scholarly journals Comparison of ICEPEL Predictions With Single-Elbow Flexible Piping System Experiment

1979 ◽  
Vol 101 (2) ◽  
pp. 142-148 ◽  
Author(s):  
M. T. A-Moneim ◽  
Y. W. Chang
Keyword(s):  
Stainless Steel ◽  
Circumferential Strain ◽  
Structural Response ◽  
Response Analysis ◽  
Piping System ◽  
System Experiment ◽  
Stainless Steel Pipe ◽  
Piping Systems ◽  
In Series ◽  
Nickel 200

The ICEPEL Code for coupled hydrodynamic-structural response analysis of piping systems is used to analyze an experiment on the response of flexible piping systems to internal pressure pulses. The piping system consisted of two flexible Nickel-200 pipes connected in series through a 90-deg thick-walled stainless steel elbow. A tailored pressure pulse generated by a calibrated pulse gun is stabilized in a long thick-walled stainless steel pipe leading to the flexible piping system which ended with a heavy blind flange. The analytical results of pressure and circumferential strain histories are discussed and compared against the experimental data obtained by SRI International.

Numerical Simulation of Residual Stress in Multi-Pass Butt-Welded Stainless Steel Pipe

2009 ◽  
Author(s):  
S. Kasa ◽  
M. Mouri ◽  
M. Tsunori ◽  
D. Takakura
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Three Dimensional ◽  
Structural Response ◽  
Welding Residual Stress ◽  
Steel Pipe ◽  
Inelastic Behavior ◽  
Axisymmetric Model ◽  
Stiffness Method ◽  
Stainless Steel Pipe

It is necessary to obtain an accurate welding residual stress distribution for the evaluation of stress corrosion cracking (SCC) behavior. However, a welding residual stress simulation for pipes is often performed by a two dimensional axisymmetric model because this type of simulation requires significant time to analyze the complicated inelastic behavior. This approximation deteriorates the modeling accuracy since the welding heat input and the structural response are approximated by axisymmetric responses although they are originally three dimensional. The authors propose “a virtual additional stiffness method” in order to improve the accuracy of the axisymmetric model. With this method, the difference between the axisymmetric model and a three dimensional behavior was greatly reduced. The virtual additional stiffness method was used to reproduce three dimensional constraints that were not taken into account in the axisymmetric model. In the case of the axisymmetric model, an unrealistic large thermal expansion was observed because of simultaneous heating along a hoop direction of the whole pipe. In order to compensate this unrealistic deformation, a virtual additional stiffness was added in axial and radial directions on the axisymmetric model. This stiffness was added by using spring elements whose positions and spring constants were determined by comparing the two and three dimensional models. Results obtained by this new method in the multi-pass butt-welded stainless steel pipe were in very good agreement with measurements of the mock-up specimens.

Stochastic Response of Piping Systems With Flexible Supports

1996 ◽  
Vol 118 (1) ◽  
pp. 109-114 ◽  
Author(s):  
H. O. Soliman ◽  
T. K. Datta
Keyword(s):  
Frequency Domain ◽  
Cross Sections ◽  
Equations Of Motion ◽  
Response Analysis ◽  
Piping System ◽  
Dynamic Stresses ◽  
Support Points ◽  
Flexible Supports ◽  
Piping Systems ◽  
Support Excitation

A frequency domain spectral analysis of piping systems with flexible supports is presented for uniformly modulated nonstationary support excitations. The support points are idealized by spring-dashpot arrangements. The equations of motion of the resulting nonclassically damped, multipoint excitation system are written and solved in terms of the absolute displacements of the dynamic DOF. This facilitates a direct computation of the dynamic stresses induced at various cross sections of the pipe segments. The method of analysis provides a quasi-stationary response based on the assumption that the modulating function varies slowly with time; the exact response analysis in frequency domain for such systems with nonstationary support excitation is difficult to determine. Using the method of analysis presented, the response of a piping system is obtained for a set of important parametric variations related to the flexibility, damping, and excitation of the supports.

Simplified Seismic Response Analysis Method Using Reduced Model of Piping System

2018 ◽  
Author(s):  
Michiya Sakai ◽  
Ryuya Shimazu ◽  
Shinichi Matsuura ◽  
Ichiro Tamura
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Seismic Response ◽  
Degrees Of Freedom ◽  
Response Analysis ◽  
Piping System ◽  
Element Analysis ◽  
Mass System ◽  
Piping Systems ◽  
Low Degrees

In the seismic response analysis of piping systems, finite element analysis is performed with analysis method guidelines [1]–[4] established based on benchmark analysis. However, since it takes a great deal of effort to carry out finite element analysis, a simplified method to analyze the seismic response of complex piping systems is required. In this research, we propose a method to reduce an equivalent spring-mass system model with low degrees of freedom, which can take into account the main mode of the complicated piping system. Simplified seismic evaluation is carried out using this spring mass system model with low degrees of freedom, and the accuracy of response evaluation is confirmed by comparison with finite element analysis.

