The most important goal of aluminum alloy high-speed ship manufacturing 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 that the faster the speed of the ship, the lower the fuel consumption, the density of aluminum alloy is only 1/3 of steel, which can greatly reduce the weight of the empty ship, this feature makes aluminum alloy very suitable for the construction of high-speed ship materials.
In addition to the strict control of the weight of the materials on board during construction, the welding design of aluminum alloy ships and the use of intermittent welding as far as possible can not only control the welding deformation, but also reduce the weight of the empty ship. However, since intermittent welding is not suitable for high stress or special areas, we should also note the following weld design requirements:
Design requirements for welds in codes for high speed ships
1. The specification requires the connection welds for double-sided continuous welding as follows: Middle stringer and plate keel, machine base and support structure, oil and water tight structure perimeter, all structures at the steering gear, bottom and bow structures within the impact area, supports and ends of stiffeners, struts, crossstays and stringer, above the propeller, All members, brackets and adjacent troughs or other structural components within a radius of at least 1.5 times the propeller diameter, web ends of troughs subjected to high shear stresses, brackets and bulkhead panels.
2, the height of the welding foot in addition to the welding coefficient in the specification is calculated, but also requires that no matter what kind of weld form and welding method is used, the welding foot of the fillet weld should be ≥3mm, but need not exceed 1.5 times the thickness of the smaller member. The foot height of intermittent welds is generally not more than 7mm.
3, in the use of intermittent welding, the toe of the elbow wrap Angle length should not be less than the height of the connecting aggregate, and not less than 75mm; When the end of the profile is beveled, especially when the end is beveled, the length of the wrapping Angle shall be the height of the profile or not less than the beveled length, whichever is greater; The vertical intersection of the ends of various openings, notches and mutually vertical connecting components shall not be less than 75mm; The continuous length of the intermittent weld is generally not less than 15 times the thickness of the plate or 75mm.
Experience supplement requirement
On the premise of meeting the requirements of the construction code, the shipyard also supplements based on the requirements of the design company, years of production experience and the feedback of the operating shipowner:
1, the side of the anti-collision fender corresponding to the longitudinal hull should be continuously welded on both sides;
2. Fillet welds of all components in seawater ballast tanks should be continuously welded on both sides;
3. The underdeck aggregate or beam corresponding to the upper bulkhead should be welded continuously on both sides;
4, mooring equipment, crane, boat frame, column, mast and hull connected structure and nearby components should be double-sided continuous welding;
5, the area that may be attached to condensate water for a long time should be welded continuously on both sides;
6, all corner arc and bevel Angle need to be double-sided continuous welding;
7. The welds at the elbow plate are double-sided continuous welding;
8. The perimeter structure of the deck or bulkhead opening shall be continuously welded on both sides.