One of the most important goals in the manufacture of aluminum alloy high-speed ships is to achieve the design speed. In order to achieve the above goals, under the same hull line and the same main engine power, the lighter the weight of the empty ship means the faster the ship's speed, the lower the fuel consumption. The density of aluminum alloy is only 1/3 of that of steel, which can greatly Reduce the weight of the empty ship, this feature makes aluminum alloy very suitable as a material for building high-speed ships.
In addition to the strict control of the weight of materials on board during construction, the welding design of aluminum alloy ships and the use of intermittent welding as much as possible can not only control welding deformation, but also reduce the weight of the empty ship. However, because discontinuous welding is not suitable for high stress or special areas, we should also pay attention to the following weld design requirements:
Design requirements for welds in high-speed ship specifications
1. The specification requires that the connection welds of double-sided continuous welding are as follows: middle girder and flat keel, machine base and supporting structure, oil-tight and watertight structure perimeter, all structures at the steering gear, bottom and head structures in the impact area , The support and end of stiffeners, pillars, cross braces and girders, above the propeller, all members, brackets and adjacent girders or other structural parts within a radius of at least 1.5 times the diameter of the propeller, The web ends, brackets and bulkheads of girders that are subject to greater shear stress.
2. In addition to calculating the height of the welding leg according to the welding coefficient in the specification, it is also required that the weld leg of the fillet weld should be Greater than or equal to 3mm, but it does not need to exceed 1.5 times the thickness of the thinner member regardless of the weld form and welding method. The height of the weld leg of the discontinuous weld is generally not more than 7mm.
3. When intermittent welding is used, the wrap angle length of the bracket toe end should not be less than the height of the connecting frame, and not less than 75mm; the end of the profile, especially when the end is tapered, the length of the wrap angle should be the height of the profile or The length of the bevel is not less than the cut length, whichever is larger; the vertical intersection between the ends of various openings and cuts and the mutually perpendicular connecting members should not be less than 75mm; the continuous length of the discontinuous weld is generally not less than 15 times the thickness of the plate or 75mm, whichever is greater. The little one
Supplementary experience requirements
On the premise of meeting the requirements of the construction specification, the shipyard also supplemented according to the requirements of the design company, years of production experience and information feedback from the operating shipowner:
1. The side anti-collision fenders shall be continuously welded on both sides of the longitudinals in the hull;
2. The fillet welds of all components in the seawater ballast tank shall be continuous welded on both sides;
3. The under-deck frames or beams corresponding to the upper bulkhead shall be continuously welded on both sides;
4. The structure connecting the mooring equipment, cranes, davits, columns, masts and the hull and nearby components shall be double-sided continuous welding;
5. The areas where condensed water may adhere for a long time should be welded continuously on both sides;
6. All corner arcs and chamfered corners need to be welded continuously on both sides;
7. The welds at the brackets are all double-sided continuous welding;
8. The perimeter structure of the deck or bulkhead opening is to be continuously welded on both sides.