Fitness for Service Assessments of Bulging and Out-of-Round Structures

2004 ◽  
Author(s):  
Peter Carter ◽  
D. L. Marriott ◽  
M. J. Swindeman
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Structural Model ◽  
External Pressure ◽  
Element Analysis ◽  
Structural Imperfection ◽  
Level 2

This paper examines techniques for the evaluation of two kinds of structural imperfection, namely bulging subject to internal pressure, and out-of-round imperfections subject to external pressure, with and without creep. Comparisons between comprehensive finite element analysis and API 579 Level 2 techniques are made. It is recommended that structural, as opposed to material, failures such as these should be assessed with a structural model that explicitly represents the defect.

Finite Element Analysis and Design of an Annular Tank

2003 ◽  
Author(s):  
Yogeshwar Hari
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Outer Cylinder ◽  
External Pressure ◽  
Seismic Load ◽  
Element Analysis ◽  
Analysis And Design ◽  
Finite Element Software ◽  
Asme Code

The objective of this paper is to design an annular tank. The annular tank is to store various criticality liquids used in today’s industry. The initial over all dimensions of the annular tank are determined from the capacity of the stored liquids. The design function is performed using the ASME Code Sec VIII Div 1. The annular tank design is broken up into (a) outer cylinder, (b) inner cylinder, (c) top cover, and (d) bottom head. It is supported at the bottom. It is anchored at the top. The deflection of the annular space is a critical requirement. Stresses are usually acceptable because the requirement is on the deflection. For vacuum condition the outer cylinder can be treated for external pressure and the inner cylinder can be treated for internal pressure. For internal pressure condition the design pressure consists of working internal pressure plus static head. For this the outer cylinder can be treated for internal pressure and the inner cylinder can be treated for external pressure. The covers are designed for internal pressure at the bottom where the pressure is the maximum. The designed dimensions are used to recalculate the stresses for the annular tank. The dimensioned annular tank is modeled using STAAD III finite element Software. The stresses from the finite element Software are compared to the stresses obtained from recalculated stresses obtained using ASME Code Sec VIII Div 1. The difference in the stress values is explained. This paper’s main objective is to compare the ASME Code to the finite element analysis. The design is found to be safe for the specific configuration considered. In addition the annular tank is checked for temperature and seismic load conditions, which the code does not address.

Stress Analysis and Progressive Failure Analysis of Multilayered Basalt/Epoxy Composites

2015 ◽  
Vol 766-767 ◽  
pp. 21-26 ◽  
Author(s):  
Alexander ◽  
B.S.M. Augustine
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Progressive Failure ◽  
Glass Fibers ◽  
External Pressure ◽  
Basalt Fibers ◽  
Element Analysis ◽  
Progressive Failure Analysis ◽  
Filament Wound

Constructions of pressure vessels like rocket launch vehicles, missiles, rocket propellant tanks, and filament wound pipes for civil and military applications are made out of high strength, high stiffness and light weight composites filaments. Filament winding techniques are used for fabrication of such cylinders and pipes. Many materials like glass fibers, carbon fibers and Kevlar fibers are used due to their good strength when it is subjected to internal pressure as well as external pressure. Basalt fibers are new materials that are fabricated from hard dense basalt rocks. Basalt fibers can be used in the place glass fibers due to their good mechanical behavior when subjected to internal pressure. Plates and beams generally resists bending loads and pipes and tube structures resists internal forces developed through internal and external pressure. This work concentrates the fabrication of filament wound pipes using filament wound techniques and the burst pressure test is carried out. In fuel tanks of rockets, If any one of the layer fails due to internal pressure, there will be mild leakage. For this reason it is mandatory to find out the ply by ply failure. The first ply failure of basalt filament wound pipes subjected to internal pressure is calculated using Finite element analysis. Then the stress and progressive failure analysis was carried out. Maximum stress failure criterion is used for the finite element analysis.

Use of the Finite Element Analysis Method in Pedodontics

2018 ◽  
Vol 55 (4) ◽  
pp. 666-675
Author(s):  
Mihaela Tanase ◽  
Dan Florin Nitoi ◽  
Marina Melescanu Imre ◽  
Dorin Ionescu ◽  
Laura Raducu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Model ◽  
Analysis Method ◽  
Ansys Software ◽  
Concentrated Force ◽  
Element Analysis ◽  
Finite Element Analysis Method ◽  
The Finite Element Analysis ◽  
Solid Type

The purpose of this study was to determinate , using the Finite Element Analysis Method, the mechanical stress in a solid body , temporary molar restored with the self-curing GC material. The originality of our study consisted in using an accurate structural model and applying a concentrated force and a uniformly distributed pressure. Molar structure was meshed in a Solid Type 45 and the output data were obtained using the ANSYS software. The practical predictions can be made about the behavior of different restorations materials.

scholarly journals Analysis for Wrinkling Behavior of Girth-Welded Line Pipe

1996 ◽  
Author(s):  
Luiz T. Souza ◽  
David W. Murray
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Internal Pressure ◽  
Experimental Test ◽  
Element Model ◽  
Element Analysis ◽  
Line Pipe ◽  
New Era ◽  
Analytical Tools

