Safe Operation and FFS Assessment for Pressure Equipment: Updated With Study for Local Metal Loss Assessment

2006 ◽  
Author(s):  
Atsushi Ohno ◽  
Yoshiaki Uno ◽  
Takayasu Tahara
Keyword(s):  
United States ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Metal Loss ◽  
Assessment Procedure ◽  
Loss Assessment ◽  
Safe Operation ◽  
Element Analysis ◽  
Assessment Procedures ◽  
Design Margin

Recently, Codes and Standards for FFS assessment has been developed and applied in United States and other countries such as API RP579 as a series of maintenance procedures for pressure equipment. Activities developing FFS assessment procedures in conjunction with new safe inspection standards are also progressing in Japan. In order to prove applicability of the FFS procedure for assessment of damaged pressure equipment, it is also important to validate how much of inservice safe margin is derived from the FFS assessment procedures in compared with design margin of pressure equipment. Local metal loss assessment procedure specified by API RP579 is studied using finite element analysis and discussed how much of in-service safe margin will be sufficient as standardized FFS assessment procedure.

Experimental and Numerical Validation of Fitness-for-Service Assessment for Cylindrical and Spherical Pressure Vessel With Local Metal Loss

2008 ◽  
Author(s):  
Takuyo Kaida
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
Axial Stress ◽  
Large Diameter ◽  
Metal Loss ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Longitudinal Length ◽  
Spherical Pressure

Fitness-For-Service (FFS) assessment procedure can be also used to determine a reduced Maximum Allowable Working Pressure (MAWP) for cylindrical and spherical pressure vessel with local metal loss. A reduced MAWP is calculated from the Remaining Strength Factor (RSF). RSF is defined as ratio between plastic collapse load of the damaged component and that of the undamaged component. RSF needs to be calculated accurately in order to continue the damaged component in service safely. In this paper, RSFs of the damaged components with variously-shaped local metal loss were investigated. Especially, effects of circumferential width of local metal loss for cylindrical pressure vessel are investigated by both hydrostatic burst test and finite element analysis (FEA). The configurations of the local metal loss are rectangle. The longitudinal length and minimum thickness are fixed. FEA using the criterion proposed by Miyazaki et al. is effective to estimate fracture ductility under the multi-axial stress condition accurately, and effects of circumferential width is evaluated. In addition, RSF for spherical pressure vessel with relatively large diameter/thickness ratio was calculated by finite element analysis. Both results were compared to the calculation results using the equation in API 579-1/ASME FFS-1. The FFS assessment procedure is validated as conservative assessment experimentally and numerically.

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.

Evaluating Dents With Metal Loss Using Finite Element Analysis

2016 ◽  
Author(s):  
Justin Gossard ◽  
Joseph Bratton ◽  
David Kemp ◽  
Shane Finneran ◽  
Steven J. Polasik
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Laser Scanner ◽  
Mechanical Damage ◽  
Third Party ◽  
Burst Pressure ◽  
Metal Loss ◽  
Surface Mesh ◽  
Element Analysis ◽  
3D Surface

Dents created by third party mechanical damage are a severe integrity threat to onshore and offshore transmission pipelines. This type of damage is often associated with metal loss, which can be introduced during the initiation of a dent or develop as a result of the presence of a dent and associated coating damage. Once a dent has been found to be associated with metal loss through excavation, there is little guidance to determine the serviceability of the anomaly. In this study, dents with associated metal loss due to corrosion examined in the field are evaluated to determine the contribution of the interacting dent and metal loss features to the associated burst pressure of the feature. Twenty dents with metal loss flaws were identified through an ILI survey while in service to capture dimensions of the dent and metal loss features. Each site was excavated and measured using a laser scanner. The laser scanner produced 3D imaging with sufficient resolution of both the dent and metal loss areas as a 3D surface mesh. The 3D surface mesh was transformed into a 3D solid mesh and analyzed using a finite element analysis software package in order to determine a predicted internal pressure that would cause failure. A subsequent statistical assessment was performed to analyze the relationship between the ILI measurements and the predicted burst pressure resulting from finite element analysis of each dent with metal loss feature. Statistical analyses were used to evaluate the prediction capabilities of burst pressures of dent with metal loss features identified through ILI, prior to excavation and direct examination.

