bluuebunny/crossref_metadata_2025_split huggingface dataset:
NeT Project Task Group 8 – An International Benchmark on Residual Stress Assessment for Welding Repair
Authors: Robin Vincent , Draup Jefri , Hendili Sofiane , Delmas Josselin , Xiong Qingrong , Smith Mike , Paget Alexandre 
Published: November 2022

Abstract
The mission of the European Network on Neutron Techniques Standardization for Structural Integrity (NeT) is to develop experimental and numerical techniques and standards for the reliable characterisation of residual stresses in structural welds. NeT was first established in 2002, and involves over 30 organisations from Europe and beyond. It operates on a “contribution in kind” basis from industrial, academic, and research facility partners. Each problem examined by the network is tackled by creating a dedicated Task Group (TG), which undertakes measurement and modelling studies and the interpretation of the results. NeT achieves this by conducting parallel measurement and prediction round robins on closely controlled and well characterized benchmark weldments. NeT TG8 follows on from the successful NeT TG1 and NeT TG4 benchmarks, which both examined welds in AISI 316L material and also NeT TG6 which examines an Alloy 600 plate containing a three pass “slot” weld made with Alloy 82 consumables. A new benchmark, NeT TG8, which examines an 18MnD5 (French nuclear code grade also named 18 MnNiMo 05) plate containing a five pass “slot” weld made with Alloy 52 consumables, has been organized to address welding repair issues. This paper describes the NeT TG8 benchmark as a whole, and presents preliminary materials characterization, residual stress measurement, and residual stress modelling results.
Development of the Technical Basis for the New Code Case “Performance and Qualification Criteria for Mitigation of Stress Corrosion Cracking by Surface Stress Improvement”
Authors: Mohr Nicholas , Tate Stephen , Albert Marc , Cho Sungwoo , Yi Won-Geun , Collin Jean , Burkardt Markus , Broussard John , Pyun Young Sik 
Published: November 2022

Abstract
Stress corrosion cracking (SCC) of nuclear power plant components is perhaps the most significant issue affecting nuclear power plant availability and plant lifetime management. Actions were taken within ASME Section III Task Group Weld Residual Stress to ensure mitigative actions, such as surface stress improvement (SSI), are taken when a construction repair is made on a surface that will be wetted and susceptible to SCC. The intent is to minimize the potential for SCC in operation by mitigating potentially susceptible areas during construction. However, no performance criteria specific to such construction repairs exist for pre-service SSI methods that mitigate SCC. Thus, TG-ASSIT is developing an alternate set of performance criteria that will be captured in a Section III Code Case. Additional testing was undertaken to support the development of this Code Case.
A number of organizations including DOOSAN and the Welding and Repair Technology Center (WRTC) and Advanced Nuclear Technology (ANT) programs of the Electric Power Research Institute (EPRI) jointly executed a three-year test program focused on evaluating the viability of novel-to-nuclear surface stress improvement techniques such as Ultrasonic Nanocrystal Surface Modification (UNSM) and Low Plasticity Burnishing (LPB) techniques. The program also included further demonstration of laser peening (LP) processes as a complement to the LP test data already captured by prior EPRI Materials Reliability Program (MRP) work (i.e., MRP-267 R2). This paper summarizes the results from the DOOSAN-WRTC-ANT test program and follow-on inspectability testing for UNSM and LPB that supports the SSI performance criteria for mitigation of SCC of ASME Section III components.
An Extended Process-Zone Modeling Framework for Overload Crack Initiation in Zr-2.5Nb Pressure Tubes
Authors: Xu Steven X. , Scarth Douglas A. , Cho David 
Published: November 2022

Abstract
Flaws found during in-service inspection of Zr-2.5Nb pressure tubes include fuel bundle scratches, debris fretting flaws, fuel bundle bearing pad fretting flaws and crevice corrosion flaws. These flaws are volumetric and blunt in nature. Crack initiation from these in-service flaws can be caused by the presence of hydrogen in operating pressure tubes and resultant formation of hydrided regions at the flaw tips during reactor heat-up and cool-down cycles.
There are two known hydride induced crack initiation mechanisms. One is delayed hydride cracking (DHC) that refers to the situations in which hydride formation and fracture occur at the same applied loads. The second crack initiation mechanism is known as overload crack initiation in a hydrided region. In this case, crack initiation occurs in the course of reactor transients when the applied stress acting on hydrided regions at flaw tips exceeds the stress at which these hydrided regions have been formed. The process-zone model was previously established to predict DHC initiation. There has been recent work to extend the process-zone model for predicting overload crack initiation in hydrided regions ahead of flaw tips. Efforts were made to identify appropriate modeling approaches for the two sequential and distinct physical stages of overload crack initiation: formation of hydrided regions with thermal cycles under constant load, and crack initiation from the pre-existing, fixed hydrided regions ahead of flaw tips under rising load (i.e. overload). The established process-zone methodology is used to model formation of hydrided regions at flaw tips with thermal cycles under constant load. A Weibull stress approach is proposed to predict fracture of the preexisting, flaw-tip hydrided regions during overload. This paper describes the extended process-zone modeling framework for overload crack initiation.
Piping Snubber Failure Experience and Mitigation
Authors: Saunders Kenneth L. , Onorato Michael 
Published: November 2022

