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.

Effect of Thickness Measurement Procedure on Stress Analysis of Pipes With Local Metal Loss

2013 ◽  
Author(s):  
Nobuyuki Yoshida ◽  
Atsushi Yamaguchi
Keyword(s):  
Decision Making ◽  
Measurement Procedure ◽  
Thickness Measurement ◽  
Burst Pressure ◽  
Metal Loss ◽  
Element Analysis ◽  
Fea Model ◽  
Laser Displacement Meter ◽  
The Difference ◽  
Corrosion Under Insulation

Fitness-For-Service (FFS) assessment using Finite Element Analysis (FEA) has been a problem in deciding yes-no which vary from evaluator to evaluator. The difference in decision making is caused by the degree of freedom in modeling a FEA model. In this study, burst pressures of pipes with local metal loss were calculated by using FEA in order to investigate the influence of thickness measurement intervals on FFS assessment. The analyzed pressures by FEA were verified by burst tests. A pipe specimen, which was thinned by corrosion under insulation in the actual plant, was used for the burst tests. Shape of the pipe specimen was measured by laser displacement meter and extracted at several types of interval. It is concluded that the analyzed pressures in various measurement intervals showed almost no difference, but were higher than the actual burst pressure of the specimen.

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.

Hierarchical Bayesian Corrosion Growth Model Based on In-Line Inspection Data

2012 ◽  
Author(s):  
M. Al-Amin ◽  
W. Zhou ◽  
S. Zhang ◽  
S. Kariyawasam ◽  
H. Wang
Keyword(s):  
Growth Model ◽  
Power Law ◽  
Management Program ◽  
Metal Loss ◽  
Hierarchical Bayesian ◽  
Natural Gas Pipelines ◽  
Mcmc Simulation ◽  
Corrosion Defects ◽  
External Corrosion ◽  
Inspection Data

A hierarchical Bayesian growth model is presented in this paper to characterize and predict the growth of individual metal-loss corrosion defects on pipelines. The depth of the corrosion defects is assumed to be a power-law function of time characterized by two power-law coefficients and the corrosion initiation time, and the probabilistic characteristics of the parameters involved in the growth model are evaluated using Markov Chain Monte Carlo (MCMC) simulation technique based on ILI data collected at different times for a given pipeline. The model accounts for the constant and non-constant biases and random scattering errors of the ILI data, as well as the potential correlation between the random scattering errors associated with different ILI tools. The model is validated by comparing the predicted depths with the field-measured depths of two sets of external corrosion defects identified on two real natural gas pipelines. The results suggest that the growth model is able to predict the growth of active corrosion defects with a reasonable degree of accuracy. The developed model can facilitate the pipeline corrosion management program.

Discussion on Plastic Collapse Criterion at High Temperatures in FFS Assessment Rules

2010 ◽  
Author(s):  
Kenji Oyamada ◽  
Shinji Konosu ◽  
Hikaru Miyata ◽  
Takashi Ohno
Keyword(s):  
Comparative Study ◽  
High Temperatures ◽  
Bending Moment ◽  
Flaw Size ◽  
Metal Loss ◽  
Plastic Collapse ◽  
Loss Assessment ◽  
Element Analysis ◽  
Diagram Method ◽  
The Difference

There are several Fitness-For-Service (FFS) standards with evaluation rules in terms of plastic collapse for a pressure vessel or piping component possessing a local metal loss area simultaneously subjected to internal pressure and bending moment. The authors have already reported the results of a comparative study of FFS rules, including the remaining strength factor (RSF) approach in Part 5 of API 579-1/ASME FFS-1 and the p-M diagram method, which pointed out that there could be significant differences in allowable flaw sizes. This paper describes an additional comparative study on the difference of allowable flaw size for local metal loss assessment between the RSF approach in Part 5 of API 579-1/ASME FFS-1 and the p-M diagram method, focusing on the effect of decreasing yield strength of the material at high temperatures, such as 350 degrees C. The allowable flaw depth at high temperatures derived from API579-1/ASME FFS-1 is larger than that derived by means of the p-M diagram method. However, it is verified by the finite element analysis that the allowable flaw size of the p-M diagram method is set on the stress state of general yielding near a local metal loss area if safety factor is not considered and it is possible to evade ratcheting due to cyclic bending moment in service, such as that caused by earthquake, etc.

