scholarly journals A Pipeline Dent Assessment Model Considering Localised Effects

2000 ◽  
Author(s):  
A. Dinovitzer ◽  
A. Bhatia ◽  
R. Walker ◽  
R. Lazor
Keyword(s):  
Service Life ◽  
Pipe Wall ◽  
Element Model ◽  
Assessment Model ◽  
Metal Loss ◽  
Concentration Effects ◽  
Pipe Segment ◽  
Weld Toe ◽  
Pipeline Design ◽  
Weld Seams

The Canadian Pipeline Design Standard (CSA Z662) [1] requires the repair of smooth dents with depths exceeding 6% of the pipeline’s outside diameter. This limit on dent depth is reduced in the presence of additional localised effects such as pipe wall gouges, corrosion or planar flaws. Furthermore, it has been observed that pipe wall metal loss, planar flaws and weld seam interaction with dents can significantly reduce the service life of a dented pipe segment. A previously developed pipeline dent assessment model, based on the actual dent profile and in-service pressure history applied to non-linear pipe finite element model with a fracture mechanics crack growth algorithm, has been used to explore the consequences of these localised effects. The effects of corrosion (uniform or local pitting), weld seams (including their weld toe stress concentration effects and residual stress fields), planar flaws (cracks) and gouges on the service life of a dent are reviewed in this investigation. The performance of the model is demonstrated based on its agreement with field observations. The dent assessment model application and validation processes has indicated that the model presented here can be reliably used to predict the service life of dented pipelines in the presence of various localised effects.

Geometric Dent Characterization

2002 ◽  
Author(s):  
A. Dinovitzer ◽  
R. Lazor ◽  
L. B. Carroll ◽  
J. Zhou ◽  
F. McCarver ◽  
...  
Keyword(s):  
Assessment Model ◽  
Pipe Material ◽  
Line Pipe ◽  
Pressure History ◽  
Line Pressure ◽  
Rapid Characterization ◽  
Pipeline Design ◽  
Weld Seams ◽  
Outside Diameter ◽  
Dent Depth

The Canadian pipeline design standard (CSA Z662) requires the repair of smooth dents with depths exceeding 6% of the pipeline’s outside diameter. This limit on dent depth is reduced in the presence of additional localized effects such as pipe wall gouges, corrosion, planar flaws or weld seams. It has been noted, however, that pipelines have operated satisfactorily with dents in excess of 10% while others with 3% dents have failed. Based upon observation of this type the question arises, “Is there more to characterizing a dent than its depth?” An ongoing group sponsored project at BMT Fleet Technology Limited (FTL) is exploring the issue of dent characterization using a dent assessment model developed at FTL. The objective of this project is to develop a rapid dent life expectancy characterization technique based upon dent geometry, line pressure history and line pipe material properties. This paper will outline the general characterization approach being considered and demonstrate some of the observed and expected relationships between service life and dent geometry. The relative importance of each dent characteristic (geometric measures, line pipe material and line pressure history) will be discussed to demonstrate the potential of the rapid characterization approach being developed.

Development and Validation of a Pipeline Buckle and Wrinkle Assessment Model

2004 ◽  
Author(s):  
A. Dinovitzer ◽  
A. Fredj ◽  
R. Lazor ◽  
R. Doblanko
Keyword(s):  
Service Life ◽  
Model Development ◽  
Development Project ◽  
Assessment Model ◽  
Fe Model ◽  
Loading Frequency ◽  
Pipe Segment ◽  
Maintenance Requirements ◽  
Development And Validation ◽  
Further Development