Abstract
One of the typical characteristics of high temperature piping systems is that they are more flexible. This is due primarily to expansion stress limits which cause the piping designer to add additional elbows and to minimize axial or lateral stops. The resulting high flexibility and low frequency piping system is vulnerable to vibration loading which may result in excessive displacements, and hence, excessive stresses. As a result, designers often add mechanical or hydraulic snubbers to piping systems to mitigate potential vibration displacements. These snubbers work well for infrequent vibration loading such as that from an earthquake. However, operational vibrations have the potential to damage these snubbers and render them ineffective. One such piping system with these supports transfers high temperature crude oil from two furnaces to a large distillation column. The large vibration displacements caused one strut and most of the mechanical snubbers to fail from fatigue loading. There was a concern that the piping itself would eventually fail from fatigue loading and that there would be a loss of the pressure boundary. Our first task was to quantify the magnitude and the type of vibration loading in this piping system. With this information, we could confirm that the observed supports’ damage was caused by the operational vibrations. We next selected and installed viscodampers that are not prone to fail from operational vibration loading. Vibration measurements confirmed the significant vibration reduction after the new style snubbers were installed.
Reorganize Significance of Mt, Ms and Plastic Zone Size Against LMSD Under Plastic Collapse Regime
Authors: Ishizaki Yoichi , Yonekawa Futoshi 
Published: November 2022

Abstract
Due to the aging of facilities, Oil and Chemical industries in Japan has been longing for using API 579-1/ASME FFS-1 [1] Part 4 and Part 5 assessment over decades. However, most of equipment are subjected to Japanese High Pressure Gas Safety Law so our industry needed to pass through the discussion in a local committee. In the local committee, there was a conflict on the significance of Folias Factor, Mt, and surface correction factor, Ms. The conflict had been a stumbling block against the formal permission to use API 579-1/ASME FFS-1 Part 4 and Part 5 assessment technology.
In 2021, throughout the long term effort of cross industry task team led by authors supported by API579-1/ASME Joint Committee on Fitness-For-Service members, the conflict has been solved in the local committee. Effective from April 1st, 2022, Oil and Chemical industry in Japan got a formal approval from the government to use API 579-1/ASME FFS-1 Part 4 and Part 5 assessment for equipment subjected to High Pressure Gas Safety Law.
Authors noticed similar conflict on the significance of Folias Factor, Mt, and surface correction factor, Ms, is also found in societies outside of Japan occasionally. Those factors are sometimes referred as “bulging factor” that sounds like those are simple conversion factors between flat plate stress and cylinder stress. However, it is not a whole picture of the factor as discussed in this paper. Therefore, it would be beneficial for future improvement of Fitness-for-Service technology to share our outcomes on the correct significance of Mt and Ms including our Lr discussion on API579-1/ASME FFS-1 Part 9 Crack Like Flaw assessment taking this opportunity. In addition, authors studied the relative relationship between plastic zone length and distance to major stress discontinuity associated with the discussion. This might be beneficial to be shared for a future discussion too.
Through this paper, significance of Mt and Ms, including derivation of Ms reinforced by FEM analysis, will be discussed. Also, plastic zone size model that can be used for a future discussion on required Lmsd, distance to major stress discontinuity, will be introduced.
Managing Dissimilar Metal Welding in Hydrogen Rich and Low Temperature Petrochemical Applications
Authors: Dalal Mitul , Hosack Allie , Park Neil , Penso Jorge 
Published: November 2022

Abstract
Dissimilar metal welds (DSMW) have been used for extensive time in hydrogen rich and low temperature petrochemical applications. Frequently they are used when there is a temperature or corrosivity stream transition aiming to optimize initial project costs. Experience shows a mix of successful and failure applications. Industry standards have slowly adding guidance to prevent failures. The wide variety to DSMWs materials combinations and service conditions poses a significant challenge for standardization. Maximizing the lives of dissimilar metal weldments requires early involvement starting with the design and continuing with the fabrication, operation, and inspection phases. Although common goal is to avoid them, in practice there are situations when is no practical to elude them when constructing new units.
In this paper in additional to a literature review section, several real examples of ferritic-ferritic, austenitic-austenitic, and ferritic-austenitic dissimilar welds are described along with the steps involved as described above to prevent failures. Butt welds and weld overlays are covered, as well as some failures. Cases covered include dissimilar metals welds in steam methane reformers, hydroprocessing and olefin units at high and low temperatures. Examples of metallurgical characterization and fitness for service assessments are included. Also, a summary of industry code guidance for designing, fabrication and inspection are included.
The paper finally includes a summary of recent research activities in this field.
Leak Testing When Revising Operating, Upset, and Design Pressures in Pressure Piping
Authors: Seipp Trevor G. , Kudzhak Dina , Mckay Boyd 
Published: November 2022

