During inspection of Offshore Oil & Gas equipment it was identified that the welding had not been performed correctly and that there was incomplete root penetration. The choice of the operator was to either shut down the operation and replace the valves or to remain in operation until a convenient time for replacement could be identified. The challenge was to determine if the incomplete welds could be safely operated until they are replaced.
BEASY was used in conjunction with the existing Engineering Critical Assessment (ECA) procedures to predict the limiting fatigue life of welded joints on the level switches piping associated with various process pressure vessels. Nondestructive testing (NDT) methods were used to determine the general location and extent of crack like defects caused by incomplete welds at pipe weld connections. Radiographs produced during the NDT program provided details such as material property zones, joint misalignments, and the location and geometry of multiple cracks both on the surface and embedded in the weld material. BEASY was used to model the exact geometry of the welds and simulate fatigue crack growth under cyclic loading for a critically located weld crack.
The results of the assessment enabled the offshore facility to remain in operation as it was demonstrated that the welds had sufficient life.