My Pipes Are Corroding! When Should I Repair? Getting the Answers You Need for Maintaining Pipeline Integrity

2015 ◽  
Author(s):  
Michael Turnquist
Keyword(s):  
Finite Element ◽  
Life Assessment ◽  
Metal Loss ◽  
Element Analysis ◽  
Element Mesh ◽  
Level 3 ◽  
External Corrosion ◽  
Remaining Life Assessment ◽  
Ultrasonic Thickness

This case study exhibits how groundbreaking inspection methodologies combined with innovative computational analysis practices demonstrate the value of conducting fitness-for-service (FFS) assessments on sectional piping. In this instance, a fitness-for-service assessment was performed on two sections of piping experiencing external corrosion at the pipe-to-elbow seam welds. A full external scan and spot ultrasonic thickness (UT) readings were used to create the corroded geometry and verify accurate measurement of the remaining thicknesses in various corroded locations. This allowed for the actual corroded profiles to be accurately modeled using finite element analysis (FEA). Complications were present when modeling the observed metal loss. Through the use of innovative finite element mesh generation practices, the actual measured corroded geometry was modeled without the need for over-conservative geometric simplification. A Level 3 FFS assessment was then performed in addition to a remaining life assessment based on observed corrosion rates. The result of this analysis was that the piping could remain in service for at least two additional years before needing repair.

Research and Application of Virtual Reality and Simulation Techniques Corporately to Tower Crane

2009 ◽  
Author(s):  
Xian-yi Meng
Keyword(s):  
Finite Element ◽  
Virtual Reality ◽  
Safety Assessment ◽  
Assessment System ◽  
Structural Safety ◽  
Analysis Software ◽  
Element Analysis ◽  
Tower Crane ◽  
Simulation Techniques ◽  
Training Cost

A method using virtual reality and finite element techniques corporately for simulation of tower crane is presented. A training and safety assessment system based on the method is created, which can be used for training operators and assessing the structural safety for a tower crane. The system can help the enterprises using tower crane reduce the training cost and work risk. Virtual reality software Virtools and finite element analysis software ANSYS are corporately used to construct the system.

Hierarchical Bayesian Corrosion Growth Model Based on In-Line Inspection Data

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Mohammad Al-Amin ◽  
Wenxing Zhou ◽  
Shenwei Zhang ◽  
Shahani Kariyawasam ◽  
Hong Wang
Keyword(s):  
Growth Model ◽  
Power Law ◽  
Management Program ◽  
Metal Loss ◽  
Hierarchical Bayesian ◽  
Natural Gas Pipelines ◽  
Mcmc Simulation ◽  
Corrosion Defects ◽  
External Corrosion ◽  
Inspection Data

A hierarchical Bayesian growth model is presented in this paper to characterize and predict the growth of individual metal-loss corrosion defects on pipelines. The depth of the corrosion defects is assumed to be a power-law function of time characterized by two power-law coefficients and the corrosion initiation time, and the probabilistic characteristics of the these parameters are evaluated using Markov Chain Monte Carlo (MCMC) simulation technique based on in-line inspection (ILI) data collected at different times for a given pipeline. The model accounts for the constant and non-constant biases and random scattering errors of the ILI data, as well as the potential correlation between the random scattering errors associated with different ILI tools. The model is validated by comparing the predicted depths with the field-measured depths of two sets of external corrosion defects identified on two real natural gas pipelines. The results suggest that the growth model is able to predict the growth of active corrosion defects with a reasonable degree of accuracy. The developed model can facilitate the pipeline corrosion management program.

