Further development of methods for integrity assessment and reliability of pipelines. Final report

The computational methods implemented in the simulation programs PROST and WinLeck were extended, improved, validated and applied within comparative benchmark studies. The results can be summarized to development and implementation of models, probabilistic topics, analysis and assessment of experimental tests and international activities. In the PROST software, technical improvements of structure mechanical assessment methods are one aspect of model extensions, namely the consideration of radially variating stress distributions, from the input up to the fracture mechanical assessment. In addition, investigations on leak rate models and asymptotic behavior of leak situations were a subject. A new feature is the continued wall thinning degradation mechanism. Extensions of the probabilistic capabilities of PROST concern new distribution functions, the distinction between aleatoric and epistemic random variables and correlations between random variables. Data-driven methods for leak frequency estimations were included in PROST. For validation purpose, different experimental tests were examined with the software. The emphasis of these validation activities was on the critical crack length (or critical load) of a cylindrical structure with wall-penetrating crack. These activities enabled a systematic evaluation of the model performance. PROST and WinLeck were applied within international benchmark activities, with the topics leak-before break, leak rates and probabilistic fracture mechanics. Further code comparisons were possible in the framework of a leak frequency pilot study.