A suite of High Rate Heavy Vacuum Gas Oil (HVGO) pumps in an operating Upgrader Plant experienced repeated failures; typically, less than 7 weeks. The need for online measuring tools arose that could measure pump and piping system strain changes with dynamic thermal gradients. The challenge was to record the effect on the entirety of pump component alignment and vibration. In current industrial practices no such tools and techniques are directly and comprehensively available for rotary equipment. Strain gauges are not accurate, and cannot provide broader real time strain mapping. Optical metrology can analyze the mechanical properties and behavior of all kinds of materials in various test scenarios. To date such methods are experimental and principally found in advanced application environments. At the time the method was unknown and especially in such a difficult industrial plant. In such a complex and extreme hot and cold operating service warm-up, cooling, with variations in flow and temperature, can directly and dynamically affect strain measurements. It was not certain whether optical meorology measurement techniques would be able to identify and correlate dynamic operating scenarios with the source of the pump and pipe hardware issues experienced in these Heavy Vacuum Gas Oil (HVGO) pump systems. The influence of the casing thickness and stiffness on the resulting vibration characteristics was investigated by using FEA and operational testing and dynamic analysis. Increasing the interface web thickness results in notable reduction in deformation. Comparison of the results of the live testing against the initial design was performed and studied for remedial action. Materials and heat treatment options were also evaluated and reported. The three-dimensional turbulent flow was modelled and analyzed. The application of those tools for this type of problem are described along with the other rigorous techniques employed. The range of tools included modal and vibration analysis, thermography, rotor and shaft dynamics, baseplate, frame, metallurgical analysis and ultimately compared with FEA, pipe stress modelling and strain analysis. This paper should be read in conjunction with PVP 2020-21204; Piping & Equipment Dynamics of High Rate HVGO Pumps.

The skirt and shell thicknesses of vertical tall pressure vessels are sometimes much increased in FPSO (Floating Production, Storage and Offloading) due to ship motion acceleration. In that case, intermediate support is used as an additional support from steel structure surrounding the vessels. By theoretical calculation, Nanjo et.al. introduced dimensionless parameter N that can represent stiffness of pressure vessel and acceleration load with the assumption of structure drift at intermediate support [1]. The authors proposed N-chart to investigate the necessity and effective elevation of intermediate support by using the parameter N . The flexibility of steel structure on the bottom affects the function of intermediate support (e.g. increasing reaction force at intermediate support, effect on bottom skirt calculation); however, the flexibility is not included in the parameter N. In this paper, an additional factor for the flexibility was studied and introduced by structural analysis. A model with flexibility of structure supporting the bottom skirt was used for the analysis. The variable flexibility of steel structure was applied to the bottom of the model to study the impact of bottom structure flexibility on the pressure vessel design. The analysis result was compared with the bottom fixed model without structure flexibility to study an additional factor. Finally, appropriate design approach for tall pressure vessels with intermediate supports was proposed.

Fiber reinforced composite structures have been increasingly used in the field of pressure vessels and piping. Various process-induced defects of composite structures are accumulated during their manufacture processes for the variations of environment temperature and humidity, pre-stress of fiber and curing temperature. Wrinkle defect is one of the most frequently encountered defects in fiber reinforced composite structures. In this paper, a new method for detecting wrinkle defects based on the relation of the displacement fields between flawed and flawless areas is proposed. The orthotropic finite element analysis codes combined with wrinkle model were developed based on Matlab platform to predict structural responses of laminates under three different loading types, including transverse compression, axial tension and bending. The effective elastic moduli disturbed by wrinkles were determined based on a mesomechanics model and a two-step homogenization procedure. Two different wrinkle models including definite and heterogeneous distributed models were considered. It is found that the out-of-plane displacement obviously increases at the wrinkle region under the axial load. The fluctuant displacement fields under axial tensile load can be clearly observed when the heterogeneity wrinkle model is considered. However, the transverse compression cannot produce any displacement distortion. All the results bring us a new idea of non-destructive evaluation for composites, wherein the defects that mainly weakening the stiffness can be detected by measuring the displacement distribution under some specified loads.

