The aim of this work is to predict the temperature field generated by welding a steel butt joint (API 5L X80). The prediction was modeled by finite element software Abaqus where the subroutine was developed in Fortran so that heat source motion may be included. The motion was based on the Goldak's double ellipsoid. In the model material nonlinearities were included such as thermophysical properties (coefficient of thermal expansion, specific heat, thermal diffusivity and thermal conductivity), which are dependent on temperature and latent heat, heat exchange by convection and radiation and mechanical boundary conditions. The thermal field predicted by the model was validated by infrared thermography. GMAW simulations with the use of an "evenmatched" solid wire (filler metal) carried out the welding process. The results obtained from the numerical model and thermography were in good agreement.