Fitness for Service Assessment on Local Metal Loss Near a Discontinuity Using Elastic-Plastic Stress Analysis

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Zhanghai (John) Wang ◽  
Samuel Rodriguez
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Material ◽  
Material Model ◽  
Metal Loss ◽  
Technical Approach ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Structural Discontinuity ◽  
Elastic Plastic Material

In fitness for service (FFS) assessments, one issue that people often encounter is a corroded area near a structural discontinuity. In this case, the formula-based sections of the FFS standard are incapable of evaluating the component without resorting to finite element analysis (FEA). In this paper, an FEA-based technical approach for evaluating FFS assessments using an elastic-plastic material model and reformed criteria is proposed.

scholarly journals An R5 Based Creep-Fatigue Critical Flaw Assessment of an In-Service Reformer Piping Tee Using Finite Element Analysis

2014 ◽  
Author(s):  
Phillip E. Prueter ◽  
David J. Dewees ◽  
Robert G. Brown
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Operating Conditions ◽  
Cyclic Plasticity ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Thermal Transients ◽  
Non Linear ◽  
Creep Fatigue ◽  
Critical Flaw

This study employs three dimensional (3D) non-linear, finite element analysis (FEA) to supplement a critical flaw sizing assessment of an in-service reformer piping tee. The analysis is guided by the EDF (Électricité de France) Assessment Procedure R5 (formerly from British Energy Generation LTD. or BEGL) as well as Part 10 of API 579-1/ASME FFS-1. Specifically, Volume 4/5 of R5, which addresses crack growth, is used to determine the largest permissible flaw as a function of operational cycles and time at temperature. Required stresses are generated using FEA as well as the simplified reference stress techniques of R5 as appropriate. The analysis explicitly considers thermal transients, as well as cyclic plasticity. Furthermore, modeling of steady state operating conditions considers creep in the FEA material model. Additionally, creep-fatigue flaw growth is considered for a range of initial defect sizes. The targeted inelastic, non-linear FEA is leveraged to remove significant uncertainty and conservatism, and the simplified techniques of R5 are employed wherever reasonable to give the most efficient analysis possible. This investigation provides estimates of flaw propagation rates based on historical cyclic operation and permits determination of reasonable inspection intervals for the reformer tee in question. Paper published with permission.

Further Improvements to ASME Section XI Code Case N-806 in a Proposed Second Revision

2019 ◽  
Author(s):  
Robert O. McGill ◽  
George A. Antaki ◽  
Mark A. Moenssens ◽  
Douglas A. Scarth
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Nuclear Industry ◽  
Metal Loss ◽  
Soil Reaction ◽  
Buried Pipe ◽  
Element Analysis ◽  
Design Factor ◽  
Evaluation Procedures ◽  
Need To Evaluate

Abstract ASME Section XI Code Case N-806, for evaluation of metal loss in Class 2 and 3 metallic piping buried in a backfilled trench, was first published in 2012. This Code Case has been prepared by the ASME Section XI Task Group on Evaluation Procedures for Degraded Buried Pipe. The Code Case addresses the nuclear industry need for evaluation procedures and acceptance criteria for the disposition of metal loss that is discovered during the inspection of metallic piping buried in a back-filled trench. In a second revision of the Code Case, several changes are proposed. First, guidance is provided for analytical evaluation of greater detail including finite element analysis methods. A new nonmandatory appendix is included to provide procedures for the evaluation of soil and surcharge loads using finite element analysis. Next, a second new nonmandatory appendix is provided giving detailed guidance on the evaluation of seismic loads. Finally, the need to evaluate the fatigue life of buried piping subjected to cyclic surface loading is now included and a design factor applied to the modulus of soil reaction is introduced. This paper presents details of the proposed changes to Code Case N-806-1 and their technical basis where applicable.