Abstract
A pressure equipment operator initiated a program to achieve compliance with a jurisdiction’s requirements for Overpressure Risk Assessment updates. The program was also initiated to provide clarifications and improvements in the pressure piping documentation where overpressure allowances were inherent in the design of heritage piping and equipment. Most of these heritage piping systems were designed between 1975 to 1995.
During that period of time, it was a common industry practice to take advantage of the provision for variations per ASME B31.3 ¶302.2.4. As per this provision, it is acceptable for occasional, infrequent and short-in-duration upset events to exceed the design condition provided that all the requirements in ¶302.2.4 are met.
The Overpressure Risk Assessment review of a large number of existing piping OPPSD systems recognized higher operating cases and higher overpressure upset cases than those in the original documentation. In most cases, the main reason for this inconsistency between the original and the recently calculated values is due to changes in API 520 / API 521 upset cases. Additionally, operating history, since facility start-up, provides data that demonstrates that upset events have occasionally exceeded the original values which are currently presented in the LDT. Updates to the original LDT are necessary to properly capture the experienced upset events, operating cases and, in some cases, design conditions. For heritage (pre-2013) pressure piping (PP) systems that require updates of the design pressure, the traditional margin provided between the new design pressure and the original leak test pressure as required by ASME B31.3 ¶345.4.2 will not be fully available to support the required rerate.
The objective of this paper is to discuss whether another leak test, at a margin of 1.5 times new design pressure, would provide any additional value in terms of incremental safety. This is discussed in the context of pressure piping systems that have been in continuous successful service for between 25 and 43 years. The mechanical integrity of these systems is being ensured by monitoring and assessment activities that have been carried out within a comprehensive Pressure Equipment Integrity Program. The paper evaluates four different cases of the pressure piping systems that are in the scope of the program, discusses the purpose of leak testing in both construction and post-construction and lists potential risks associated with re-performing leak tests. The paper also provides recommendations for when a prior leak test is sufficient to demonstrate that a rerated piping system with a successful service history is suitable for the new service conditions.
Technical Justification to Extend Girth Weld Examination Intervals
Authors: Cohn Marvin J. 
Published: November 2022

Abstract
The American Society of Mechanical Engineers (ASME) Power Piping Code B31.1 discusses operation and maintenance piping system program requirements in Chapter VII. These program requirements for covered piping systems (CPS) operating in the creep range include the process of piping system walkdowns and the assessment of piping system integrity. For CPS operating in the creep range, this paper provides a methodology to justify extending examination intervals for girth welds subject to low stresses and high remaining useful lives (RULs) considering the observed field anomalies.
Piping system walkdowns frequently reveal piping support issues such as bottomed-out, topped-out, or broken spring hangers (Cohn, M.J., Gialdini, R.J., and Nye, O.B., 2021). These unintended field anomalies should be evaluated to determine the possible impact at the piping system girth welds.
The author’s strategy assumes that the unexamined girth welds have no significant fabrication defects, that future operation is similar to the past, that there are no future malfunctioning supports, and that there is no future significant off-design event. Evaluation of the first set of nondestructive examination (NDE) results will provide higher confidence in subsequent RUL estimates.
The assessment of the piping system integrity for malfunctioning supports includes calculating the highest ranked locations of consumed creep life and implementing applicable NDE at the selected high priority locations. The author’s strategy is to select locations with estimated RULs less than 20 years for NDE during the next scheduled outage. Locations with estimated RULs between 20 and 50 years are medium priority ranking and may be examined during the next scheduled outage, depending on the available resources. Locations with estimated RULs beyond 50 years can have much longer examination intervals.
The process of 1) comprehensive piping system walkdowns, 2) simulation as-found stress analyses to the observed field displacements, 3) NDE at the minimum remaining creep life locations, and 4) determining the next set of minimum creep life locations has been used to evaluate the current piping system integrity and provide additional confidence in safely operating the piping system until the next scheduled outage.
Several case studies are discussed to illustrate the piping system integrity evaluation process. This strategy typically identifies a few critical girth welds to be examined during the next scheduled outage and provides justification to extend examinations of girth welds with estimated remaining creep rupture lives beyond 50 years.
Additive Manufacturing of Monel K-500 via Directed Energy Deposition for Pressure Vessel Applications
Authors: Chen Ze , Wang Chengcheng , Kandukuri Sastry Yagnanna , Zhou Kun 
Published: November 2022

