Safety of pressure equipment in exploitation is of great importance and needs to be at a high level. Recently, this goal is achieved by implementing years of experience into regulations and standards, along with developing and improving materials, technologies and test methods for manufacturing and exploitation of pressure equipment.
Methods for designing pressure equipment typically involve calculations which do not take into account defects within the material that can lead to crack initiation, which in turn can result in failure. Methods described in this paper focus on crack behaviour and its relation to the type and amount of present defects in the material.
Experience suggests that, despite high demands for pressure equipment quality, failures can still occur in exploitation. In order to avoid this, pressure equipment should be tested in exploitation. In addition, adequate documentation needs to be developed in order to provide a basis for defining these tests.
It can be seen that pressure equipment failures are caused only by cracks. Other types of defects do not lead to failure directly, but may cause crack initiation. Thus, exploitation tests are mainly focused on cracks, while taking into account other defects that could lead to their initiation.
Keywords: non-destructive testing, pressure equipment, crack, welded joint