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Wire ropes G 8 - 1

Revision October 2002

G8 Wire ropes

Contents Page

8.1 General information 2

8.1.1 Introduction 2

8.1.2 Characteristics in use 2

8.1.3 Wear 2

8.1.4 References 3

8.2 Rope terminology 3

8.2.1 Structure of a stranded rope 3

8.2.2 Direction and type of lay 3 8.2.3 Cross- and parallel lay 4

8.2.4 Additional terms 5

8.3 Rope technology 6

8.3.1 Cores 6

8.3.2 Compacted strands 7

8.3.3 Cross- and parallel lay ropes 8

8.3.4 Rope drums and rope sheaves 8

8.3.5 Distortion of ropes 9

8.4 Handling 12

8.4.1 Transport and storage 12

8.4.2 Installation 12

8.4.3 Cutting to length 12

8.4.4 Winding onto drums 13

8.4.5 Influence of the direction of lay 13

8.4.6 Maintenance 14

8.5 Examination 15

8.5.1 General 15

8.5.2 Scope, execution and point of discard 15

8.5.3 Rope sheaves and rope drums 19

8.5.4 Stainless steel wire ropes 19

8.5.5 Overloading 20



G 8 - 2 Wire ropes


G 8 Wire ropes

8.1 General information

8.1.1 Introduction

Wire ropes are safe and reliable components if dimensioned and selected in accordance with the

conditions of operation. This assumes that the entire rope drive is in all details (sheaves, drums

fleet angle etc.) matched to the envisaged type of use.

Ropes are redundant. i.e. in contrast to chains breakage of a single element (single wire) does not

result in total failure.

The wire ropes shown in the Lifting Appliances Regulations (Table 44) are predominantly now

only used for conventional cargo gear. For ship’ s cranes on the other hand, special rotation-free

ropes with a high fill factor and in some cases compacted strands are used.

8.1.2 Characteristics in use

Due to the subdivision of the metal cross-section into individual wires and the ability of the wi res

in the rope structure to slide, wire ropes flex well.

If a wire does break, the remaining wires take over the load intended for the broken wire without

any noticeable increase in loading. Due to the twisting the broken wire resumes car rying a full

load a short distance on from the break.

Due to the high breaking load of the wires, wire ropes of small cross-section can transmit large

forces.

Wire ropes retain their carrying capacity and their characteristics in use even at low temperatures.

Wire ropes attain their maximum breaking load after a short running-in period but then decrease

with time in use. The drop is substantially due to loss of metall cross-section as a result of

abrasion and corrosion, and to wire breaks.

This fact is allowed for by the introduction of a coefficient of utilization (see Lifting Appliances

Regulations). This explains the reliability mentioned at the beginning in combination with regu lar

examinations.

8.1.3 Wear

Ropes running over sheaves and drums become fatigued by a combination of bending, tensile-,

torsional- and compression loading. In addition there is abrasive wear and corrosion.

If the rope is properly made and the entire rope drive properly designed there will be an increa sing

number of outside wire breaks as the rope fatigues progressively.

After a certain period in use, the wires in a rope do not break jointly but gradually. Thus the

number of breaks per unit length may be used as a criterion for the point of discard of running

ropes.

Plastic rope sheaves have advantages and disadvantages. Amongst other things they protect the

outer wires so that an assured assessment of the point of discard on the basis of outer wire

breaks is no longer possible. GL thus demands at least one steel sheave in a suitable place in

every rope drive or possibly other suitable measures resp. proof of the recognisability of point of discard by trials.



Wire ropes G 8 - 3


8.1.4 References

Wire ropes in total represent an almost inexhaustible field for specialisation. All statements in this

subsection thus represent only an extract of essentials from the entire specialist literature.

Answers to further questions may be given by, or obtained through, Head Office.

The majority of the statements which follow were kindly made available by

– Drahtseilwerk Saar GmbH

– Ingenieurbüro für Fördertechnik

Dipl.-Ing. Roland Verreet

8.2 Rope terminology

8.2.1 Structure of a stranded rope

8.2.1.1 Stranded ropes

The most-used wire ropes - stranded ropes –

consist of strands wound helically around a

core.

