bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Fatigue Life Evaluation With Experimental Results for Type III Accumulators
Authors: Kim Sang-Won , Yoshikawa Nobuhiro , Kobayashi Hiroshi , Fujisawa Toshiro , Sano Takeru 
Published: November 2018

Composite Reinforced Accumulator (CRA) is widely used in hydrogen stations. A high-cost pressure cycle test is mandatory to ensure the safety of accumulator in present regulations. To reduce the high cost, the aim is to develop a methodology of numerical fatigue life prediction of CRA with results of pressure cycle tests.
An axisymmetric finite element model for the Type III accumulator is created and actual loading process including autofrettage pressure is simulated. Stress amplitude caused by pressure cycle is evaluated based on the instructions in KD-3 of ASME BPVC VIII 3-2015. By comparing stress amplitude distributions with the leak positions after the pressure cycle test, and plotting the results in the design fatigue curve, it could be shown that fatigue life prediction of Type III accumulator can be done by precise finite element analysis of the liner including dome part, where the principal axes of stress change in pressure cycle.
Seismic Test Analysis Evaluation of Motor-Operated Valve Actuators for Nuclear Power Plant
Authors: Kojima Nobuo , Tsutsumi Yoshitaka , Yonekura Kazuyoshi , Nishino Koji , Watanabe Yukio , Kumagai Shin , Kamino Hiroyuki 
Published: November 2018

The function of motor-operated valves provided in nuclear power plants during an earthquake has been previously evaluated on the basis of seismic test results; however, since the response acceleration has increased with a recent reassessment of standard earthquake ground motions, it is necessary to evaluate their function during high acceleration earthquakes.
In order to carry out seismic test analysis, we examined the compression characteristics of the gaskets in three kinds of representative valves, in terms of the current load and slide coefficient, by element tests. We created an analysis method using the finite element method which used the gasket’s characteristics, and the result of these analyses could explain the loosing and the amplitude of the bolt connecting force and gasket slipping at the time of excitation to the safety side.
According to the analysis, the actuator connection part of the motor-operated butterfly valve showed a seismic resistance of 20 × 9.8m/s2 and other parts showed a seismic resistance of 30 × 9.8m/s2.
A Proposal of Cladding Materials for Coke Drum Based on Fatigue Tests
Authors: Nabeshima Hiroshi , Shishido Yasuhiko , Kouno Nobuhisa , Murakami Takushi 
Published: November 2018

Coke drums undergo cyclic operations typically in temperatures ranging from the ambient temperature to about 500°C. Generally, coke drums are fabricated from clad plates consisting of chromium-molybdenum low alloy steel as the base metal and ferritic stainless steel typically Type 410S stainless steel (TP.410S) as cladding material. TP.410S cladding material is used for protection against sulfide corrosion.
Coke drums frequently display major cracking on the inside surface of their circumferential weld along the fusion line between restoration weld and the TP.410S cladding. Moreover, an array of cracks commonly referred to as “elephant skin” are typically observed proximity to the major cracks. These cracks have been reported by multiple papers, particularly in the API Technical Report 934-G, up to the present and primarily attributed to the thermal fatigue which occurs from the repeated thermal loads experienced during each operating cycle. When the existence of severe cracks is recognized, users are forced to schedule extensive repairs.
The authors conducted fatigue tests employing coupons made from two kinds of cladding material, TP.410S and Alloy 625, which simulate the circumferential weld seam of coke drums. The paper summarizes the essential properties for the cladding material in order to delay cracking on the inside surface and proposes new common cladding materials which could be employed for coke drums based on test results.
A Probabilistic Approach for the Assessment of LOC Events in Steel Storage Tanks Under Seismic Loading
Authors: Paolacci Fabrizio , Corritore Daniele , Caputo Antonio C. , Bursi Oreste S. , Kalemi Bledar 
Published: November 2018

