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9

01 - WIRE ROPE & STRAND

Working Load Limit (WLL)

The WLL is the safe load that a rope can carry on a particular

service. The WLL should be based on the minimum breaking

force, not the actual breaking force, which can vary depending

on Construction and size. The recommended minimum design

factors for steel wire ropes under general conditions are as per

AS2759.

Ropes that are used on appliances complying with any of the

parts of the AS1418 or AS1735 series of Standards shall be

subject to design factors specified by those standards. AS1666

series of standards specifies the design factors for wire rope

used in wire rope slings.

Design factors less than the above may be used, subject to the

appropriate risk assessment being done by a competent person

for a particular application.

Due account should be taken of the number of parts and the

efficiency whenever the design factor of a system is being

determined.

Regulatory authorities or other Standards may require other

design factors.

Efficiency of Terminal Rope Attachments

When calculating the working load limit of a wire rope sling

an allowance is made for the terminations. The table below

(extracted from AS2759) gives the percentage that should be

applied to a WLL calculation involving a particular rope fitting.

(a) Turnback eye with

pressed aluminium

alloy ferrule.

(b) Flemish eye with

pressed sleeve.

(c) Hand-spliced eye.

(d) Open swaged socket.

(e) Closed swage socket.

(f) Open poured socket.

(g) Closed poured

socket.

Figure 5.3 (in part) Terminal Rope Attachments.

Type of rope fitting

or end attachment

Typical tensile

efficiency % (Note 1)

Resistance to

vibration and impact

Ease of fitting in field Refer to notes below

Turnback eye with pressed aluminium alloy ferrule:

≤ 80(mm) rope diameter

95

Good

-

2 & 3

> 80(mm) rope diameter

90

Good

-

-

Flemish eye with pressed sleeve:

≥ 80(mm) rope diameter

95

Good

-

2 & 3

> 80(mm) rope diameter

90

Good

-

-

Hand spliced eye:

≥ 8 ≤ 20(mm) rope diameter

90

Good

Good

1

≥ 20 ≤ 60(mm) rope diameter

80

Good

Good

1

> 60(mm) rope diameter

75

Good

-

1

Open swaged socket

100

Good

Fair

2 & 3

Closed swaged socket

100

Good

Fair

2 & 3

Open poured socket

100

Fair

Good

2

Closed poured socket

100

Fair

Good

2

Wedge grip capel

100

Fair

Good

2

Wedge type socket

80

Fair

Excellent

-

Eye with wire rope grips

80

Good

4 & 5

Eye with fist grips

80

Good

Very good

4 & 5

Notes:

1.

Where lang’s Lay rope is used, the efficiency is up to 15% less than that given

2.

Fitting in the field is not uncommon, but specialised equipment is necessary.

3.

Fitting in field is generally restricted to ropes with a diameter of no more than 20mm.

4.

Not to be used for lifting applications.

5.

When fitted with the required number of wire rope grips, refer to AS2076 or the manufacturers recommendation.