Inspection has revealed pipeline buckles and wrinkles promoted by thermal loads, differential settlement, slope movement and other pipe-soil interaction modes, as well as, cold field bends during construction. While all agree that pipeline wrinkles are undesirable, the urgency of their repair is not commonly understood. In general, it is accepted that the onset of wrinkling does not result in a loss of integrity because pipeline steels are adequately ductile to support large monotonic strains. It is also known that loading is displacement-controlled, thus applied load relief occurs during wrinkle formation. Although failure can occur with only a few strain reversals, the low loading frequency provides time to react. This paper will describe the steps and tools required to define the maintenance requirements for a pipeline wrinkle or to evaluate the effectiveness of remediation techniques. The paper will focus on the results of a preliminary wrinkle model development project aimed at assembling a practical technique capable of predicting the service life of a buckled or wrinkled pipe segment. The LS-DYNA non-linear finite element (FE)-based numerical wrinkle and buckle formation and growth model, developed at BMT Fleet Technology Limited, will be described along with its validation through comparison with full-scale trials and existing design criteria. The paper also discusses the use of the FE model predicted through-life wrinkle behavior to estimate the wrinkle service life and describe the way forward for the further development and implementation of this approach.

scholarly journals Evaluation of Moisture and Decay Models for a New Design Framework for Decay Prediction of Wood

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 721
Author(s):  
Jonas Niklewski ◽  
Philip Bester van Niekerk ◽  
Christian Brischke ◽  
Eva Frühwald Hansson
Keyword(s):  
Service Life ◽  
Wood Decay ◽  
Element Model ◽  
Digital Design ◽  
Design Guideline ◽  
Digital Performance ◽  
Detail Design ◽  
Non Linear ◽  
Service Life Design ◽  
Life Design

Performance-based, service-life design of wood has been the focus of much research in recent decades. Previous works have been synthesized in various factorized design frameworks presented in the form of technical reports. Factorization does not consider the non-linear dependency between decay-influencing effects, such as between detail design and climate variables. The CLICKdesign project is a joint European effort targeting digital, performance-based specification for service-life design (SLD) of wood. This study evaluates the feasibility of using a semi-empirical moisture model (SMM) as a basis for a digital SLD framework. The performance of the SMM is assessed by comparison against a finite element model (FEM). In addition, two different wood decay models (a logistic, LM, and simplified logistic model (SLM)) are compared. While discrepancies between the SMM and FEM were detected particularly at high wood moisture content, the overall performance of the SMM was deemed sufficient for the application. The main source of uncertainty instead stems from the choice of wood decay model. Based on the results, a new method based on pre-calculated time series, empirical equations, and interpolation is proposed for predicting the service life of wood. The method is fast and simple yet able to deal with non-linear effects between weather variables and the design of details. As such, it can easily be implemented as part of a digital design guideline to provide decision support for architects and engineers, with less uncertainty than existing factorized guidelines.

Pipeline On-Bottom Stability Analysis Based on FEM Model

2011 ◽  
Author(s):  
Yong Bai ◽  
Zhimeng Yu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Design Procedure ◽  
Element Model ◽  
The Finite Element Method ◽  
Fem Model ◽  
Engineering Software ◽  
Calculation Results ◽  
Pipeline Design ◽  
Element Method

Pipeline on-bottom stability is one of the sophisticated problems in subsea pipeline design procedure. Due to the uncertainty of the pipe-soil interaction and environment loads, including wave, current, or earthquake, etc., it is classified as the typical nonlinear problem. The Finite Element Method is introduced into pipeline engineering several years ago. More and more special engineering software such as AGA, PONDUS are available in market. However, when doing a project, some abnormal data was found when compared the DnV calculation results and AGA. In order to know the behavior of pipeline on seabed under wave and current load, finite element method – ABAQUS is introduced to do this analysis. The ABAQUS/explicit is used to simulate 600s pipeline dynamic response. The pipeline is supposed to be exposed on seabed and the selected seabed model is large enough to avoid the edge effect. ABAQUS calculation results are compared with the requirements in DnV rules to verify the validity of finite element model.

