Pipeline Integrity Management Under Geohazard Conditions (PIMG)
Chapter 21 PIPE GIRTH WELDS UNDER PLASTIC STRAINING: FULL-SCALE TESTING AND STRAIN-BASED APPROACHES
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Published:2020
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ABSTRACT
Strain-based design and fracture assessment of pipelines is becoming increasingly important because large pipeline networks tend to be placed in challenging environments where they might undergo large strains due to ground movement, for example. The integrity of pipeline girth welds in such conditions should be assessed using strain-based design and fracture assessment approaches instead of traditional stress-based engineering critical assessment. This paper describes two large-scale pipe tests containing girth welds with notches at the weld centreline subject to large strains with and without internal pressure, respectively. The experimental results are used to investigate existing strain-based design and assessment methods. The results show that most existing methods are conservative or over-conservative with regard to the test results in terms of strain capacity. However, some methods give non-conservative crack driving force at specific strain levels. Recommendations for future work in order to reach a satisfactory approach are proposed.