The damage states in a storage tank subjected to seismic loading can induce loss of containment (LOC) with possible consequences (fire, explosion, etc..) both for the surrounding units and people. This aspect is particularly crucial for the Quantitative Risk Analysis (QRA) of industrial plants subjected to earthquakes. Classical QRA methodologies are based on standard LOC conditions whose frequency of occurrence is mainly related to technological accident rather than natural events and are thus useless. Therefore, it is evident the necessity of establishing new procedures for the evaluation of the frequencies of occurrence of LOC events in storage tanks when subjected to an earthquake.
Consequently, in this work a simple procedure founded on a probabilistic linear regression-based model is proposed, which uses simplified numerical models typically adopted for the seismic response of above ground storage tanks. Based on a set of predetermined LOC events (e.g. damage in the pipes, damage in the nozzles, etc..), whose probabilistic relationship with the local response (stress level, etc..) derives from experimental tests, the probabilistic relationship of selected response parameters with the seismic intensity measure (IM) is established. As result, for each LOC event, the cloud analysis method is used to derive the related fragility curve.
Root Cause and FFS Analysis of a Dent in a 22mm Thick Elliptical Head
Authors: Schreurs Pascal , Kusters Stan 
Published: November 2018

This paper describes the failure of a jacketed vessel. The product pressure is 16 barg (inner vessel; D = 2200 mm) and is heated with thermal oil in the jacket (operated at 4barg). The jacket is split up in different zones which can be opened and closed separately. After a shut down, several valves were not opened properly. This resulted in blocking-in of the jacket on the top head of the vessel during the start-up and operation of the vessel. The vessel was heated to the operating temperature (±250°C), causing a pressure increase of the blocked-in thermal oil. The jacket has a wall thickness of 10 mm, and the vessel head has a wall thickness of 22 mm. Because of the pressure increase, failure occurred at a nozzle weld on the inner pressure vessel shell. This resulted in a leakage of thermal oil into the vessel. The jacket itself deformed but did not fail.
Based on a detailed FE analysis, it has been concluded that failure occurred as a result of (local) buckling of the 22mm thick elliptical head (diameter of ±2.200mm). This paper describes the failure that occurred and the assessments performed to determine and validate the root cause of the failure. A level 3 assessment according to ASME VIII div 2 Part 5 (1) was used to determine if the vessel is still safe for operation.
Long-Term Operation of BWR RPV and its Internals
Authors: Cronvall Otso 
Published: November 2018

This study concerns the long-term operation (LTO) of a boiling water reactor (BWR) reactor pressure vessel (RPV) and its internals. The main parts of this study are: survey on susceptibility to degradation mechanisms, and computational time limited ageing analyses (TLAAs).
The ageing of nuclear power plants (NPPs) emphasises the need to anticipate the possible degradation mechanisms. The BWR survey on susceptibility to these uses the OL1/OL2 RPVs and significant internals as a pilot project.
It is not necessary to carry out the TLAAs for all components. Some components were excluded from the TLAAs with a screening process. To do this, it was necessary to determine the component specific load induced stresses, strains and temperature distributions as well as cumulative usage factor (CUF) values.
For the screened-in components, the TLAAs covered all significant time dependent degradation mechanisms. These include (but are not limited to):
• irradiation embrittlement,
• fatigue,
• stress corrosion cracking (SCC), and
• irradiation accelerated SCC (IASCC).
For the components that were screened-in, the potential to brittle, ductile or other degradation was determined. Only some of the most significant cases and results are presented. According to the analysis results, the operational lifetime of the OL1/OL2 RPVs and internals can safely be extended from 40 to 60 years.
Repair and FFS of Vacuum Column for Corrosion Under Insulation
Authors: Adusumilli Yeswanth Kumar , Chiluvuri Siva Kumar , Cheta Ayman 
Published: November 2018

