This document specifies requirements and provides recommendations applicable to the following types of fixed steel offshore structures for the petroleum and natural gas industries: caissons, free-standing and braced; jackets; monotowers; towers. In addition, it is applicable to compliant bottom founded structures, steel gravity structures, jack-ups, other bottom founded structures and other structures related to offshore structures (such as underwater oil storage tanks, bridges and connecting structures), to the extent to which its requirements are relevant. This document contains requirements for planning and engineering of the following tasks: a) design, fabrication, transportation and installation of new structures as well as their future removal; b) in-service inspection and integrity management of both new and existing structures; c) assessment of existing structures; d) evaluation of structures for reuse at different locations. NOTE 1 Specific requirements for the design of fixed steel offshore structures in arctic environments are presented in ISO 19906 [9]. NOTE 2 Requirements for topsides structures are presented in ISO 19901-3, for marine operations in ISO 19901-6, and for the site-specific assessment of jack-ups in ISO 19905-1.