bluuebunny/crossref_metadata_2025 huggingface dataset:
Crude Furnace Creep Assessment and High Temperature Degradation
Authors: Lee Gary Y. H. , Kwon Ohgeon , Ramli Zuwairi , Mohamad Afifi Zaki
Published: October 2017

Creep calculations indicate a crude furnace radiant section carbon steel tubes exceeding their life fraction due to flame impingement reaching up to 700°C for a year. The ambiguity of the temperature and material data means the life fraction of creep calculations were based on limited inspection data and infra-red scanning giving a conservative indication of end of life. Due to unavailable tubes in stock, a planned pit stop cannot be arranged due to economic and safety reasons as the furnace may not be started back up safely. To safeguard the integrity of the furnace until the planned outage, the temperature on the furnace tube was stabilized to a current limit of 540°C through improvements in burner operations. The crude diet was also maintained within the crude acceptance envelope. Visual checks at every shift were done to ensure no observation from tube bulging or uneven flame pattern.

A decision tree was created to facilitate quick decision making using a go/no go criteria of which tubes to replace during the August 2015 planned turnaround. The criteria set for the decision tree required tube wall thickness, surface hardness test, tube outer diameter ring gauge to be examined. Failing any of the criteria will require the tube to be replaced. The replaced tubes (one worst and one representative) will also be lab tested through destructive examination to identify the degradation mechanism and high temperature properties of the worst tubes to quantitatively define the high temperature properties and life fraction of the tubes that are left in the furnace. The lab test will provide results after a year of creep testing and can give assurance of continued furnace operation for 4 more years until the next outage. The final decision after the examination based on the decision tree was made required 17 tubes to be replaced in this turnaround. The worst degraded tubes were found to be at the vicinity of the initial observed location around the flame impingement zone.
Comparison About Standards of Fiber-Reinforced Plastic Pressure Vessels Between China and America
Authors: Yang Yuqing , Shu Wenhua , Luo Xiaoming , Wen Xiang , Si Jun , Zhang Ting , Wang Huanan
Published: October 2017

The paper briefly gives a summary of standard developments on fiber-reinforced plastic pressure vessels home and abroad. The management and basic technical requirements of FRP vessels are presented in the latest edition Chinese code Supervision Regulation on Safety Technology for Stationary Pressure Vessel (TSG 21-2016). Primary contents of China National Standard General Requirements of Fiber Reinforced Plastics Pressure Vessel (draft standard for approval) are introduced. Comparisons and investigations on FRP are conducted based on difference between China National Standard and ASME BPV CODE X -2015 Fiber-Reinforced Plastic Pressure Vessels, focusing on application scope, design qualification, procedure qualification, inspection and so on. The research will lay a solid foundation for Chinese development in the FRP fields in the future.
Fatigue Analysis of Small Bore Copper Nickel Full Encirclement Sleeve and Socket Welds Under Pressure Cycling
Authors: Jones Michael , Wilson James , Harris Alex
Published: October 2017

Sleeve and socket welds are often used in small bore nuclear power plant pipework where access is too limited to allow a conventional butt-weld. These welds are also used in process plants and pipelines as a permanent repair to reinforce areas such as cracks and corrosion that might threaten the structural integrity of the component. The fillet weld associated with this type of joint is particularly susceptible to lack of fusion defects which can be problematic to detect using conventional volumetric inspection techniques. The stress concentration associated with this type of defect will impact the fatigue life and pressure retaining ability of the joint.

This paper provides examples of Copper/Nickel (CuNi) sleeve weld defects and presents an approach for determining the fatigue life of socket welds due to pressure cycling within a Pressurised Water Reactor (PWR) environment. This approach is based on modelling lack of fusion features using a database of sleeve and socket weld Non-Destructive Testing (NDT) records and calculating the stress range in the remaining ligament using textbook calculations. Sensitivity studies presented herein show the impact of lack of fusion and pipe size/thickness on fatigue life.
Presentation of New Edition of RCC-M Code in 2017
Authors: Malouines Philippe , Fabre Melanie
Published: October 2017

The paper will cover the general approach followed by nuclear code RCC-M [1] of AFCEN, the French Society for Design, Construction and In-Service Inspection Rules for Nuclear Island Components, in codes and standards setting, from the technical and organizational points of views. The latest issue of RCC-M code edited in beginning of 2017 will be explained and commented. Main new topics of activity of RCC-M subcommittee will be also addressed: improvement in nonlinear analysis methods, technical qualification of active equipment, material and manufacturing techniques changes, principles of demonstration of code conformity with regulation, comparison with other codes and standards. The presentation highlights how the industrial experience is currently integrated into the RCC-M codes, and how code members had demonstrated the conformity with European essential safety requirements for pressure equipment. Processes for updates, interpretations and inquiries will be also addressed.
Evaluation of Weibull Parameters by Different Small Punch Tests Samples Based on Beremin Model
Authors: Guan Kaishu , Guo Linling , Fu Mingxue
Published: October 2017

Small punch testing technology is used for quantifying the mechanical properties of bulk materials with greatly reduced volume. However, as the volume decrease, the ductile to brittle transition region of the specimen will move to lower temperature. That means a small punch specimen and a bulk specimen may fracture under different regime. For this case, it’s difficult to obtain fracture toughness of bulk materials from the small punch tests. In this paper, a new approach, which is based on Beremin local approach, to evaluate the Weibull parameters of bulk materials in the ductile to brittle transition region by small punch tests has been proposed.