One of the vacuum column made of Carbon steel (SA 285 Gr. C) was found with severe corrosion under insulation during turnaround inspection. The equipment was in service for the past 46 years. The corrosion was around the full circumference of the column at a location immediately above the stiffener ring. The wall loss was extensive, which mandated a welded full circumferential patch to encapsulate the corroded region. A full circumferential lap patch with reinforcement plug welds was designed as per ASME PCC-2 [2], fabricated and installed at site. During the dye penetrant examination of the patch plate welds, fine cracks were noted at the toe of the fillet welds. A subsequent PAUT (Phased Array Ultrasonic Testing) of patch plate welds, showed that the cracks were in column shell (base material) surface initiating from toe of the fillet weld of the patch and beneath the fillet weld.
The cracks found in first few sections of welds were ground and re-welded with appropriate pre-heating and post-heating. However, some cracks were still observed in base material, although with reduced magnitude compared to previous welding. Despite proper controls in place during the welding, the challenge was, some minor cracks were re-occurring at the base material surface below fillet welds. A multi discipline review was carried out to understand the potential root cause for the cracks, detailed assessment of risks and impact due to the cracks. A risk based approach was followed, in evaluating cracks for acceptance based on API 579-1/ASME FFS-1 [1], for continued service of the column and to minimise the extension of turn around duration. Later, a long-term plan was made to replace the equipment.
Research and Development of Viscous Fluid Dampers for Improvement of Seismic Resistance of Thermal Power Plants: Part 4 — Experimental Study on Environmental Applicability and Durability of Damper
Authors: Tanaka Go , Minagawa Keisuke , Aida Kiyoshi , Fujita Satoshi 
Published: November 2018

A purpose of this study is an improvement of seismic proof construction for power plants to supply power stably at an emergency. At present, the most common type of power generation in Japan is thermal. In particular, coal-fire becomes base load power. A proposal of this study is that boiler structure is applied vibration control. The way is that a damper used viscous fluid is set instead of stopper between the boiler and the support structure. However, inside temperature of the boiler structure is higher than the environment of the general because it uses burning of coal and steam. Therefore, this paper shows that the damper has applicability for the environment of the boiler structure.
Then it is necessary for structures to endure earthquake with long duration and long period component in Japan. The 2011 off the Pacific coast of Tohoku Earthquake had the largest energy in history of Japan with them. The damage occurred not only in Tohoku but also in far Tokyo and Osaka. Moreover, it is predicted that large earthquakes with them at the south Pacific coast of Japan occur. This paper shows that the developed damper is effective in earthquake with these characteristics by analyses and component tests.
Long-Term Performance of Elastomer Seals: From Aging Tests to Lifetime Estimations
Authors: Jaunich Matthias , Kömmling Anja , Horn Jutta , Völzke Holger , Wolff Dietmar 
Published: November 2018

Elastomers show a high versatility which makes them ideal materials for sealing applications in various fields. Especially under changing application conditions the high recovery potential of this class of material is beneficial to compensate temperature or pressure fluctuation, and geometrical changes resulting from mechanical loads in e.g. accident conditions. Out of these reasons elastomers are also used in containers for low and intermediate level radioactive waste and for spent fuel transportation casks. In casks designed for low and intermediate level waste elastomer seals can act as primary seal responsible for the containment function whereas in spent fuel storage and transportation casks (dual purpose casks (DPC)) elastomer seals are used as auxiliary seals to allow leakage rate measurements of metal barrier seals. An inherent prerequisite for this kind of application is the long time-scale of operation without or with limited possibility of seal replacement. In Germany an interim storage license for DPC’s is typically issued for 40 years, a timeframe which might increase in the future due to challenges of the final repository siting procedure. For low and intermediate level waste, also long time periods are required before final disposal can be achieved. Therefore, the performance of elastomer seals over extended time periods is, as for other applications, of high importance.
A typical approach to ensure long-term functionality is to perform accelerated aging tests to calculate an estimated lifetime by assuming e.g. Arrhenius like equations for the timetemperature relationship. This approach requires a suitable end of life criterion considering the application of interest. This often can represent a challenge on its own.
As BAM is involved in most of the cask licensing procedures and especially responsible for the evaluation of cask-related long-term safety issues we initiated several test programs for investigating the behavior of elastomer seals. Experiments concerning the low temperature performance down to −40 °C and the influence of gamma irradiation have been started first. Currently the thermal aging behavior of elastomer seals, which is the topic of this contribution, is examined.
For our aging investigations we use a broad approach to first determine the property changes in different elastomer materials due to thermo-oxidative aging at elevated temperatures and secondly, we test how the typical methods of lifetime extrapolation can be applied to these results. This approach enables us to detect and exclude undesired side effects which very often influence lifetime estimations. In this contribution, our recent results are extended. The results show that lifetime estimation based on single material properties can be misleading and therefore a combination of several methods is recommended.
An Iterative Method for Solving Static Piping Analysis Including Friction Between Pipes and Support
Authors: Anderegg Martin 
Published: November 2018

