5.2.14.16   Securing with steel strapping
The example uses 32x16 blued steel strap, i.e. steel strapping of a width of 3.2 cm or 32 mm and a thickness of 0.16 cm or 1.6 mm, because when specifying steel strap, the first number is the width in millimeters and the second number the thickness in tenths of a millimeter. The "Guidelines for the correct stowage and securing of cargoes for carriage in ocean-going ships" provide the following rule of thumb for the nominal breaking load (BL) of blued steel strap: width x thickness x 85. The maximum securing load should amount to at most 70% of the BL, so giving the following calculations:

 BL = b x d x 85 = 3.2 x 0.16 x 85 = 43.52 [kN] BL = b x d x 85 = 32 x 1.6 x 85 = 4,352 [daN]

Since the MSL can amount to at most 70% of the BL, the MSL is determined as follows:

 MSL = BL x 0.7 = 43.52 x 0.7 = 30.464 [kN] MSL = BL x 0.7 = 4,352 x 0.7 = 3,046.4 [daN]

Steel strapping of the stated quality and type is sufficient to provide lateral securing of the slab. The four working parts of the two loop lashings on each side could theoretically provide a securing force of 121.856 kN or 12,185.6 daN. Even if the effective forces are assumed to be reduced to a certain extent due to the lashing angle, securing will be adequate.

Steel strapping can only be used for securing if the lashing points are suitable for this purpose, i.e. they must have straight portions of sufficient width for the entire width of the steel strap to lie against. Unsuitable lashing points are those in which the steel strap does not lie flat over its width and, when subjected to tension, is bent in the transverse direction.

 Lashing point suitable for steel strapping Lashing point unsuitable for steel strapping

Advantages of steel strapping are that it can be applied very cheaply and it is relatively strong. Disadvantages, however, are its very low elasticity and the impossibility of retensioning. When applying steel strapping, it is thus advisable to combine it with an elastic material and segments of used tires are suitable for this purpose. This markedly increases the elasticity of the overall lashing and the tire rubber also provides excellent edge protection.

 Securing a slab with steel strapping

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