Application of JSME Seismic Code Case by Elastic-Plastic Response Analysis to Practical Piping System

2018 ◽  
Author(s):  
Akihito Otani ◽  
Satoru Kai ◽  
Naoaki Kaneko ◽  
Tomoyoshi Watakabe ◽  
Masanori Ando ◽  
...  
Keyword(s):  
Seismic Design ◽  
Evaluation Methodology ◽  
Design Rule ◽  
Design Evaluation ◽  
Response Analysis ◽  
Piping System ◽  
Plastic Response ◽  
Seismic Code ◽  
Elastic Plastic ◽  
Piping Systems

A Code Case in the framework of JSME Nuclear Codes and Standards is being developed to incorporate a seismic design evaluation methodology for piping by means of advanced elastic-plastic response analysis methods and strain-based fatigue criteria. The Code Case as an alternative seismic design rule over the current rule will provide a more rational seismic design evaluation than the current criteria. This paper demonstrates an application result of the JSME Seismic Code Case to an actual complex piping system. The secondary coolant piping system of Japanese Fast Breeder Reactor, Monju, was selected as a representative of the complex piping systems. The elastic-plastic time history analysis for the piping system was performed and the piping system has been evaluated according to the JSME Seismic Code Case. The evaluation by the Code Case provides a reasonable result in terms of the piping fatigue evaluation that governs seismic integrity of piping systems. Moreover, it is found that the supporting forces and the response accelerations of the piping system obtained by the elastic-plastic response analysis also become more rational results than those with the current elastic response analysis. The contradiction of two requirements in piping design, flexibility for thermal expansion and rigidity for seismic response, can be effectively relaxed by use of the Code Case being developed.

scholarly journals Response of Piping Tees to Propagating Detonations

2013 ◽  
Author(s):  
Thomas C. Ligon ◽  
David J. Gross ◽  
Joseph E. Shepherd
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Structural Response ◽  
Initial Pressure ◽  
Finite Element Simulations ◽  
Steel Plates ◽  
Digital Data ◽  
304 Stainless Steel ◽  
Piping System ◽  
Piping Systems

This paper reports the results of experiments and finite element simulations on the structural response of piping systems to internal detonation loading. Specifically, the work described in this paper focuses on the forces that are produced at tee-junctions that lead to axial and bending structural responses of the piping system. Detonation experiments were conducted in a 2-in. (50 mm) diameter schedule 40 piping system that was fabricated using 304 stainless steel and welded to ASME B31.3 standards. The 4.1 m (162-in.) long piping system included one tee and was supported using custom brackets and cantilever beams fastened to steel plates that were bolted to the laboratory walls. Nearly-ideal detonations were used in a 30/70 H2-N2O mixture at 1 atm initial pressure and 300 K. Pressure and hoop, axial, and support strains were measured using a high-speed (1 MHz) digital data acquisition system and calibrated signal conditioners. It was concluded that detonations propagate through the run of a 90° tee with relatively little disturbance in either direction. The detonation load increases by approximately a factor of 2 when the detonation enters through the branch. The deflections of the cantilever beam supports and the hoop and axial pipe strains could be adequately predicted by finite element simulations. The support loads are adequately predicted as long as the supports are constrained to the piping. This paper shows that with relatively simple models, quantitative predictions of tee forces can be made for the purposes of design or safety analysis of piping systems subject to internal detonations.

Investigation on Method of Elasto-Plastic Analysis for Piping System Made of Stainless Steel: Secondary Benchmark Analysis

2017 ◽  
Author(s):  
Masashi Arai ◽  
Nobuyuki Kojima ◽  
Takuro Kabaya ◽  
Satoru Hirouchi ◽  
Masatsugu Bando
Keyword(s):  
Stainless Steel ◽  
Piping System ◽  
Maximum Strain ◽  
Benchmark Analysis ◽  
Draft Code ◽  
Plastic Analysis ◽  
Piping Systems ◽  
Tee Joints ◽  
Possible Cause ◽  
Shape Data

