This Part 4-3 of ÖNORM EN 1993 provides principles and application rules for the structural design of cylindrical steel pipelines for the transport of liquids or gases or mixtures of liquids and gases at ambient temperatures, which are not treated by other European standards covering particular applications. This ÖNORM is specifically intended for use on: Buried pipelines in settlement areas and in non-settlement areas; Buried pipelines crossing dykes, traffic roads and railways and canals. The design of pipelines involves many different aspects. Examples are routing, pressure safety systems, corrosion protection, construction and welding, operation and maintenance. For aspects other than the structural design of the pipeline itself, reference is made to the relevant European standards listed in 1.3. This is also the case for elements like valves, fittings, insulating couplings, tees and caps. Pipelines usually comprise several associated facilities such as pumping stations, operation centres, maintenance stations, etc. each of them housing different sorts of mechanical and electrical equipment. Since these facilities have a considerable influence on the continued operation of the system, it is necessary to give them adequate consideration in the design process aimed at satisfying the overall reliability requirements. However, explicit treatment of these facilities, is not included within the scope of this ÖNORM.