RISK-BASED MANAGEMENT OF STRUCTURAL INTEGRITY FOR BASS STRAIT PLATFORMS

2001 ◽  
Vol 41 (1) ◽  
pp. 727
Author(s):  
A.D. Barton
Keyword(s):  
Structural Integrity ◽  
Risk Model ◽  
Offshore Platforms ◽  
Integrity Assessment ◽  
Inspection And Maintenance ◽  
Tubular Joint ◽  
Maintenance Activities ◽  
Consistent Basis ◽  
Inspection Data ◽  
Inspection Techniques

Esso Australia Pty Ltd (Esso) has embraced the framework of risk management to improve the focus and priorities of its inspection and maintenance activities. Structural integrity is one of the disciplines that has adopted a risk-based approach to inspection and integrity assessment and this has been applied to Esso/BHP’s 18 offshore platforms located in Bass Strait.The paper provides a discussion of the issues faced in the management of structural integrity of offshore platforms which lead to the development of a risk-based inspection (RBI) strategy. RBI is applied to improve the prediction of the structures’ condition and provides a consistent basis for continued improvement in the future. The RBI model generates targeted inspection workscopes for each platform that, coupled with the implementation of appropriate inspection techniques, ensure that the integrity of the platforms can be managed with greater confidence and at lower cost.The RBI approach has resulted in reduced focus on traditional areas of uncertainty such as fatigue of tubular joints, and increased focus on secondary structures, for example service caissons. This shift in focus is made possible by building into the risk model a calibration process that considers previous inspection data. A key component of this calibration is a new method developed to calibrate tubular joint fatigue lives.

Dynamic Fracture Parameters and Calculations for 3-D Cracks

2003 ◽  
Author(s):  
Wing Cheng ◽  
Shigeru Itoh
Keyword(s):  
Dynamic Loading ◽  
Dynamic Fracture ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Welding Process ◽  
Fracture Parameter ◽  
Integrity Assessment ◽  
Fracture Parameters ◽  
Cracked Structures ◽  
Geometrical Factors

Welded structures such as armor fighting vehicles, shipboard structures or munitions systems are required to sustain intense and rapidly applied dynamic loading due to gun firings, impact of enemy munitions and extreme loading from accident scenarios. Flaws are normally found in various extents in welds depending on quality control of the welding process. It is important to determine critical flaw sizes of three-dimensional cracks in a welded joint under dynamic loading introduced by the above scenarios. Calculation of dynamic fracture parameters of the three-dimensional cracks of various geometrical factors at different locations is important for use the crack growth evaluation, flacture and structural integrity assessment. This paper summarizes the methodologies and results of the dynamic fracture parameter calculations for stationary three-dimensional cracks in cracked structures subjected to both static and dynamic loads.

Plastic Limit Loads for Through-Wall Cracked Pipes Using Finite Element Limit Analysis

2006 ◽  
Vol 321-323 ◽  
pp. 724-728
Author(s):  
Nam Su Huh ◽  
Yoon Suk Chang ◽  
Young Jin Kim
Keyword(s):  
Finite Element ◽  
Limit Analysis ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Limit Load ◽  
Plastic Behavior ◽  
Plastic Limit ◽  
Integrity Assessment ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

The present paper provides plastic limit load solutions for axial and circumferential through-wall cracked pipes based on detailed three-dimensional (3-D) finite element (FE) limit analysis using elastic-perfectly plastic behavior. As a loading condition, both single and combined loadings are considered. Being based on detailed 3-D FE limit analysis, the present solutions are believed to be valuable information for structural integrity assessment of cracked pipes.

Validation of a Finite Element Toolbox for Studying Flaw Interaction

2020 ◽  
Author(s):  
Harry E. Coules
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Large Scale ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Integrity Assessment ◽  
Linear Elastic ◽  
Wide Range ◽  
Parametric Studies ◽  
Elastic Crack

Abstract Structural integrity assessment often requires the interaction of multiple closely-spaced cracks or flaws in a structure to be considered. Although many procedures for structural integrity assessment include rules for determining the significance of flaw interaction, and for re-characterising interacting flaws, these rules can be difficult to validate in a fracture mechanics framework. int_defects is an open-source MATLAB toolbox which uses the Abaqus finite element suite to perform large-scale parametric studies in cracked-body analysis. It is designed to allow developers of assessment codes to check the accuracy of simplified interaction criteria under a wide range of conditions, e.g. for different interacting flaw geometries, material models and loading cases. int_defects can help analysts perform parametric studies to determine linear elastic crack tip stress field parameters, elastic-plastic parameters and plastic limit loads for simple three-dimensional cracked bodies relevant to assessment codes. This article focusses on the validation of int_defects using existing fracture mechanics results. Through a set of validation examples, int_defects is shown to produce accurate results for a very wide range of cases in both linear and non-linear cracked-body analysis. Nevertheless, it is emphasised that users of this software should be conscious of the inherent limitations of LEFM and EPFM theory when applied to real fracture processes, and effects such as constraint loss should be considered when formulating interaction criteria.

