Section 1 General requirements

1.1.1 All parts of the structure are to be designed to withstand the most severe combination of overall and local loadings to which they may be subjected. Permissible stresses for direct calculation methods are to comply with the requirements of Pt 4, Ch 5 Primary Hull Strength.

1.1.2 The local effects of the loadings listed in Pt 4, Ch 3, 4 Structural design loads are to be considered and all parts of the structure are to be examined individually as necessary, and the calculations submitted. The minimum Rule scantlings of all structures are also to comply with the requirements of this Chapter, as applicable.

1.1.3 The design heads for local strength of column-stabilised, sea bed-stabilised and self-elevating units are to be in accordance with Pt 4, Ch 6, 2 Design heads.

1.1.4 The local strength of ship units is to comply with Pt 10 SHIP UNITS. The local strength of other surface type units is to comply with Pt 4, Ch 4, 4 Surface type units.

1.1.5 The scantlings of machinery seatings are to be specially considered. On self-propelled units, full details of power, and RPM, etc., are to be submitted.

1.1.6 The connections to anchor points as defined in Pt 3, Ch 10, 6.1 General 6.1.4 and the structure in way of fairleads, chainstoppers, winches, etc., forming part of anchoring or positional mooring systems are to be designed for a working load equal to the breaking strength of the mooring or anchoring lines as applicable, see also Pt 3, Ch 10, 11 Anchor winches and windlasses. Permissible stresses are to be in accordance with Pt 4, Ch 5, 2.1 General 2.1.1. Special consideration will be given to grouped line redundant positional mooring systems.

1.1.7 Supply boat moorings and supporting structure are to be designed for a working load equal to the breaking strength of the mooring line. Permissible stresses are to be in accordance with Pt 4, Ch 5, 2.1 General 2.1.1.

1.1.8 Towing brackets and supporting structure are to be designed for a working load equal to the breaking strength of the towline in accordance with the requirements of Pt 4, Ch 9 Anchoring and Towing Equipment.

1.1.9 The supporting structure in way of lifeboat davits is to be designed for the dynamic factors defined in Pt 4, Ch 4, 1.9 Lifeboat platforms and the permissible stress levels are to comply with loadcase (a) in Pt 4, Ch 5, 2.1 General 2.1.1.

1.1.10 The supporting structure to turret bearings on ship units is to comply with Pt 10 SHIP UNITS.

1.1.11 The scantlings of product swivels are to be determined in accordance with Pt 3, Ch 13, 6 Mechanical items and the supporting structure is to be integrated into the unit’s hull structure and the local permissible stresses are to comply with Pt 4, Ch 5 Primary Hull Strength.

1.1.12 The supporting structures to production and process plant are to comply withPt 3, Ch 8 Process Plant Facility.

1.1.13 When a DRILL notation is to be assigned, the scantlings of the drilling derrick are to be determined in accordance with Pt 3, Ch 7 Drilling Plant Facility. The supporting sub-structure is a classification item and calculations are to be submitted in accordance with Pt 3, Ch 7 Drilling Plant Facility. The sub-structure is to be integrated into the unit’s hull structure and the local permissible stresses are to comply with Pt 4, Ch 5 Primary Hull Strength.

1.1.14 The application of the requirements for local scantlings to a column-stabilised unit is shown in Pt 4, Ch 6, 1.1 General 1.1.14.

Figure 6.1.1 Application of the requirements for local scantlings to a column-stabilised unit