This paper focuses on the choice of specimen types of small punch test based on Beremin model. Four different types of specimens were tested at ductile to brittle transition region. i.e. ( a ) two kinds of linear notched small punch test specimen (LNSP), (b) two kinds of center holed small punch test specimen (CHSP). All notches of the specimens were machined by electric discharge method, and both sides of the specimens were grinded and polished.

The results showed that 0.5mm CHSP (center holed small punch test specimen) is the best choice for small punch test based on Beremin model according to experimental curves, SEM (scanning electron microscope) analysis, and result of finite element simulation. Furthermore, the cumulative failure probability in ductile-to-brittle transition region by small punch tests was obtained and the method of calculating Weibull parameters (m,σu) is analyzed.
Study of Reactor Internal Bolt Behaviors Under Lateral Loads
Authors: Gao Yong-Jian , Feng Shao-Dong , Yu Qing , Chen Bing-Bing , Lin Shao-Xuan , Zhang Zhai
Published: October 2017

In calculating the bolt stresses under lateral loads, such as caused by the differential thermal movement between two components — problems often found in the reactor internal design, the boundary condition of the bolt is usually conservatively assumed to be in a guided-cantilever beam mode, i.e., the bolt head is not allowed to rotate. In reality, the bolt head could rotate to a certain degree and, furthermore, the bolt head could slip, a form of loosening, under the lateral loads.

A series of lateral load-deflection tests was conducted on bolts of different sizes and different lengths, with different preloads, to study the bolt behaviors, including when the bolts start to slip and what is the effect of preloading on the slippage. Furthermore, finite element studies were conducted to correlate the test results to find the proper boundary condition to be used in the bolt stress calculation.
Ductile Damage Assessment Using Continuum Damage Mechanics and Methodology for High Strain-Rate Damage Analysis
Authors: Sancho Alexander , Hooper Paul A. , Davies Catrin M.
Published: October 2017

The interest of this research is to assess the experimental techniques used for ductile damage measurement both in quasistatic and high strain-rate conditions. The results can later be used for the calibration of Continuum Damage Mechanics (CDM) models.

A procedure for the evaluation of damage accumulation in quasi-static conditions is presented. The technique used to measure damage is based on the elastic modulus calculation from unloading and reloading cycles performed at different stages of plastic deformation. Tests have been performed in a continuous manner and the strain variations have been recorded using a small gauge extensometer. This methodology includes a second experiment in which the geometry of the specimen is monitored, allowing to extract the true stress-strain behaviour of the material even after necking phenomenon starts. The proposed methodology has been applied to stainless steel 304L.

Regarding the high strain-rate conditions, a continuous test cannot be performed due to physical as well as practical difficulties. Therefore, an interrupted methodology has been devised in which the plastic deformation is applied at high strain-rate and the damage measurement is performed separately in quasi-static conditions. An experimental rig has been developed to interrupt high-speed tensile tests at strain-rates up to 103s−1. Its design and preliminary calibration are analysed and its future use for damage assessment discussed.
Remaining Life Enhancement Technology: Lifting and Tilting Tall Vessels — A Coke Drum Case-Study (Without Cranes)
Authors: Kaye Alwyn
Published: October 2017

Throughout the refining industry, there is a need to increase the return on investment of aging assets. Remaining life technology application and development is widely adopted to increase value from existing infrastructure and equipment. In this paper, an innovative way of continuing to utilize compromised vessels was creatively pursued. The technique and principles can be applied to vessels or equipment that is known to have shape deficiencies without having to replace sections, components, whole shells, drums, towers or casings. In this way, the costly rebuild work and greater loss of production can be avoided. Replacement was circumvented in a Delayed Coking Unit (DCU) for a Canadian oilsands upgrader.