Environmental Impact Analysis of Water Environment in Coal Mining Areas Based on Matter-Element Model

2010 ◽  
Vol 108-111 ◽  
pp. 403-408 ◽  
Author(s):  
Qi Liang Wang ◽  
Lei Wang
Keyword(s):  
Coal Mining ◽  
Large Scale ◽  
Impact Analysis ◽  
Water Environment ◽  
Element Model ◽  
Evaluation Index System ◽  
Assessment Model ◽  
Environment Impact ◽  
Mining Areas ◽  
Matter Element Model

In connection with the problems that coal mining accounts for water environment pollution and socio-economic development, the main factors was analyzed. From water environment system, ecological system and socio-economic system, corresponding evaluation index system was perfected and became fit for factual situation. Matter-element model of water environment impact evaluation was constructed and used to evaluate four large-scale coal mining areas. The results showed that assessment model in accordance with the objective reality. Compared with other evaluation models, matter-element model is more accurate and comprehensive. By matlab, a calculating program was made and can be dynamically amended.

The Influence of Internal Pressure on Pipeline Natural Frequency

2009 ◽  
Author(s):  
Andre´ Luiz Lupinacci Massa ◽  
Nelson Szilard Galgoul ◽  
Nestor Oscar Guevara Junior ◽  
Antonio Carlos Fernandes ◽  
Fa´bio Moreira Coelho ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Natural Frequency ◽  
Axial Force ◽  
Natural Frequencies ◽  
Pipe Wall ◽  
Element Model ◽  
Straight Pipe ◽  
Temperature Expansion ◽  
Force Concept

Galgoul et al. (2004) have written a previous paper in which they have pointed out the conservatism of the latest recommendations for pipeline freespan evaluations, associated to the way the axial force is considered in the determination of the pipeline natural frequency. First because it fails to consider the fact, that the axial force of a sagging pipe, subject to temperature expansion, is much smaller than that of a straight pipe. Second because the effective axial force caused by internal pressure should not be used to determine the pipeline natural frequency. Fyrileiv and Collberg (2005) also discussed this aspect. In order to back up their previous arguments the authors decided to perform some tests an axially restrained pipeline at both ends, which was pressurized in order to justify their claims that these pipelines are not only under tension (and not compression), but also that their natural frequencies increase instead of reducing, although they do bend out because of the pressure, reaching a point of instability. The authors understand the effective axial force concept and the enormous simplifications, which it brings to an otherwise cumbersome problem, but wish to emphasize that these advantages are not unlimited and that this is one of these restrictions. To back up the text results a finite element model has been produced, in which the internal pressure is taken into account as it actually is (and not as an axial force) to show that the pipe wall stresses can only be obtained correctly in this manner.

scholarly journals Numerical Analysis and Strength Evaluation of an Exposed River Crossing Pipeline with Casing Under Flood Load

2018 ◽  
Author(s):  
Xiaoben Liu ◽  
Hong Zhang ◽  
Mengying Xia ◽  
Yanfei Chen ◽  
Kai Wu ◽  
...  
Keyword(s):  
Finite Element ◽  
Flow Velocity ◽  
Yield Criterion ◽  
Element Model ◽  
Failure Criteria ◽  
General Purpose ◽  
Von Mises Stress ◽  
Critical Flow Velocity ◽  
Pipe Segment ◽  
Von Mises

Pipelines in service always experience complicated loadings induced by operational and environmental conditions. Flood is one of the common natural hazard threats for buried steel pipelines. One exposed river crossing X70 gas pipeline induced by flood erosion was used as a prototype for this study. A mechanical model was established considering the field loading conditions. Morison equations were adopted to calculate distributional hydrodynamic loads on spanning pipe caused by flood flow. Nonlinear soil constraint on pipe was considered using discrete nonlinear soil springs. An explicit solution of bending stiffness for pipe segment with casing was derived and applied to the numerical model. The von Mises yield criterion was used as failure criteria of the X70 pipe. Stress behavior of the pipe were analyzed by a rigorous finite element model established by the general-purpose Finite-Element package ABAQUS, with 3D pipe elements and pipe-soil interaction elements simulating pipe and soil constraints on pipe, respectively. Results show that, the pipe is safe at present, as the maximum von Mises stress in pipe with the field parameters is 185.57 MPa. The critical flow velocity of the pipe is 5.8 m/s with the present spanning length. The critical spanning length of the pipe is 467 m with the present flow velocity. The failure pipe sections locate at the connection point of the bare pipe and the pipe with casing or the supporting point of the bare pipe on riverbed.

