Effect of Mechanical Model on Limit Load Analysis of High Pressure Heater Tubesheet

2017 ◽  
Author(s):  
Yan-Nan Du ◽  
Xiao-Ying Tang ◽  
Jia-huan Wang ◽  
Zhi-Gang Yang ◽  
Yi-Feng Ren ◽  
...  
Keyword(s):  
High Pressure ◽  
Mechanical Model ◽  
High Stress ◽  
Local Stress ◽  
Limit Load ◽  
Element Model ◽  
Plastic Collapse ◽  
Analysis Design ◽  
Load Analysis ◽  
Collapse Assessment

Tubesheet is the main part of high pressure heater, which is very thick based on chinese code GB151 for the design of heat exchangers. Increased tubesheet with large thermal stress are not conducive to manufacture, heat transmission and detection. The stress and structure of tubesheet are so complex that the time costs too large during the analysis design, and stress classification exists uncertainty. Limit load method contributes to tubesheet lightweight. 3-D finite element model used for analysis design should be simplified reasonably. In this paper, the effect of mechanical model on limit load analysis of high pressure heater tubesheet conforming to the design-by-analysis code is researched. It is found that the tubesheet could pass the plastic collapse assessment, and the thickness of tubesheet could be decreased. The difference between the equivalent sold tubesheet model and the whole tubesheet model exists during plastic collapse assessment. Though the local stress distribution is different, the limit load results occurred plastic collapse by the equivalent sold tubesheet model is close to that by the whole tubesheet model. The limit load occurred plastic collapse is influenced by max circular diameter of tube layout little. The reason is attributed to original tubesheet owning enough rigidity related to thickness, and high stress appeares on the inner wall of jointing of tubesheet with head. The equivalent sold tubesheet model could be used for primary evaluation of limit load, and the whole tubesheet model is suited for partial analysis. The results provide some reference for the design-by-analysis of high pressure heater tubesheet.

Pressure-Plus-Moment Limit-Load Analysis for a Cylindrical Shell Nozzle

1987 ◽  
Vol 109 (3) ◽  
pp. 297-301 ◽  
Author(s):  
C. J. Tabone ◽  
R. H. Mallett
Keyword(s):  
Cylindrical Shell ◽  
Three Dimensional ◽  
Limit Load ◽  
Element Model ◽  
Combined Loading ◽  
Inelastic Behavior ◽  
Limit Loads ◽  
Out Of Plane ◽  
Load Analysis ◽  
The Moment

A finite element model of a nozzle in a cylindrical shell is analyzed for three cases; pressure, out-of-plane moment and combined pressure plus out-of-plane moment. The model uses three-dimensional finite elements and the analysis considers inelastic behavior at small displacements. Load versus displacement behavior is given for the three cases. Estimates of limit loads are obtained based upon extrapolation of load versus inverse displacement data curves. An interaction expression is used to show the effect of the combined loading for a case in which an internal pressure reduces the moment capability of the nozzle by 35 percent.

Fatigue Life Investigation of a High Pressure Inner Casing Under In-Service Conditions

2016 ◽  
Author(s):  
Hui Hong ◽  
Weizhe Wang ◽  
Zhenwei Cai
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
High Stress ◽  
Element Model ◽  
Steam Pressure ◽  
Strain Behavior ◽  
Service Conditions ◽  
High Stress Level

The fatigue life of a specific inner casing of an ultra-supercritical steam turbine was investigated under a half year in-service conditions. The Ramberg-Osgood model and Manson-Coffin-Basquin strain-life equation were used to describe the stress-strain behavior and calculate the fatigue damage. A temperature comparison was performed to validate the reliability of finite element model. The results showed that fluctuating steam pressure rather than temperature had more significant effect on the variation of stress in the casing. Locations with high stress level were prone to cause larger fatigue damage. Statistical analysis was carried out to reveal that over half fluctuations of steam pressure could cause damage.