A flange connection consists of the flange, gasket, bolts, and pipe. In a flange design stage, the flange rigidity index is checked to ensure the leak tightness of the flange connection. Technically, the flange rigidity index was theoretically derived by the function of flexure induced into the flange by both bolt tension and internal pressure. However, some of the factors used to calculate the flange rigidity index were determined by regression formulas. On the other hand, the rotation angle of the flange is also limited to determine the allowable bolt pre-tension. To better understand the flange rigidity index, flange rigidity index and flange rotation angle were compared. The flange rotation angle was calculated using Finite Element Analysis (FEA). For the evaluation model, NPS 3, 6, 12, 18, 24 for classes 150, 300, 600, 900, 1500 integral-type flanges were selected. Typical gasket seating and operating conditions were considered in this study. In gasket seating condition, the required minimum bolt load was applied. In operating condition, internal pressure and uniform temperature were simultaneously applied to the FEA model. From the analysis results, it was concluded that the specified flange rigidity indexes may underestimate the leak tightness for lower pressure and large flange types.

This paper presents several modeling methods for performing a valve assembly modal analysis. It discusses the background of the methods, their strengths and limitations, and then introduces a new approach that can be used in performing valve modal analysis. An early paper presents a classical approach based on a lumped mass model and the Rayleigh energy principal to determine primary mode natural frequencies. A follow up paper reaffirms the classical method and introduces enhancements. A recent paper provides a comparative study of the classical approach, laboratory testing, and solid modeling results using the finite element analysis program ANSYS Mechanical. In this paper, a third approach is presented, which is an extension of the classical method, where 3-D beam-based geometry is defined using the ANSYS SpaceClaim program that is then ported to ANSYS Mechanical. The classical and solid modeling approaches from the previously cited papers are reviewed to highlight the modeling evolution and then the newly developed approach is presented. An example is presented that compares natural frequency results of the new method and the previous methods. The motivation for the new method is to provide better compatibility with 3-D piping system models, which are typically used to study the effect of valve mass and stiffness on system response without the complexity of a solid model or the difficulty of communicating the details of a classical model to the system modeler. Much of the process of creating a 3-D beam model is automated. It uses input from an existing classical model and employs the following ANSYS software packages: SpaceClaim, Workbench, Mechanical, and ACT. A great feature of the resulting 3-D model is that beam geometry is more realistic to scale, and therefore provides valuable user feedback for checking model validity. This approach is an improvement over the classical model where only manual data input validation is possible. Other benefits of the new method are covered in greater detail in the paper.

Securing adequate seismic safety margins has been important in safety reviews regarding the seismic design of equipment and piping systems in nuclear power plants, and there exists an increasing need for a more exact method for evaluating these margins. To this end, it is reasonable to take into account the reduction of seismic responses resulting from inelastic deformation. The authors studied this approach utilizing an elastic allowable limit in existing standard. The applicability of the proposed evaluation method was investigated by comparison with the conventional evaluation method. The proposed method consists of an inelastic dynamic analysis and an elastic-static analysis. The elastic-static analysis uses a load obtained from the inelastic dynamic analysis. For the investigation, the result obtained from the proposed method was compared with that obtained from the conventional elastic analysis to quantify the reduction in responses leading to seismic safety margins. For the comparison, the authors constructed three models that simulate a cantilever-type beam, four-legged tank, and core shroud and applied them to the analysis herein, and the applicability of our method was discussed for these models. In this paper, we present three topics. First, we present a scheme for developing the design approach of using inelastic analysis. Second, we report a sensitivity study of model parameters, such as yielding stress and second stiffness, done by analyzing the cantilever-type beam for the proposed method. Finally, we report the application of the method to the four-legged tank and core shroud.

Reinforced Concrete (RC) frame structures that were designed and built according to older standards can be damaged during destructive earthquakes as a result of insufficient lateral strength and/or deformation capacity. Such structures must be retrofitted to satisfy the current requirements and to survive future earthquakes. Owing to its high lateral strength and stiffness capacity of an RC wall, the post-installation of an RC wall in a non-ductile frame for retrofit is a widely used retrofitting technique. However, for frame structures with low-strength concrete, the typically used connected construction method on the interface between existing and new concrete may be not able to provide effective force transfer, and may cause unexpected brittle failure in the retrofitted structure. Such unexpected brittle failure may reduce the seismic capacity of the structure and threaten its safety. Therefore, in this experimental investigation, two retrofitting methods that use a post-installed RC wall are proposed to improve the load transfer mechanism on the interface. The first involves a wall with diagonal rebar and boundary spirals, and the second involves a wall with an additional inner frame. A typical traditional retrofitting specimen was constructed and tested for comparison. Reversed cyclic loading is used to test the seismic capacity of the specimens. Finally, post-embedded piezoceramic-based sensors were used to monitor the structural health and detect damage in one of specimens during the test. The experimental results demonstrate the effectiveness of the piezoceramic-based approach to structural health monitoring and the ability of the method to detect damage in shear governed RC structures under seismic loading.