In this case study, principles were taken from the building transportation and moving industry and applied to lifting and tilting of 145ft (44.2m) high coke drums. The ability to tilt and re-align a vessel of 14 storey (equivalent height) thin shell coke drum was believed to be possible and was subsequently performed successfully, at this location, multiple times. These were the largest coke drums in the world (at the date of their fabrication in 2006). The design and engineering issues are discussed in detail, including the techniques and analysis, stability, protection against buckling and finally; inspection and verification.
Experimental Investigation and Finite Element Analysis on Cold-Stretching for Austenitic Stainless Pressure Vessels
Authors: Han Yu , Wang Kesheng
Published: October 2017

Cold-stretching is an effective way to make the pressure vessels lighter. A test vessel with austenitic stainless steel was designed and manufactured based on the current criterion, and the cold-stretching process was carried out. The deformation of each part of the vessel under the pressure of each stage were measured by the resistance strain gauge in its measurement range. The finite element method is used to calculate the deformation trend of the whole process of cold-stretching. In addition, the strain of complex deformation at nozzle and its surrounding was analyzed by FEM.
Application of Partial Safety Factors for Fitness-for-Service Assessment of Pressure Equipment With Local Metal Loss
Authors: Kaida Takuyo , Sakai Shinsuke
Published: October 2017

Reliability analysis considering data uncertainties can be used to make a rational decision as to whether to run or repair a pressure equipment that contains a flaw. Especially, partial safety factors (PSF) method is one of the most useful reliability analysis procedure and considered in a Level 3 assessment of a crack-like flaw in API 579-1/ASME FFS-1:2016. High Pressure Institute of Japan (HPI) formed a committee to develop a HPI FFS standard including PSF method. To apply the PSF method effectively, the safety factors for each dominant variable should be prepared before the assessment. In this paper, PSF for metal loss assessment of typical pressure vessels are derived based on first order reliability method (FORM). First, a limit state function and stochastic properties of random variables are defined. The properties of a typical pressure vessel are based on actual data of towers in petroleum and petrochemical plants. Second, probability of failure in several cases are studied by Hasofer-Lind method. Finally, PSF’s in each target probability of failure are proposed. HPI published a new technical report, HPIS Z 109 TR:2016, that provide metal loss assessment procedures based on FORM and the proposed PSF’s described in this paper.
Effects of Chattering on Surface Integrity in Robotic Milling of Alloy 690
Authors: Maurotto A. , Tunc L. T.
Published: October 2017

Manufacturing components for the nuclear industry requires large enclosed machining centres capable of accommodating the sheer size of the parts. Those machining centres are expensive to commission and they need a large infrastructure leading to the high costs associated with manufacturing. Robotic machining offers noticeable infrastructure savings. This could narrow down the infrastructure requirements leading to a general reduction of the high cost associated with new nuclear build.

Machining robots generally suffer from reduced static and dynamic stiffness when compared with machining centres. This renders them more prone to chatter type of vibrations. Especially at relatively low speed cutting of super-alloys, the low frequency modes of the robot may be excited at high amplitudes due to the high cutting forces at low excitation frequencies. In this paper, the effects of chattering, due to the dynamics of the machining robot, on surface integrity are evaluated comparing stable, mild and severe chattering conditions. Surface roughness and residual stresses are evaluated in robotic milling of alloy 690 using ceramic inserts. The results are discussed focusing on the effects of chatter vibrations due to the machining robot on the surface integrity.
A Case Study for the Low Fidelity Modeling of Threaded Fasteners Subject to Tensile Loadings at Low and High Strain Rates
Authors: Mersch John P. , Smith Jeffrey A. , Johnson Evan P.
Published: October 2017

A series of tests on NAS1352-06-6P threaded fasteners were coupled with analysis to fit constitutive models, evaluate multiple modeling approaches, and ultimately predict failure. Experiments loading the fasteners in tension at both quasistatic and dynamic loading rates were performed to obtain calibration and validation data for the analysis. The fastener was modeled with two low-fidelity approaches — a “plug” of hex elements retaining the nominal fastener geometry (without threads) and a “spot weld”, which incorporates similar geometry but the fastener is sliced near its mid-plane to define a tensile load-displacement relationship between the two exposed surfaces — to accommodate the use of these modeling methods in a larger, more detailed finite element analysis. Both modeling approaches were calibrated using quasistatic test data and then extended to the dynamic analyses to compare with the analogous test results. The analysis accurately reproduces most acceleration time-histories observed in the dynamic testing but under predicts failure, indicating the possible presence of strain rate effects that have been neglected in the constitutive models.
Overview of Revisions to the ASME Boiler and Pressure Vessel Code Section VIII Division 3 for the 2017 Edition and Near Future
Authors: Peters Daniel , Mital Gregory , Maslowski Adam P.
Published: October 2017

This paper provides an overview of the significant revisions pending for the upcoming 2017 edition of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Section VIII Division 3, Alternative Rules for Construction of High Pressure Vessels, as well as potential changes to future editions under consideration of the Subgroup on High Pressure Vessels (SG-HPV). Changes to the 2017 edition include the removal of material information used in the construction of composite reinforced pressure vessels (CRPV); this information has been consolidated to the newly-developed Appendix 10 of ASME BPVC Section X, Fiber-Reinforced Plastic Pressure Vessels. Similarly, the development of the ASME CA-1, Conformity Assessment Requirements standard necessitated removal of associated conformity assessment information from Section VIII Division 3. Additionally, requirements for the assembly of pressure vessels at a location other than that listed on the Certificate of Authorization have been clarified with the definitions of “field” and “intermediate” sites. Furthermore, certain design related issues have been addressed and incorporated into the current edition, including changes to the fracture mechanics rules, changes to wires stress limits in wire-wound vessels, and clarification on bolting and end closure requirements. Finally, the removal of Appendix B, Suggested Practice Regarding Post-Construction Requalification for High Pressure Vessels, will be discussed, including a short discussion of the new appendix incorporated into the updated edition of ASME PCC-3, Inspection Planning Using Risk Based Methods.