8.2.1.2 Strands

Strands consist of one or more layers of wires

twisted helically around a core.

8.2.1.3 Cores

Cores consist of natural or synthetic fibrous

material or of wires, which can be inserted

twisted or untwisted.

The term „laying“ means the same as the term

„ twisting“ (strands) or „ stranding“ (ropes).

8.2.2.1 Direction of lay of the strand

The direction of lay of the strand is the di-

rection of the helix of the rope wire. A di-

stinction has to be made between right hand lay(symbol z) and left hand lay (symbol s) strands.

8.2.2 Direction and type of lay



G 8 - 4 Wire ropes


8.2.2.2 Direction of lay of the rope

The direction of lay of the rope is the direction of the helix of the outer strands. A distinction is

made between right hand lay (symbol Z) and left hand lay (symbol S) ropes.

8.2.2.3 Type of lay of the rope

a) Parallel lay (langs lay) b) Cross lay (ordinary lay)

The wires in the strands have the same

direction of lay as the strands in the rope.

Symbol zZ or sS

The wires in the strands have the oppo-

site direction of lay to the strands in the

rope. Symbol sZ or zS

8.2.3 Cross - and parallel lay

The statements which follow refer to laying of multi-layer wires into strands (twisting). They

analogously also apply to the laying of multi-layer strands into ropes (stranding).

8.2.3.1 Cross lay (ordinary lay)

In cross lay, the wires in the different layers of a strand have different lay lengths (pitches). The

wires of adjacent layers thus cross, thence the name.

8.2.3.2 Parallel lay (langs lay)

In parallel lay, the wires in the different layers of a strand have the same lay lengths (pitches). The

wires of all layers thus have line contact.

This laying of strands is used in making

- Seale

- Warrington

- Filler

- Warrington-Seale



Wire ropes G 8 - 5


8.2.3.3 Composite lay

Composite lay is a combination of cross and parallel lay. A representative of this way of con-

structing strands is for instance „Warrington decked“.

8.2.4 Additional terms

8.2.4.1 Rotation-resistant

A wire rope is rotation-resistant if under the influence of an unguided load it rotates only a little

about its longitudinal axis or if with the rope ends guided it exerts only a little torque onthe end

fittings.

8.2.4.2 Rotation-free

A wire rope is rotation-free if under the influence of an unguided load it does not rotate about its

longitudinal axis or if with the rope ends guided it does not exert any torque on the end fittings.

Ropes cannot be made absolutely rotation-free except by braiding.

8.2.4.3 Stress-relieved

Stress-relieved wire ropes have the elastic springiness of the wires caused by laying totally orsubstantially eliminated by spiral preforming. The wires and strands lie „dead“ within the rope

form and do not spring, or spring only a little, out of that form at wire breaks or when the seizing

at the end is removed.



G 8 - 6 Wire ropes


8.3 Rope technology

8.3.1 Cores

8.3.1.1 Fibre core

A fibre core serves as an elastic backing for the outer strands and as a lubricant reservoir. Its elastic

prevents stress peaks under dynamic loading.

The quoted advantages may in service turn into disadvantages. The reserve of lubricant is as a rule used

up after a short time, whereupon the fibre core serves as a reservoir for moisture from the ambient air.

As a result of the high deformability of the

fibre core, the geometry of the rope alters with

increasing length of service, which may result

in adjoining outer strands making contact andpremature failure of the rope.

Particularly in the presence of large radial for-

ces, such as can for example arise in multiple

layer spooling, ropes with a fibre core are

insufficiently dimensionally stable.

8.3.1.2 Steel core

Ropes with a steel core are called all-steel ropes.

The low flexibility of a steel core causes the

ropes to be dimensionally highly stable, which

has a favourable effect on service life.

