An equation to predict maximum pipe stress incorporating internal and external loadings on buried pipes

Pipelines used for water and other services are very important lifelines in modern society. As many of these pipelines have been laid sometime in the last century or earlier, in most cases their condition has deteriorated primarily by electro-chemical and (or) micro-biological corrosion. This paper describes the application of 3-D finite element method to analyse a buried pipe subject to external and internal loads. Firstly, the finite element model is validated against the data from field tests. Subsequently, the results of these 3-D finite element analyses are used to develop a closed-form expression to predict maximum stresses in pipes of different sizes buried in different soil types. Having obtained a good agreement between the proposed model outcomes and 3-D FE results, the proposed model has been validated against the field test data under different internal and external loadings. The verified outcomes of the model revealed that it can be used to predict maximum stresses without conducting full scale finite element analyses, which often requires specific computational resources and computational skills. Further, the proposed model can be used in probabilistic analyses where a large number of calculations need to be carried out to account for uncertainty of the input variables.