We present an iterative method to solve static piping analysis including Coulomb friction between pipes and supports. It is known that the most stable method to find the solution of this problem is to look for the correct stiffness to add in the plane orthogonal to the direction of the restraints for the resulting forces to be of correct intensity. The naivest way to pick the stiffnesses at each step is to choose the ones that would give the correct forces intensities if the displacements were correct. It is very effective in term of precision, but sometimes slow in term of execution. The penalty comes from the fact that the stiffness matrix is different at each iteration and thus that it must be factorized again. In this article we propose a way to increase the speed of convergence: selecting a subset of supports among the ones where convergence is the worst, and introducing sub-iterations focusing only on those supports can reduce the number of main iterations. Those sub-iterations can be calculated at a much lesser cost than the main ones by using the generalized Sherman-Morrison formula.
This algorithm was successfully implemented into the piping analysis software PIPESTRESS version 3.9.1 developed by DST Computer Services SA (the version number is temporary, the release date is Q3/Q4 of 2018).
Results and Correlations From Analyses of the ENSA ENUN 32P Cask Transport Tests
Authors: Kalinina Elena A. , Gordon Natalie , Ammerman Douglas J. , Uncapher William L. , Saltzstein Sylvia J. , Wright Catherine 
Published: November 2018

An ENUN 32P cask supplied by Equipos Nucleares S.A. (ENSA) was transported 9,600 miles by road, sea, and rail in 2017 in order to collect shock and vibration data on the cask system and surrogate spent fuel assemblies within the cask.
The task of examining 101,857 ASCII data files — 6.002 terabytes of data (this includes binary and ASCII files) — has begun. Some results of preliminary analyses are presented in this paper.
A total of seventy-seven accelerometers and strain gauges were attached by Sandia National Laboratories (SNL) to three surrogate spent fuel assemblies, the cask basket, the cask body, the transport cradle, and the transport platforms. The assemblies were provided by SNL, Empresa Nacional de Residuos Radiactivos, S.A. (ENRESA), and a collaboration of Korean institutions. The cask system was first subjected to cask handling operations at the ENSA facility. The cask was then transported by heavy-haul truck in northern Spain and shipped from Spain to Belgium and subsequently to Baltimore on two roll-on/roll-off ships. From Baltimore, the cask was transported by rail using a 12-axle railcar to the American Association of Railroads’ Transportation Technology Center, Inc. (TTCI) near Pueblo, Colorado where a series of special rail tests were performed. Data were continuously collected during this entire sequence of multi-modal transportation events. (We did not collect data on the transfer between modes of transportation.)
Of particular interest — indeed the original motivation for these tests — are the strains measured on the zirconium-alloy tubes in the assemblies. The strains for each of the transport modes are compared to the yield strength of irradiated Zircaloy to illustrate the margin against rod failure during normal conditions of transport.
The accelerometer data provides essential comparisons of the accelerations on the different components of the cask system exhibiting both amplification and attenuation of the accelerations at the transport platforms through the cradle and cask and up to the interior of the cask. These data are essential for modeling cask systems.
This paper concentrates on analyses of the testing of the cask on a 12-axle railcar at TTCI.
Correlating Coke Drum Profiles With Observed Surface Damage
Authors: Araque Egler D. , Rutt Daryl K. , Love Darren R. , Park Stephen M. , Clark Rick D. , Dawson Jason J. 
Published: November 2018