Additionally, this paper discusses some areas in Section VIII Division 3 under consideration for improvement. One such area involves consolidation of material models presented in the book into a central area for easier reference. Another is the clarification of local strain limit analysis and the intended number and types of evaluations needed for the non-linear finite element analyses. The requirements for test locations in prolongations on forgings are also being examined as well as other material that can be used in testing for vessel construction. Finally, a discussion is presented on an ongoing debate regarding “occasional loads” and “abnormal loads”, their current evaluation, and proposed changes to design margins regarding these loads.
An Investigation of I-II Mixed Mode Structures With Stop Hole Technique Based on Extended Finite Element Method
Authors: Miao Xin-Ting , Zhou Chang-Yu , He Xiao-Hua
Published: October 2017

Extended finite element method (XFEM) is adopted in this paper to study crack growth path and loading capability for modified compact tension shear (CTS) specimen with stop hole ahead of crack tip. Elliptical stop holes with different values of b/h are considered, where b and h are radii of the ellipse parallel and vertical to the crack. When b/h is 1 (circle stop hole), the locations of crack initiation turn clockwise gradually as the loading angle β (angle between the loading direction and the crack plane) decreases. When b/h is not equal to 1 (elliptical stop hole), the locations of crack initiation are all near the long axis end point of the ellipse no matter what the mode mixity is. Curves of load-COD and ultimate loads are presented for different mixed mode loadings, it can be obtained that for mode I dominant crack loading capability increases, though for mode II dominant crack loading capability decreases due to the stop hole technique. For mode I dominant crack the loading capability increases as the value of b/h decreases, and for mode II dominant crack the trend of loading capability with b/h changes gradually oppositely. The difference of crack initiation locations for different stop holes is due to the stress concentration considering both curvatures and the loading modes. And the difference of loading capability for specimens with stop holes under different mixed mode loadings is due to the shear action due to the discrepancy between the positive and negative stresses. Therefore, stop hole technique can be used to change the crack initiation location in order to avoid the important component and improve the loading capability by choosing an appropriate hole shape.
On the Use of Proper Fragility Models for Quantitative Seismic Risk Assessment of Process Plants in Seismic Prone Areas
Authors: Alessandri Silvia , Caputo Antonio C. , Corritore Daniele , Renato Giannini , Paolacci Fabrizio , Phan Hoang Nam
Published: October 2017

Quantitative Risk Assessment (QRA) is a classical method for the calculation of risk in process plants, which is based on the logic of the consequence analysis. This intrinsically probabilistic method has been thought for classical accident conditions, where the damage events and the relevant consequences start from a preselected component and a standard loss of containment (LOC) and follow all possible scenarios for the calculation of individual and societal risk. This final risk metric is usually expressed in terms of probability of fatality in a specific location of the surrounding area or a certain number of fatalities in the area surrounding the accident. In presence of Na-Tech events, like earthquakes, a multi-source condition can be caused by multi-damage conditions simultaneously involving more than one equipment, which in turn can generate a multiple-chain of events and consequences. In literature, several attempts of modifying the classic QRA approach to account for this important aspect have been formalized without converging toward a unified approach.

In this paper, a fragility-based method for Quantitative Seismic Risk Analysis (QSRA) of a process plant is investigated. This method takes into account all possible damage/losses of containment conditions in the most critical equipment, e.g., storage tanks. Fragility curves, which are analytically evaluated for each unit with respect to its seismic damage conditions, are utilized inside the procedure. The Monte Carlo Simulation (MCS) method is then used with the aim to follow all steps of QSRA. In particular, starting from the seismic hazard curve of the site where the plant is placed, a multi-level approach is proposed. In this approach, the first level is represented by the components seismically damaged, whereas the following levels are treated through a classical consequence analysis, including the propagation of multiple simultaneous and interacting chains of accidents. These latter are applied by defining proper correspondences for all relevant equipment between structural damage (i.e., limit states) and LOC events. The application of the method to an actual process plant permits to investigate its high potentiality and the dependency of the risk assessment from the proper fragility models.
Univariate Fragility Models for Seismic Vulnerability Assessment of Refinery Piping Systems
Authors: Caprinozzi Stefano , M. Ahmed Mohammad , Paolacci Fabrizio , Bursi Oreste S. , La Salandra Vincenzo
Published: October 2017

Piping systems of energy industries in oil & gas play a critical role in meeting the increasing global energy demand. A great portion of these pipelines is located in high seismic-prone areas. Such systems have been found to be quite vulnerable to seismic events. Current seismic design approaches to piping systems are mainly based on the allowable stress method, even though more modern design methods are currently available for buildings or nuclear power plants; for example, the Performance-Based Earthquake Engineering (PBEE) framework has not been applied yet to piping systems and relevant structures. In this respect, both information about the quantification of limit states for pipes and adequate non-linear structural models for seismic analysis of piping systems and relevant structures are very limited.

