Where are cracks most likely to occur in a pressure vessel?

Cracks in pressure vessels are most likely to occur near weld seams due to several factors associated with the welding process and the materials involved. During welding, the heat generated introduces thermal stresses that can lead to microstructural changes in the material. This can create areas of weakness where cracks can initiate under stress or pressure. Additionally, the cooling process of welded joints can contribute to the development of residual stresses, which further increases susceptibility to cracking.

Weld seams often experience different thermal expansion properties compared to the base materials, leading to potential stress concentrations that are not present in the homogeneous sections of the vessel. Such conditions make weld seams critical points for damage.

Understanding the prevalence of cracks at weld seams is essential for inspection planning and risk assessment in maintaining the integrity of pressure vessels. Inspectors often pay close attention to these areas during examinations to identify early signs of cracking or other forms of degradation.