good slinging practice - Site Safe

GOOD SLINGING PRACTICE
BASIC RULES ... 5
5.1. KNOW THE EFFECT OF REEVING ON SLINGS.
"Reeving" is the practice of wrapping a sling around an object, and either doubling it
back on the hook, or passing one eye of the sling through the other and then to the
hook.
This practice is also known as "choking", or "nipping".
This practice is perfectly safe when done properly, BUT you MUST realise that the act
of reeving creates an "included angle" within the sling which reduces the permissible
load on that sling.
And NEVER bang the hook down on to the load. You are NOT making the sling more
secure - in fact, you are creating larger loads in the sling by increasing the included
angle.
It also increases the crushing force on the load.
Any sling reeved around a load needs to have a SWL which is
TWICE that of a vertical sling.
To work out the sling loads for a reeved sling, use the following formula.
This will work for any reeved sling with an included angle LESS that
120°, which must be the absolute maximum angle.
An example has been shown.
R
Load = W.
Note protection on sharp corners.
L
T = Tension in each slinging leg.
L = Length of each leg.
R = Rise.
W = Load to be lifted.
CRANEAGE - SLINGING: BASICS PAGE 10
T =
1/2 W x L
R