Assessment of Interacting Corrosion Defects in Thin-Walled Pipes

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Ahmed A. Soliman ◽  
Mohammad M. Megahed ◽  
Ch. A. Saleh ◽  
Mostafa Shazly
Keyword(s):  
Nonlinear Finite Element ◽  
Metal Loss ◽  
Test Results ◽  
Defect Depth ◽  
Element Analysis ◽  
Shell Elements ◽  
Codes Of Practice ◽  
Useful Life ◽  
Corrosion Defects ◽  
Interaction Rule

Abstract Corrosion in pipes is usually found in the form of closely spaced defects, which eventually reduce the pipe pressure carrying capacity and piping planned useful life. Codes and standards have been developed to evaluate the effect of such form of metal loss on the piping pressure carrying capacities. However, predictions of such codes are usually conservative, and hence, there is a need to assess their degree of conservatism. The present paper utilizes nonlinear finite element analysis (FEA) in estimating pressure carrying capacities of defective pipes, and hence provides an evaluation of codes degree of conservatism. Shell elements with reduced thickness at the corrosion defect are adopted and their accuracy is assessed by comparison with those of solid elements as well as experimental test results. The influence of defects interaction is investigated by considering two neighboring defects in an inclined direction to each other. The influence of inclination angle, inclined proximity distance between the two defects, and the defect depth to wall thickness ratio are investigated. Comparisons were made with predictions of codes of practice in all cases. Code predictions were found to be conservative compared to FEA results. Furthermore, the interaction rule embedded in the codes for checking for interaction leads to inaccurate predictions for closely spaced defects as it does not include the effect of defect depth.

Burst Tests on Pipeline Containing Irregular Shaped Corrosion Defects

2008 ◽  
Author(s):  
Adilson C. Benjamin ◽  
Aldo R. Franzoi ◽  
Jose´ Luiz F. Freire ◽  
Ronaldo D. Vieira ◽  
Jorge L. C. Diniz
Keyword(s):  
Depth Profile ◽  
Effective Area ◽  
Metal Loss ◽  
Defect Depth ◽  
Corrosion Defect ◽  
Spark Erosion ◽  
X80 Steel ◽  
Corrosion Defects ◽  
Tubular Specimens ◽  
Outside Diameter

A corrosion defect can be considered as being of a regular shape if its defect depth profile is relatively smooth and the longitudinal area of metal loss is approximately rectangular. A corrosion defect can be considered as being of an irregular shape if its defect depth profile presents one or more major peaks in depth. In this paper the burst tests of four tubular specimens are presented. In these tests the tubular specimens were loaded with internal pressure only. The specimens were cut from longitudinal welded tubes made of API 5L X80 steel with a nominal outside diameter of 457.2 mm (18 in) and a nominal wall thickness of 7.93 mm (0.312 in). Each of the four specimens had one external irregular shaped corrosion defect, machined using spark erosion. Measurements were carried out in order to determine the actual dimensions of each tubular specimen and its respective defect. Tensile specimens and impact test specimens were tested to determine material properties. The failure pressures measured in the laboratory tests are compared with those predicted by six assessments methods, namely: the ASME B31G method, the RSTRENG 085dL method, the DNV RP-F101 method for single defects, the RPA method, the RSTRENG Effective Area method and the DNV RP-F101 method for complex shaped defects.

New Safety Assessment System for Corroded Underground Pipelines

2009 ◽  
Author(s):  
Szabolcs Sza´vai ◽  
Gyo¨ngyve´r B. Lenkey
Keyword(s):  
Safety Assessment ◽  
Safety Margin ◽  
Assessment System ◽  
Metal Loss ◽  
Safety Factors ◽  
Element Analysis ◽  
Underground Pipelines ◽  
Corrosion Defects ◽  
The Difference ◽  
External Corrosion

The most important question for the user is if pipelines having metal loss defect could be operated safely, if any pipe sections should be repaired or replaced, and how much is the reserved safety against a possible failure. There are several engineering methods for determining the safety margin of operation but those are usually quite conservative. For this reason Lenkey has proposed safety diagrams based on finite element analysis of external corrosion defects in underground pipelines [4]. These safety diagrams could be used to determine safety factors in a less conservative way for critical situations during the pipeline operation. The FEM calculations have been verified by burst tests carried out on several pipe sections. In the present paper the results of some further analyses are presented about the difference between the measured, numerically and analytically determined failure pressure values.

Inelastic Behavior of Threaded Piping Connections: Reconciliation of Experimental and Analytic Results

2011 ◽  
Author(s):  
Yonghee Ryu ◽  
Anahid Behrouzi ◽  
Tsega Melesse ◽  
Vernon C. Matzen
Keyword(s):  
Inelastic Behavior ◽  
Test Results ◽  
Element Analysis ◽  
Shell Elements ◽  
Rotational Spring ◽  
Beam Elements ◽  
Piping Systems ◽  
Threaded Joints ◽  
Rigid Connection ◽  
Euler Bernoulli Beam

Modeling the behavior of piping systems with threaded joints is difficult because the joints do not act as rigid connections. At one level of approximation the connection can be modeled as a semi-rigid connection using a rotational spring. This study modeled a straight pipe using either Euler-Bernoulli beam elements [4] or Finite Element Analysis (FEA) shell elements and a support condition using the rotational spring. Laboratory tests were conducted on 1 in. diameter specimens of black iron Schedule 40 pipe in a cantilever configuration. The specimen was loaded monotonically into the inelastic region. A Ramberg-Osgood model [5] was used to represent the rotational spring and the correlation between test results and analytical predictions was quite good.