Applying Finite Element Based Limit Load Analysis Methods to Structures Under Dynamic Loads

2014 ◽  
Author(s):  
Martin R. Booth
Keyword(s):  
Finite Element ◽  
Limit Load ◽  
Dynamic Loads ◽  
Plastic Collapse ◽  
Strength Assessment ◽  
Dynamic Events ◽  
Applied Loading ◽  
Analysis Technique ◽  
Dynamically Loaded ◽  
Load Analysis

To conduct an ASME III NG-3200 limit load strength assessment, it is required to determine the structure’s limit load under a particular loading configuration, and compare it against the applied loading represented as a static equivalent. Typically, the process is applied to static problems which have well-defined loading characteristics. When the limit load has been determined, often through the use of finite element (FE) based methods, the margin against plastic collapse is simple to calculate. For dynamically loaded structures, however, the process is more complicated since there are no ASME guidelines for expressing dynamic loads as their static equivalent. Thus, relating limit load analyses to dynamic events is not clear. This paper proposes an analysis technique which makes use of FE methods to apply the principles of limit load analysis to dynamically loaded structures. The primary benefit is that reserve factors against plastic collapse, in accordance with ASME III NG-3200 assessment criteria, can be calculated.

Study on the Effect of Axial Flaw Length on Limit Bending Load of Wall Thinned Straight Pipes by Large Strain Finite Element Analyses

2012 ◽  
Author(s):  
Yoshiaki Ito ◽  
Toshiyuki Meshii
Keyword(s):  
Finite Element ◽  
Fracture Mode ◽  
Large Strain ◽  
Local Stress ◽  
Limit Load ◽  
Crack Model ◽  
Element Analysis ◽  
Bending Load ◽  
Load Analysis ◽  
Planar Flaw

In this paper, we examined the effect of axial flaw length δz (Fig. 1) on limit bending load Mc of wall-thinned straight pipes by large strain finite element analysis (FEA). In the past, Han et al. [1] studied the effect of axial flaw length δz on limit bending load Mc of wall-thinned straight pipes by limit-load analyses. Han et al.’s [1] results indicated the trend which the Mc monotonically decreased with the increase in δz. If this finding is accepted, the Mc for a crack is larger than that for a non-planar flaw (wall thinning), and as a result, using the crack model for a non-planar flaw would be non-conservative. In contrast, Tsuji and Meshii [2] demonstrated by their tests that the Mc showed the maximum for a small δz. They estimated that this inconsistency was mainly due to the fact that Han et al. [1] and other researchers always assumed the fracture mode as the collapse, but the cracking was observed in Tsuji’s [2] experiment for small δz. Therefore in this work, we examined the effect of axial flaw length δz on limit bending load Mc of wall-thinned straight pipes by large strain FEA and applying Domain Collapse Criterion (DCC) [3] (which can predict fracture mode and the Mc accurately) to FEA results. In concrete, we attempted to reproduce Tsuji and Meshii’s experimental results [2] by FEA that the Mc showed the maximum for a small δz. In addition, we tried to understand the reason why limit-load analysis failed to predict this tendency. The results showed that large strain FEA with DCC [3] reproduced the Mc-δz relationship observed in the experiments. The inconsistency of Mc-δz relationship between Tsuji and Meshii’s experiment [2] and Han et al.’s limit-load analysis [1] and others analysis was estimated on due to the limit-load analysis failed to predict the failure for the flaw with a small δz, in which the failure mode is governed by the local stress (cracking) and not by the plastic deformation in a large volume (collapse).

Topology Optimization Design of High Pressure Storage Tank Structure

2012 ◽  
Vol 430-432 ◽  
pp. 828-833
Author(s):  
Qiu Sheng Ma ◽  
Yi Cai ◽  
Dong Xing Tian
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Topology Optimization ◽  
Storage Tank ◽  
Optimization Design ◽  
Influence Factors ◽  
Element Model ◽  
Design Variables ◽  
Calculation Results ◽  
Pressure Storage

In this paper, based on ANSYS the topology optimization design for high pressure storage tank was studied by the means of the finite element structural analysis and optimization. the finite element model for optimization design was established. The design variables influence factors and rules on the optimization results are summarized. according to the calculation results the optimal design result for tank is determined considering the manufacturing and processing. The calculation results show that the method is effective in optimization design and provide the basis to further design high pressure tank.