Abstract
Metal additive manufacturing has rapidly revolutionized the production processes across various industries. Laser-assisted powder-fed directed energy deposition (DED) has eminent advantages such as high deposition rate, capability for cladding and repairing valuable parts, and great potential for in-situ alloying, which are highly desirable attributes for pressure vessel applications. This study used DED to process Monel K-500, a nickel-based alloy approved by the American Society Of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Fully dense Monel K-500 parts were printed by DED with the tensile strength of ∼ 20% and elongation of ∼ 120% higher than their casted counterparts. Besides, the anisotropy of mechanical properties of DED fabricated Monel K-500 parts were investigated. This work provides a technical reference for industries to utilize DED to manufacture Monel K-500 parts with desirable performance for pressure vessel applications.
High Temperature Flaw Evaluation Code Case: Technical Basis and Examples
Authors: Brust Frederick , Sallaberry Cedric , Messner Mark 
Published: November 2022

Abstract
The Working Group on High Temperature Flaw Evaluation, which currently reports to both Section XI and Section III Division 5, has developed Code Case to address high temperature flaw evaluation. The evaluation procedures are based on accepted methods used by other Code bodies around the world. The Code Case integrates the creep rupture rules of Section III Division 5 and the fracture rules in Section XI which are enhanced to address high temperature crack growth. This Code Case will eventually reside in Section XI Division 2 within the Reliability and Integrity Management Program. The purpose of this procedure is to evaluate the growth of a single, characterized flaw for a defined evaluation period in a metallic component where the future thermomechanical loads are known or approximated. The procedure describes the growth of the flaw under periods of constant primary load. Crack growth is accumulated in discrete increments over a series of time increments Δt and continues until one of the following occurs: (i) The remaining ligament fails due to the interaction of net section yield or unsteady time independent crack growth, evaluated using a Failure Assessment Diagram (FAD) defined with Section XI rules. (ii) The remaining ligament fails due to creep rupture over a time less than the time increment Δt using Section III Division 5 rules. (iii) The crack exceeds the depth limits for specific components provided in the relevant Section XI appendix. (iv) The simulation time reaches the end of the evaluation period. Several application examples are provided.
Weld Residual Stress Modeling of and Fracture Assessment of Layered Pressure Vessels
Authors: Brust F. W. 
Published: November 2022

Abstract
NASA has hundreds of non-code layered pressure vessel (LPV) tanks that hold various gases at pressure. Many of the NASA tanks were fabricated in the 1950s and 1960s and are still in use. An agency wide effort is in progress to assess the fitness for continued service of these vessels. Layered tanks typically consist of an inner liner/shell (often about 12.5 mm thick) with different layers of thinner shells surrounding the inner liner each with thickness of about 6.25-mm. The layers serve as crack arrestors for crack growth through the thickness. Most tanks have between 4 and 20 layers. Cylindrical layers are welded longitudinally with staggering so that the weld heat affected zones do not overlap. The built-up shells are then circumferentially welded together or welded to a header to complete the tank construction. This paper presents results which consider weld residual stress and fracture assessment of some layered pressure vessels. This is part of the much larger probabilistic fitness for service evaluation of these tanks. All fabrication steps are modeled, and the high-level proof testing of the vessels has an important effect on the final WRS state. Because the tanks have low toughness the weld residual stress state has an important effect on the fitness for service of these tanks and are tabulated for use in the probabilistic code.
Design Modification Implementations for Mitigating the Reactor Inner Zone Inlet Header Temperature in CANDU Reactor Units
Authors: Tang Preston , Li Bing , Bhatia Akash , Cramer Leon 
Published: November 2022

Abstract
The Reactor Inner Zone Inlet Header (RIZIH) temperatures have raised more rapidly in the CANDU units in general, compared to the original aging predictions. This adverse trend is caused by a degradation mechanism that affecting heat exchange efficiency in certain areas of the process systems. The main contributor to the RIZIH temperature increase is the fouling in the preheaters and steam generator/boilers due to magnetite deposits on tube internal diameters. The RIZIH temperature rise had caused units de-rates to ensure the reactor safety and comply with the regulatory requirements. As reported in a previous PVP paper (PVP2017-65096), multiple design alternatives were considered and evaluated to address the adverse condition, the best design option with a piping modification by adding external feedwater bypass of high pressure heater was selected to improve RIZIH temperature control. Following the conceptual engineering, preliminary design and detail design, the engineering change was implemented in two CANDU reactor units between 2018 and 2019. This paper reports out the field physical implementations and discusses the effectiveness of the design change on mitigating the RIZIH temperature rise, it also presents the operational and financial benefits actualized through observations of the two implementing units.