A STUDY ON FAILURE OF CROSS ARMS IN TRANSMISSION LINE TOWERS DURING PROTOTYPE TESTING

2005 ◽  
Vol 05 (03) ◽  
pp. 435-455 ◽  
Author(s):  
N. PRASADA RAO ◽  
S. J. MOHAN ◽  
N. LAKSHMANAN
Keyword(s):  
Finite Element ◽  
Transmission Line ◽  
Nonlinear Finite Element ◽  
Test Results ◽  
Nonlinear Finite Element Method ◽  
Element Analysis ◽  
Plate Elements ◽  
The Finite Element Analysis ◽  
Different Types ◽  
The Cross

In this paper, the need for testing of transmission line towers is emphasized. The failure of cross arms that constitute a part of the tower body is analyzed by the nonlinear finite element method. The finite element analysis results are compared with the test results and the reasons for failure are discussed in detail. The cross arm is modeled using beam and plate elements. Four different types of towers with cross arms are considered. The effect of inner triangulation formed by the redundant patterns on the cross arm performance is studied. The effect of staggering secondary bracings in elevation and plan of the cross arm and detailing of cross arm tips (loading points) are also studied.

Experimental Investigation and Nonlinear Finite Element Analysis of U-Shaped Steel-Concrete Composite Beam

2012 ◽  
Vol 166-169 ◽  
pp. 477-481
Author(s):  
Wen Hu Li ◽  
Feng Hua Zhao
Keyword(s):  
Finite Element Analysis ◽  
Experimental Investigation ◽  
Finite Element ◽  
Composite Beam ◽  
Failure Modes ◽  
Theoretical Calculations ◽  
Nonlinear Finite Element Analysis ◽  
Nonlinear Finite Element ◽  
Test Results ◽  
Element Analysis

U-shaped steel –concrete composite beam is a new form of structure components. Through the test of three groups of specimens, the failure modes of structure components, the strain distribution of cross-section, and the load –deformation relationship are analyzed. A preliminary understanding of mechanical characteristics and deformation performance is got from the experimental investigation. The composite beam element is used to conduct nonlinear Finite Element Analysis. Based on the theoretical calculations and experimental investigation, a practical formula of U-shaped steel- concrete composite beam deformation is established. Moreover, the calculated result is in good agreement with the test results.

Study on Pulsed Eddy Current Nondestructive Testing Technology for Pipeline Corrosion Defects Based on Finite Element Method

2011 ◽  
Vol 120 ◽  
pp. 36-41 ◽  
Author(s):  
Han Wu Liu ◽  
Shan Ping Zhan ◽  
Yun Hui Du ◽  
Peng Zhang
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Induced Voltage ◽  
Defect Depth ◽  
Element Analysis ◽  
Pulsed Eddy Current ◽  
The Finite Element Analysis ◽  
Corrosion Defects ◽  
Pipeline Corrosion ◽  
Detection Coil

According to the principle and the type of the oil pipeline corrosion, we use the square wave of wide spectrum, strong signal transmission capability and a certain duty ratio as the excitation source of the pulsed eddy current. The finite element analysis software ANSYS is used to establish a three-dimensional finite element model of the pipeline corrosion defects by applying the boundary conditions of square wave excitation to simulate the distributions of current and induced magnetic field in the pipeline under various defect volumes. It can solve the induced voltage variation with time on detection coil, and can accomplish the finite element analysis and the nondestructive testing about the pipeline internal corrosion defects with the insulation layer and the protection layer. The results of the study show: When there is no corrosion defect in the pipeline, the electric current in the pipeline is basically even distribution. The magnetic field is distributed for the symmetrical vortex shape from head to foot, and it has not obviously gather phenomenon. When there are some corrosion defects in the pipeline, the electric current forms partial symmetrical vortex shape in both sides of the corrosion defect, and it is obviously assembled in the defect place. The simulation results of the different size defects show that the maximum magnetic field strength and the maximum current value increase with the defect depth increasing, while the output voltage decreases with the defect depth increasing. By extracting the induced voltage signals on the detection coil in a certain excitation condition, the quantitative detection of the pipeline corrosion defects can be achieved.

scholarly journals Shrinkage and temperature reinforcement in concrete liquid-containing structures.

