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.

Nonlinear Analysis of Pressurized Piping Elbows Subjected to Out-of-Plane Bending

2006 ◽  
Vol 306-308 ◽  
pp. 351-356 ◽  
Author(s):  
Asnawi Lubis ◽  
Jamiatul Akmal
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Cross Section ◽  
Bending Moment ◽  
Pressure Reduction ◽  
Element Analysis ◽  
Out Of Plane ◽  
Plane Bending ◽  
Reduction Effect

The behavior of piping elbows under bending and internal pressure is more complicated than expected. The main problem is that the coupling of bending and internal pressure is nonlinear; the resulting stress and displacement cannot be added according to the principle of superposition. In addition, internal pressure tends to act against the effect caused by the bending moment. If bending moment ovalise the elbow cross-section, with internal pressure acting against this deformation, then the ovalised cross section deform back to the original circular shape. It is then introduced the term “pressure reduction effect”, or in some literature, “pressure stiffening effect”. Current design piping code treats the pressure reduction effect equally for in-plane (closing and opening) moment and outof- plane moment. The aim of this paper is to present results of a detailed finite element analysis on the non-linear behavior of piping elbows of various geometric configurations subject to out-of-plane bending and internal pressure. Specifically the standard Rodabaugh & George nonlinear pressure reduction equations for in-plane closing moment are checked in a systematic study for out-of-plane moment against nonlinear finite element analysis. The results show that the pressure stiffening effects are markedly different for in-plane and out-of-plane bending.

Limit Loads for Pipe Elbows With Internal Pressure Under In-Plane Closing Bending Moments

1998 ◽  
Vol 120 (1) ◽  
pp. 35-42 ◽  
Author(s):  
M. A. Shalaby ◽  
M. Y. A. Younan
Keyword(s):  
Finite Element Analysis ◽  
Internal Pressure ◽  
Limit Load ◽  
Nonlinear Finite Element ◽  
Radius Of Curvature ◽  
Plastic Collapse ◽  
Bending Moments ◽  
Element Analysis ◽  
Pipe Bend ◽  
Limit Loads

The purpose of this study is to determine limit loads for pipe elbows subjected to in-plane bending moments that tend to close the elbow (i.e., decrease its radius of curvature), and the influence of internal pressure on the value of the limit load. Load-deflection curves were obtained, and from these curves plastic collapse or instability loads at various values of internal pressure were determined. This was done for different pipe bend factors (h = Rt/r2) using the nonlinear finite element analysis code (ABAQUS) with its special elbow element. The limit load was found to increase and then decrease with increasing pressure for all the elbow geometries studied.

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.

Shakedown Limit Load Determination for a Kinematically Hardening 90-Degree Pipe Bend Subjected to Constant Internal Pressure and Cyclic Bending

2007 ◽  
Author(s):  
Hany F. Abdalla ◽  
Mohammad M. Megahed ◽  
Maher Y. A. Younan
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Plastic Material ◽  
Kinematic Hardening ◽  
Limit Load ◽  
Material Behavior ◽  
Pipe Bend ◽  
Cyclic Bending ◽  
Perfectly Plastic ◽  
Shakedown Limit

A simplified technique for determining the shakedown limit load of a structure employing an elastic-perfectly-plastic material behavior was previously developed and successfully applied to a long radius 90-degree pipe bend. The pipe bend is subjected to constant internal pressure and cyclic bending. The cyclic bending includes three different loading patterns namely; in-plane closing, in-plane opening, and out-of-plane bending moment loadings. The simplified technique utilizes the finite element method and employs small displacement formulation to determine the shakedown limit load without performing lengthy time consuming full cyclic loading finite element simulations or conventional iterative elastic techniques. In the present paper, the simplified technique is further modified to handle structures employing elastic-plastic material behavior following the kinematic hardening rule. The shakedown limit load is determined through the calculation of residual stresses developed within the pipe bend structure accounting for the back stresses, determined from the kinematic hardening shift tensor, responsible for the translation of the yield surface. The outcomes of the simplified technique showed very good correlation with the results of full elastic-plastic cyclic loading finite element simulations. The shakedown limit moments output by the simplified technique are used to generate shakedown diagrams of the pipe bend for a spectrum of constant internal pressure magnitudes. The generated shakedown diagrams are compared with the ones previously generated employing an elastic-perfectly-plastic material behavior. These indicated conservative shakedown limit moments compared to the ones employing the kinematic hardening rule.

