Thinning of the weld material at a fin-fan outlet nozzle was identified during routine inspection. The client performed a Fitness-for-Service analysis in-house and found stresses in the component to be acceptable. However, per API 579 requirements the proximity of the weld material loss to a flange dictated a higher level analysis.
Our engineering team built a Finite Element (FEA) model of the outlet nozzle assembly, including the nozzle and flange, and an idealized representation of the cast tee. Internal operating loads, such as temperature and pressure, were considered. The flange is a restraint for a large pipe run and therefore global loads were also considered. Our results indicated that the vessel remained fit-for-service. Based on material loss data the nozzle remaining service life was also estimated and provided to the client.