CALCULATION OF APPROXIMATE BREAKING STRENGTH AND SAFE WORKING LOAD FOR MANILA ROPE
Method of finding the Breaking Strength (B.S) is to divide the square of the diameter of the rope in millimetres by 200.
Example of a diameter 24mm Manila Rope:
Breaking strength = diameter² / 200
= 24² / 200
= 576 / 200
= 2.88 tonnes (approx. 3 tonnes)
Safe Working Load (S.W.L)
Method of finding the Safe Working Load (S.W.L) is to divide the Breaking Strength by factor of safety.
The following factors of safety for ropes are used generally:
Lifts and hoist - 12
Running rigging and slings - 8
Other purposes - 6
Safe Working Load = Breaking Strength / Safety Factor
= 3 tonnes / 6
= 0.5 tonnes
CALCULATION OF APPROXIMATE BREAKING STRENGTH (B.S) AND SAFE WORKING LOAD (S.W.L) FOR POLYPROPYLENE ROPE
Method of finding the Breaking Strength (B.S) is to divide the square of the diameter of the rope in millimetres by 77 tonnes.
Example of a diameter 24mm Polypropylene Rope:
Breaking strength = diameter² / 77
= 24² / 77
= 576 / 77
= 7.48 tonnes (approx. 7 tonnes)
Method of finding the Safe Working Load (S.W.L) is to divide the Breaking Strength by a safety factor of 6.
Safe Working Load = Breaking Strength / Safety Factor
= 7 tonnes / 6
= 1.18 tonnes( approx. 1 ton)
CALCULATION OF APPROXIMATE BREAKING STRENGTH (B.S) AND SAFE WORKING LOAD (S.W.L) FOR POLYETHYLENE ROPE
Method of finding the Breaking Strength (B.S) is to divide the square of the diameter of the rope in millimetres by 106 tonnes.
Example of a diameter 24mm Polyethylene Rope:
Breaking strength = diameter² / 106
= 24² / 106
= 576 / 106
= 5.43 tonnes (approx. 5 tonnes)
Method of finding the Safe Working Load (S.W.L) is to divide the Breaking Strength by a safety factor of 6.
Safe Working Load = Breaking Strength / Safety Factor
= 5 tonnes / 6
= .83 tonnes