8.3.1.3 Plastic intermediate layer

Wire ropes with a plastic intermediate layer,

i.e. between the steel core and the outer strands,

combine the advantages of the fibre core with

those of the all-steel rope.

The plastic layer seals -in the lubricant of the

steel core, ensuring i ts adequate lubrication.

Water and dirt cannot penetrate. Lands between

the outer strands prevent their contact.

Due to their high degree of structural stability,

ropes with a plastic intermediate layer are very

suitable for multiple layer spooling.



Wire ropes G 8 - 7


8.3.2 Compacted strands

During the manufacture of compacted strands, round wires are first laid into conventional strands

which are then plastically deformed in a drawing die. This reduces the diameter of the strand and

smoothes its outside surface. The lines of contact between individual wires become areas of

contact, the radii of curvature of individual wires at the surface of the strand increase.

Ropes with compacted strands have a higher breaking load and greater flexibility than similar

ropes with conventional strands and lodge better in the sheaves. Due to the substantially in-

creased dimension of the outer wires they are also more resistant to abrasion and corrosion.

The outer wires of adjacent layers of ropes with compacted strands cannot interlock, thus wire

ropes with compacted outer strands are particularly suitable for multiple layer spooling.



G 8 - 8 Wire ropes


8.3.3 Cross - and parallel lay ropes

8.3.3.1 Cross lay ropes

In cross lay ropes (symbol zS or sZ) the outer wires at the surface of the rope lie roughly along

the rope axis. For most applications cross lay ropes are more suitable than parallel lay ropes.

Broken outer wires generally occur sooner in cross lay ropes than in parallel lay ones, which

means increased safety.

8.3.3.2 Parallel lay ropes

In parallel lay ropes (symbol sS or zZ) the outer wires are strongly inclined to the rope axis. Due to

the better contact conditions in the sheave groove, parallel lay ropes are preferred for high

loadings. Particularly in cases of multiple layer spooling, parallel lay ropes are superior to cross

lay ones as the outer wires of adjacent layers of rope cannot interlock and damage each other.

8.3.4 Rope drums and rope sheaves

8.3.4.1 Rope drums

Rope drums are important elements of a rope drive. A distinction is made between grooved and

plain drums, and between single layer and multiple layer drums.

To ensure proper spooling behaviour on the rope drum, the following rules are to be observed:

8.3.4 .1.1 One layer drums

The direction of lay of the wire rope should be chosen to be opposed to the direction of hand of

the drum (see 8.4.5).

8.3.4.1.2 Multiple layer drums

For multiple layer spooling the following generally applies:

- a wedge should be used to facilitate the rope 'climbing' to the second and third layer

- the first layers of rope should be laid under tension(see 8.4.4)

- the direction of lay of the rope should be chosen according to 8.4.5.



Wire ropes G 8 - 9


8.3.4.1.3 Drums with Lebus grooving

Conventional grooving makes a screw-thread pattern on the drum. The layers of rope that follow

must then in each case be spooled-on in opposite direction, i. e. the ropes cannot be guided by

the preceding layer. That means the ropes can ride up or cut into the lower layers.

Aside from the disadvantages arising from this such as damage to the ropes and oscillations due

to uneven spooling-on and -off, fast-running drums get out of balance because transition to the

next layer occurs always at the same point on the circumference.

In the Lebus rope groove system the grooves run at right angles to the drum axis over the major

part of the circumference. The transition from one groove to the next takes place in two steps at

two opposed points on the drum.

This system provides better guidance of the ropes by the preceding layer and at the same time

avoids getting out of balance.

Drums with Lebus grooving are especially suitable for use in combination with spooling devices

for a large number of layers of rope.

8.3.4.2 Rope sheaves

No specific requirements have been laid down for the materials of rope sheaves. For assembled

sheaves all normal-strength steels are suitable. For cast sheaves two materials are given in the

Lifting Appliances Regulations; grey cast iron is not acceptable.

In the meantime rope sheaves made from certain polyamide-based synthetic materials have also

been approved.

