Abstract
Wide plate tests have been recognized as the “benchmark” for measuring the tensile strain capacity of pipeline girth welds. Numerical analysis in recent years, however, showed that the tensile strain capacity of a pipe could be reduced by the application of internal pressure. A series of full-scale experimental tests of 12.75- inch OD X65 ERW pipes were conducted with and without internal pressure to examine the effects of internal pressure on tensile strain capacity. The test setup was carefully designed to provide high quality data for the validation of prior numerical predictions and for the development of future predictive models. The background information leading to the current work is first reviewed in this paper. The design of the full-scale tests, including the instrumentation plan and test setup is described. The initial test results are shown in conjunction with numerical simulation of the results. Overall the test results conclusively demonstrated that the tensile strain capacity of pipelines having circumferential planar defects could be reduced by 50% or more when internal pressures equivalent to Classes 1 and 2 designs are applied. The reduction in tensile strain capacity is consistent with predictions from numerical models.
Curved wide plate (CWP) tests are often viewed as being able to produce “benchmark” data of the tensile stress and strain capacities of pipeline girth welds. For instance, wide plate test data were the basis of the Tier 2 EPRG Guidelines on girth weld defect acceptance criteria [Hopkins, et al., 1991] with plastic collapse as the limit state [Denys, 1992, 1995]. In the context of strain-based design, wide plate tests have being used to determine tensile strain capacity [Denys et al., 2000, 2004a, 2004b] and even for welding procedure qualifications [Hukle, el al., 2005].
Author:
Wang, Y.-Y., Horsley, D. and Stephens, M.
Publisher:
ISOPE International Offshore and Polar Engineering Conference
Year Published:
2008
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