Structural Integrity Assessment Criteria and Service Life Prediction of Cold Wrinklebends

2012 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Finite Element ◽  
Service Life ◽  
Structural Integrity ◽  
Pipeline Steel ◽  
Three Dimensional ◽  
Computation Time ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Fea Model ◽  
Hardening Models

Three-dimensional elastic-plastic finite element analysis (FEA) is performed in this paper to simulate the complicated stresses and deformation of wrinklebends in a pipeline from its bending formation to operation under cyclic loading. Three plastic hardening models (isotropic, kinematic and combined isotropic/kinematic) are discussed and used in FEA of wrinklebend response that considers strain hardening and Bauschinger effects. The FEA simulation is carried out first for an elbow held at constant pressure while subject to cyclic bending, which serves as a benchmark case. The results show that the three hardening models lead to very different outcomes. Comparable FEA simulations are then developed for wrinklebends under cyclic pressure. Detailed parametric analysis is considered, including finite-element type, element sensitivity, computation time, and material input data. Based on those results viable nonlinear FEA model is developed as the basis to quantify wrinklebend response under service-like conditions. Based on the FEA results, fatigue damage is quantified using the Smith, Watson and Topper (SWT) parameter, and thereafter a damage criterion is proposed to predict the fatigue life of a wrinklebend under the pressure cycles of 72%–10% of SMYS for typical X42 pipeline steel. The results show that the wrinkle aspect ratio H/L is a key parameter to control the service life of a wrinklebend.

A Comparison of Two- and Three-Dimensional Fracture Assessments in the Presence of Residual Stresses

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
S. J. Lewis ◽  
C. E. Truman ◽  
D. J. Smith
Keyword(s):  
Residual Stresses ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Major Effect ◽  
Probabilistic Methods ◽  
Secondary Importance ◽  
Integrity Assessment ◽  
Path Independence ◽  
Out Of Plane ◽  
Failure Predictions

The influence of various assumptions on the modeling of cleavage fracture in the presence of residual stresses was investigated. Analyses were undertaken for modified single edge notched bend specimens, manufactured from A533B ferritic steel. The influence of residual stress fields, introduced by a method of in-plane compression, was investigated through the use of a modified J-integral, designed to retain path independence in the presence of initial stress and strain fields and nonproportional loading. Application of modified J values to predict fracture using probabilistic methods, and their use in a well-known structural integrity assessment code, showed that assumptions about levels of out-of-plane constraint, material hardening behavior, and the method of crack introduction have a significant influence on the conservatism of the resulting failure predictions. It was found that more realistic modeling of crack introduction had a major effect on the accuracy of failure predictions, with the effects of material hardening being of secondary importance.

Loading Condition Evaluation for Structural Integrity Assessment of RPV due to PTS Event Based on Three-Dimensional Thermal-Hydraulics and Structural Analyses

2016 ◽  
Author(s):  
Shumpei Uno ◽  
Jinya Katsuyama ◽  
Tadashi Watanabe ◽  
Yinsheng Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Loading Condition ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Loading Conditions ◽  
Integrity Assessment ◽  
Coolant Water ◽  
Condition Evaluation

For structural integrity assessment on a reactor pressure vessel (RPV) of pressurized water reactor during the pressurized thermal shock (PTS) events, thermal histories of coolant water and heat transfer coefficient between coolant water and RPV are important influence factors. The former is determined on the basis of thermal-hydraulics (TH) analyses simulating PTS events and the latter is derived from Jackson-Fewster correlation using TH analysis results. Using these factors, subsequently, loading conditions for structural integrity of RPVs are evaluated by structural analyses. Nowadays, three-dimensional TH and structural analyses are recognized as precise methods for assessing structural integrity of RPVs. In this study, we performed the TH and structural analyses using a three-dimensional model including cold-leg, downcomer and beltline region of RPV in order to evaluate loading conditions during a PTS event more accurately. Distributions of temperature of coolant water and heat transfer coefficient on the surface of RPV were calculated by TH analysis. Loading condition evaluation was then performed by structural analysis using these values and taking the weld residual stress due to weld-overlay cladding and post-weld heat treatment into consideration. From these analyses, we obtained histories and distributions of loading conditions at the reactor beltline region of RPV. Based on the analysis results of loading conditions, we discussed the conservativeness of current structural integrity assessment method of RPV prescribed in the current codes through the comparison of the loading conditions due to a PTS event.

Study on Structural Integrity Assessment of Reactor Pressure Vessel Based on Three-Dimensional Thermal-Hydraulics and Structural Analyses

2014 ◽  
Author(s):  
Jinya Katsuyama ◽  
Genshichiro Katsumata ◽  
Kunio Onizawa ◽  
Tadashi Watanabe ◽  
Yutaka Nishiyama
Keyword(s):  
Pressure Vessel ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Reactor Core ◽  
Reactor Pressure Vessel ◽  
Thermal Hydraulics ◽  
Pressurized Water ◽  
Integrity Assessment ◽  
Coolant Water ◽  
Reactor Pressure

In the structural integrity assessment of a pressurized water reactor pressure vessel (RPV) during pressurized thermal shock (PTS) events, the thermal history of the coolant water and the heat transfer coefficient between the coolant water and RPV are dominant factors. These values can be determined on the basis of thermal-hydraulics (TH) analysis simulating PTS events and Jackson-Fewster correlation. Subsequently, using these values, structural integrity assessments of RPV are performed by structural analysis; e.g., loading that affects crack propagation is evaluated. Three-dimensional TH and structural analyses are recommended for precise assessments of the structural integrity of RPV. In this study, we performed TH and structural analyses simulating typical PTS events using three-dimensional models of cold-leg, downcomer and RPV to more accurately assess the structural integrity of RPV. From these analyses, we obtained loading histories from the reactor core region of RPV in which a crack is postulated in the structural integrity assessment. We discuss the conservativeness of current analysis methods on the structural integrity assessment of RPV through the comparison of loading conditions due to PTS events.

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