The current work is an outcome of more than one year efforts and researches done by two enthusiastic students who are quite promising in FEA according to their early resume and many professionals including Dr. Hossein Tourang who played a great role in inspiring and encouraging those two along the preparation of this text. Regarding the reader consideration, some points about our work are worth mentioning: 1. We studied almost every major references and sources regarding the subject and verified our numerical results through them. So after realizing a novel and original approach to welding process simulation by means of FEA we felt a demand to clarify the simulation process and to interpret its numerical result 2. Many useful FEA coupled-analysis tips about initial and boundary conditions, pre-process input data, meshing rules and so on are reviewed in this text which makes one independent from writing complex subroutines and/or purchasing additional plug-ins for usual purposes. After all, pipe line damages are considerably hazardous in power plants specially nuclear facilities, therefore predicting their life-time is of the highest priority. This text can be a guide for the matter