Demands on the modern designer are increasing, and the fields he or she must cover are many. The designer has to decide what conditions a product must be able to meet, what material to use and how the welding process affects structures in the form of deformations caused by weld shrinkage. He/she also needs to consider the possibilities and limitations of the production unit as well as the manufacturing costs. Most important, the designer must understand and be able to assess a structure under different loads. A welded structure subject to fatigue is an especially important area. This handbook covers all the fields mentioned above and contains numerous design tips and discussions around favourable and less favourable designs. The behaviour of welded structures under different conditions is explained and discussed. Many examples of stress analysis of welded structures are also provided. This 6:th edition is a translation of the Swedish 5:th edition, printed in 2014. Some adjustments have been made to comply with the latest international standards and to take advantage of the latest research within the fields of welding and design. Primarily, this book is written to be used as a handbook within the industry, but it is also suitable as course literature at universities or for industrial training and further education. Claes Olsson has a life-long experience regarding technical analyses and strength assessments. Today he is responsible for TechStrat of Sweden AB, a company offering strategic technical advices and know-how to the industry.