This paper provides investigation on method of elasto-plastic analysis for practical seismic design of nuclear piping system made of austenitic stainless steel. Our policy for the evaluation is that material properties used in the benchmark analyses are based on Japanese standard in nuclear design. The result of the first phase of this benchmark analysis intended for carbon steel piping systems has been provided in ASME PVP2016-63186[1]. In secondary benchmark analysis, analytical investigations focused on austenitic stainless steel piping were conducted. These analysis objects are two vibrating tests (model 1: piping containing an elbow, model 2:piping containing a tee). The elasto-plastic characteristic based on bilinear plasticity model based on the draft code case of JSME (Japan Society of Mechanical Engineers) was used in analyses. Additionally, analyses using the elasto-plastic characteristic which made yield point and 2nd modulus as a parameter were also carried out. For the model 1, the maximum strain estimated by elasto-plastic analysis using the elasto-plastic characteristics of stainless steel material determined as proposed by the draft code case of JSME agreed well, but on the safe side, with the experiment. However, this is not the case for the model 2: the maximum strain estimated using the same elasto-plastic characteristics was underestimated compared with the experiment. However, for both the models 1 and 2, the elasto-plastic behavior of the piping systems estimated by this analysis was approximately the same between the analysis with the material’s elasto-plastic characteristics approximated by bilinear plasticity modeling proposed by the draft code case of JSME and that approximated by the same bilinear plasticity modeling but with different setting of yield point and 2nd modulus values of the material. A possible cause of the underestimate that occurred in the model 2 is, according to the shape data of the tee, that the wall thickness of the tee is so large that its connection with the main and branch pipes has a large, step-like change in thickness, as opposed to the model that was designed without referencing the shape data. Another possible cause of this underestimate is coarse meshes of elements of the model. In order to improve analytical accuracy, it is necessary to add a method for modeling tee joints to the draft code case. To this end, a database of the shape of tee joints should be developed in cooperation with the manufacturers so that an optimum modeling method can be developed. As mentioned above, according to the result of elasto-plastic analyses for the model 1 (piping containing an elbow) and model 2 (piping containing a tee), it is necessary to develop a modeling method for tee joints. It is likely possible to directly use the elasto-plastic characteristics of carbon steel for the purpose of analyzing a piping of stainless steel.

Fracture Estimation Method for Pipe With Multiple Circumferential Surface Flaws

2009 ◽  
Author(s):  
Yinsheng Li ◽  
Kunio Hasegawa ◽  
Kunio Onizawa ◽  
Masayoshi Shimomoto
Keyword(s):  
Stainless Steel ◽  
Nuclear Power ◽  
Numerical Solutions ◽  
Estimation Method ◽  
Arbitrary Distribution ◽  
Piping System ◽  
Piping Systems ◽  
Asme Code ◽  
As Stress ◽  
Steel Piping

When a flaw is detected in a stainless steel piping system of a nuclear power plant during in-service inspection, the fracture estimation method provided in the codes such as the ASME Code Section XI or the JSME S NA-1-2004 can be applied to evaluate the integrity of the pipe. However, in these current codes, the fracture estimation method is only provided for the pipe containing a single flaw, although independent multiple flaws such as stress corrosion cracks have actually been detected in the same circumference of stainless steel piping systems. In this paper, a fracture estimation method is proposed by formula for multiple independent circumferential flaws with any number and arbitrary distribution in the same circumference of the pipe. Using the proposed method, the numerical solutions are compared with the experimental results to verify its validity, and several numerical examples are provided to show its effectiveness.

The Role of Displacement-Controlled Stresses in Critical Flaw Size Determination for Piping Systems

2008 ◽  
Author(s):  
Peter C. Riccardella ◽  
Paul Hirschberg ◽  
Ted Anderson ◽  
Greg Thorwald ◽  
Eric Scheibler
Keyword(s):  
Stainless Steel ◽  
Thermal Expansion ◽  
Nuclear Power ◽  
Power Plants ◽  
Bending Moment ◽  
Flaw Size ◽  
Piping System ◽  
Nuclear Plants ◽  
Piping Systems ◽  
Critical Flaw

A debate has long ensued in ASME Subcommittee XI regarding the need to include displacement-controlled (secondary) stresses in critical flaw size calculations for austenitic weldments. There is general agreement that inclusion of secondary stresses is not necessary for highly ductile piping materials such as wrought stainless steel and high nickel alloys. However, some stainless steel weldments are classified as “low-toughness” because, although not considered brittle, they exhibit lower toughness than wrought stainless steel. The Code requires the inclusion of global secondary stresses, such as piping thermal expansion loads, in critical flaw size calculations for such weldments, albeit at reduced safety factors. The Code requirements are less clear for dissimilar metal weldments, such as Alloy 82/182, which were often used for ferritic nozzle to safe-end welds in nuclear power plants, and which have proven in service to be susceptible to a form of stress corrosion cracking. Analyses are presented in this paper that shed additional light on the subject. Finite element analyses (FEA) of a straight pipe with a through-thickness crack were used to determine the effect on bending moment and crack driving force due to an imposed end rotation. Moment and J-integral knock-down factors are computed for a range of crack sizes for two different pipe lengths. Piping analyses are also presented for two typical PWR surge lines, which are among the highest secondary stress locations in U.S. nuclear plants. These analyses predict the maximum rotation at the surge nozzle that could be produced by the secondary loads (anchor movement + thermal expansion + stratification), and compare that to rotations that were sustained in full scale pipe tests containing large complex cracks. The analyses demonstrate that secondary loads would be substantially reduced prior to fracture of a cracked weldment, and that they are therefore of reduced significance in critical flaw size calculations. A general method for estimating the effect of secondary loads on pipe fracture as a function of relative piping system and crack section stiffness is suggested.

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