prBAS EN ISO 19901-3:2025

This document provides requirements, guidance and information for the design and fabrication of topsides structure for offshore structures, including in-service, pre-service and post-service conditions. The actions on topsides structure and the action effects in structural components are derived from this document, where necessary in combination with other International Standards in the ISO 19901 series (e.g. ISO 19901-1 for wind actions - see 7.6.2, ISO 19901-2 for seismic actions - see 7.7) and ISO 19902 for fatigue design (see 6.7). This document is applicable to the following: —     topsides of fixed offshore structures; —     discrete structural units placed on the hull structures of floating offshore structures and mobile offshore units; —     topsides of arctic offshore structures, excluding winterization (see ISO 19906). If any part of the topsides structure forms part of the primary structure of the overall structural system which resists global platform actions, the requirements of this document are supplemented with applicable requirements in ISO 19902, ISO 19903, ISO 19904-1, ISO 19905-1, ISO 19905-3 and ISO 19906. For those parts of floating offshore structures and mobile offshore units that are chosen to be governed by the rules of a recognized classification society, the corresponding class rules supersede the associated requirements of this document. This document also addresses prevention, control and assessment of fire, explosions and other accidental events. The fire and explosion provisions of this document can be applied to those parts of the hulls of floating structures and mobile offshore units that contain hydrocarbon processing, piping or storage. NOTE          Requirements for structural integrity management are presented in ISO 19901-9. This document applies to structural components including the following: —     primary and secondary structure in decks, module support frames and modules; —     flare structures; —     crane pedestal and other crane support arrangements; —     helicopter landing decks (helidecks); —     permanent bridges between separate offshore structures; —     masts, towers and booms on offshore structures. This document provides requirements for selecting and using a national building standard with a correspondence factor for determining the resistance of rolled and welded non-circular prismatic components and their connections.