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.

Case Study: Non-Conventional Remaining Life Assessment of a Significant Dent in a Subsea Pipeline Scheduled for Decommissioning

2019 ◽  
Author(s):  
A. Brett ◽  
A. Russell
Keyword(s):  
Life Assessment ◽  
Remaining Life ◽  
Element Analysis ◽  
Oil Pipeline ◽  
The North ◽  
Pressure Spike ◽  
The North Sea ◽  
Specific Assessment ◽  
Remaining Life Assessment

Abstract An inline inspection of a subsea oil pipeline located in the North Sea identified a large top of line dent. The pipeline was scheduled for decommissioning within 3 years, however conventional fatigue assessment of the dent indicated that the pipeline could become unsafe before the scheduled decommissioning date. As the required remaining life could not be justified by conventional assessment, a review was completed to determine whether a case-specific assessment methodology could be developed to reduce the conservatism, while reliably demonstrating that the pipeline could be safely operated up until the planned decommissioning date. This review identified that the pipeline had a unique pressure history, which included a large one-off pressure spike that had occurred following detection of the dent. This raised the possibility of a pseudo-hydrotest type assessment to justify the required remaining life. This paper describes the non-conventional pseudo-hydrotest assessment that was undertaken for the dent to demonstrate acceptability, which used a combination of state of the art finite element analysis and fatigue crack growth assessment.

Die Face Morphing With Formability Assessment

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Liang Zhou ◽  
S. Jack Hu ◽  
Thomas B. Stoughton
Keyword(s):  
Finite Element ◽  
Mapping Function ◽  
Strain Increment ◽  
Die Design ◽  
Element Analysis ◽  
Element Mesh ◽  
Die Surface ◽  
Mapping Process ◽  
Face Morphing

A die face morphing concept was recently introduced for quick die design for evolutionary products from their prior generations. Based on this concept, this paper proposes a strain increment method for early formability assessment by predicting strain distribution directly from the part-to-part mapping process. This method consists of mapping the finite element mesh to the part geometry, solving a part-to-part mapping function with smoothness and strain gradient penalties, and extracting strain increment from geometric morphing. It is shown, through a case study, that the strain field estimated by the proposed strain increment method compares well with that from the direct finite element analysis. Since this method does not require the knowledge on new die surface, such formability assessment can serve as a tool for early manufacturing feasibility analysis on the new part design.

scholarly journals The intervals method: a new approach to analyse finite element outputs using multivariate statistics

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3793 ◽  
Author(s):  
Jordi Marcé-Nogué ◽  
Soledad De Esteban-Trivigno ◽  
Thomas A. Püschel ◽  
Josep Fortuny
Keyword(s):  
Finite Element ◽  
Difficult Case ◽  
Multivariate Statistical ◽  
Element Analysis ◽  
Element Mesh ◽  
New Approach ◽  
Generalist Species ◽  
Novel Method ◽  
Analyse Data

Background In this paper, we propose a new method, named the intervals’ method, to analyse data from finite element models in a comparative multivariate framework. As a case study, several armadillo mandibles are analysed, showing that the proposed method is useful to distinguish and characterise biomechanical differences related to diet/ecomorphology. Methods The intervals’ method consists of generating a set of variables, each one defined by an interval of stress values. Each variable is expressed as a percentage of the area of the mandible occupied by those stress values. Afterwards these newly generated variables can be analysed using multivariate methods. Results Applying this novel method to the biological case study of whether armadillo mandibles differ according to dietary groups, we show that the intervals’ method is a powerful tool to characterize biomechanical performance and how this relates to different diets. This allows us to positively discriminate between specialist and generalist species. Discussion We show that the proposed approach is a useful methodology not affected by the characteristics of the finite element mesh. Additionally, the positive discriminating results obtained when analysing a difficult case study suggest that the proposed method could be a very useful tool for comparative studies in finite element analysis using multivariate statistical approaches.

Elasto-Plastic Coupled Temperature-Displacement Finite Element Analysis of Two-Dimensional Rolling-Sliding Contact With a Translating Heat Source

1991 ◽  
Vol 113 (1) ◽  
pp. 93-101 ◽  
Author(s):  
S. M. Kulkarni ◽  
C. A. Rubin ◽  
G. T. Hahn
Keyword(s):  
Finite Element ◽  
Half Space ◽  
Plastic Material ◽  
Element Model ◽  
Rolling Contact ◽  
Two Dimensional ◽  
Element Analysis ◽  
Element Mesh ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

The present paper, describes a transient translating elasto-plastic thermo-mechanical finite element model to study 2-D frictional rolling contact. Frictional two-dimensional contact is simulated by repeatedly translating a non-uniform thermo-mechanical distribution across the surface of an elasto-plastic half space. The half space is represented by a two dimensional finite element mesh with appropriate boundaries. Calculations are for an elastic-perfectly plastic material and the selected thermo-physical properties are assumed to be temperature independent. The paper presents temperature variations, stress and plastic strain distributions and deformations. Residual tensile stresses are observed. The magnitude and depth of these stresses depends on 1) the temperature gradients and 2) the magnitudes of the normal and tangential tractions.