The frequency and extent of vessel bulging and cracking being registered in delayed coke drums throughout the global coking industry has accelerated significantly as refinery operators reduce their cycle times. Several theoretical approaches have been developed to identify how a bulged area may lead to drum damage; however, limited information has been presented to match the theoretical predictions with actual surface damage reported by coke drum operators.
The results of hundreds of laser scans spanning the last 25 years have been analyzed to correlate vessel bulging with observed surface damage. Specific categorizations of bulge profiles, and the proximity of these to circumferential weld seams (circs), have been calibrated against hundreds of real-world examples of drum damage and failure, including through wall cracking and stress cracking of the cladding, and further associated with the triggers for repair strategies implemented by industry leading refiners.
Strong correlations between specific aspects of bulge profiles and the presence of surface damage were found resulting in an assessment tool that can rank and prioritize coke drum distortions on the likelihood of damage, and can serve as a useful guide for planning future coke drum maintenance.
Proposed Methodology Changes to Determine Minimum Design Metal Temperature of ASME/API Impact Tested Materials Based on Fracture Mechanics
Authors: Kummari Seetha Ramudu , Macejko Brian , Prueter Phillip E. 
Published: November 2018

For equipment designed to ASME or API standards, it is common practice to perform impact testing of base material and/or weldments to establish the Minimum Design Metal Temperature (MDMT). The impact test is typically a Charpy V-Notch (CVN) test and the test temperature is set equal to the MDMT. The required Charpy energy at MDMT can vary anywhere from 10 ft-lbs to 40 ft-lbs depending on material specification, thickness, and the ASME/API standard. The detailed historical background behind the Charpy energy requirements of different ASME/API standards is not well documented. Additionally, no credit is given for post weld heat treatment (PWHT) of impact tested materials. The CVN tests are used because they are quick and economical for quality control, but the tests only provide a relative indication of material toughness. Consequently, the current impact test requirements lead to inconsistent results in brittle fracture assessments, conducted through explicit fracture mechanics.
In this paper, two examples are presented to highlight the inconsistencies of the current impact test requirements. A methodology of estimating MDMT for impact tested materials based on fracture mechanics, consistent with Welding Research Council (WRC) Bulletin 562 [1] is also presented. Furthermore, this methodology explicitly accounts for the effects of PWHT (and the influence of weld residual stress on crack driving force) for impact tested materials. A methodology of adjusting MDMT for in-service impact tested materials is also presented. In the interest of moving towards harmonizing the impact test requirements, an alternative procedure for establishing impact test requirements is presented for ASME/API consideration.
The Fracture Limit of Steel-Frame Members Under Dynamic Repeated Loads Through the Shaking Table Test
Authors: Shiomi Kensuke , Wada Yusuke 
Published: November 2018

Recently, much larger earthquakes are considered in the seismic designs of steel-frame structures in Japan. Under these severe ground motions, it is expected that not only the elasto-plastic deformation but also the fracture of the structural members could occur during the earthquakes. And through these situations, the more advanced seismic design or evaluation method which allow the partial destruction inside the structure and prevent from the worst-case scenario like the whole collapse are coming to be demanded. One of the ways to achieve this demand is considering the effects of not only the elasto-plastic deformation but also the fracture of structural members in the seismic analysis. In order for that, it is important to clarify the fracture limit of steel-frame members precisely under the dynamic load. Many static tests to clarify the members’ ultimate behavior were conducted in the past, but the dynamic tests were not well enough.
In this research, the vibration tests were conducted to clarify the fracture limit of steel-frame members under the dynamic load. The behavior of the steel-frame members until the fracture was obtained by applying the repeated dynamic bending deformation with the shaking table. Also, The FEM analysis for the shaking table test results was conducted. Through the tests and the analysis study which simulates the test results, the mechanism of the member fracture occurred in the test under the dynamic loads were examined.