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Commemorative Magazine
IIW International Conference 2012 - Abstracts
ture, whether remedial action can be deferred until sometime in the future, or whether repairs are needed immediately. The procedure may also be applied at the design stage, subject to the same restrictions, to hypothetical defects, in order to set inspection sensitivity or to check that a proposed component is tolerant to defects. The procedure should be applicable to defects, which are caused by time-dependent environmental phenomena where the degraded material property is available and can be used in performing the life assessment analysis set out. Cracks in welds are an important complication in the analysis step and need special treatment. In most cases the measurement of residual stresses is not a practical solution and factors on stress level may need to be considered. In addition, properties of the heat-affected zone and the weld metal usually differ from those of the parent material and the local residual stress may need to be taken into account. However, the interactions between these regions are not always clear or well documented. Therefore, this paper will aim at clarifying a route for assessing welded components without the need for a full scale numerical analysis. The work to be presented has been developed by the ASTM E.08 Creep Crack committee and by the pre-standards VAMAS (Versailles project on Advances Materials and Standards) TWA31 committee on crack growth in welded components containing residual stress.
which very often act in synergism. As earlier damage can be detected, the more reliable repair or replacement strategies can be applied and the component safely can stay in service and lifetime can be extended. Within this strategy NDT as an online monitoring tool becomes more and more important. The contribution reports to R&D results obtained in the last decade in the German nuclear safety research program where early materials damage characterization by NDT was the important task to develop lifetime monitoring sensors and techniques based on NDT for characterizing material degradation by thermal aging, fatigue and neutron degradation prior to the development of macroscopic cracks.
Paper 3: Residual Stress Improvement Techniques for Weld Repairs: Basic Principles and Practical Applications
By: Dr. Pingsha Dong, The University of New Orleans, USA Abstract: This presentation will start with a brief highlight of what has been achieved over the last few decades in understanding residual stress development mechanisms, particularly those contributing to residual stress features that are shown of critical importance to fatigue and fracture in the context of fitness for service. Basic stress improvement principles are then deduced with the aid of a few simple analytically-solvable examples. These examples quantitatively illustrate the underpinning stress relief mechanisms associated with various forms of pre- and post-welding deformation processes by thermal and/or mechanical means. As an extension of these principles and known stress relief mechanisms, some of the widely used stress relief procedures, such as uniform PWHT, local PWHT, as well as mechanical techniques such hydro-proof loading, are analyzed to quantify both their effectiveness and limitations on a number of elected industrial applications. Finally, a series of recent novel applications of these stress improvement principles will be demonstrated. They are taken from recent plant life extension efforts in power generation and petrochemical industries, including: a) a sequential “hot compression” technique for residual stress mitigation in a superheater header repair; b) an induction-based stress improvement technique for reheat cracking mitigation in high-temperature stainless steel piping system; and c) weld sequence optimization of a bimetallic weld repair in a reactor vessel hot leg.
Paper 2: The Future Role of NDT as Part of Predictive Maintenance Strategies in Lifetime and Aging Management – More Than Only a Quality Tool to Control Repair
By: Dr. Gerd Dobmann, Fraunhofer-IZFP, Germany Abstract: Traditionally, NDT is an essential part in quality management during manufacturing of products in order to guarantee an imperfection–free component. However, imperfection-free has here the meaning that on the statistical basis of a well-defined and known technical reliability of the applied techniques imperfections can be detected (probability of detection, POD) which are larger than the physical limit of detectability. More complicated is the ability of NDT to describe in classification and sizing of the different kind of imperfections which are influenced very much by the manufacturing technology and the special kind of component, so also in welding and joining technology. A second important field of NDT is the early detection of damage developing and induced in service of components under thermal, mechanical and corrosive loads
22 65TH IIW Annual Assembly & International Conference
IIW 2012
Table of Contents for the Digital Edition of IIW 2012
IIW 2012
Contents
Welcome Message
Annual Assembly Location
Colorado
Denver
General Information
IIW 65th Annual Assembly
IIW International Conference 2012 - Program
IIW International Conference 2012 - Abstracts
Speaker Bio Information
Smartphone App
Social Program
Technical Visits
Social Tours
Tour Schedule
Advertising Sponsor Profiles
Commission XIII Fracture Mechanics Seminar
IIW 2012 Sponsors
IIW 2012 - IIW 2012
IIW 2012 - Cover2
IIW 2012 - Contents
IIW 2012 - Welcome Message
IIW 2012 - 3
IIW 2012 - Annual Assembly Location
IIW 2012 - 5
IIW 2012 - Colorado
IIW 2012 - 7
IIW 2012 - Denver
IIW 2012 - 9
IIW 2012 - General Information
IIW 2012 - 11
IIW 2012 - 12
IIW 2012 - IIW 65th Annual Assembly
IIW 2012 - 14
IIW 2012 - 15
IIW 2012 - IIW International Conference 2012 - Program
IIW 2012 - 17
IIW 2012 - 18
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IIW 2012 - IIW International Conference 2012 - Abstracts
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IIW 2012 - Speaker Bio Information
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IIW 2012 - Smartphone App
IIW 2012 - Social Program
IIW 2012 - Technical Visits
IIW 2012 - 51
IIW 2012 - Social Tours
IIW 2012 - 53
IIW 2012 - 54
IIW 2012 - Tour Schedule
IIW 2012 - Advertising Sponsor Profiles
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IIW 2012 - 60
IIW 2012 - Commission XIII Fracture Mechanics Seminar
IIW 2012 - IIW 2012 Sponsors
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IIW 2012 - Cover3
IIW 2012 - Cover4
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