A Burst Capacity Model for Corroded Pipelines Subjected to Combined Internal Pressure and Longitudinal Compression

2021 ◽  
Author(s):  
Shulong Zhang ◽  
Wenxing Zhou
Keyword(s):  
Internal Pressure ◽  
Correction Factor ◽  
Oil And Gas ◽  
Large Set ◽  
Finite Element Analyses ◽  
Longitudinal Compression ◽  
Combined Loads ◽  
Capacity Model ◽  
Proposed Model ◽  
Semi Empirical

Abstract The present study proposes a new semi-empirical burst capacity model for corroded oil and gas pipelines under combined internal pressure and longitudinal compression. The proposed model evaluates the burst capacity of a corroded pipeline under combined loads as the burst capacity of the pipeline under internal pressure only, which is developed in a recently completed study, multiplied by a correction factor to account for the effect of the longitudinal compression. Extensive parametric elastoplastic finite element analyses (FEA) are carried out, the results of which are used as the basis to develop the correction factor as a function of the corrosion defect sizes and magnitude of the longitudinal compressive stress. The proposed model is validated by a large set of parametric FEA and full-scale burst tests reported in the literature, and is shown to provide marked improvements over two existing models, the DNV and RPA-PLLC models, for corroded pipelines under combined loads.

Interaction Assessment of Diagonally-Spaced Identical Corrosion Defects and Fully-Aligned Unequal-Sized Corrosion Defects Under Combined Loads

2021 ◽  
Author(s):  
Shulong Zhang ◽  
Wenxing Zhou
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Oil And Gas ◽  
Three Dimensional ◽  
Element Model ◽  
Interaction Effects ◽  
Longitudinal Compression ◽  
Combined Loads ◽  
Corrosion Defects ◽  
The Finite Element Model

Abstract In this study, the interaction effects of closely-spaced corrosion defects on the burst capacity of oil and gas pipelines under combined internal pressure and longitudinal compression are investigated by using parametric three-dimensional elasto-plastic finite element analyses. Full-scale burst tests reported in the literature are used to validate the finite element model. It is observed that the interaction effects of diagonally-spaced defects on the burst capacity is strongly related to the overlapping portion of the defect width or circumferential spacing between the two defects. The analysis results indicate that the strongest interaction between diagonally-spaced defects under combined loads occurs if the defects have zero circumferential separation. The interaction weakens as the defects are more and more overlapped or separated circumferentially. It is also observed that the interaction effect associated with longitudinally- or circumferentially-aligned, unequal-sized corrosion defects is negligible under the internal pressure only or combined loads.

Failure Pressure Estimation of Corroded Pipeline with Different Depths of Interacting Defects Subjected to Internal Pressure

2013 ◽  
Vol 393 ◽  
pp. 1005-1010
Author(s):  
Ariz Ahmad Azmy ◽  
Saravanan Karuppanan ◽  
Azmi Abdul Wahab
Keyword(s):  
Finite Element ◽  
Chemical Composition ◽  
Internal Pressure ◽  
Oil And Gas ◽  
Operating Pressure ◽  
Finite Element Analyses ◽  
Defect Depth ◽  
Failure Pressure ◽  
Different Depths ◽  
Fea Analysis

Pipelines are one of the most reliable and safest ways to transport oil and gas from one location to another. However, if not handled and maintained properly, they will cause major destruction should one of these pipelines burst. A pipeline which has oil or gas flowing through it will be subjected to internal pressure due to the flow of the oil or gas. Furthermore, the chemical composition of the oil and gas acts as a corrosive agent towards the pipeline. The corrosion eventually becomes defects thus compromising the pipeline integrity. In addition, if two defects are close enough, they are treated as interacting defects. In this work, the pipeline integrity was first calculated using DNV RP-101 codes. After calculating the maximum operating pressure for the pipeline using the codes, Finite Element Analyses using ANSYS were carried out to simulate and model the pipeline with the interacting defects. The maximum operating pressure given by the FEA was then compared to the DNV codes. We found that despite consistency between DNV codes, the FEA analysis showed that geometry plays an important part in determining the values of failure pressure. The FEA analysis showed that by increasing the ratio of depth between the interacting defects, the failure pressure decreases. This was likely because defects of larger depths are more likely to fail at lower pressures. This contradicts the results obtained from DNV codes where the failure pressure is constant for the same effective defect depth over thickness, (d12/t)*.

scholarly journals A Semi-Empirical Model for Predicting Frost Properties

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 412
Author(s):  
Shao-Ming Li ◽  
Kai-Shing Yang ◽  
Chi-Chuan Wang
Keyword(s):  
Thermal Conductivity ◽  
Linear Programming ◽  
Numerical Model ◽  
Empirical Model ◽  
Quantitative Method ◽  
Predictive Ability ◽  
Dimensionless Temperature ◽  
Crystal Shape ◽  
Proposed Model ◽  
Semi Empirical

In this study, a quantitative method for classifying the frost geometry is first proposed to substantiate a numerical model in predicting frost properties like density, thickness, and thermal conductivity. This method can recognize the crystal shape via linear programming of the existing map for frost morphology. By using this method, the frost conditions can be taken into account in a model to obtain the corresponding frost properties like thermal conductivity, frost thickness, and density for specific frost crystal. It is found that the developed model can predict the frost properties more accurately than the existing correlations. Specifically, the proposed model can identify the corresponding frost shape by a dimensionless temperature and the surface temperature. Moreover, by adopting the frost identification into the numerical model, the frost thickness can also be predicted satisfactorily. The proposed calculation method not only shows better predictive ability with thermal conductivities, but also gives good predictions for density and is especially accurate when the frost density is lower than 125 kg/m3. Yet, the predictive ability for frost density is improved by 24% when compared to the most accurate correlation available.

