The majority of pressure equipment is made from joining by welding parts or sub-assemblies. Welded structure should be produced by spending minimum of cost, assuring in the same time required function and safety. By proper selection of welded joint and material, designer determines the properties of final product, and also possibility of its fabrication. The greatest attention during designing and fabrication of pressure equipment should be paid to the most vulnerable part of a welded joint, its heat-affected zone. In current paper, an approach in solving the problem of cylindrical vessel under internal pressure containing an axial crack is presented.