Buckling Strength of Towers Having Partial Metal Loss on Shell Under Overturning Moment

2015 ◽  
Author(s):  
Masayuki Ozaki ◽  
Atsushi Yamaguchi ◽  
Takuyo Kaida ◽  
Satoshi Nagata
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Metal Loss ◽  
Element Analysis ◽  
Buckling Strength ◽  
Buckling Stress ◽  
Critical Issues ◽  
Process Plants ◽  
Overturning Moment ◽  
Good Agreement

Reliability of Fitness-For-Service assessment has become more important especially for the aged pressure equipment such as towers in process plants put in service operation over decades. The effects of partial metal loss on buckling strength of the towers subject to overturning moment due to seismic or wind load are one of the critical issues to be clarified. The present paper simulates the buckling strength of towers under overturning moment by means of finite element analysis considering the condition that the shell has suffered from partial metal loss, and evaluates the validity of the buckling stress formulae of API 579-1/ASME FFS-1, NASA, and Donnell. It has been demonstrated that the buckling strength predicted by API formulae shows fairly good agreement with that simulated by finite element analysis. Finite element analysis results have shown that the axial length of metal loss does not affect the buckling stress very much while the buckling stress depends on the circumferential width of metal loss. It has been revealed that the API formulae underestimate the buckling stress when the width of metal loss is smaller than about 30 deg. The paper proposes the modification to the API formulae in this condition that gives more accurate buckling stress than the original formulae.

Remaining Strength in Pressure Vessels With Pitting Type Metal Loss: Part 1

2018 ◽  
Author(s):  
J. J. Trujillo-Tadeo ◽  
J. L. González-Velázquez ◽  
D. I. Rivas-López
Keyword(s):  
Finite Element ◽  
Corrosion Damage ◽  
Pressure Vessels ◽  
Metal Loss ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Element Simulation ◽  
Main Factors ◽  
Synergistic Behavior

This work proposes an assessment procedure for the determination of the remaining strength in pressure vessels with pitting type metal loss, trough the developed of integrity diagrams according to the pitting density, pitting depths and the internal pressure of the component using Finite Element Analysis simulations. The simulations results indicate that the pitting density and depths according to the Gumbel Max Distribution, are the main factors that determine the mechanical integrity of the component; where 45% damaged area by pitting generates a stress concentration that multiplies at least ten times the stress compared with components without defects, since these variables present a synergistic behavior in the stress state. The proposed assessment procedure facilitates the evaluation of the components that present pitting corrosion damage, due to the geometric and population effect of the pitting is considered in the finite element simulation.

Nonlinear FEA of a Corroded Pipe

2015 ◽  
Author(s):  
Venkata M. K. Akula
Keyword(s):  
Finite Element Analysis ◽  
Sensitivity Analysis ◽  
Finite Element ◽  
Structural Response ◽  
Design Parameters ◽  
Collapse Load ◽  
Safe Operation ◽  
Element Analysis ◽  
Parametric Sensitivity ◽  
Newton Raphson

Analysis of pipelines subjected to corrosion is critical to ensure their integrity and safe operation. Although regulatory codes such as ASME, API, etc. can provide guidance in determining the fitness of a pipeline, often finite element analysis is needed to more accurately predict the structural response. In this paper, we present the techniques that could be used for performing buckling analysis of a pipe with a surface flaw. Several procedures, available in Abaqus, such as the nonlinear Newton-Raphson solver, the implicit dynamics solver, etc. are discussed in the context of predicting the collapse load. The assumptions associated with the use of each solver are presented along with a discussion on their predictive capabilities. Thereafter, parametric sensitivity analysis to study the influence of the design parameters on the collapse load is discussed. The sensitivity analysis requires automating the entire simulation workflow, including the flaw geometry, for predicting the collapse load.

Sign in / Sign up

Export Citation Format

Share Document