Dražan Kozak

Influence of Technological Flaw Occurred during Welding of Header-Nozzle Joint Using SAW Welding Process on the Strength of Welded Joint

This paper deals with the influence of technological flaw, occurred during welding of header-nozzle joint using SAW welding process, on the strength of welded joint. Three models of welded joints geometry are modeled: model without flaw, model with assumption of flaw existence around whole length of welded joint in form of torus with 1 mm diameter (the most dangerous case) and model with largest measured flaw with 1 mm diameter and with length of 8 mm. Numerical analyses using finite element method have been conducted. From obtained results it can be concluded that technological flaw occurred during process of welding does not influence the static strength of welded joint because there is no increase in stress, which is in all three models lower than yield strength. Even in the worst case scenario, when flaw with same diameter as largest detected flaw (1 mm) would occur along whole length of weld, it is not registered stress increasing in the region of weld joint subjected to internal pressure of 102 bar. Since there is no significant stress concentrations around flaws in all three models i.e. stresses do not exceed yield strength of material, there are no plastic deformations.