4 Strength of Securing Equipment

table 1

 4.1 Manufacturers of securing equipment should at least supply information on the nominal breaking strength of the equipment in kilonewtons (kN).^footnote

 4.2 "Maximum securing load" (MSL) is a term used to define the load capacity for a device used to secure cargo to a ship. "Safe working load" (SWL) may be substituted for MSL for securing purposes, provided this is equal to or exceeds the strength defined by MSL.

Where practicable, the MSL should preferably be marked on the securing equipment.

The MSLs for different securing devices are given in table 1 if not given under 4.3.

The MSL of timber should be taken as 0.3 kN/cm² normal to the grain.

Table 1 – Determination of MSL from breaking strength

 4.3 Particular securing devices (e.g. fibre straps with tensioners or special equipment for securing containers) may be marked with a permissible working load, as prescribed by an appropriate authority. This may be taken as the MSL.

 4.4 When the components of a lashing device are connected in series (e.g. a wire to a shackle to a deckeye), the minimum MSL in the series should apply to that device.

 4.5 Where temporary welded fittings are used, they should be designed to be adequate for the expected loading, and installed by qualified welders in accordance with established welding procedures. The design and placement of these fittings should be such as to minimize bending.

 4.6 Simple stoppers may be used to provide securing against sliding. These are generally welded to a surface by fillet welds, characterized by thickness (a) and length (l). A face plate should be provided against the cargo piece so that welds are not loaded by a shear force at right angles to the weld direction or by significant bending forces. As a simple rule of thumb for welded steel stoppers, the MSL of single-lay weld leg can then be approximated as 4 kN/cm (l) normal to the face plate, assuming 5 mm weld thickness (a). For a triple-lay weld leg, MSL can be taken as 10 kN/cm normal to the face plate.

Figure 16.1 – Welding of steel stoppers

 4.7 All securing devices to be accounted for in the balance calculations described in this annex should be capable of transferring forces directly from the vessel to the cargo or vice versa, in order to reflect their MSLs. For that purpose, lashings should be attached to fixed securing points or strong supporting structures marked on the cargo item or advised as being suitable, or taken as a loop around the item with both ends secured to the same side as shown in figure 7 in annex 5 of the Code. Lashings going over the top of the cargo item, whose only function is to increase friction by their pre-tension, cannot be credited in the evaluation of securing arrangements under this annex.