Modelling of multipass welding by defining the complete computational model at the start of the analysis requires special procedures for activation of elements at the times when the corresponding parts of the welds are made. The developed logic for handling this is applicable in any situation where elements are defined in an initial geometry which has been changed at the time when the elements are activated as in a large deformation analysis. The current implementation is for two-dimensional models but can be extended to three-dimensional cases as well