The paper presents results for finite element analysis of full-sized girth-welded specimens of line pipe and compares these results with the behavior exhibited by test specimens subjected to constant axial force, internal pressure and monotonically increasing curvatures. Recommendations for the ‘best’ type of analytical finite element model are given. Comparisons between the behavior predicted analytically and the observed behavior of the experimental test specimens are made. The mechanism of wrinkling is explained and the evolution of the deformed configurations for different wrinkling modes is examined. It is concluded that the analytical tools now available are sufficiently reliable to predict the behavior of pipe in a manner that was not previously possible and that this should create a new era for the design and assessment of pipelines if the technology is properly exploited by industry.

Elastic and elastic-plastic finite element analysis of hollow tubes with axisymmetric internal projections under combined axial and pressure loading

2001 ◽  
Vol 36 (4) ◽  
pp. 373-390 ◽  
Author(s):  
S. J Hardy ◽  
M. K Pipelzadeh ◽  
A. R Gowhari-Anaraki
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Plastic Material ◽  
Axial Loading ◽  
Material Model ◽  
Pressure Loading ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Applied Loading

This paper discusses the behaviour of hollow tubes with axisymmetric internal projections subjected to combined axial and internal pressure loading. Predictions from an extensive elastic and elastic-plastic finite element analysis are presented for a typical geometry and a range of loading combinations, using a simplified bilinear elastic-perfectly plastic material model. The axial loading case, previously analysed, is extended to cover the additional effect of internal pressure. All the predicted stress and strain data are found to depend on the applied loading conditions. The results are normalized with respect to material properties and can therefore be applied to geometrically similar components made from other materials, which can be represented by the same material models.

scholarly journals Effect of Ovality in Inlet Pigtail Pipe Bends Under Combined Internal Pressure and In-Plane Bending for Ni-Fe-Cr B407 Material

2017 ◽  
Vol 62 (3) ◽  
pp. 1881-1887
Author(s):  
P. Ramaswami ◽  
P. Senthil Velmurugan ◽  
R. Rajasekar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Limit Load ◽  
Outer Radius ◽  
Factor H ◽  
Geometrical Shape ◽  
Element Analysis ◽  
Pipe Bend ◽  
Plane Bending

Abstract The present paper makes an attempt to depict the effect of ovality in the inlet pigtail pipe bend of a reformer under combined internal pressure and in-plane bending. Finite element analysis (FEA) and experiments have been used. An incoloy Ni-Fe-Cr B407 alloy material was considered for study and assumed to be elastic-perfectly plastic in behavior. The design of pipe bend is based on ASME B31.3 standard and during manufacturing process, it is challenging to avoid thickening on the inner radius and thinning on the outer radius of pipe bend. This geometrical shape imperfection is known as ovality and its effect needs investigation which is considered for the study. The finite element analysis (ANSYS-workbench) results showed that ovality affects the load carrying capacity of the pipe bend and it was varying with bend factor (h). By data fitting of finite element results, an empirical formula for the limit load of inlet pigtail pipe bend with ovality has been proposed, which is validated by experiments.

A Comparative Study on Mechanical Behavior of Pipe-Socket Threaded Joints With Taper-Taper Threads and Taper-Parallel Threads Combinations by Finite Element Analysis and Experiments

2018 ◽  
Author(s):  
Satoshi Nagata ◽  
Shinichi Fujita ◽  
Toshiyuki Sawa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Service Condition ◽  
Internal Thread ◽  
Element Analysis ◽  
Strain Pattern ◽  
External Thread ◽  
Thread Length ◽  
The Difference

There are two types of combination between external and internal threads used in threaded pipe connections for pressure piping specified in industrial standards like JIS as well as ISO. One is the combination that taper external thread of pipe is engaged with taper internal thread of a fitting. The other is that taper external thread of pipe is engaged with parallel internal thread of a fitting. Taper thread is always used for external thread outside the pipe wall. Both taper thread and parallel one are applicable to internal thread inside the fittings. This paper evaluates the mechanical behaviors of threaded pipe-socket joints (or pipe-coupling joints) and the difference due to the thread type combinations by means of axisymmetric finite element analysis for 3/4” and 3” joints. The analysis shows that the taper-taper threads combination establishes the full-length contact over the engaged threads but the taper-parallel has only a pair of threads in contact at the 1st engaged thread from the end of socket, and the difference results in the different behaviors of the joints. Stress and strain pattern also completely differ due to the difference in the engaged thread length. No significant effect of the size has been found in the present analysis for 3/4”and 3” joints. Experimental tightening tests and pressure leak tests have also been carried out for 3/4” and 3” joints with taper-taper threads combination. The measured experimental stress for 3/4” joints has shown an agreement with the simulated one fairly well. The pressure leak tests have demonstrated that the taper-taper threaded pipe-socket joints can hold internal pressure without leakage without using thread seal tape or jointing compound under low-pressure service condition. The 3/4” joints have started leaking at 1–4MPaG of internal pressure. The 3” joints haven’t shown leakage even at 6MPaG of internal pressure applied.

