Cargo securing - different methods
Securing of cargo can be made by any or in a combination of the following methods:
Examples of blocking: front wall, wedges, dunnage bags, chocks and beams.
Examples of lashings are web lashings, loadbinders with chain and fixed winches. The equipment can be used in different applications e.g. top-over lashings (friction lashing), direct lashings and loop lashings.
Means that the cargo is mechanically locked to the load bearer. One example is twistlock for containers.
Different kinds of lashings
To use a web lashing, or textile lashing, is one of the most common ways of securing cargo. One method that is often used is a top-over lashing (friction lashing). When using a top-over lashing the cargo is pressed down against the load carrier by the tensioning force built up in the lashing, simplified one could say that the weight is “increased”. This combined “weight” in interaction with the actual friction between the cargo and the load carrier's surface prevents the cargo from sliding. This type of lashing is also used to prevent cargo from tipping and/or to wander.
The tensioning force for the current lashing can be found on the marking (label) of the lashing and is called STF. When using the lashing as a direct lashing or a loop-lashing the strength in straight pull is used. When doing so the LC, or Lashing Capacity, is used.
A chain lashing is used in the same way as a web lashing with the distinction that it is more commonly used as a direct lashing. With a chain lashing in G80 or G100 much higher values for LC and STF are reached.
Fixed winches are often mounted on the outside of the load bearer. The can be of a simple configuration with a slotted axis, tensioning device and locking or a little bit more advanced being encapsulated containing a web storage. They can be bolted or welded in place.
The making and the marking of a lashing
The choice of lashing is decided by what kind of cargo to be secured and also of what kind of load carrier that will carry the cargo (rail, road, sea etc.)
Since May 2001 lashings, with few exceptions*, are produced in accordance with EN-12195** within the European Union. These lashings must be provided with a marking that at least contains the following information:
Lashing capacity (LC)
The lashing value allowed to calculate with, received by a straight pull in the endfittings. This value is used when the lashing is used as a direct lashing or loop-lashing. The value is given in daN for web lashings, and kN for chain lashings.
1 daN ≈ 1 kg
1 kN = 100 daN
Standard Hand Force (SHF)
The Standard Handeling Force the ratchet is designed for. Normally this is 50 daN (50 kg).
Standard Tension Force (STF)
Indicates the tensioning force received when the ratchet is handled with the given SHF (normally 50 daN). It is this value that is used calculating the need for top-over lashings (friction lashings).
Webb and chain identifying
On the label (or marking tag) is also noted what material the webbing is made of or what grade the loadbinder and chain is made of.
Breaking Strength (BS)
The breaking strength is the force a new lashing shall withstand in straight pull. Which means that if the hooks are to be pulled straight away from each other the lashing shall perform at least the breaking strength stated.
In general Forankra does not quote this value on our lashings. Today cargo securing calculations should be done in accordance with EN 12195-1 even if formally the Swedish regulations TSVFS 1978:10 and VVFS 1998:95 are still in force until the ongoing revision is completed.
* e.g.a lashing on board a ship can be marked and constructed in a different way.
** EN 12195-2 for synthetic lashings, EN 12195-3 for chain lashings.
Calculating number of lashings needed for transport
In order to calculate number of lashings needed for transports and how to use them we recommend our guide ”Lathund för lastsäkring” (Swedish only) or contact us for a recommendation.