The recommended sheave diameters to the bottom of the groove are to be taken from the GL

Lifting Appliances Regulations. To provide optimal support for the rope, the diameter of the

groove should be 1.06 to 1.08 times that of the rope.

Occasionally rope imprints are visible in the bottom of the groove; there are various possible

causes for this. As a rule the use of ropes of a different make, particularly ones with compacted

outside strands, provides an effective cure. Relubrication of the wire ropes at regular intervals can

also reduce this form of wear (see also 8.5.3.1).

8.3.5 Distortion of ropes

8.3.5.1 GeneralRopes may be distorted by external loads or by influences from within the rope drive.

As shown in the figure below and starting from the location of the distortion, this causes an in-

crease/decrease in the lay length.



G 8 - 10 Wire ropes


In the case of non-rotation free ropes, a distortion means an increase in the internal torque on the

side where the lay length is decreased; inversely a reduction on the other side.

In the case of rotation-free ropes, the internal torques balance out see 8.3.5.2.2). Distortion of

such ropes thus produces a torque both on the side where the lay length is decreased and on that

where it is increased.

8.3.5.2 Distortion by external loads

For a distortion due to rotating loads, the statements given under 8.3.5.1apply.

For a tensile loading due to external unguided loads, the following statements apply:

8.3.5.2.1 Non-rotation free ropes

In a non-rotation free rope an external tensile loading causes a torque which tries to rotate the

rope and the load in the opposite direction to that of the lay.

8.3.5.2.2 Rotation free ropes

Rotation free ropes have steel-wire-rope cores laid in the opposite direction to that of the outer

strands. The geometric structure of these ropes is so chosen that the torsional moments of the

core and those of the outer strands over a wide load range compensate each other but for a small

residual value.

In rotation free ropes external tensile loading produces only a little torque.

8.3.5.3 Distortion due to influences within the rope drive

Ropes can be distorted within a drive by rope sheaves and drums if they do not enter precisely

aligned with the plane of the sheave or the plane of the groove on rope drums.

8.3.5.3.1 Distortion by rope sheaves

If a rope does not enter precisely in the sheave

plane it first touches the groove flange and

then rolls down into the bottom of the groove,

being distorted appropriately in the process.

Large fleet angles particularly make this effect

more pronounced.

In cases of multiple reeving the effects may be

cumulative so that in the case of a tackle with

many parts strong distortion of the rope may

be observed.

Because of greater surface friction at the point

of contact, the effect is greater with plastic

sheaves than with steel ones.



Wire ropes G 8 - 11


8.3.5.3.2 Distortion due to grooved drums

In the case of ropes entering grooved drums the conditions are similar to those described in

8.3.5.3.1.

In the case of grooves cut like screw threads a deflection angle is in practice unavoidable so thatthe rope is distorted continuously.

To keep this distortion as small as possible, the rules listed under 8.4.5 are to be observed.

8.3.5.4 Use of swivels

8.3.5.4.1 Non-rotation free ropes

Non-rotation free ropes must not be operated with a swivel because they untwist under load and

twist again when the load is removed.

This twisting under load leads to a shift of the loads within the rope, i.e. the outer strands unload

whereas the inner lays must carry more load.

The continual untwisting and retwisting plus the shifting of the internal loads results in early rope

fatigue not visible from outside.

8.3.5.4.2 Rotation free ropes

Rotation free ropes may be operated with a swivel. Their breaking load is not reduced by this, nor

do these ropes untwist and retwist under load changes.

These ropes are not exposed to any internal wear effects by the use of swivels. A swivel may

even undo again twists which have ar isen within a rope drive (see 8.3.5.3).

8.3.5.5 Twisting of lower cargo blocks

Modern deck cranes have a lower cargo block suspended from ropes as far apart as possible. This

is necessary to provide the maximum possible resistance to twisting - an absolute necessity e.g.

when using a power swivel.

The resistance to twisting derives from the raising of the load associated with this and increases

until both ropes come together.