Finite Element Analysis of the Shell of GIS Busbar Tube

2014 ◽  
Vol 889-890 ◽  
pp. 1406-1409 ◽  
Author(s):  
Ming Jian Jian ◽  
Guang Cheng Zhang ◽  
Du Qing Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Internal Pressure ◽  
Gas Pressure ◽  
Thickness Direction ◽  
Element Analysis ◽  
Finite Element Software ◽  
Concentration Degree ◽  
Inside Out

By finite element software ANSYS a model of GIS busbar tube was established for investigating the effect of the gas pressure on the shell. The results shows that the stress concentration degree is higher on the shoulder between the main tube and the branch pipes under the internal pressure and the gravity, and the highest value is 44.92MPa which is far lower than the admissible stress. Stress changed along the thickness direction, and its value decreased gradually from the inside out. The distributions of the strain and deformation are similar to that of the stress.

Design of the Full Scale Experiments for the Testing of the Tensile Strain Capacity of X52 Pipes With Girth Weld Flaws Under Internal Pressure and Tensile Displacement

2014 ◽  
Author(s):  
Celal Cakiroglu ◽  
Samer Adeeb ◽  
J. J. Roger Cheng ◽  
Millan Sen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Tensile Strain ◽  
Oil And Gas ◽  
Full Scale ◽  
Element Analysis ◽  
Simultaneous Application ◽  
Strain Capacity ◽  
Tensile Strain Capacity

Pipelines can be subjected to significant amounts of tensile forces due to geotechnical movements like slope instabilities and seismic activities as well as due to frost heave and thaw cycles in arctic regions. The tensile strain capacity εtcrit of pipelines is crucial in the prediction of rupture and loss of containment capability in these load cases. Currently the Oil and Gas Pipeline Systems code CSA Z662-11 0 contains equations for the prediction of εtcrit as a function of geometry and material properties of the pipeline. These equations resulted from extensive experimental and numerical studies carried out by Wang et al [2]–[6] using curved wide plate tests on pipes having grades X65 and higher. Verstraete et al 0 conducted curved wide plate tests at the University of Ghent which also resulted in tensile strain capacity prediction methods and girth weld flaw acceptability criteria. These criteria are included in the European Pipeline Research Group (EPRG) Tier 2 guidelines. Furthermore Verstrate et al 0 introduced a pressure correction factor of 0.5 in order to include the effect of internal pressure in the tensile strain capacity predictions in a conservative way. Further research by Wang et al with full scale pipes having an internal pressure factor of 0.72 also showed that εtcrit decreases in the presence of internal pressure [10]–[15]. In their work, Wang et al presented a clear methodology for the design of full scale experiments and numerical simulations to study the effect of internal pressure on the tensile strain capacity of pipes with girth weld flaws [10]–[15]. However, there has been limited testing to enable a precise understanding of the tensile strain capacity of pipes with grades less than X65 as a function of girth weld flaw sizes and the internal pressure. In this paper the experimental setup for the testing of grade X52 full scale specimens with 12″ diameter and ¼″ wall thickness is demonstrated. In the scope of this research 8 full scale specimens will be tested and the results will be used to formulate the tensile strain capacity of X52 pipes under internal pressure. The specimens are designed for the simultaneous application of displacement controlled tensile loading and the internal pressure. Finite element analysis is applied in the optimization process for the sizes of end plates and connection elements. Also the lengths of the full scale specimens are determined based on the results from finite element analysis. The appropriate lengths are chosen in such a way that between the location of the girth weld flaw and the end plates uniform strain zones could be obtained. The internal pressure in these experiments is ranging between pressure values causing 80% SMYS and 30% SMYS hoop stress. The end plates and connection elements of the specimens are designed in such a way that the tensile displacement load is applied with an eccentricity of 10% of the pipe diameter with the purpose of increasing the magnitude of tensile strains at the girth weld flaw location. The results of two full scale experiments of this research program are presented. The structural response from the experiments is compared to the finite element simulation. The remote strain values of the experiment are found to be higher than the εtcrit values predicted by the equations in 0.

Study on the Stress Concentration at the Round Corners of Flat Heads in Pressure Vessels Subjected to Internal Pressure

1996 ◽  
Vol 118 (4) ◽  
pp. 429-433
Author(s):  
H. Chen ◽  
J. Jin ◽  
J. Yu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Concentration ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Stress Index ◽  
Element Analysis ◽  
Approximate Formulas

Results from finite element analysis were used to show that the stress index kσ and the nondimensionalized highly stressed hub length kh of a flat head with a round corner in a pressure vessel subjected to internal pressure are functions of three dimensionless parameters: λ ≡ h/dt, η ≡ t/d, and ρ ≡ r/t. Approximate formulas for estimating kσ and kh from λ, η, and ρ p are given. The formulas can be used for determining a suitable fillet radius for a flat head in order to reduce the fabricating cost and to keep the stress intensity at the fillet under an acceptable limit.

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