One of the key ingredients of PBEE approach for the assessment of the seismic vulnerability of existing structures is the evaluation of fragility curves, namely the probability of exceeding a certain level of damage for a given seismic intensity measure (IM). However, the contributions in the literature on this delicate aspect are very limited.

This paper deals with such a problem by using a very popular method, namely the Cloud Analysis, originally developed as a method for probabilistic seismic demand analysis of civil structures. This method is here applied to a typical piping system for process plants. For this purpose, the structure is properly modelled, especially support structure and pipe, including pipe fittings like elbows and bolted flange joints. Using natural accelerograms selected from the PEER database and in accordance with given hazard conditions, the probabilistic seismic demand analysis is performed adopting different engineering demand parameters (EDP) consistent with the damage states expected in the pipes and fittings and in the support structure.

According to the results of experimental tests campaign performed in the past by some of the authors on flanged joints, and elbows, different damage states (leakage, yielding, rupture) have been identified and related to the corresponding EDP and the corresponding probability of exceeding has been determined by assuming a lognormal distribution of the response. The analysis intends to recognise the most probable damage condition in a refinery piping system subjected to a seismic input.
Safety Margin Optimisation by Probabilistic Analysis
Authors: Stefanini L. , Blom F. J.
Published: October 2017

Deterministic assessment codes can contain large safety factors that give very conservative results. By applying probabilistic analysis to these deterministic assessments, an implicitly accepted probability of failure can be determined. The probability of failure is implicit because it is calculated with the parameter values resulting in a state that is deterministically accepted by the code [2]. When these probabilities are compared for similar deterministic assessments, the excess conservatism can be shown and possibly reduced.

During the present study a probabilistic analysis of the critical crack length initiation was performed. Such analysis led to the formulation of a corrective action proposal to the Master Curve approach given in BS7910:2013 Annex J.

Firstly a deterministic calculation was performed with the Kr-Lr method to define the Critical Length of a through-wall circumferential crack present in a nuclear reactor’s piping. The value of Kmat used in the Kr-Lr method was calculated for a probability of 0.05 and with T0 directly measured (T0 a unique value).

The second step was to pass to probabilistic calculation. Here Kmat was calculated from both T0 directly measured and T0 estimated by Charpy-V tests (T0 as a distribution). The results from these calculations gave the probability of a crack being equal to the Critical Crack Length. Moreover, these results showed that the Tk safety margin introduced in BS7910:2013 Annex J introduce an excess conservatism.

Results from the probabilistic calculations were then compared to the implicitly accepted failure probability Pf (5%) that results from deterministic analysis (T0 considered as a single value) to account for the effects of T0 distribution. An optimized Tk was then found to account for the real uncertainty of the statistical distribution.

Finally, excluding a dependency on the yield stress, the Tk optimization method was generalized. A new correlation for the Tk safety margin is proposed.
Numerical Simulation of a Highly Compressed Saturated Water Flashing Flow
Authors: Jo Jong Chull , Jeong Jae Jun , Yun Byong Jo , Moody Frederick J.
Published: October 2017

Transient fluid velocity and pressure fields in a pressurized water reactor (PWR) steam generator (SG) secondary side during the blowdown period of a feedwater line break (FWLB) accident were numerically simulated employing the saturated liquid flashing model. This model is based on the assumption that compressed water in the SG is saturated at the beginning and decompresses into the two-phase region where saturated vapor forms, creating a mixture of steam bubbles in liquid by bulk boiling.

The numerical calculations were performed for two cases where the outflow boundary condition is different from each other; one is specified as the direct blowdown discharge to atmospheric pressure and the other is specified as the blowdown discharge to an extended calculation domain with atmospheric pressure on its boundary.

To effectively simulate the saturated water flashing from the SG following the FWLB accident, the physical SG model was simplified as a vertical once-through SG to which a feedwater pipe is attached. However, the physical geometry of the analysis model was modeled as realistically as possible in terms of the SG tube bundle height, the SG inner diameter and porosity, the inner diameter and length of broken feedwater pipe part, etc. It was considered that the SG shell-side and the attached feedwater pipe were initially filled with high pressure saturated water. The pressure in the steam space was 7.5 MPa. For the calculation of the two-phase flow during high pressure saturated water flashing from the SG through the broken feedwater pipe, the inhomogeneous two-fluid model was used.

The present simulation results were discussed through a comparison with the predictions using a simple non-flashing model neglecting the effects of phase change.