2021 ◽  
Author(s):  
Nima Ziaolhagh
Keyword(s):  
Nonlinear Finite Element ◽  
Structural Elements ◽  
Concrete Member ◽  
Minimum Area ◽  
Element Analysis ◽  
Concrete Walls ◽  
Tensile Stresses ◽  
Concrete Members ◽  
Reinforced Concrete Walls ◽  
Codes Of Practice

Cracking due to shrinkage is a widespread problem in large concrete members such as walls and slabs. When shrinkage strains are restrained, tensile stresses develop in concrete. Concrete cracks when tensile stresses exceed the tensile strength of concrete. In general, concrete standards and codes of practice recommend a minimum area of reinforcement for shrinkage and temperature effects. In some cases, large structural elements provide significant restraint to a concrete member that the specified minimum area of reinforcement needs to be increased. This research studies the response of reinforced concrete walls to shrinkage strains. In this study, nonlinear finite element analysis is applied to simulate the cracking behaviour of concrete and predict crack pattern and tensile stresses in reinforcement in the vicinity of cracks. This research is looking for the effective shrinkage and temperature reinforcement in liquid-containing structures where cracking of concrete is of major concern.

Prediction of Corrosion Defect Failure Pressure for Finite Length Defects

2004 ◽  
Author(s):  
Duane S. Cronin
Keyword(s):  
Finite Length ◽  
Three Dimensional ◽  
Defect Depth ◽  
Material Loss ◽  
Element Analysis ◽  
Failure Pressure ◽  
Dimensional Finite Element ◽  
Corrosion Defects ◽  
Three Dimensional Finite Element ◽  
Analytical Approaches

Corrosion defects commonly occur on operating pipelines due to a loss of protection in a corrosive environment. These defects require practical and accurate assessment, particularly for older pipeline systems, to determine the need for remediation or allow for continued operation. Previous research has shown that appropriate application of full three-dimensional finite element analysis, and newly developed analytical approaches, can provide very accurate predictions of failure pressure but require detailed material and geometric data. Although this is important, a simpler method that allows for efficient evaluation of large amounts of data is also desirable. A method has been developed from an existing analytical solution by assuming a defect can be characterized in terms of the total defect length, and a constant defect depth equal to the maximum defect depth. In general this produces a conservative estimate of the material loss. This finite-length defect solution is in good agreement with experimental data for idealized defects, and provides reasonable predictions of burst pressure, with a minimum amount of data, when applied to real corrosion defects.

Simulation and Bogie Testing of a New Cable Barrier Terminal

2003 ◽  
Author(s):  
John D. Reid ◽  
Nicholas R. Hiser ◽  
Tony J. Paulsen
Keyword(s):  
Nonlinear Finite Element ◽  
Test Results ◽  
Cable System ◽  
Element Analysis ◽  
Roadside Safety ◽  
The Road ◽  
Crash Testing ◽  
Cable Systems ◽  
Pass Through ◽  
Steel Cables

Roadside barriers of various designs are extensively used for the purpose of shielding obstacles along the road from impact with errant vehicles. One commonly applied roadside barrier system is a cable system, consisting of three steel cables supported by weak steel posts. Due to an increase in the use of cable systems, a tangent to the roadway, as opposed to flared away from the roadway, crashworthy end terminal has been designed by the Midwest Roadside Safety Facility. The design goal was to effectively disengage the pre-tensioned cables at the end anchor point when impacted on the end by a vehicle, allowing the vehicle to pass through the system virtually unobstructed. It is the objective of this study to help evaluate the new design through bogie testing and nonlinear finite element analysis using LS-DYNA. Based on bogie test results and detailed analysis of the simulation results, it was concluded that the new cable end terminal was ready for full-scale crash testing.

scholarly journals NONLINEAR FINITE ELEMENT ANALYSIS OF NONSEISMICALLY DETAILED INTERIOR RC BEAM-COLUMN CONNECTION UNDER REVERSED CYCLIC LOAD

2017 ◽  
Vol 24 (4) ◽  
pp. 369-386
Author(s):  
Teeraphot Supaviriyakit ◽  
Amorn Pimanmas ◽  
Pennung Warnitchai
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Cyclic Load ◽  
Nonlinear Finite Element Analysis ◽  
Nonlinear Finite Element ◽  
Test Results ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Reversed Cyclic

This paper presents a nonlinear finite element analysis of non-seismically detailed RC beam column connections under reversed cyclic load. The test of half-scale nonductile reinforced concrete beam-column joints was conducted. The tested specimens represented those of the actual mid-rise reinforced concrete frame buildings designed according to the non-seismic provisions of the ACI building code.  The test results show that specimens representing small and medium column tributary area failed in brittle joint shear while specimen representing large column tributary area failed by ductile flexure though no ductile reinforcement details were provided. The nonlinear finite element analysis was applied to simulate the behavior of the specimens. The finite element analysis employs the smeared crack approach for modeling beam, column and joint, and employs the discrete crack approach for modeling the interface between beam and joint face. The nonlinear constitutive models of reinforced concrete elements consist of coupled tension-compression model to model normal force orthogonal and parallel to the crack and shear transfer model to capture the shear sliding mechanism. The FEM shows good comparison with test results in terms of load-displacement relations, hysteretic loops, cracking process and the failure mode of the tested specimens. The finite element analysis clarifies that the joint shear failure was caused by the collapse of principal diagonal concrete strut.  

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