ISO 19901-3:2010 gives requirements for the design, fabrication, installation, modification and structural integrity management for the topsides structure for an oil and gas platform. It complements ISO 19902, ISO 19903, ISO 19904‑1, ISO 19905‑1 and ISO 19906, which give requirements for various forms of support structure. Requirements in ISO 19901-3:2010 concerning modifications and maintenance relate only to those aspects that are of direct relevance to the structural integrity of the topsides structure.

The actions on (structural components of) the topsides structure are derived from ISO 19901-3:2010, where necessary in combination with other International Standards in the ISO 19901 series. The resistances of structural components of the topsides structure can be determined by the use of international or national building codes, as specified in ISO 19901-3:2010. If any part of the topsides structure forms a primary structural component of the overall structural system of the whole platform, the requirements of ISO 19901-3:2010 are supplemented with applicable requirements in ISO 19902, ISO 19903, ISO 19904‑1, ISO 19905‑1 and ISO 19906.

ISO 19901-3:2010 is applicable to the topsides of offshore structures for the petroleum and natural gas industries, as follows:

• topsides of fixed offshore structures;
• discrete structural units placed on the hull structures of floating offshore structures and mobile offshore units;
• certain aspects of the topsides of arctic structures.

ISO 19901-3:2010 is not applicable to those parts of the superstructure of floating structures that form part of the overall structural system of the floating structure; these parts come under the provisions of ISO 19904‑1. ISO 19901-3:2010 only applies to the structure of modules on a floating structure that do not contribute to the overall integrity of the floating structural system.

ISO 19901-3:2010 is not applicable to the structure of hulls of mobile offshore units.

ISO 19901-3:2010 does not apply to those parts of floating offshore structures and mobile offshore units that are governed by the rules of a recognized certifying authority and which are wholly within the class rules.

Some aspects of ISO 19901-3:2010 are also applicable to those parts of the hulls of floating offshore structures and mobile offshore units that contain hydrocarbon processing, piping or storage.

ISO 19901-3:2010 contains requirements for, and guidance and information on, the following aspects of topsides structures:

• design, fabrication, installation and modification;
• in-service inspection and structural integrity management;
• assessment of existing topsides structures;
• reuse;
• decommissioning, removal and disposal;
• prevention, control and assessment of fire, explosions and other accidental events.

ISO 19901-3:2010 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.