Interaction of Longitudinal Corrosion Defects on a Pipeline

2018 ◽  
Author(s):  
Jason C. Land ◽  
Thomas Yahner ◽  
William V. Harper ◽  
Michiel P. H. Brongers ◽  
Jeffrey Kobs
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Longitudinal Direction ◽  
Probability Of Failure ◽  
Exclusion Principle ◽  
Metal Loss ◽  
Element Analysis ◽  
Statistical Interaction ◽  
Corrosion Defects ◽  
Pipe Joint

Longitudinal corrosion defects in pipelines can be formed from external or internal metal loss, from selective seam corrosion, or from clustering of corrosion defects in the longitudinal direction. Standard assessments of such defects are traditionally performed on an individual basis, but research has shown that unique challenges arise when multiple defects are present on the same pipe joint. Multiple longitudinal defects can be evaluated using a combined probability of failure (PoF) methodology based on the dependence of the interaction. This paper presents results of such an evaluation, in which finite element analysis (FEA) was applied to calculate energy densities at the most sensitive defect elements. The methodology provided a measure of the interaction dependence. The combined statistical interaction of defects can be calculated using an adaptation of the inclusion-exclusion principle, where overlapping non-linear energy densities are calculated.

Evaluation of Groove Radius Assessment Criteria Based on Brittle and Ductile Local Failure Models

2016 ◽  
Author(s):  
Gregory W. Brown ◽  
Lucie Parietti ◽  
Brian Rose ◽  
Ted L. Anderson
Keyword(s):  
Ductile Failure ◽  
Metal Loss ◽  
Plastic Collapse ◽  
Loss Assessment ◽  
Element Analysis ◽  
Failure Models ◽  
The Difference ◽  
Collapse Failure ◽  
Tip Radius ◽  
Weibull Stress

API 579-1/ASME FFS-1[1] Part 5 (2007 edition) contains procedures for assessing local metal loss based on failure by plastic collapse. Equation (5.10) defines “acceptable” tip radii for grooves to ensure a plastic collapse failure mode. Grooves failing the radius check must be treated as a crack-like flaws. The validity of Equation (5.10) is questionable, and it may be excessively conservative. This paper presents new rules for groove assessment based on brittle and ductile failure models. Computation of the Weibull stress using finite element analysis (FEA) was employed to determine the minimum groove radius required to eliminate the possibility of cleavage fracture. The Bao-Wierzbicki ductile failure model was used with FEA to evaluate burst pressure and to determine a new groove radius criterion defining the plastic collapse regime, allowing categorization as metal loss. Groove-like flaws categorized as neither sharp cracks nor as metal loss are evaluated using an effective toughness concept. This concept quantifies the difference in fracture response between a sharp crack and a notch with a finite tip radius. The upcoming 2016 API 579-1/ASME FFS-1 rules remove the excessive conservatism found in Part 5 of the 2007 edition and avoid the abrupt transition between crack and metal loss assessment types based on groove radius.

Analysis of the Safety Factors of Municipal Road Undercrossing Existing Bridge Based on Fuzzy Analytic Hierarchy Process Methods

2021 ◽  
pp. 036119812110318
Author(s):  
Yonghong Yang ◽  
Yu Chen ◽  
Zude Tang
Keyword(s):  
Safety Assessment ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Safety Evaluation ◽  
Safety Factors ◽  
Analytic Hierarchy ◽  
Road Engineering ◽  
Existing Bridges ◽  
Hierarchy Process ◽  
Engineering Projects

Increasing traffic volume and insufficient road lanes often require municipal roads to be reconstructed and expanded. Where a road passes under a bridge, the reconstruction and expansion project will inevitably have an impact on the bridge. To evaluate the safety impact of road engineering projects on bridges, this paper evaluates the safety of the roads and ancillary facilities of highway bridges involved in municipal road engineering projects. Based on a comprehensive analysis of the safety factors of municipal roads undercrossing existing bridges, a fuzzy comprehensive analytic hierarchy process (AHP) evaluation method for the influence of road construction on the safety of existing bridges is proposed. First, AHP is used to select 11 evaluation factors. Second, the target layer, criterion layer, and index layer of evaluation factors are established, then a safety evaluation factor system is formed. The three-scale AHP model is used to determine the weight of assessment indexes. Third, through the fuzzy comprehensive AHP evaluation model, the fuzzy hierarchical comprehensive evaluation is carried out for the safety assessment index system. Finally, the fuzzy comprehensive evaluation method is applied to the engineering example of a municipal road undercrossing an existing expressway bridge. The comprehensive safety evaluation of the existing bridge reflects the practicability and feasibility of the method. It is expected that, with further development, the method will improve the decision-making process in bridge safety assessment systems.

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