Finite Element Modeling of Buried Longitudinally Welded Large-Diameter Oil Pipelines Subject to Fatigue

The design and construction of large-diameter buried pipelines primarily for crude oil transportation is governed in Canada by CSA Z662, ASME B31.4, and ASME BPVC Section VIII. Although these codes provide general guidelines on pipeline design, many aspects of modelling the pipeline are not given in detail, and the results can vary significantly based on how these details are modelled. Engineers often adopt a very conservative approach and this results in pipelines that are over-designed and therefore unnecessarily costly. Following the design code, this thesis provides a detailed fatigue analysis (FA) of a large-diameter buried liquid pipeline and incorporates the effects of the stress concentrations associated with manufacturing defects and tolerances. A stress analysis of the pipe is first performed using the finite element method (FEM), and results obtained are used in conjunction with both elastic and elastic-plastic FA life assessment models to predict fatigue damage (FD). The results of a FEM and FA performed on four standard pipeline OD’s show that a 20% increase in the outside diameter (OD) to wall thickness (WT) ratio can be achieved when plasticity is considered. This is equivalent to one to two increments of standard WT or the percent reduction of a pipeline construction cost. In the analyses process, where the code leaves significant room for interpretation, this thesis provides clarity on appropriate procedures to follow. Examples include how to accurately model the weld profile, and the misalignments due to the manufacturing process. Furthermore, a simple calculation tool is developed that can be used to approximate hot-spot elastic stresses.

Name thesis:degree_name

Master of Science (MSc)

Discipline thesis:degree_discipline

Engineering – Mechanical & Manufacturing

Grantor dc:publisher.institution

Schulich School of Engineering

Year dc:date.issued

2019

Author dc:creator

• Anisimov, Evgeny

Advisors dc:contributor.advisor

• Singh, Meera N. K.
• Sudak, Leszek Jozef

Committee members dc:contributor.committeemember

• Singh, Meera N. K.
• Ghasemloonia, Ahmad
• Dann, Markus R.
• Sudak, Leszek Jozef

• Large Diameter Pipeline Fatigue
• Fatigue of Welded Connections
• Elastic-Plastic Fatigue Analysis
• Fatigue Damage

Statement dc:rights

• University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

en

DOI

http://dx.doi.org/10.11575/PRISM/35729

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/109466