Anisotropic composite cylinders and pressure vessels have been widely employed in automotive, aerospace, chemical and other engineering areas due to high strength/stiffness-to-weight ratio, exceptional corrosion resistance, and superb thermal performance. Pipes, fuel tanks, chemical containers, rocket motor cases and aircraft and ship elements are a few examples of structural application of fiber reinforced composites (FRCs) for pressure vessels/pipes. Since the performance of composite materials replies on the tensile and compressive strengths of the fiber directions, the optimum design of composite laminates with varying fiber orientations is desired to minimize the damage of the structure. In this study, a complete mathematical 3D elasticity solution was developed, which can accurately compute stresses of a thick multilayered anisotropic fiber reinforced pressure vessel under force and pressure loadings. A rotational variable is introduced in the formalism to treat torsional loading in addition to force and pressure loadings. Then, the three-dimensional Tsai-Wu criterion is used based on the analytical solution to predict the failure. Finally, a global optimization algorithm is used to find the optimum fiber orientation and their best combination through the thickness direction.

Additional lateral load tests, with improved techniques, were conducted on M22 stainless bolts to supplement the series of metric system stainless bolt tests which were conducted previously. Using the strain gage-deflection data collected from the entire set, i.e., of different sizes and different lengths, of the bolt tests, the “rigidity coefficient”, which is used in calculating the deflection of the bolts under lateral loads, using the conventionally assumed effective shank length, is derived. Alternatively, a new analytical effective shank length, which is more accurate than the conventional assumed effective shank length, derived from the test data, is proposed.

To avoid unacceptable vibration of suction and discharge piping for reciprocating pumps and compressors, acoustic and mechanical response analyses are to be carried out. These analyses are generally provided by the suppliers of such equipment. This paper explains the fundamentals behind an acoustic and mechanical response analysis and provides a simple set of consolidated design and engineering rules. The paper encourages application of these rules while developing the equipment and piping layout as well as pipe support configuration. The aim of these rules is to minimize the chance for the ultimate supplier’s detailed acoustic & mechanical response analysis to recommend significant changes to the design in a late stage of a project. Specific emphasis is placed on how the support stiffness affects the natural frequency of the piping system and a practical methodology is provided to account for this in pipe support span calculations. This paper also describes the process information that needs to be submitted to the supplier to conduct a meaningful acoustic as well as mechanical response analysis. Acknowledging requirements for lines in pulsating service at a late stage in the project, not providing the supplier with the required process information or a piping and support configuration that is not ‘mature’ enough will most likely result in significant delay and cost.

Pipe support and restraint assemblies are an integral part of engineered piping systems for power, petrochemical, refinery, and process industries. Such assemblies are specially designed and analyzed for the purpose of transferring loads from piping to building structure or supplemental steel structure. Thus, a support assembly protects the piping, or any other components, from damage that may result from startup, shutdown, shocks from valve operation, water hammer, steam hammer, wind, seismic, and other catastrophic events such as pipe rupture or explosions. It also restrains against unacceptable movements in the piping system while preserving movement due to thermal growth. The support and restraint stiffness values are utilized based on assumptions and calculations of load versus displacement. A case study of pipe support elements is performed in various static and dynamic load cases to determine the effects of assumptions of utilizing one stiffness value versus multiple stiffness values within an assembly. Additionally, the stiffness for the connected building structure opens more assumptions within industry practice. Multiple industry practices of stiffness values are integrated into this research to compare and contrast the realistic attributes of each.

