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Question - What does WLL mean on my rigging?

Answer - WLL is the abbreviation for Working Load Limit. It means the maximum allowable load that a piece of rigging equipment can safely lift, it is also sometimes called “rated load” or “rated capacity”.

Rigging users must be aware that the WLL of a piece of rigging may be reduced by several factors such as temperature, environment, angle of loading or type of hitch used.  


Question - What is the difference between a Clevis and a Shackle?

Answer - ASME B30.26 describes a Shackle as being “a U-shaped, load bearing connector designed to be used with a removable pin”.

Although a shackle is “clevis” shaped the important thing to note is that it is designed for load bearing.

Clevis’s are used in many applications that are not load bearing. 


Question - How many slings can I place on a hook?

Answer - This would depend on the style of hook being used, For a regular Single Point Hook it is recommended that a maximum of 2 slings are used on the hook, if the user needs to use more than 2 slings to lift the load then a collector ring such as a Link or Shackle should be used between the Hook and the Slings

If the hook is a Duplex or Quad Hook (2 or 4 pointed) then the Hook points must be equally loaded to balance the forces on the Hook.


Question - Is it my Employers or my responsibility to make sure my Rigging is safe to use?

Answer - The Alberta OH&S Regulation say,


12(1) An employer must ensure that all equipment used at a work site

(a) is maintained in a condition that will not compromise the health or safety of workers using or transporting it,

(b) will safely perform the function for which it is intended or was designed,

(c) is of adequate strength for its purpose, and

(d) is free from obvious defects.

Duties of workers

14(2) A worker must immediately report to the employer equipment that

(a) is in a condition that will compromise the health or safety of workers using or transporting it,

(b) will not perform the function for which it is intended or was designed,

(c) is not strong enough for its purpose, or

(d) has an obvious defect.

So from this we can see that both the Employer and the Worker have some responsibility to make sure the Rigging is safe to use.


Question - My Eyebolts don’t have a WLL marked on them, are they safe to use?

Answer - The ASME B30.26 standard says  

26-2.5.1 Turnbuckle, Eyebolt, and Eye Nut Identification

Each turnbuckle, eyebolt, and eye nut shall be marked to show

(a) name or trademark of manufacturer

(b) size or rated load

(c) grade for alloy eyebolts

So the WLL limit does not have to be marked on the Eyebolt if the size is, as the user you must make yourself aware of the WLL by referring to the manufacturers specification for the style, size and material of the Eyebolts you are using. 


Question -  What is the difference between Tonne and Ton? 

Answer - The Tonne is a metric unit of measurement, which is made up of 1000 kgs.  (Sometimes referred to as a Long Ton), The Ton is a US unit of measurement, which is made up of 2000 lbs.  (Sometimes referred to as a Short Ton)

There is approximately a 10% difference in weight between a Tonne and a Ton.

The conversion between the two is as follows

1 US Ton = 2000 lbs = 907 kgs = 0.91 Tonne.

1 Tonne = 2205 lbs = 1000kgs = 1.102 US Ton.

So a user of rigging equipment must be aware of the WLL of the equipment and whether it’s marking is in the US or the Metric System.