Simple reflection shows that the resistance increases with the distance apart of the ropes and

decreases with increasing height of suspension.

This form of suspension of a lower cargo block requires rotation resistant or rotation free ropes,

or else paired left hand lay and right hand lay non rotation free ropes which compensate each

other’ s torsional moments.



G 8 - 12 Wire ropes


8.4 Handling

8.4.1 Transport and storage

8.4.1.1 Transport

Damage of any kind during transport must be

avoided by all means.

The wire rope, delivered in a coil or on a reel,

should if possible not be brought into direct

contact with a metal hook or the fork of a fork

lift truck but instead be transported using

(e.g.) textile slings.

A reel is expediently lifted by means of a bar

through its axis bore.

8.4.1.2 Storage

Wire ropes should be stored in a cool, but at any rate clean and dry, place. Any floor contact during

storage, transport or installation is to be avoided.

8.4.2 Installation

During installation care must be taken to ensure that ropes are unwound and layed-on without twisting

or external damage. Unwinding is to be done by turning of coil or reel.

Twisting results in differences in length between exterior and interior elements of the rope which latercan appear as birdcaging.

With comparatively small-scale lifting gear the old rope is usually first removed, then the new rope

installed.

In the case of larger-scale lifting gear it is recommended that the new wire rope is pulled in using the old

one. The connection between the two ropes must then guarantee that no twist is transferred from the old

rope to the new.

A possible alternative, particularly for first-time rigging, is to use a thinner rope, with the help of which

the wire rope itself is then drawn in.

Following installation of a new rope, several runthroughs of the normal operating cycle should be carried

out with a light load (approx. 10% SWL). That settles in the rope component parts and rope life is

increased. This applies especially before a load test.

8.4.3 Cutting to length

Hand cutters are sufficient for cutting ropes of diameters up to about 8 mm. For larger diameters

however, use of a right-angle grinder is recommended.

The wire ropes must in every case be carefully seized with iron wire on either side of the point of cut to

prevent the rope ends springing apart or the strand- and rope lay lengths changing. This applies

particularly when cutting rotation resistant or rotation free wire ropes whose strands have oftenintentionally not been pre-formed by the manufacturer.



Wire ropes G 8 - 13


8.4.4 Winding onto drums

For proper spooling onto the drum, in cases of multiple layer spooling and here in particular if the

so-called Lebus grooving is used, it is of the greatest importance that the wire rope is led onto the

drum under tension. That tension should be of the order of 1 to 2 % of the minimum breaking loadof the rope.

If the bottom layers are too loose, the upper layers may under load insert themselves between

ropes in the lower ones and under certain circumstances even become jammed. When reeling-off

the rope, the direction of spooling can then suddenly reverse, causing an instantaneous lifting of

the downward-moving load. In most cases it is sufficient to wind the wire rope onto the drum

normally, then reel it off and wind it on again with the aid of an external load.

8.4.5 Influence of the direction of lay

Selection of the correct direction of lay is of great importance for the proper functioning of a rope

drive. The wrong direction leads to a buildup of lay twist, spooling problems and deformation of

the wire rope.

For the frequent case of the single-layer rope drum the rules set out below apply, the direction of

hand of a drum being determinable as follows:

Starting from the fixing point ? of the rope on the drum the turns to the leaving part are to be

followed:

If the finger moves clockwise, the drum is right

hand and needs a left hand lay rope.

If the finger moves anticlockwise the drum is

left hand and needs a right hand lay rope.



G 8 - 14 Wire ropes


In multiple layer spooling the direction of spooling on the drum changes from layer to layer, so

the direction of lay of the rope ought also to change from layer to layer. In that case the direction

of lay of the rope is matched by the manufacturer to the layer which does the most work.

In a rope drive with multi-part reeving the influence of the fleet angel between the rope sheaves is

often greater than that of the rope drum. In this case also the manufacturer must match the

direction of lay of the rope to the reeving.

8.4.6 Maintenance

The service life of a wire rope can be substantially extended by regular maintenance.

