The Effects of Exploitation Conditions and Welding on Crack Initiation and Propagation in a Starting Pressure Vessel

Abstract

Cracks and other defects that can occur in pressure vessel have been a significant practical problem for the integrity of such vessels for a very long time, and these defects can initiate and propagate due to various factors, such as the development technology or manufacturing processes, welding activities, exploitation conditions to which the vessel is subjected, or environmental effects. For some of the previously mentioned influences that can affect crack initiation it is impossible to predict whether or not they will cause problems, since they depend on several factors. In this paper, the effect of exploitation conditions and welding of starting pressure vessels on crack initiation and propagation is presented. The starting pressure vessel is a part of he boiler installation within the Obrenovac thermal power-plant, and is used for moisture separation. The crack was located in the welded joint between one of the connecting branches and the starting pressure vessel, which was subjected to relatively variable exploitation conditions. Effects that could lead to crack initiation and propagation were analysed, along with potential solutions that could help in avoiding these issues. Short theoretical reviews of requirements that must be met by pressure vessels (in terms of standards) are shown, as well as the theoretical observations related to the effect of welding activities and the consequences of defects that could occur.