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DNV-OS-C102 Structural Design of Offshore Ships

Sec.2: cture and elements not covered by Rules for

B: Selection of Material

B400: Topside structure and elements not covered by Rules for Classification of Ships Pt.3 Ch.1

Sec.2
B 400   Topside structure and elements not covered by Rules for Classification of Ships Pt.3 Ch.1

Guidance note:
The consequence of failure may be quantified in terms of residual strength of the structure when considering failure of the actual component.

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Sec.2 B

Table B1 Material Classes
Material class	Structural member	Equivalent structural category in the DNV-OS-C101
I	— Outfitting steel — Mezzanine decks, platforms — Pipe support structure — Laydown platforms — Doubler plates, closer plates and support infill steels in topside structures 1)	Secondary
II	— Stair towers — Topside modules (plate, web frame, girder) 2) — Main structures in riser hold — Longitudinal and transverse bulkheads in way of moonpool and setback area — Offshore Crane boom rest and main supporting structures
III	— Main girders and columns in truss work type modules — Topside support stools and main supporting structures — Pipe/riser rack stanchions — Main structures in drill-floor and substructure — Main supporting structures for helideck 3) — Crane pedestal (shipboard and offshore) — Flare tower — Foundations and main supporting structures of heavy machinery and equipment: e.g. thruster, gantry and rail, chain stoppers, offloading riser fairleads, anchor line fairleads, winches, davits, hawser brackets for shuttle tanker, towing brackets etc.	Primary
IV	— Deck and bottom corner plates in way of moonpool — Foundations and main supporting structures for derrick (substructure) — Foundations and main supporting structures for flare tower and offshore crane pedestal — Main supporting structures for turret	Special
To have the same minimum yield strength as the material to which they are attached Stiffener and other local members (brackets, collar plates, web stiffeners) are classified as Class I. For material selection of helideck and substructure, see DNV-OS-E401 Note: Main structures and main supporting structures are primary load bearing members such as plates, girders, web frames/bulkheads and pillars

Sec.2 B
404   Alternatively materials for the specific structural members specified in Table B1 may be selected based on equivalent structural category in accordance with the principles given in DNV-OS-C101.