Journals Proceedings

Abstract

Welding is the primary joining technology used to make continuous pipelines in the industry. The thermal and mechanical loading in the process has a profound impact on the integrity of the pipeline over its service life. An accurate and thorough assessment is needed on the associated residual stress and its effect on the structural properties of the pipeline. 3D simulations of stress in girth welded pipe sections have been carried out using the Abaqus CAE software in two steps, the first being the thermal modelling with a moving hot spot and added mass whereas the second being the stress or mechanical analysis. In the Thermal Model, it was observed that the distribution of heat in the heat affected zone (HAZ) was maximal at the apex of the heat flux whereas minimum at the start and end points indicating that heat was trapped in the middle region which is responsible for the fluctuations in the heat distribution in these zones. Contour plots of these results further confirm same pattern of temperature distribution. This further implies that the quantity of heat inputted into the model affects the geometry of the model. The design as well as the diameter of the pipe also affected the geometry. It has therefore been deduced that the convective heat was retained within the welding spool for some length of time approximately 10 seconds in the middle region of the weld prior to cooling. The significance of the radiative heat distribution was also considered in the final result as a result of the cavities present within the model. Due to insufficient time, the thermal analysis has been projected in this paper. The Stress analysis will follow in due course.