The importance of fluid-elastic forces in tube bundle vibrations can hardly be over-emphasized, in view of their damaging potential. In the last decades, advanced models for representing fluid-elastic coupling have therefore been developed by the community of the domain. Those models are nowadays embedded in the methodologies that are used on a regular basis by both steam generators providers and operators, in order to prevent the risk of a tube failure with adequate safety margins. From an R&D point of view however, the need still remains for more advanced models of fluid-elastic coupling, in order to fully decipher the physics underlying the observed phenomena. As a consequence, new experimental flow-coupling coefficients are also required to specifically feed and validate those more sophisticated models. Recent experiments performed at CEA-Saclay suggest that the fluid stiffness and damping coefficients depend on further dimensionless parameters beyond the reduced velocity. In this work, the problem of data reduction is first revisited, in the light of dimensional analysis. For single-phase flows, it is underlined that the flow-coupling coefficients depend at least on two dimensionless parameters, namely the Reynolds number Re and the Stokes number Sk . Therefore, reducing the experimental data in terms of the compound dimensionless quantity V r = Re/Sk necessarily leads to impoverish results, hence the data dispersion. In a second step, experimental data are presented using the dimensionless numbers Re and Sk . We report experiments, for a 3 × 5 square tube bundle subjected to water transverse flow. The bundle is rigid, except for the central tube which is mounted on a flexible suspension allowing for translation motions in the lift direction. The evolutions of the flow-coupling coefficients with the flow velocity are determined using two different experimental procedures: (1) In the direct method, an harmonic motion of increasing frequency is imposed to the tube. (2) In the indirect method, the coefficients are obtained from the modal response of the tube (frequency, damping). The coefficient identification was performed well beyond the system instability boundary, by using active control, allowing an exploration of a significant range of flow velocity. For a given Sk , the results show that: (a) at low Re , the flow-coupling coefficients are close to zero; (b) at intermediate Re , the flow stabilizes the tube; (c) at high Re , the flow destabilizes the tube, leading to a damping-controlled instability at a critical Re . Reducing the data in terms of Re and Sk clarifies the various experimental “branches”, which are mixed when using V r . The two identification techniques lead to reasonably compatible fluid-elastic coefficients.

This paper proposed a homogenization model, and compiled a VUMAT subroutine to simulate the tension and shear of fiber-reinforced pultrusion composite (FRPC). Experiments were also performed to verify the accuracy of the homogenization model. The results show that, the simulation results agree well with the experiment data. The stiffness and strength increase with the increase of the diameter of the carbon composite part. The limit shear load and the horizontal shear strength decrease with the increase of the span. When FRPC is under shear with smaller span, the matrix tensile damage initiates first and it is the dominate failure mode, then the matrix and fiber compression damage occur at where the indenters contact. However, with the increase of the span, the delamination damage between the wound glass-fiber reinforced composite and pultrusion glass-fiber reinforced composite occurs and becomes the dominate failure mode for FRPC shear.

A total of 12 flange assemblies, spanning both class 300 and 600 were instrumented with ultrasonic transducers and observed following differing assembly patterns to gain insight into the BFJ elastic interactions. Each flange assembly was additionally tested to multiple load targets to monitor the overall sensitivity of interaction to load. Analytical work following the data collection led to the development of a simplified installation method and sequencing that dramatically reduces the work effort required to effectively close a joint while being independent of fastener condition or tool selection. The range of validity for the simplified method is further extended with linear multivariate solving techniques and accelerated joint “snugging” to promote joint stiffness. Limits on the acceptable load achievement was set to < 5% error on the average load and < 10% normalized standard deviation to be considered acceptable when targeting Appendix-O calculated loads of ASME PCC-1. Validation of the proposed method was undertaken by the University of Houston at the Bechtel WATC facility with support of Carber Engineering which included full size pressure testing following joint assembly. The observations made from the 60+ full size trials then served to validate FEA work towards the analysis of the remaining sizes of class 300/600 from 4″ to 24″.

In-plane fluidelastic instability is a dynamic phenomenon requiring fluid coupling of at least two degrees-of-freedom, in this case, at least two flexible tubes. Due to the nature of the mechanism causing streamwise fluidelastic instability, a purely experimental or an unsteady determination would require intensive experimental effort. As a compromise between experimental effort and prediction accuracy, the quasi-steady model is used in the current study. In the present work, previously measured quasi-steady and unsteady forces are used to estimate the time delay first between the displacement of an oscillating tube and the forces generated on itself then the time delay between the displacement of a central oscillating tube and the forces induced on the adjacent tubes. The estimated time delays are then used together with drag coefficients and derivatives to predict the in-plane fluidelastic instability in a rotated triangular tube array of P/D = 1.5 subjected to two-phase flow. The results closely replicate dynamic test results and confirm the predominance of the stiffness controlled mechanism and the potential of the quasi-steady model in accurately predicting streamwise fluidelastic instability in arrays subjected to two-phase flows.

Ductile damage appears in ductile metallic materials when these undergo sufficient plastic deformation, and it is caused by voids and microcracks that are formed within the material due to those severe conditions. The main interest of the present research is to experimentally characterise ductile damage in different conditions of strain rate (from quasi-static to 10 3 s −1 ) and temperature (from −80°C to 180°C). Estimations of damage accumulation along the plastic regime have been taken by measuring the stiffness reduction of the material. The effects of strain localisation and necking have been accounted for by monitoring the changes in the geometry of the specimens during the test. At high speed these experiments have required the use of an in-situ shadowgraph method to monitor the sample silhouette and accurately calculate stress-strain behaviour throughout the test. The design of a novel experimental rig to perform high speed interrupted tensile tests has also been needed, in order to measure the damage accumulation in those conditions. The low and high temperature tests have been carried out inside an environmental chamber maintaining the rest of the technique unchanged. These experiments at varying strain rate and temperature have allowed to better understand the effect these conditions have on damage properties.

