Theoretical and Experimental Investigations on Integrity Assessment of Pipes and Elbows From the Faculty of Mechanical Engineering of the University of Stuttgart for the attainment of the Honour of a Doctorate of Engineering Sciences (Dr.-Ing.) Treatise Approved Presented by Jayanta Chattopadhyay, M.Tech., India Main assessment : Prof. Dr.-Ing.habil E.Roos Second assessment : Prof. Dr.-Ing. U.Gampe thDate of Oral Examination : 16 November 2004 2004 Materials Testing Institute (MPA), University of Stuttgart - ii - Preface This work has been carried out by me while working as Scientific Officer in Bhabha Atomic Research Centre (BARC), Mumbai, India in collaboration with MPA, Stuttgart, Germany. I convey my acknowledgement to the concerned authorities in BARC and University of Stuttgart for granting me the permission to pursue Doctorate of Engineering in the University of Stuttgart under the Indo-German bilateral project. I am extremely grateful to Prof. Dr.-Ing habil Eberhard Roos, Director, MPA, University of Stuttgart for helping me in every possible way to complete my Doctorate. Without this, my Doctorate would never have been possible. I am thankful to Prof. Dr.-Ing. U.Gampe, University of Dresden for assessing my doctoral thesis. I am also grateful to Mr. H.S.