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.

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.

Using Finite Element Analysis to Prioritize ILI Calls for Combined Features: Dents in Bends

2018 ◽  
Author(s):  
David Kemp ◽  
Justin Gossard ◽  
Shane Finneran ◽  
Joseph Bratton
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Metal Loss ◽  
Remaining Life ◽  
Case Scenario ◽  
Element Analysis ◽  
Pipe Bend ◽  
Worst Case ◽  
Worst Case Scenario ◽  
Combined Features

Pipeline in-line-inspections (ILI) are used to assess and track the integrity of pipelines, aiding in identifying a variety of features such as: metal loss, dents, out-of-roundness, cracks, etc. The presence of these features can negatively affect the operation, integrity, and remaining life of a pipeline. Proper interpretation of the impacts these features may have on a pipeline are crucial to maintaining the integrity of a pipeline. Several codes and publications exist to assess the severity of these features under known operating conditions, either through empirical formulations or more detailed analysis, in order to aid the operator in determining a corrective action plan. These empirical formulations are generally applicable to assess a singular defect but require a more detailed assessment to evaluate combined defects (i.e. dent in a bend). These detailed assessments typically require a higher level numerical simulation, such as Finite Element Analysis (FEA). This detailed FEA can be quite costly and time consuming to evaluate each set of combined features in a given ILI run. Thus, engineering judgement is critical in determining a worst-case scenario of a given feature set in order to prioritize assessment and corrective action. This study aims to assess dent features (many associated with metal loss) occurring in a pipe bend to determine a worst-case scenario for prioritization of a given feature listing. FEA was used to simulate a field bend of a given radius and angle in order to account for residual stresses in the pipe bend. A rigid indenter was used to form a dent of the approximate length, width, and depth from the ILI data. Separate models were evaluated considering the dent occurring in the intrados, extrados, and neutral axis of the pipe bend to evaluate the worst-case scenario for further assessment. The resulting stresses in the pipe bend-dent geometry, under proper loading were compared to the same dent scenario in a straight pipe segment to develop a stress concentration factor (SCF). This SCF was used in the API 579-1/ASME FFS-1 Fitness for Service (API 579) [1] methodology to determine the impact on the remaining life of the combined features.

The Evaluation of Failure Pressure for Corrosion Defects Within Girth or Seam Weld in Transmission Pipelines

2004 ◽  
Author(s):  
Young-pyo Kim ◽  
Woo-sik Kim ◽  
Young-kwang Lee ◽  
Kyu-hwan Oh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Limit Load ◽  
The Body ◽  
Element Analysis ◽  
Burst Test ◽  
Corrosion Defect ◽  
Seam Weld ◽  
Failure Assessment ◽  
Corrosion Defects

The failure assessment for corroded pipeline has been considered with the burst test and the finite element analysis. The burst tests were conducted on 762mm diameter, 17.5mm wall thickness and API 5L X65 pipe that contained specially manufactured rectangular corrosion defect. The failure pressures for corroded pipeline have been measured by burst testing and classified with respect to corrosion sizes and corroded regions — the body, the girth weld and the seam weld of pipe. Finite element analysis was carried out to derive failure criteria of corrosion defect within the body, the girth weld and the seam weld of the pipe. A series of finite element analyses were performed to obtain a limit load solution for corrosion defects on the basis of burst test. As a result, the criteria for failure assessment of corrosion defect within the body, the girth weld and the seam weld of API 5L X65 gas pipeline were proposed.

Sign in / Sign up

Export Citation Format

Share Document