RULES DET NORSKE VERITAS (DNV) = STRUCTURES = - Boat Design Net

Amended July 2011, see page 3 Rules for High Speed, Light Craft and Naval Surface Craft, January 2011Pt.3 Ch.3 Sec.8 – Page 39Fig. 2Intermittent welds202 Double continuous welds are required in the following connections irrespective of the stress level:— oiltight and watertight connections— connections in foundations and supporting structures for machinery— all connections in way of the steering gear arrangement— connections in rudders, except where access difficulties necessitate slot welds— all connections in a region above the propeller extending a radius of minimum 1.5 x the propeller diameter— connections at supports and ends of stiffeners, pillars, cross ties and girders— centreline girder to keel plate— all structures in ballast tanks and other tanks holding corrosive liquids.C. Size of ConnectionsC 100 Fillet welds, general101 Unless otherwise stated, the requirements for throat thicknesses are given for double continuous filletwelds. It is assumed that the welding consumables used will give weld de posits with yield strength accordingto Pt.2 Ch.3 Sec.2 Table C2.102 The throat thickness of double continuous fillet weld is not to be less than:t = 0.42 t 0 (mm)t 0 = thickness in mm of thinner of the plates.The throat thickness is not to be less than 2 mm.The throat thickness may have to be increased when considered necessary due to a high stress level.103 The throat thickness of intermittent welds is to be as required in 102 for double continuous weldsprovided the welded length is not less than:— 80% of total length in the slamming area forward of amidships— 60% of total length for connections in tanks and bottom aft of amidships— 45% of total length for connections elsewhere.t 0 = as given in 102.Total length means total length of double continuous welds.104 Double continuous welds may be required in:— slamming area— engine room area— adjacent to tanks.C 200 Fillet welds and penetration welds subject to high tensile stresses201 In structural parts where high tensile stresses (> 50 N/mm 2 ) act through an intermediate plate (see Fig.1)DET NORSKE VERITAS AS