Interpretation of the effect of hydrostatic test in components working under pressure

Abstract

After construction and installation, the natural gas and oil transport structures must undergo hydrostatic tests before their installation and periodically during commissioning. These hydrostatic tests can be classified into two categories: resistance test and leak proof test. The application of an overload is a spectacular phenomenon and can be used as an example while testing components working under pressure. This is a destructive control method. If a critical fault, with respect to the proof test, exists in the pipeline, the latter is destroyed. If not, (i.e., not broken), the lower than critical defects will see their subsequent propagation by fatigue slowed down or even eliminated due to the effect of overload. Tow-dimensional finite element method is utilized to analyze the plasticity-induced crack closure phenomenon in a cracked pipe under variable amplitude loading conditions. To accurately capture this process the choice of material model employed is of significant importance, therefore this paper considers the Lemaitre-Chaboche model, with isotropic hardening and nonlinear kinematic hardening. The study shows significant results obtained while employing this model.