High pressure hydrogen storage tank is a key component in hydrogen supply systems of the fuel cell vehicles. Composite hydrogen storage tanks own some advantages such as high stiffness, density and strength, and the composite tanks for storage of 70 MPa hydrogen is the hotspot of research. However, composite hydrogen storage tanks have the potential leakage and explosion hazards in the process of using due to the flammable and explosive storage medium. hydrogen cycle test is an important means to detect the macroscopic strength, safety margin, structure design rationality and reliability of composite hydrogen storage tanks. The relevant standard of 70MPa composite hydrogen storage tanks is not yet introduced in China. At present, the european union, Japan and the international standardization organization have formulated the composite hydrogen storage tanks standard or code, which have an important reference for the formulation of the relevant standards in china. In this study, foreign standards related hydrogen cycling test content such as (EU) 406-2010, ANSI HGV 2-2014, ISO CD 19881-2015, SAE J2579-2013 and ECE/TRANS/180-2013 are systematically studied, which could be helpful for the establishment of relevant standards in China and the development of hydrogen cycle test equipment.

Seismic responses from linear and nonlinear dynamic analyses of reinforced concrete (RC) shear walls are compared to see how the damping ratio and cracking behavior affect the dynamic response of the RC structures used in the nuclear power plant. The nonlinear dynamic analyses are conducted based on the numerical model which is developed to simulate the nonlinear hysteretic behavior of RC structures subjected to in-plane shear. Through comparison of the obtained numerical results with experimental data such as load-displacement relationships and response time-histories, the developed numerical model is validated. The acceleration response spectra from the nonlinear dynamic analysis results of selected RC shear wall and those from linear dynamic analysis with combinations of the damping ratio and concrete stiffness considerations according to the level of earthquake loads and the resultant stresses are addressed.

The concept of primary/secondary categorization is first reviewed and generalized for its application to a non-linear oscillator subjected to a seismic load. Categorizing the seismic load requires calculating the input level associated with the oscillator ultimate capacity and comparing it to the level associated with the plastic yield. To resolve this problem, it is assumed that the non-linear oscillator behaves like a linear equivalent oscillator, with an effective stiffness (or frequency) and an effective damping. However, as it is not a priori possible to predict the equivalent stiffness and damping, a wide range of possibilities is systematically considered. The input motion is represented by its conventional response spectrum. It turns out that key parameters for categorization are i) the “effective stiffness factor” (varying from 0 for perfect damage behaviour to 1 for elastic-perfectly plastic) and the slope of the response spectrum in the vicinity of the natural frequency of the oscillator. Effective damping and spectrum sensitivity to damping play a second order role. A formula is presented that enables the calculation of the primary part of a seismically induced stress as a function of both the oscillator and input spectrum features. The formula is also presented in the form of a diagram. This paper follows-up on a similar paper presented by the author at the PVP 2017 Conference [1]. The new development introduced here is that the oscillator exhibits hardening capacity, while no hardening was assumed in [1]. It appears that the conclusions are slightly modified but the trend is very similar to the non-hardening case. Regarding piping systems, it appears that even when experiencing large plastic strains under beyond design input motions, their observed effective frequency is very close to their natural frequency, decreasing only by a few percents (experimental data from USA, Japan and India are processed). These observations lead to the conclusion that the seismic load, or the seismically induced inertial seismic strains, should basically be regarded as secondary.

Without additional mass, the tuned mass damping (TMD) shield building for AP1000 Nuclear Power Plants (NPPs) was achieved easily by changing the stiffness and damper between parts of shield building. Meanwhile, the new TMD structure combined the structural features of the shield building with TMD technology. The optimal model for the new structure was built and the optimal stiffness and damper of TMD bearing were given on the dynamic characters of the shield building and its parts. The vibration mitigation mechanism and reduction effect were clearly stated by using base shear force transfer function. By comparing with the seismic responses of the traditional model and the base isolation model, the influence factors of the new TMD structure, such as the mechanism of TMD bearing, the gravity liquid tank mass, and the earthquake waves under different sites were studied. The new TMD structure is tested to satisfy the NPPs seismic safety requirements, stable reduction efficiency, anti-seismic robust characteristics and adaptive site.