8.4.6.1 Cleaning

Very dirty wire ropes must be cleaned externally from time to time. For effective cleaning, special

rope cleaning appliances are needed.

8.4.6.2 Relubrication

During manufacture, a wire rope receives intensive lubrication intended to provide protection

against corrosion and improve the mutual friction values between the elements of the rope and

those between wire rope and rope sheave or drum. However this reserve is only enough for a

limited time so that regular relubrication is necessary.

Galvanised ropes also have to be relubricated regularly if they are used for running rigging. The

galvanising serves exclusively as protection against corrosion whereas the lubricant reduces the

friction within the rope and when running over rope sheaves and drums.

8.4.6.3 Removing broken wires

If ends of broken wires are found which might lie across adjacent wires and then destroy these

also when running over sheaves, these broken end must be removed.

The best method for this is to move the wire ends backwards and forwards by hand or using a

tool until they break at the point where they are held in the strand structure.

8.4.6.4 Shortening

It can sometimes be recognised that certain sections of a rope are much more worn than others,

because due to the way of working of the lifting gear or their location in the rope drive they are

loaded more heavily and frequently.

In such cases the service life can be increased by shortening the rope at the fixing point by a span

and thus moving heavily loaded sections into a less heavily loaded region.

A prerequisite for shortening ropes is of course an adequate length to begin with.



Wire ropes G 8 - 15


8.5 Examination

8.5.1 General

According to the statements under 8.1, wire ropes are reliable components if the entire rope drive

has been properly designed and the lifting gear is operated within the limits set for it by the

design.

The above observations are based on the assumption of regular inspections, also while operating.

The condition and characteristics of ropes change as time in use increases, i.e. they wear and thus

have only a limited service life (see 8.5.2.3.1). This statement does not contradict the quoted

reliability, rather it underlines the importance of the suggestions which follow.

8.5.2 Scope, execution and point of discard

8.5.2.1 Scope of the examination

Ropes are as a matter of principle to be checked over their whole length for possible deformation.

Additionally they must be examined at the ends and over selected zones for wear, broken wires

and corrosion.

Comments on some critical rope zones are given below as follows:

8.5.2.1.1 End fittings

The end fittings detract the elasticity of the wire rope thus, as a rule, reduce the breaking load of

wire ropes at these spots. (Rope sockets are best, rope terminals may reduce the breaking load to

90 %, whereas splices may cause a reduction down to 70 %)

The fittings apply additional pressures to the rope and the transition zone s are often stressed by

rope vibration. Here wire breaks and corrosion are to be expected. (For examination see8.5.2.2.4)

8.5.2.1.2 Rope zones on rope drums

Places where ropes cross on rope drums are subject to increased wear; this also applies to zones

of contact with the drum flanges. Here wear and wire breaks are to be expected.

8.5.2.1.3 Equalising sheaves

If both ends of a rope are led onto drums, equalising sheaves are often fitted midway along the

rope drive. The rope is here by no means stationary, rather is subject to continuous movementcaused e.g. by swinging loads or uneven spooling. Here wire breaks and also corrosion are fre-

quently to be found.

8.5.2.2 Execution of the examination

Supplementing the statements on point of discard, some references regarding defects to be ex-

pected and practical execution follow.

8.5.2.2.1 Documentation

Before starting the examination, the suitability (minimum breaking load, rope diameter, type) and

age of the wire rope should be established by inspection of the rigging plans and the associated

rope certificates (see also 8.5.2.3.1).



G 8 - 16 Wire ropes


.5.2.2.2 Rope diameter

Wire ropes must be measured from strand

crown to strand crown (see Fig. a)

A measurement in accordance with Fig. b gives

too low a value.

For measuring the diameter or ropes with an

uneven number of outside strands, employment

of a caliper with wide measuring surfaces is

recommended because these ropes always have a

valley opposite a crown.

In all cases two rope diameters at right angles to each other should be measured at every measurement

point, so that any potential faults in the "roundness" of the rope are also detected.

