EEMUA Publication 159 is considered to be the most comprehensive users' guide available on aboveground vertical cylindrical, steel storage tanks. It 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. EEMUA 159 offers guidance on tanks built to BS, EN or API standards for the storage of petroleum and chemical feed-stocks and products and refrigerated gases. These standards include BS 2654, API 620 and API 650, DIN 4119-1 and -2, CODRES, G0801 and EN 14015. The new edition introduces what is believed to be the world's only combined theory of risk based inspection (RBI) and reliability centred maintenance (RCM) - the "probabilistic preventive maintenance methodology". 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.