The Assessment of the Probabilistic Burst of Honed Steel Pipes Based on Elastic Plastic Behavior

The paper aims to assess the elastic-plastic behaviour of the honed pipes made of steel type E355 subjected to cyclic interior pressure using experimental methods and numerical analysis. In every industry domain, the pipes with thin or thick walls subjected to internal pressure are used. Regardless of the material they are used, the pipes are stressed on axial and circumferential directions, in time. Being subjected to variations of pressure or increasing of pressure over the allowable limit, the pipes can explode causing many damages. The pipes explosion subjected to internal pressure can be predicted knowing the elastic-plastic behavior of the pipe. Starting from theory of stresses in thin and thick pipes, the paper approaches the elastic - viscous and plastic behavior of the steel pipes subjected to periodical internal pressure by experimental. Besides identifying the rheological behavior of thin and thick pipes experimentally tested, the state of stresses and strains were analyzed by numerical method. The behavior of thick wall pipes differs from that of thin-walled pipes, both in terms of rheological and state of stresses and strains. The paper combines experiment and numerical methods for determining the probabilistic burst of the steel pipe. The samples (thin and thick wall pipes) were subjected to 20 loading cycles at 400 bar: the first 10 cycles of loading and unloading were produced for 60 second/cycle and than the other 10 cycles were produced for 120 second/cycle. The exterior diameter of tested pipes was measured both after 30 seconds of loading and after 30 seconds without pressure. These measurements were repeated for each cycle.