Safe use and purpose of steel wire ropes

Designated use:
C
rane ropes for lifting of loads in accordance with their technical specifications and conditions of use. This also includes compliance with the manufacturer’s instructions for first use, operation, maintenance and testing.
Any other use, especially exceeding the specified lifting capacity and operation or assembly by untrained persons is deemed improper.

Selection
Selection of running wire ropes. The selected wire rope must be strong enough. Applicable directives, standards and regulations must be observed. Certex recommends selection in accordance with ISO 4308-1 “Cranes and Lifting appliances – Selection of wire rope”. Other, local regulations and manufacturers’ information may also need to be taken into account. Apart from the strength of ropes, various wire rope types and designs have different properties which offer many additional criteria for selection. The selection of a wire rope implies examining the positive and negative properties of the different designs for each application in order to find the most suitable rope. A specialist may find a discarded wire rope very useful in this respect. We will gladly assist you in finding the optimal rope for your application.

The following information is not binding and does not substitute the applicable standards, directives and regulations.

Strength
A rope selection factor (C) must be found to select a rope of adequate strength pursuant to ISO 4308-1 for a specific purpose within a group of mechanisms.

C=√ Zp/K’ xRo

C   = Rope selection factor
K’   = Minimum breaking load factor (see ISO 2408)
Ro = Minimum tensile strength of the wire used in the rope
Zp = Minimum coefficient of utilisation (see table)

Minimum coefficient of utillisation (Zp)

Mechanism groupM1M2 M3M4M5M6M7M8
Zp cable drives3.153.353.554.004.505.607.109.00
Zp Pendant and stay ropes2.502.503.003.504.004.505.005.00
Mechanism group and minimum coefficient of utilisation ZP
Values for mobile cranes acc. to ISO 4308-2 on request

Minimum breaking load factor (K’)
The minimum breaking load factor for different rope constructions is given in EN 12385-4 or ISO 2408.
K’ may also be calculated as follows:

K’ = Minimum breaking load factor
ƒ = Fill factor
k = Stranding loss factor

K’ = ƒnxk/4

The table below gives K’ values for different rope designs. Depending on the mechanism group, the nominal strength of the wire (1960 N/mm² in this case) and the rope tension, this may be used to determine the minimum wire rope diameter of the specific rope design.

Rope typeFill factorStranding factorMin. breaking load factor
FkK’
Verostar0.6200.8600.419
Veropro 80.6700.8500.447
Veropower 60.7200.8500.481
Veropower 80.7500.8700.512
Stratoplast0.6170.8600.417
Turboplast0.6650.8500.444
Stratolift0.6610.8600.446
Turbolift0.7340.8300.478
CTE0.6200.7510.366
6x36 IWRC0.5800.7820.356
6x36FC0.5000.8400.330
8x19S IWRC0.5740.7510.356
The above data are for information only.
Contact your CERTEX branch for detailed information

Minimum rope diameter
Finding the minimum rope diameter in acc. with ISO 4308-1

d min = CS

d min = Minimum rope diameter
C = Rope selection factor
S = Max. rope tension, in Newtons

Minimum breaking load
Acc. to ISO4308-1

F min = SxZp

S = Max. rope tension in Newtons
Zp = Minimum coefficient of utilisation acc. to table

Design
In addition to the strength, the selected wire rope must also be suited to the specific application. Different rope designs have very divergent properties.

Never replace one rope design with another without expert advice.

Special conditions of use
Provide as much information as possible when ordering wire ropes. Fundamental information is given in the crane book. Further data on issues such as working temperature, use in aggressive media etc. are of paramount importance for selection and safe operation of your wire ropes and equipment.

Temperatures
Wire ropes with fibre cores and/or aluminium mechanical splices must not be used where working temperatures exceed 100 degrees Celsius. Wire ropes can be used down to - 60ºC.

Working temperature100-200 ºC200-300 ºC300-400 ºC+ 400 ºC
Reduction in lifting capacity10%25%35%100%
Never use wire ropes in temperatures above 400°C.