8.5.2.2.3 Wire breaks

Determination of the number of wire breaks is effected by an external visual inspection. Electromagnetic

procedures are for a number of reasons not particularly suitable for shipboard lifting gear.

The zones selected for this check (see 8.5.2.1) must first be marked and cleaned, then all wire breaks are

to be counted by a visual inspection and feeling all over the circumference of the wire. The feeling part is

important because with pre-formed wires the ends of the broken wires often do not protrude beyond the

rope outline.

Breaks in outside wires occurring not on the

crown of a strand but rather where two ad-

jacent wires touch or even on the underside of

the strand are hard to identify.

In the case of thin ropes which can be totally

unloaded, such wire breaks can be revealed by

bending the rope (see illustration).



Wire ropes G 8 - 17


8.5.2.2.4 End fittings

For the examination of end fittings the following notes should be o bserved:

a) In the case of rope ends cast into sockets the wires should be inspected for breaks and corro-

sion where they emerge from the casting; there is danger of corrosion at that point.

Sheathings or other protective coatings must be removed for examination, if need be.

Increased corrosional danger exists for lower rope sockets on which, depending on location,

arrangement and design, water is continuously gathered wetting the rope at the protruding

spot.

In case of increased corrosion the rope may be cutted and newly socketed if this is possible

due to sufficient wire rope length.

b) Ropes fitted with clamps are to be inspected for wire breaks at the clamps. Additionally the

material of the clamps is to be checked for cracking.

c) Where detachable rope connectors such as e.g. wedge sockets are used, the rope is to be in-spected for wire breaks and corrosion at the gripping point. Loosening of the rope bonding

may cause the rope to slip.

d) Splices are to have the zone of the splice inspected for wire breaks. The tucked strands must

sit firmly within the splice structure.

e) End fittings on rope drums must be inspected for slackening and corrosion.

8.5.2.2.5 Deformation

In running wire ropes, the earliest damage is normally to be expected in the main working zone, i.e.

where the maximum number of bending cycles occurs.

Rope deformation such as waviness, birdcaging or loop formation may however also be found

outside the main working zone. This damage is caused by excess length of strands or wires and

can be forced out of the main working zone by sheaves.

This kind of rope damage can also arise before the rope drum or the end fitting.

8.5.2.3 Point of discard

8.5.2.3.1 General

Owing to the difficulty of establishing internal wear and corrosion with certainty, running wire

ropes of ship's lifting gear on deck should generally not stay in service for more than at most 10

years, even if no external damage can be found.

Standing wire ropes have a different conservation and should generally not stay in service for

more than 15 years. Ropes may only be longer in use i f a "Certificate of Fitness" has been issued

by a recognized specialized firm, or the wire rope maker, based on a respective examination.

Furthermore wire ropes must be discared if one or more of the forms of damage described below

is/are identified:



G 8 - 18 Wire ropes


8.5.2.3.2 Reduction in diameter

a) Corrosion and abrasion

Wire ropes must be discarded if their diameter has been reduced by corrosion and/or abra-

sion by 10 % compared to the nominal value

b) Rope deformation

Wire ropes must be discarded if their diameter has been reduced by deformation of the rope

by 15 % compared to the nominal value.

8.5.2.3.3 Wire breaks

If a rope drive has been designed properly the number of wire breaks increases with the length of

time in service.

Wire ropes must be discarded if in any length of 8 times the rope diameter the number of visible

wires identified as broken exceeds 10 % of the total number of wires in the rope.

8.5.2.3.4 Rope deformation

Wire ropes must be discarded if one or more of the deformations illustrated below has/have ari-

sen.

In the case of waviness deformation the point of discard is attained if the deformation has reached

a wave height of 1/3 of the rope diameter.



Wire ropes G 8 - 19


8.5.2.3.5 Temperature

Wire ropes which have been subjected to excessive heating are to be discarded. Heating rope

wires to temperatures above about 300 °C will lead to a considerable reduction in wire strength.

