Ranking Models for Managing the Integrity of Ageing Pipelines

Abstract

SNAM operates more than 29,000 km of gas transmission pipelines in Italy. The pipelines have diameters up to 56″, with different MAOP up to 75 bar. The oldest ones were built in the 40s and new ones are nowadays under construction. Italy, like most of the European countries, is characterized by a high level of anthropic presence on the territory; moreover, many pipelines cross the country from south to north, passing through the Appennini mountains, where there are many areas with geological instabilities (landslides). Different pipelines can have different features, issues and challenges, but, for all of them, the TSO must guarantee a high level of safety in terms of structural integrity. In such a scenario, a TSO must tackle many questions in order to properly manage the integrity of its pipelines that compose the complex asset that is the whole network: where do I need to do local actions? Is there any pipeline that is convenient to totally replace? Which ones of the existing unpiggable pipelines should I invest to make piggable? Is there a way to establish the priorities for all these actions? SNAM built two tools to prioritize such actions on all its pipelines: the first tool is a model able to produce a ranking of all the pipelines as a function of the technical convenience for their replacement, the second tool is a model that produce a ranking of all the pipelines as a function of the technical convenience to make them piggable. Both the models provide numerical and objective tools, based on technical local data of the pipelines and of the territorial context, that can be applied at once to the whole network and that help the TSO in the strategical decision making oriented to the best management of the integrity of the ageing asset.