4 Other Types of Joints

4.1 Lapped joints

4.1.1 Areas

4.1.2 Overlap width

Where overlaps are adopted, the width of the overlap is not to be less than three times, but not greater than four times the as-built thickness of the plates being joined, see Figure 8. Where the as-built thickness of the thinner plate being joined has a thickness of 25 mm or more, the overlap will be subject to special consideration.

Figure 8 : Fillet weld in lapped joint

4.1.3 Overlaps for lugs

The overlaps for lugs and collars in way of cut-outs for the passage of stiffeners through webs and bulkhead plating are not to be less than three times the thickness of the lug but need not be greater than 50 mm.

4.1.4 Lapped end connections

Lapped end connections are to have continuous welds on each edge with leg length, ℓ_leg in mm, as shown on Figure 8 such that the sum of the two leg lengths is not less than 1.5 times the as-built thickness of the thinner plate.

4.1.5 Overlapped seams

Overlapped seams are to have continuous welds on both edges, of the sizes required by [2.5.2] for the boundaries of tank/hold or watertight bulkheads. Seams for plates with as-built thickness of 12.5 mm or less, which are clear of tanks/holds, may have one edge with intermittent welds in accordance with [2.5.2] for watertight bulkhead boundaries.

4.2 Slot welds

4.2.1

Slot welds may be adopted in very specific cases subject to the approval of the Society. However, slot welds of doublers on the outer shell and strength deck are not permitted within 0.6 L amidships.

4.2.2

Slots are to be well-rounded and have a minimum slot length, ℓ_slot of 75 mm and width, w_slot of twice the as-built plate thickness. Where used in the body of doublers and similar locations, such welds are in general to be spaced a distance, s_slot of 2 ℓ_slot to 3 ℓ_slot but not greater than 250 mm, see Figure 9. The size of the fillet welds is to be determined from second formula shown in [2.5.2] using t_as-built of the thinner plate and a weld factor of 0.48.

Figure 9 : Slot welds

4.2.3 Closing plates

For the connection of plating to internal webs, where access for welding is not practicable, the closing plating may be attached by slot welds to face plates fitted to the webs.

4.2.4

Slots are to be well-rounded and have a minimum slot length, ℓ_slot of 90 mm and a minimum width, w_slot of twice the as-built plate thickness. Slots cut in plating are to have smooth, clean and square edges and are in general to be spaced a distance, s_slot not greater than 140 mm. Slots are not to be filled with welding.

4.3 Stud and lifting lug welds

4.3.1

Where permanent or temporary studs or lifting lugs are to be attached by welding to main structural parts in areas subject to high stress, the proposed locations are to be submitted for approval.