In addition to the wire rope itself, all other parts of a rope drive with which the rope comes into

contact are to be examined.

A wire rope stretches under load; it shortens when unloaded. In the course of this, rope zones

which during the change in load happen to be on a sheave or in the lead-in zone of the drum

perform movements relative to the contact surface; during the stretching process they are pulled

over that surface. These relative movements cause abrasion both on the wire rope and on the

surface of the sheave and the drum.

This abrasion normally is distributed evenly over the length of the rope/the circumference of rope

sheaves and -drums. In the case of lifting gear with an ever repeated movement sequence it may

however be that the rope zones/contact surfaces affected are always the same and are thus

subjected to grater wear. This applies in particular to the zones of ropes leading onto rope drums.

8.5.3.1 Rope sheaves

The grooves of the ro pe sheaves should be smooth, with a diameter 1.06 to 1.08 times that of the

rope.

If the groove is too narrow, the rope is exposed to pressure in a radial direction. This loading

leads to premature wire breaks or changes of shape of the rope.

If the groove is too wide, it does not provide the rope with enough contact surface and lateral

support. The increased pressure on the bottom of the groove and the additional stresses due to

the greater deformation of the rope (ovalization of the rope) result in a reduction of service life.

Gouging and other surface changes reduce the service life of the rope. If a negative image of the

rope resting in the sheave has been formed in the base of the groove, this may provide optimum

bearing characteristics for the rope in use, but a replacement rope would no longer fit into the

contours and would rapidly be destroyed. When a rope is changed, sheaves with such marking

must be changed as well.

The faces of the rope sheaves must also be inspected regularly. Traces of abrasion indicate that

because the deflection angle is too great the rope initially makes contact with the face and then

slides down into the bottom. This can lead to twisting and deformation of the rope (see 8.3.5.3.1).



G 8 - 20 Wire ropes


If this is possible with the rope unloaded, the sheaves should also be rotated to check for free

running of the bear ing and eccentricity.

8.5.3.2 Rope drums

The above observations regarding rope grooves and deflection angles correspondingly also

apply to rope drums.

8.5.4 Stainless steel wire ropes

The above statements regarding wear, deformation and wire breaks correspondingly also apply to

stainless steel wire ropes.

Stainless steels are not t ruly non-corroding. The chromium additament in these steels reacts with

the oxygen in the air to form a protective film. If oxygen is excluded and in combination with

humidity that film can break down and the steel begins to corrode.

For adequate protection of the rope wires against crevice corrosion in the maritime atmosphere

the active total „W“ must be at least 29. This means

W = Cr [%] + 3,3 x Mo [%] ≥ 29

A high active total on the other hand means that the wires are relatively brittle compared with

normal rope wires, which reduces the capacity for reverse bending.

Stainless steel wire ropes are therefore less suitable for the running parts of lifting gear and the

launching gear of life-saving appliances. Using them for the latter anyway does not make sensebecause under a SOLAS requirement boat falls generally have to be renewed after 5 years.

For the reasons given, stainless steel wire ropes are predominantly to be found on yachts and

sailing ships. Here also their service life is not unlimited, being determined a.g. by vibrations, end

fittings, fatigue in the case of running gear plus crevice corrosion.

8.5.5 Overloading

Overloaded wire ropes break in a characteristic fashion, usually recognisable by the appearance

of the break.

Under load the helically-wound strands try to straighten, and apply pressure on one another atthe contact points.

If the load increase to exceed the breaking strength, pressure between the strands increases to a

point where individual wires are sheared through. This further increases the force on the remai-

ning load-bearing wires so that the process of destruction proceeds ever more rapidly. The last

individual wires are then torn apart like tensile test specimen.

Typically, two sorts of wire breaks are then to be found where the rope has parted. One sort has

the wires looking as if they had been cut trough at 45° (see Fig. a); the other wires have tensile

test specimen like necking with a conical point at one end and a conical cup at the other (see

Fig. b).



Wire ropes G 8 - 21


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