Preface to second edition  Upon the initiative of power plant manufacturers and users the first edition was revised to adapt to the state-of-the-art. The update is intended on the one hand to adapt the guide-line to new preservation methods and materials, and on the other hand to give recom-mendations for preservation methods for the period of time starting after manufacture until initial start-up. In addition, further relevant power plant components were included in the guideline.   This guideline was established to the best of our knowledge and belief, but does not pre-tend to completely cover all aspects or preservation. It is considered a practical guide and is not intended to replace the technical knowledge of its users. No liability will be taken for the correctness of its contents, since especially plant-specific peculiarities have to be taken into account in each individual case. Practical information was included in the detailed description of methods, planning and execution of preservation. Special emphasis was placed on the control and proof of the preservation measures and results. The preservation methods shown shall not be understood to apply alternatively or additionally to any other method. The complete or extractive use of the preservation methods is left to the parties involved and shall be agreed between purchaser and supplier in each individual case. All preservation measures should be covered by, controlled and documented in a quality management system. Users of this guideline are therefore asked to inform the VGB on experience gained with and proposals for improving this guideline so that the VGB, upon evaluation of the information provided, may supplement or change this guideline appropriately. We would also like to mention that the companies and associations having participated in the establishment of this guideline, especially the authors, are prepared to proffer advice regarding the planning and performance of the various process steps, but also in the case of divergent opinions and contract-related matters.