A Finite Element Analysis for Magnetostrictive Thin Film Structures and Its Experimental Verification

2006 ◽  
Vol 306-308 ◽  
pp. 1151-1156 ◽  
Author(s):  
Chong Du Cho ◽  
Heung Shik Lee ◽  
Chang Boo Kim ◽  
Hyeon Gyu Beom
Keyword(s):  
Thin Film ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Geometric Feature ◽  
Hysteresis Phenomenon ◽  
Finite Element Code ◽  
Element Analysis ◽  
Element Mesh ◽  
Magnetostrictive Actuators ◽  
Large Length

In this paper, a finite element code especially for micro-magnetostrictive actuators was developed. Two significant characteristics of the presented finite element code are: (1) the magnetostrictive hysteresis phenomenon is effectively taken into account; (2) intrinsic geometric feature of typical thin film structures of large length to thickness ratio, which makes it very difficult to construct finite element mesh in the region of the thin film, is considered reasonably in modeling micro-magneostrictive actuators. For verification purpose, magnetostrictive thin films were fabricated and tested in the form of a cantilevered actuator. The Tb-Fe film and Sm-Fe film are sputtered on the Si and Polyimide substrates individually. The magnetic and magnetostrictive properties of the sputtered magnetostrictive films are measured. The measured magnetostrictive coefficients are compared with the numerically calculated ones.

Finite Element Mesh Generator Applying Constraints’ Propagation and Isoparametric Mapping

1991 ◽  
Author(s):  
J. Rodriguez ◽  
M. Him
Keyword(s):  
Finite Element ◽  
Mesh Generation ◽  
Element Model ◽  
Finite Element Mesh ◽  
Fe Model ◽  
Element Analysis ◽  
Element Mesh ◽  
Mesh Generator ◽  
Generation Algorithm ◽  
Essential Input

Abstract This paper presents a finite element mesh generation algorithm (PREPAT) designed to automatically discretize two-dimensional domains. The mesh generation algorithm is a mapping scheme which creates a uniform isoparametric FE model based on a pre-partitioned domain of the component. The proposed algorithm provides a faster and more accurate tool in the pre-processing phase of a Finite Element Analysis (FEA). A primary goal of the developed mesh generator is to create a finite element model requiring only essential input from the analyst. As a result, the generator code utilizes only a sketch, based on geometric primitives, and information relating to loading/boundary conditions. These conditions represents the constraints that are propagated throughout the model and the available finite elements are uniformly mapped in the resulting sub-domains. Relative advantages and limitations of the mesh generator are discussed. Examples are presented to illustrate the accuracy, efficiency and applicability of PREPAT.

Finite Element Simulation of the Sachs Boring Method of Measuring Residual Stresses in Thick-Walled Cylinders

2003 ◽  
Vol 125 (3) ◽  
pp. 274-276 ◽  
Author(s):  
R. R. de Swardt
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Data Reduction ◽  
High Speed ◽  
High Strength ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Element Mesh ◽  
Reduction Methods ◽  
Data Reduction Method

During a recent study the residual strain/stress states through the walls of autofrettaged thick-walled high-strength steel cylinders were measured with neutron diffraction, Sachs boring and the compliance methods (Venter et al., 2000, J. Strain Anal. Eng. Des., 35, pp. 459–469). The Sachs boring method was developed prior to the advent of high speed computers. A new method for the data reduction was proposed. In order to verify the proposed procedure, the Sachs boring experimental method was simulated using finite element modeling. A residual stress field was introduced in the finite element method by elasto-plastic finite element analysis. The physical process of material removal by means of boring was simulated by step-by-step removal of elements from the finite element mesh. Both the traditional and newly proposed data reduction methods were used to calculate the residual stresses. The new data reduction method compares favorably with the traditional method.

Formulation of Three-Dimensional Green’s Function and its Application to Fatigue Life Evaluation of Pressurizer

2006 ◽  
Vol 324-325 ◽  
pp. 387-390
Author(s):  
Yoon Suk Chang ◽  
Shin Beom Choi ◽  
Jae Boong Choi ◽  
Young Jin Kim ◽  
Myung Jo Jhung ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Green’S Function ◽  
Green's Function ◽  
Three Dimensional ◽  
Stress Transfer ◽  
Life Assessment ◽  
Element Analysis ◽  
Fatigue Evaluation ◽  
Effective Assessment

Major nuclear components have been designed by conservative codes to prevent unanticipated fatigue failure. However, more realistic and effective assessment is necessary in proof of continued operation beyond the design life. In the present paper, three-dimensional stress and fatigue evaluation is carried out for pressurizer employing complex full geometry itself instead of conventional discrete subcomponents. For this purpose, temperature and mechanical stress transfer Green’s functions are derived from finite element analyses and applied to critical locations of pressurizer. In accordance with comparison of resulting stresses obtained from the Green’s function and detailed finite element analysis, suitability of the specific Green’s function is investigated. Finally, prototype of fatigue life assessment results is provided along with relevant ongoing activities.

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