The Failure Window Method and Its Application in Pipeline Burst

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Zhanfeng Chen ◽  
Hao Ye ◽  
Sunting Yan ◽  
Xiaoli Shen ◽  
Zhijiang Jin
Keyword(s):  
Internal Pressure ◽  
Maximum Stress ◽  
Oil And Gas ◽  
Maximum Shear Stress ◽  
High Accuracy ◽  
Burst Pressure ◽  
Empirical Equations ◽  
Integrity Assessment ◽  
Wall Thinning ◽  
Window Method

Accurate prediction of the burst pressure is indispensible for the engineering design and integrity assessment of the oil and gas pipelines. A plenty of analytical and empirical equations have been proposed to predict the burst pressures of the pipelines; however, it is difficult to accurately predict the burst pressures and evaluate the accuracy of these equations. In this paper, a failure window method was presented to predict the burst pressure of the pipes. First, the security of the steel pipelines under the internal pressure can be assessed. And then the accuracy of the previous analytical and empirical equations can also be generally evaluated. Finally, the effect of the wall thinning of the pipes on the failure window was systemically investigated. The results indicate that it is extremely formidable to establish an equation to predict the burst pressure with a high accuracy and a broad application, while it is feasible to create a failure window to determine the range of the dangerous internal pressure. Calculations reveal that some predictions of the burst pressure equations like Faupel, Soderberg, Maximum stress, and Nadai (1) are overestimated to some extent; some like ASME, maximum shear stress, Turner, Klever and Zhu–Leis and Baily–Nadai (2) basically reliable; the rest like API and Nadai (3) slightly conservative. With the wall thinning of the steel pipelines, the failure window is gradually lowered and narrowed.

Predicting strains in embedded reinforcement based on surface deformation obtained by digital image correlation technique

2021 ◽  
Author(s):  
Ali Mirzazade ◽  
Cosmin Popescu ◽  
Thomas Blanksvärd ◽  
Björn Täljsten
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Surface Deformation ◽  
Local Strain ◽  
Surface Strain ◽  
Image Correlation ◽  
Correlation Technique ◽  
Proposed Model ◽  
Structural Inspection ◽  
Semi Empirical

<p>This study is carried out to assess the applicability of using a digital image correlation (DIC) system in structural inspection, leading to deploy innovative instruments for strain/stress estimation along embedded rebars. A semi-empirical equation is proposed to predict the strain in embedded rebars as a function of surface strain in RC members. The proposed equation is validated by monitoring the surface strain in ten concrete tensile members, which are instrumented by strain gauges along the internal steel rebar. One advantage with this proposed model is the possibility to predict the local strain along the rebar, unlike previous models that only monitored average strain on the rebar. The results show the feasibility of strain prediction in embedded reinforcement using surface strain obtained by DIC.</p>

Impact of Curbside Parking on Bicycle Lane Capacity in Nanjing, China

2018 ◽  
Vol 2672 (31) ◽  
pp. 120-129 ◽  
Author(s):  
Xiaofei Ye ◽  
Xingchen Yan ◽  
Jun Chen ◽  
Tao Wang ◽  
Zhao Yang
Keyword(s):  
Middle Position ◽  
Capacity Model ◽  
Operational Characteristics ◽  
Proposed Model ◽  
Volume Relationship ◽  
Lane Width ◽  
Relationship Model ◽  
Bicycle Lane

As roadway resources are being occupied by curbside parking and because of the operational characteristics of parking maneuvers, the capacity of the adjacent travel lane can be significantly reduced. To analyze the influence of curbside parking on the capacity of the bicycle lane, a conflict technique based on additive conflict flow was applied to establish the base capacity model. The actual capacity of the bicycle lane with curb parking was then established by adjusting the base capacity to reflect the influence: lane width, the time influence of parking maneuvers, and proportion of e-bikes. Eight datasets from the exclusive bicycle lanes with different widths and parking maneuvers were collected in Nanjing, China for calibration and evaluation purposes. As a result of a higher number of parking maneuvers, the Emeiling Road was taken as the main case study. The capacity of the bicycle lane was calculated, and the effectiveness of the proposed method was validated by the speed-density-volume relationship model. The proposed model was applied to analyze the effect of different positions of parking berths on the capacity. The results indicate that, with around 65% share of e-bikes, the estimated capacity of Emeiling Road is 2622 bicycles/h, decreasing by 47.10% under the influence of curbside parking. The results also imply that the berths near the openings of the isolation belt have less influence than those in the middle position. These findings could be helpful and useful for practitioners to improve the capacity of bicycle lanes under the influence of curbside parking.

