A Fracture Mechanics Evaluation of Flaws in Pipeline Girth Welds PDF Download

Author: Richard Palmer Reed
Publisher:
ISBN: 9781581452440
Category : Pipelines
Languages : en
Pages : 23

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Author: Harold Berger
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: HI. McHenry
Publisher:
ISBN:
Category : Carbon-manganese steel
Languages : en
Pages : 11

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Book Description
Size limits for surface flaws in pipeline girthwelds are calculated on the basis of fracture mechanics analysis. Parameters for the analysis were selected from data on a 1.22-m-diameter (48 in.), 12-mm-thick (0.46 in.) pipe welded by the shielded metal-arc process. The minimum fracture toughness of the welds as determined by the crack opening displacement (COD) method was 0.1 and 0.18 mm (0.004 and 0.007 in.), depending on the flaw location. The yield strength of the welds was 413 MPa (60 ksi). Because the toughness to yield strength ratio was high, elastic-plastic fracture mechanics analysis methods were required to determine critical flaw sizes. Four approaches were employed: (1) a critical COD method based on the ligament-closure-force model of Irwin; (2) the COD procedure of the Draft British Standard Rules for Derivation of Acceptance Levels for Defects in Fusion Welded Joints; (3) a plastic instability method based on a critical net ligament strain developed by Irwin; and (4) a semi-empirical method that uses plastic instability as the fracture criterion developed by Kiefner on the basis of full-scale pipe rupture tests. Allowable flaw sizes determined by the Draft British Standard method are compared with the critical flaw sizes calculated using critical-COD and plastic instability as the respective fracture criteria. The results for both axial- and circumferential-aligned flaws vary significantly depending on the analysis model chosen. Thus, experimental work is needed to verify which model most accurately predicts girthweld behavior.

Author: National Institute of Standards and Technology (U.S.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 452

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Author:
Publisher:
ISBN:
Category : Weights and measures
Languages : en
Pages : 456

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Author: Thomas A. Cruse
Publisher: ASTM International
ISBN: 0803109725
Category : Fracture mechanics
Languages : en
Pages : 936

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Author: R. de Wit
Publisher:
ISBN:
Category : Collapse
Languages : en
Pages : 16

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Analytical models based on fracture mechanics technology are developed to establish predicted critical defect sizes for sharp, circumferential defects in pressurized pipe. These models are only intended to provide a theoretical basis for establishing predicted critical defect sizes. The general problem considered here is that of a surface-defect in a plate; that is, the flat plate analogy is used here for a pipeline. Failure is considered to occur when the ligament ruptures and provides a leakage path. The fracture mechanics model used, called the collapsed ligament model, is based on the work of Erdogan and Bakioglu, which is in turn based on the Dugdale model. The collapsed ligament model assumes plastic collapse in the depth direction but any fracture mechanics model in the length direction. To illustrate the use of these theoretical models for defects in pressurized pipes, curves are derived that show the predicted critical defect sizes. In these curves, the defect depth is plotted versus the defect length for a given set of material properties and applied stress. Defects having sizes that fall below this curve are not expected to extend. On the other hand, it is assumed that defects with sizes which fall above the curve will extend.

Author: K Macdonald
Publisher: Elsevier
ISBN: 0857092502
Category : Technology & Engineering
Languages : en
Pages : 353

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The failure of any welded joint is at best inconvenient and at worst can lead to catastrophic accidents. Fracture and fatigue of welded joints and structures analyses the processes and causes of fracture and fatigue, focusing on how the failure of welded joints and structures can be predicted and minimised in the design process.Part one concentrates on analysing fracture of welded joints and structures, with chapters on constraint-based fracture mechanics for predicting joint failure, fracture assessment methods and the use of fracture mechanics in the fatigue analysis of welded joints. In part two, the emphasis shifts to fatigue, and chapters focus on a variety of aspects of fatigue analysis including assessment of local stresses in welded joints, fatigue design rules for welded structures, k-nodes for offshore structures and modelling residual stresses in predicting the service life of structures.With its distinguished editor and international team of contributors, Fracture and fatigue of welded joints and structures is an essential reference for mechanical, structural and welding engineers, as well as those in the academic sector with a research interest in the field. - Analyses the processes and causes of fracture and fatigue, focusing predicting and minimising the failure of welded joints in the design process - Assesses the fracture of welded joints and structure featuring constraint-based fracture mechanics for predicting joint failure - Explores specific considerations in fatigue analysis including the assessment of local stresses in welded joints and fatigue design rules for welded structures

Author: Lewis
Publisher: ASTM International
ISBN: 9780803107304
Category : Technology & Engineering
Languages : en
Pages : 666

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Author: United States. National Bureau of Standards
Publisher:
ISBN:
Category :
Languages : en
Pages : 686

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