Calculation of Welding Deformations in a Pipe Flange Master’s thesis in Applied Mechanics

Reducing post welding processing of flanges due to distortion is a big cost and time saver for the oil and gas industry. Vector Technology Group AS experience different deformations in flange welded to pipes designs, and the reason for these deformations are crucial when designing to reduce them. Two flange designs are provided and the investigation is made with the commercial software ANSYS, where the entire welding procedure is modeled. The flanges are welded on to a pipe of the same diameter and thickness using TIG welding, experimental results are only available as measurements of displacements and rotations at certain locations for the flange. Since ANSYS is not an established welding simulation software, a benchmarking is made to a well-known FE-simulation from 1978. The software ANSYS works with some restrictions when modeling welding, for example the element birth and death techniques incorporated makes the handling of adding filler material easy, but when modeling solid-solid phase changes the software does not seem to cope. In the present simulations, the flanges are modeled in two-dimensional axisymmetric models with different boundary conditions in order to simulate different techniques of fixing the work pieces whil