EEMUA Publication 159 is considered to be the most comprehensive users' guide available on above ground vertical cylindrical, steel storage tanks. It is also used worldwide by regulators as an example of what good practice looks like.EEMUA 159 is intended to assist in the establishment of essential inspection and maintenance requirements in order to minimise in-service problems and extend the useful life of these storage tanks. It offers guidance on tanks built to BS, EN or API standards for the storage of petroleum and chemical feed-stocks and products, and non-refrigerated gases. These standards include BS 2654, API 620 and API 650, DIN 4119-1 and -2, CODRES, G0801 and EN 14015. In addition, since EEMUA 159 contains information on many topics that are not covered in API 653, the EEMUA publication can be considered complementary to the API standard.This new edition builds on previous work with additional material to reflect the advances in technology, understanding and operational information. Chapters that have been significantly updated include those on corrosion of tanks, general inspection techniques and interpretation of inspection data, fixed roofs, floating roofs, hydrotesting and probabilistic preventive maintenance (PPM). There are also completely new chapters on mothballing, turn-around procedures, aluminium domes and operation at elevated temperatures. Significantly, a new climate code has been added for Arctic conditions. There is also more focus on innovations and new inspection techniques.The PPM methodology provides what is believed to be the world's only combined theory of risk based inspection (RBI) and reliability centred maintenance (RCM). The different and non-harmonised methodologies of RBI and RCM, since their initiations throughout various aspects of industry (not only storage tanks), have never been combined in the way proposed and implemented in EEMUA 159. The process is time-based, condition-based and reactive.The publication sets out key features for planning and executing inspection, maintenance and repair works. It includes descriptions of the key tank components that require inspection and maintenance, degradation mechanisms and common inspection techniques, and details on tank lifting.Comprehensive guidance is given on many key design features, on common problems experienced during operation and on repair methods. There are numerous new sections, such as on snow loading, planar tilt and overplating. Appendices offer guidance on how to perform assessment calculations on tank components, illustrated by means of sample calculations, as well as on repair methods.