Effects of Soil Non-Linearity on the Dynamic Behavior and Fatigue Life of Pipeline Spans Subjected to Slug Flow

2010 ◽  
Author(s):  
Euro Casanova ◽  
Armando Blanco
Keyword(s):  
Fatigue Life ◽  
Slug Flow ◽  
Element Model ◽  
Vibration Response ◽  
Perfectly Plastic ◽  
Equilibrium Configurations ◽  
Non Linear ◽  
Cyclic Damage ◽  
Pipeline Design ◽  
Soil Pipe

Offshore production fields require long submarine pipelines for transporting production fluids that are inherently multiphase. This condition and hydraulic sizing of pipelines lead often to the development of slug flow patterns in which condensate slugs traveling in the pipeline, act as moving gravity loads for the piping structure, therefore producing a dynamic response especially important for the free spans. Recently some authors have shown that this phenomenon may produce a cyclic damage that could reduce in a significant way the fatigue life of the pipelines, thus constituting a governing mechanism in their design. On the other hand, pipe-soil interaction has also been identified as an important factor in pipeline design and fatigue life; in particular it is important for determination of the static equilibrium configurations and the vibration response of free spanning pipelines. In this work a previously presented numerical model which combines fluid equations for predicting slug characteristics and a structural finite element model for the pipelines transporting slugs, is improved by introducing non linear characteristics of seabed supports. Different seabed supports (linear, perfectly plastic, and non linear with tension cut-off) and different properties of soil-pipe interaction (stiffness, damping and length of soil-pipe interaction) are considered, and their effects on vibration response and fatigue life are compared. Results show that soil pipe interaction is an important parameter in vibration response and fatigue life for pipeline spans subjected to slug flow.

Modeling Preharvest and Harvest Interventions for Escherichia coli O157 Contamination of Beef Cattle Carcasses

2011 ◽  
Vol 74 (9) ◽  
pp. 1422-1433 ◽  
Author(s):  
CHARLES C. DODD ◽  
MICHAEL W. SANDERSON ◽  
MEGAN E. JACOB ◽  
DAVID G. RENTER
Keyword(s):  
Escherichia Coli ◽  
Assessment Model ◽  
Sensitivity Analyses ◽  
Feed Additive ◽  
Future Research ◽  
Escherichia Coli O157 ◽  
Concentration Effects ◽  
Modeling Framework ◽  
E Coli ◽  
Carcass Contamination

Field studies evaluating the effects of multiple concurrent preharvest interventions for Escherichia coli O157 are logistically and economically challenging; however, modeling techniques may provide useful information on these effects while also identifying crucial information gaps that can guide future research. We constructed a risk assessment model with data obtained from a systematic search of scientific literature. Parameter distributions were incorporated into a stochastic Monte Carlo modeling framework to examine the impacts of different combinations of preharvest and harvest interventions for E. coli O157 on the risk of beef carcass contamination. We estimated the risk of E. coli O157 carcass contamination conditional on preharvest fecal prevalence estimates, inclusion of feed additive(s) in the diet, vaccination for E. coli O157, transport and lairage effects, hide intervention(s), and carcass intervention(s). Prevalence parameters for E. coli O157 were assumed to encompass potential effects of concentration; therefore, concentration effects were not specifically evaluated in this study. Sensitivity analyses revealed that fecal prevalence, fecal-to-hide transfer, hide-to-carcass transfer, and carcass intervention efficacy significantly affected the risk of carcass contamination (correlation coefficients of 0.37, 0.56, 0.58, and −0.29, respectively). The results indicated that combinations of preharvest interventions may be particularly important for supplementing harvest interventions during periods of higher variability in fecal shedding prevalence (i.e., summer). Further assessments of the relationships among fecal prevalence and concentration, hide contamination, and subsequent carcass contamination are needed to further define risks and intervention impacts for E. coli O157 contamination of beef.

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