Based on the comparative discussions, the applicability of each of the non-flashing liquid discharge and saturated liquid flashing discharge models to the confirmatory safety evaluations of new SG designs was examined.
Effect of Soil Displacement Rate and Complex Loading on Soil-Pipe Interaction: A Physical Prototype Model
Authors: Wong C. K. , Wan R. G. , Wong R. C. K.
Published: October 2017

Buried pipeline systems may traverse sections in moving soil masses. Large strains may be accumulated in buried pipes under long-term ground movements, and it may affect the performance of the pipes. It is a common practice in that a stress relief procedure is applied to the pipe by removing the soil around the pipe to allow the pipe to spring back to its initial state. Pipeline engineers and designers need to assess the frequency of stress relief to maintain the integrity of the pipeline to prolong its operation. The frequency of applying necessary remediation measures depend on; the rate of soil displacement, soil-pipe interaction, severity of loading, and soil conditions.

A physical model has been designed and fabricated to investigate these critical effects on soil-pipe interaction. This model comprises a steel circular soil chamber (1.5 m in diameter and 1.2 m in height) rested on a rail system, and a steel pipe (150–300 mm in diameter) being embedded in a compacted soil inside the chamber. This system has unique features: (i) facilitating the pipe be subjected to relative displacements in complex oblique (combined longitudinal-transverse) loading, (ii) simulating the low soil displacement rates in the field (50 mm per year), and (iii) testing of different soil types. Test results obtained from this research program will be used to evaluate the existing guidelines (e.g., American Lifelines Alliance (ALA) and Pipeline Research Council International (PRCI)).
Fuzzy Semi-Active Control of Multi-Degree-of-Freedom Structure Using Magnetorheological Elastomers
Authors: Xuan Bao Nguyen , Komatsuzaki Toshihiko , Iwata Yoshio , Asanuma Haruhiko
Published: October 2017

Magnetorheological elastomer (MRE), used in semi-active control, has recently emerged as a smart material that could potentially improve traditional systems in controlling structural vibrations. This study considers two main issues concerning the application of an MRE. The first issue is the modelling and identification of the viscoelastic property, and the second is the formulation of an effective control strategy based on the fuzzy logic system. Firstly, a nonlinear dynamic MRE model was developed to simulate the dynamic behavior of MRE. In this model, the viscoelastic force of the material as an output was calculated from displacement, frequency, and magnetic flux density as inputs. The MRE model consisted of three components including the viscoelasticity of host elastomer, magnetic field-induced property, and interfacial slippage that were modeled by analogy with a standard linear solid model (Zener model), a stiffness variable spring, and a smooth Coulomb friction, respectively. The model parameters were identified by manipulating two sets of data that were measured by changing applied electric current and harmonic excitation frequency. A good agreement was obtained between numerical and experimental results. The proposed model offers a beneficial solution to numerically investigate vibration control strategies. Secondly, a fuzzy semi-active controller was designed for seismic protection of building with an MRE-based isolator. The control strategy was designed to determine the command applied current. The proposed strategy is fully adequate to the nonlinearity of the isolator and works independently with the building structure. The efficiency of the proposed fuzzy semi-active controller was investigated numerically by MATLAB simulations, whose performance was compared with that of passive systems and a system with traditional semi-active controller. Numerical results show that the developed fuzzy semi-active controller not only mitigates the responses of both the base floor and the superstructure, but also has an ability to control structural vibrations adaptively to the different intensity ground motions.
Evaluation on Microstructure and Mechanical Properties of Welded Joints by GMAW in UNS N10003 Alloy
Authors: Yu Kun , Jiang Zhenguo , Shi Xianwu , Li Chaowen , Chen Shuangjian , Li Zhijun , Tao Wang , Zhou Xingtai
Published: October 2017

UNS N10003 alloy is a primary material of the Thorium Molten Salt Reactor (TMSR) in China that is a suitable candidate reactor of the Generation IV nuclear reactors. Gas metal arc welding (GMAW) is more effective than gas tungsten arc welding (GTAW) which is usually used to weld nickel-base alloys. In order to improve welding efficiency, it is necessary to weld nickel-base alloys using GMAW. The purpose of this work is to evaluate effect of GMAW on microstructure evolution and mechanical properties in UNS N10003 alloy. The results of microstructure showed that the sound welded joint without hot cracking can be obtained, although quantities of M6C-γ eutectic phases with large size were precipitated in fusion zone (FZ) and transformed in heat affected zone (HAZ) because of element segregation. The results of microhardness test indicated that there was no softened zone in the welded joint. The results of tensile test at room temperature and high temperature showed that the short-term time-independent strength was not damaged by the formation of large M6C-γ eutectic phases.
Weld Repair of C, Cr-Mo Cokedrums (and Pressure Vessels) Without PWHT
Authors: Kaye Alwyn , Lester Patrick , Barborak Darren
Published: October 2017

Many of the Cr{1-1/4 to 2-1/4}-Mo{1/2 to 1} pressure vessels in the refining and petrochemical industries such as process reactors, distillation columns, separators, pressurized storage vessels, and heat exchangers are typically vertical columns, most often supported by a circular skirt. Typically, design considerations for these vessels and support skirts are for operating under continuous “steady-state” conditions, where temporary stresses due to short-term “transient” events such as start-up and shutdown are often ignored. Consequences of dynamic and cyclic loading play a very significant role in their life and performance. For Coke drums, survey data from API shows that the skirt-to-drum attachment weld and adjoining area appears to be the most problematic, frequently experiencing low-cycle fatigue cracking due to concentrated stresses.