Predictions of Endwall Losses and Secondary Flows in Axial Flow Turbine Cascades

1987 ◽  
Vol 109 (2) ◽  
pp. 229-236 ◽  
Author(s):  
O. P. Sharma ◽  
T. L. Butler
Keyword(s):  
Flow Visualization ◽  
Secondary Flow ◽  
Axial Flow ◽  
Secondary Flows ◽  
Integral Boundary ◽  
Realistic Interpretation ◽  
Proposed Model ◽  
Flow Theories ◽  
Semi Empirical ◽  
End Wall

This paper describes the development of a semi-empirical model for estimating end-wall losses. The model has been developed from improved understanding of complex endwall secondary flows, acquired through review of flow visualization and pressure loss data for axial flow turbomachine cascades. The flow visualization data together with detailed measurements of viscous flow development through cascades have permitted more realistic interpretation of the classical secondary flow theories for axial turbomachine cascades. The re-interpreted secondary flow theories together with integral boundary layer concepts are used to formulate a calculation procedure for predicting losses due to the endwall secondary flows. The proposed model is evaluated against data from published literature and improved agreement between the data and predictions is demonstrated.

Buckling Resistance of Large Diameter Spiral Welded Linepipe

2004 ◽  
Author(s):  
Tom Zimmerman ◽  
Chris Timms ◽  
Jueren Xie ◽  
James Asante
Keyword(s):  
Oil And Gas ◽  
Weld Seam ◽  
Large Diameter ◽  
Ground Movement ◽  
Finite Element Analyses ◽  
Line Pipe ◽  
Diameter Pipe ◽  
Buckling Resistance ◽  
Analytical Research ◽  
Full Scale Tests

This paper contains the results of an experimental and analytical research program to determine the compressive buckling resistance of large-diameter, spiral-welded linepipe. Buckling resistance is important for pipe intended for service in Arctic, oil and gas pipeline systems, where pipes may be subjected to high bending strains caused by various ground movement events. The experimental work consisted of four full-scale tests of 30-inch (762 mm) diameter pipe subjected to various combinations of internal pressure, axial force and bending. The pipe specimens were fabricated using two material grades (X70 and X80) and two D/t ratios (82 and 48). Finite element analyses of the four tests were conducted to develop a better understanding of specimen behavior. The results suggest that spiral welded linepipe is as good as longitudinally welded line pipe in terms of buckling capacity. The spiral weld seam was in no way detrimental to the pipe performance.

SEMI-EMPIRICAL KERNEL FUNCTION FOR THE ANALYSIS OF FIBER BRAGG GRATINGS UNDER TEMPERATURE DISTRIBUTIONS

2011 ◽  
Vol 25 (31) ◽  
pp. 4208-4211
Author(s):  
JINHO BAE ◽  
CHONG HYUN LEE ◽  
JOON-YOUNG KIM ◽  
YUN-HAE KIM
Keyword(s):  
Kernel Function ◽  
Coupling Coefficient ◽  
Fundamental Matrix ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Thermal Change ◽  
Temperature Distributions ◽  
Proposed Model ◽  
Thermal Changes ◽  
Semi Empirical

To analyze the various Fiber Bragg gratings (FBGs) with thermal changes, we present how makes a kernel function to translate the information of thermal change into coupling coefficient and detuning factor. We also propose an accurate and versatile extended fundamental matrix model (EFMM) with the kernel function. The proposed model is then can be used to design the piecewise uniform FBGs with the thermal changes. Sensitivity of a temperature variation is performed using Mote Carlo simulations.

scholarly journals Let Them Learn

2021 ◽  
Vol 7 (2) ◽  
pp. 230-260
Author(s):  
Christian Martinez
Keyword(s):  
Critical Analysis ◽  
Oil And Gas ◽  
Common Law ◽  
Case Law ◽  
The Self ◽  
Self Assessment ◽  
Proposed Model ◽  
Design Build ◽  
Free Flow Of Information ◽  
Flow Of Information

Organizations often conduct probing self-studies to review internally existing policies, procedures, and business methods. Yet, despite an increasing social need for these studies, the Texas legislature has yet to construct a privilege designed to protect an organization from being harmed from these studies by adverse litigants. The self-critical analysis privilege, or SCAP, is an alluring, common law doctrine that protects the free flow of information sharing through an organization’s self-assessment. This Comment proposes a model statute for the codification of the SCAP for the consideration of the Texas legislature. This model statute is not a general codification of the privilege. Instead, the statute is meant to apply only to Texas’s Design-Build industry. This Comment discusses the significant policy considerations supporting the SCAP and analyzes case law to derive proper drafting language. Although this proposed model statute narrowly applies to Texas’s Design-Build industry, the hope is to have a workable statute that could apply to general products, oil and gas, and other property related industries.

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