Spirally welded pipelines (extensively used in liquid transmission pipeline systems) may contain manufacturing anomalies that are susceptible to fatigue growth. To account for the angle of these cracks, with respect to the longitudinal pipe axis, modifications to inputs of crack assessment models are required.
Using the widely-used pipeline assessment model CorLAS®, we worked with Enbridge Pipelines to investigate two input modifications:
- Consideration of the normal stress component perpendicular to the angled crack, for which we developed a stress transformation calculator; and
- Using an effective crack length calculated as the longitudinal projection of the full length of an angled crack, which we adapted from API 579 and BS7910 standards.
Mark Neuert is presenting findings of this review at the upcoming International Pipeline Conference in Calgary, Alberta on September 27, 2018 at 8:30 a.m. to 12:00 p.m. The presentation will be in MacLeod Hall D. You will learn about the modifications evaluated and how they affect failure pressure calculations in comparison to validated finite element results.
The entire paper – “Assessment of Pipeline Spiral Weld Cracks Subjected to Internal Pressure” – is available through the 2018 International Pipeline Conference.