A methodology for repairing the skirt attachment weld of Cr-Mo pressure vessels is provided. When designing a repair approach, consideration should include material and aged condition, extent and location of defects, welding process and consumables, and codes, standards, and regulatory guidelines. When repair by weld metal buildup to rebuild a skirt-attachment weld configuration is considered, weld procedure qualification and adequate mock-ups should be performed in order to ensure a sound repair. Further, when invoking a code compliant repair without post-weld heat treatment by controlled deposition welding or temper bead techniques, proper training of welder operators should be conducted to ensure the techniques are implemented properly.

A case study is provided for a Coke drum, where the original design and fabrication of the skirt attachment included an initial SAW weld metal buildup on the 2.25Cr (P5A) cone followed by an SMAW/GTAW attachment weld to the 1.25Cr skirt (P4). During a plant shutdown, a surface breaking crack was detected in the skirt to shell attachment weld by Dye Liquid Penetrant Testing (D-LPT) and confirmed with Magnetic Particle Testing (MPT). Subsequent examination by Phased Array Ultrasonic Testing (PAUT) discovered a large number of volumetric indications, oriented towards the knuckle section internally. The repair approach consisted of 1) Completely remove the existing skirt and the attachment weld (knuckle) in segments, 2) Inspect the cone for remaining flaws, 3) Excavate and repair flaws in cone using temper bead technique, 4) Rebuild knuckle area for skirt to cone attachment with an increased radius using temper bead welding techniques, 5) Install new skirt sections using controlled deposition welding technique. Temper Bead and Controlled Deposition repair welding techniques were utilized to avoid conventional post-weld heat treatment requirements, significantly improving the turn-around time in the field.
Seismic Qualification of Piping Systems by Detailed Inelastic Response Analysis: Part 1 — A Code Case for Piping Seismic Evaluation Based on Detailed Inelastic Response Analysis
Authors: Morishita Masaki , Otani Akihito , Watakabe Tomoyoshi , Nakamura Izumi , Shibutani Tadahiro , Shiratori Masaki
Published: October 2017

A Code Case in the framework of the Nuclear Codes and Standards of Japan Society of Mechanical Engineers (JSME) is currently under development to incorporate seismic design evaluation methodologies for piping systems by detailed inelastic response analysis and strain-based fatigue criteria as an alternative design rule to the current rule, in order to provide a more rational seismic design evaluation by taking directly the response reduction due to plasticity energy absorption into account. The Code Case provides two strain-based criteria; one is a limit to maximum amplitude of equivalent strain amplitude derived from detailed analysis and the other is a limit to the fatigue usage factor also based on the equivalent strain amplitude. The Code Case also provides an evaluation method by simplified inelastic analysis with an additional damping taking the response reduction due to plasticity into account. Some discussions are provided on the adequacy of additional damping in the simplified inelastic analysis and the safety margin and reliability of fatigue evaluation by the detailed inelastic response analysis provided in the Code Case.
An Integration Method for Assessing the Operational Reliability of Underground Gas Storage in Depleted Reservoir
Authors: Yu Weichao , Min Yuan , Huang Weihe , Wen Kai , Zhang Ye , Gong Jing
Published: October 2017

Underground gas storage (UGS), as a key component of natural gas pipeline network, can not only be used as emergency gas source under pipeline system failure situation, but it is also available for seasonal peak shaving under pipeline system normal situation. Therefore, in order to meet the natural gas needs, it is of vital importance to safeguard the security of UGS operation and assess the reliability of UGS. The aim of the overall study is to develop an integration method for assessing operational reliability of UGS in depleted reservoir under different injection-production scenarios whereas existing studies only assess single component or subsystem reliability. According to function zoning, UGS is separated into reservoir, well system containing multiple injection/production wells and surface system, and reservoir and surface system are connected through well system. At the first step of reliability assessment, the hydraulic calculation including gas injection process calculation and gas production process calculation is adopted to obtain the operation parameters of each component in UGS. Next, reliability of reservoir, injection/production well and equipment in surface system are evaluated using operation parameters and Monte Carlo approach. The reliability of subsystem, such as well system and surface system, are then calculated according to system reliability theory. Finally, operational reliability of UGS is obtained, which reflects the capacity of performing gas injection-production function. Two test cases are given to illustrate the integration method.
Selection of Bolt Preload for Impulsively Loaded Vessels
Authors: Duffey Thomas A. , Hess Joseph E. D.
Published: October 2017

