Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Fracture Toughness Characterization of High-Pressure Pipe Girth Welds Using Single-Edge Notched Tension SE(T) Specimens

Published

Author(s)

Enrico Lucon, Timothy S. Weeks, James Gianetto, W. R. Tyson, D. Y. Park

Abstract

The safety and reliability of large-diameter pipelines for the transport of fluid hydrocarbons is being improved by the development of high-strength steels, advanced weld technologies and strain-based design (SBD) methodologies. Strain-based design imposes a limit on the applied strains rather than the applied stresses. For high-pressure pipelines, SBD requires an assured strength overmatch for the weld metal as compared to the base material, in order to avoid strain localization in the weldment during service. Achieving the required level of strength overmatch, as well as acceptable ductility and low-temperature fracture toughness, is a challenge as the pipe strength increases. Published studies show that low constraint geometries such as Single-Edge Bend, SE(T), or shallow notched Single-Edge Bend, SE(B), specimens represent a better match for the constraint conditions of surface-breaking circumferential cracks in large-diameter pipelines during service [1]. However, the SE(T) geometry is not included in any of the most widely used elastic-plastic fracture mechanics (EPFM) test standards. A procedure has been developed for performing and analyzing SE(T) toughness tests using a single-specimen technique, which includes formulas for calculating J integral and Crack-Tip Opening Displacement (CTOD), as well as estimating crack size using rotation-corrected elastic unloading compliance. Crack-resistance curves and critical toughness values obtained from shallow-crack SE(T) specimens (a0/W = 0.25) are compared to shallow-crack (a0/W = 0.25) SE(B) specimens. We believe that the SE(T) methodology is mature enough to be considered for inclusion in future revisions of EPFM standards such as ASTM E1820 and ISO 12135.
Citation
Materials Performance and Characterization
Volume
4
Issue
2

Citation

Lucon, E. , Weeks, T. , Gianetto, J. , Tyson, W. and Park, D. (2014), Fracture Toughness Characterization of High-Pressure Pipe Girth Welds Using Single-Edge Notched Tension SE(T) Specimens, Materials Performance and Characterization, [online], https://doi.org/10.1520/MPC20130098 (Accessed August 19, 2022)
Created August 28, 2014, Updated November 10, 2018