Due to the harsh environment at sea and the frequent lifting of offshore containers, there are strict requirements on the lifting lugs of offshore containers.
- The design of lifting lugs should not exceed the limit formed by the outer surface of the frame, except the limit of the top.
- Lifting lugs are to be reasonably designed so that the slings connected to them are not entangled with containers or cargo.
- The design of the lugs is to allow free movement of the shackles and slings without damaging the lugs.
- In order to avoid lateral bending moment, in the hoisting state, the eye plate of the lifting lug should be coplanar with the vertical plane where the corresponding limb cable is located, and the maximum manufacturing tolerance is ±2.5.
- When there are four lifting lugs, the relative positions between the lifting lugs should be arranged as a rectangle. The length difference between the two diagonals of the rectangle shall not exceed 0.2% of the nominal diagonal length or 5 mm, whichever is greater.
- The design of lifting lugs should be matched with shackles, and one kind of lifting lugs should not be matched with shackles of various specifications. The clearance between the shackle pin and the lug hole should not exceed 6% of the diameter of the shackle pin.
- The thickness of the lug hole shall not be less than 75% of the width of the shackle body.
- If the lifting force is transmitted through the thickness direction (Z direction) of the plate, the plate used should have the corresponding mechanical properties in the Z direction. When plates with a thickness less than 15mm are used, an engineering justification for the material used shall be based on mechanical testing, ultrasonic testing, or review of chemical and mechanical properties.
- Lifting lugs are to be connected to the frame by full penetration welding. It is recommended that the lifting lugs be connected to the main structural frame beams by inserting the lifting lugs into the slots of the main structural beams.