Guidance for the appropriate preload for bolted joints is well established for static pressure loading as well as cyclic loading. The goal for bolt-preload selection in these cases is generally leak prevention, alleviation of bolt loosening, and minimization of fatigue loading of the closure bolts. For impulsively loaded containment vessels, such as those governed by the rules of ASME Code Case 2564 in Section VIII, Div. 3, much less is known regarding appropriate bolt-preload selection. In this paper, a simplified, upper-bound bolt-preload methodology is developed to evaluate the role of bolt preload on peak bolt stress, including the effect of transient vessel motions. The simplified model for the bolted joint and vessel is solved in closed form for exponential pressure-pulse loading on the interior of a spherical containment vessel. Detailed finite element calculations are also performed using a refined model to more precisely examine the role of bolt preload. Comparisons of the approximate bolt-preload methodology with the detailed finite element results are then presented, along with comparisons to a lower-bound solution reported earlier. It is shown that the peak bolt stress predicted by the detailed finite element model is bounded from above and below by the simplified solutions. Implications on the role of bolt preload on peak dynamic bolt stress are given for sudden pressure-pulse loading. Goals and requirements for selecting bolt preload for impulsively loaded vessels are briefly discussed.
Effects of Notch Acuity on Fracture Toughness Measurements
Authors: Park Dong-Yeob , Gravel Jean-Philippe , Duan Da-Ming
Published: October 2017

Effects of initial crack-tip acuity on toughness measurements has been evaluated through extensive small-scale toughness testing — single-edge notched tension and bend (SE(T) and SE(B)) — at room temperature using two X70 pipeline steels and girth welds. In order to investigate effects of different crack tip radii on toughness, some specimens were notched to the target initial crack size using electrical discharge machining (EDM), and no further fatigue precracking was made. On the other hand, other specimens were EDM-notched and then fatigue-precracked to the target crack size according to the current practice of ASTM E1820. The results show that effects of crack tip acuity on toughness measurement are significant especially at the crack-tip blunting stage. The EDM precrack increased toughness measurements by a factor of up to 1.6 and 2 for SE(B) and SE(T), respectively, at 0.2 mm of crack extension, compared to the fatigue precrack.
Identification of Two-Phase Flow Patterns Using Support Vector Classification
Authors: Benito Ines , Mureithi Njuki W.
Published: October 2017

Two-phase flows are preponderant in industrial components. The present work deals with external two-phase flows across tube banks commonly found in heat exchangers, boilers and steam generators. The flows are generally highly complex and remain theoretically intractable in most cases. The two-phase flow patterns provide a convenient albeit qualitative means for describing and classifying two phase flows. The flow patterns are also closely correlated to fluid-structure interaction dynamics and thus provide a practically useful basis for the study of two-phase flow-induced vibrations.

For internal two-phase flows, maps by Taitel et al. (1980) and others have led to detailed and well defined maps. For transverse flows in tube bundles, there is significantly less agreement on the flow patterns and governing parameters. The complexity of flow in tube arrays is an obvious challenge. A second difficulty is the definition of distinct flow patterns and the identification of parameters uniquely identifying the flow patterns.

The present work addresses the problem of two-phase flow pattern identification in tube arrays. Flow measurements using optical as well as flow visualization via high-speed videos and photography have been conducted. To identify the flow patterns, an artificial intelligence machine learning approach was taken. Pattern classification was achieved by designing a support vector machine (SVM) classifier. The SVM achieves quantitative and non-subjective classification by mapping the flow patterns in a high dimensional mathematical space in which the different flow patterns have unique characteristics.

Details of the flow measurement, parameter definition and SVM design are presented in the paper. Flow patterns identified using the SVM are presented and compared with previously identified flow patterns.
Evaluation of Blast Loads From Pipe Ruptures
Authors: Geng Jihui , Thomas Kelly
Published: October 2017

High-pressure pipeline ruptures are a credible explosion hazard at many industrial facilities. The blast field generated by a pipe rupture is highly directional. However, there have been few evaluations of the directional blast loads produced by pipe ruptures. This paper addresses the blast loads generated by a typical “fish mouth” type pipe rupture. The effects of five key parameters on the resulting directional blast field were examined: rupture opening speed, final rupture opening area, pipe diameter, initial gas pressure, and initial gas temperature. The resultant blast loads were compared to those based on existing blast curves for Pressure Vessel Bursts (PVB), the most common of which is based on an assumption of a spherical vessel geometry and instantaneous failure of the entire pressure vessel boundary. The effective gas volume (i.e., number of pipe diameters) required to achieve reasonable agreement between the blast load based on existing PVB blast curves and that resulting from a high-pressure pipeline fish mouth rupture for a specified direction was determined.
Finite Element Analysis of a Quick-Actuating Closure
Authors: Ricco Giovanni
Published: October 2017

This paper provides a FEA of a specific type of Quick-Actuating Closure which uses an external cylindrical retaining ring. An equation is provided to find the minimum coverage angle of the retaining ring so that the ring will not rotate when loaded by the closure door.