This paper analyzes the equivalent stress on stainless steel test specimens. At the beginning of the paper, the plane theory of elasticity and basic equations needed to calculate the equivalent stress of the chamber is described. After that, the calculation of stress for the given data was performed. The second part of the paper describes the experimental part. Here is a method of determining residual stresses by means of tensometry that measures the deformation by which stresses are calculated in the vicinity of the weldment. An analytical and numerical analysis for the case of the stress of the test speciment by internal pressure was performed. Numerical analysis of residual stresses in welding via thermal stresses for a presumed temperature difference was performed. This analysis is based on finite element method. The stress calculation was performed using the ANSYS 16.2 Workbench program package. In the end, a comparison of the results between the solutions obtained by the theory of elasticity and numerical solutions without the effect of residual stress was performed. A comparison of the results between experimental measurements was made depending on the thickness of the chamber, ie., heat input. Numerical solutions also show the influence of residual (thermal) stresses on the thickness of the chamber, ie. heat input.