Quantify Resonance Inspection With Finite-Element-Based Modal Analyses

2010 ◽  
Author(s):  
K. Lai ◽  
X. Sun ◽  
C. Dasch
Keyword(s):  
Finite Element ◽  
High Stress ◽  
Mesh Size ◽  
Element Model ◽  
Sensitivity Study ◽  
Production Level ◽  
Mode Shapes ◽  
Resonance Spectroscopy ◽  
Frequency Spectra ◽  
Resonance Frequencies

Resonance inspection uses the natural acoustic resonances of a part to identify anomalous parts. Modern instrumentation can measure the many resonant frequencies rapidly and accurately. Sophisticated sorting algorithms trained on sets of good and anomalous parts can rapidly and reliably inspect and sort parts. This paper aims at using finite-element-based modal analysis to put resonance inspection on a more quantitative basis. A production-level automotive steering knuckle is used as the example part for our study. First, the resonance frequency spectra for the knuckle are measured with two different experimental techniques. Next, scanning laser vibrometry is used to determine the mode shape corresponding to each resonance. The material properties including anisotropy are next measured to high accuracy using resonance spectroscopy on cuboids cut from the part. Then, finite element model (FEM) of the knuckle is generated by meshing the actual part geometry obtained with computed tomography (CT). The resonance frequencies and mode shapes are next predicted with a natural frequency extraction analysis after extensive mesh size sensitivity study. The good comparison between the predicted and the experimentally measured resonance spectra indicate that finite-element-based modal analyses have the potential to be a powerful tool in shortening the training process and improving the accuracy of the resonance inspection process for a complex, production level part. The finite element based analysis can also provide a means to computationally test the sensitivity of the frequencies to various possible defects such as porosity or oxide inclusions especially in the high stress regions that the part will experience in service.

Design & Analysis of Steam Drum Based on ASME Boiler and Pressure Vessel Code, Section VIII Div.2 & Div.3

2016 ◽  
Vol 852 ◽  
pp. 511-517
Author(s):  
Vishal Payghan ◽  
Dattatray N. Jadhav ◽  
Girish Y. Savant ◽  
Sagar Bharadwaj
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Pressure Vessel ◽  
Design Parameters ◽  
Plastic Collapse ◽  
Finite Element Stress Analysis ◽  
Process Plant ◽  
Section Viii ◽  
Design Requirements ◽  
Steam Drum

Process plant industries have equipment working on high pressure and high temperature environments. The ASME Boiler and Pressure Vessel Code, Section VIII provides rules for construction of the pressure vessel. The purpose of this paper is to have comparative study for design and analysis of steam drum using ASME Section VIII Div. 2 and Div. 3. Steam drum is a part of boiler system and works at high pressure and high temperature. Normally, Steam drum design is based on ASME Section VIII Div. 2, Part 4, design by rule and Part 5, design by analysis; which has been carried out in the present study. In this paper, design of the same equipment is studied using Part KD, Design requirements of ASME Section VIII Div. 3 with similar design parameters. Finite Element Stress Analysis of both design has been done as per code requirements to check the plastic collapse. In this study, it is observed that there is reduction in the required thickness for design based on Div. 3. Finally, the reduced required thickness leads to considerable weight reduction of the equipment and thus increased competitiveness.

Design of Lateral Tee for Steam Pipe in Power Plants

2015 ◽  
Author(s):  
Hyeon Su Kim ◽  
Sehwan Jeong ◽  
Dong Ju Lee ◽  
Ha Geun Kim ◽  
Sang Beom Shin
Keyword(s):  
Power Plants ◽  
High Stress ◽  
Local Failure ◽  
Design Criteria ◽  
Plastic Collapse ◽  
Damage Analysis ◽  
Service Temperature ◽  
Creep Fatigue ◽  
Fatigue Damage Analysis ◽  
Steam Pipe

The purpose of this study is to evaluate the design verification of the welded type 45° lateral tee for the steam pipe in power plants. For it, first, the stress analysis was carried out under design condition in accordance with ASME Sec. VIII Div. 2 in order to evaluate the possible occurrence of plastic collapse and local failure. And next, the creep-fatigue damage analysis was performed under the normal operating condition in accordance with ASME Sec. III Subsection NH considering the service temperature of 566°C. From the results, it was found that the welded type 45° lateral tee satisfies the design criteria corresponding to the plastic collapse and the local failure. However, it has a probability of creep rupture during the design life due to the high stress localized in the crotch region. Therefore, a welded type 90° lateral tee was also evaluated with the same analysis procedures to consider the influence of the geometry at the crotch region. Based on the results, the welded type 90° lateral tee satisfies the design criteria of the plastic collapse, local failure and the creep-fatigue strength. This result indicated that an optimal shape design of the crotch region shall be required in order to secure the creep strength of the welded type 45° lateral tee having high service temperature.

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