12735 wire rope siling-safety criateria for inspection proc

8/18/2019 12735 Wire Rope Siling-safety Criateria for Inspection Proc

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IS 12785 : 1994IS 8792 : 1986

( vm g;i*wqIndian Standard

WIRE ROPE SLINGS - SAFETY CRITERIA ANDINSPECTION PROCEDURES FOR USE

First Revision )

UDC 621’86’065 : 614’8

@I BIS 1994

BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

February 1994 Price Group 6

( Reaffirmed 1999 )


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Wire Ropes and Wire Products Sectional Committee, HMD 10

NATIONAL FOREWORD

This Indian Standard which is identical with IS0 8792 : 1986 ‘Wire rope slings - Safety criteriaand inspection procedures for use’ issued by the International Organization for Standardization( IS0 ), was adopted by the Bureau of Indian Standards on the recommendation of Wire Ropesand Wire Products Sectional Committee ( HMD 10 ) and approval of the Heavy MechanicalEngineering Division Council.

This standard was first published in 1989 as ‘Guidelines for use of wire rope slings’. Consequentupon the publication of IS0 8792 : 1986, this standard ( including its title ) has been revisedby adopting IS0 8792 : 1986 in toto to align its requirements with international practices.

The text of IS0 standard has been approved for publication as Indian Standard withoutdeviations. Certain conventions are however not identical to those used in Indian Standards.Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appear referring to this standard, theyshould be read as ‘Indian Standard’.

b) Comma ( , ) has been used as a decimal marker while in Indian Standards, the currentpractice is to use point . ) as the decimal marker.

The concerned technical ccmmittee has reviewed the provisions of IS0 7531 referred in thisadopted standard and has decided that it is acceptable for use in conjunction with this standard.

In reporting the results of a test or analysis made in accordance with this standard, if the finalvalue, observed or calculated, is to be rounded off, it shall be done in accordance withIS 2 : 1960 ‘Rules for rounding off numerical values ( revised 1’


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IS 12735 : 1994IS0 8792 : 1986

Indian Standard

WIRE ROPE SLINGS - SAFETY CRITERIA ANDINSPECTION PROCEDURES FOR USE

Firs t Revis ion )

1 Scope and field of application 2 Reference

This International Standard lays down safety criteria and IS0 7531, Wire rope s l ings for general purpo ses -inspection procedures for the regular use of wire sling ropes. Character is t ics and speci f ica t ions . 11

NOTES

1 The speclftcations and testing of slings are specified in IS0 7531 3 Slinging methods2 The use of wire rope slings IS frequently covered by nationalregulations; these would take precedence over this InternationalStandard

Table 1 gives a summary of commonly used and approvedslinging methods for single-leg slings and two-legged slings.

1) At present at the stage of draft


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IS 12735 : 1994IS0 8792 : 1986

Slinging method

Table 1 Slinging methods

Type of sling__ ___I-

Single-leg sling Two~legged slinq’) Endless sling

single double single double

Direct attachment

Choke hitch

_______

basket hitch

-.----.._------ ..- -_.-_ .._. ..__ ~~~~~.----

2


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I s 12735: 1994IS0 8792 : 1986

4 Use of wire rope slings cl the relevant leg angle does not exceed that for whichthe sling is rated and marked;

4.1 Before lifting a load

4.1.1 It is necessary to ensure that the load is suitable forlifting with a wire rope sling. The sling shall not be allowed todamage the load nor shall the sling itself be damaged. It thesling is to be attached to the load, me points used forattachment, e.g. lugs and eyebolts, should be suitable andadequate for the purpose of lifting the load.

4.1.2 The mass of the load to be lifted shall be assessed (seeannex 6). If the gross mass is not marked, the information maybe obtained from the consignment notes, manuals, plans, etc.If there is no informatlon. the mass should be assessed by theperson responsible for the lifting.

d) the sling is not bent around any sharp corners thatmight damage the sling or reduce its effective strengthwhere necessan/, suitable packing pieces should be used;

NOTES

1 A sharp corner IS considered to have a radius of cclrvaturca ofless than the rope diameter.

2 When a rope is bent over Its own diameter, It can lose 50of its original strength.

e) and, when using a choke hitch, to ensure that

I the angle of choke is allowed to form itself naturallyand is not forced,

4.1.3 Once the slinging method has been decided on, asuitable sling shall be chosen and the working load limit (WLL)

2) a thimble or stirrup is used, where practicable, at theeye to reduce damage to the rope and thereby prolongthe life of both the eye and the main part of the rope;

shall be adequate for the load to be lifted. f) a sling in choke hitch is not used to turn, rotate or dracl a

As far as is reasonably practicable, the effective diameters ofpins, hooks or other components over which soft eyes are usedshall not be less than twice the rope diameter.

load unl&s special precautions are taken to ensure thatneither the sling nor the load is damaged - such specialprecautions may entail a reduction of the safe working load;

4.1.4 It is necessary to ensure that the sling is in good con-dition. Slings found to be damaged or to have deteriorated tosuch an extent that they are considered not safe for use shall be

withdrawn from service immediately (see clause 5).

g) a tag line(s) or control rope(s) is available to assist in thecontrol of the swing or rotation of the load.

4.3 Raising or lowering the load

4.1.5 It is necessary to ensure that the load will be balancedwhen lifted The slings shall be attached to designed ,iftingpoints, where provided. If llftmg points are not marked on theload, the position of the centre of gravity shall be assessed. Thetype of sling and the slinging methods used shall ensure thatthe load will not topple or slip. The supporting hook shall bepositioned directly above the centre of gravity. Where this isnot practicable, particular care shall be taken when lifting theload (see 4.3)

When raismg or lowering the load, it is necessary to ensure that

a) a recognized code of signals is used which is fullyunderstood by all concerned;

b) there is nothtng to prevent the tree movement of rtwload, e.g. bolts holding down the load or joirrtin l;

c) there are no obstacles, such as cables or popes, whic:tlcan be fouled, and there is sufficierlt height for the Ilfr.

4.1.6 It is necessary to ensure that the load contains no looseaccessories. If the load comprises a number of pieces, forinstance a bundle of pipes, a slinging method shall be chosenwhich will secure all the pieces.

The sling shall not be attached to banding or strapping unlessthey are designed for lifting purposes.

d) every person concerned with the operation can ser:

and/or communicate with all other persons concernec

e) all personnel are clear of the load;

NOTE If a person has to br: near the I o i l t l pcc~nl ~3rc tlarirtl;startIny the hoisting and conlr~ of the rnovem:lit~ of thtl 104shocM hr taken

4.1.7 If a sling leg is likely to rotate during lifting of the load,handsplices shall not be used.

f) the load IS balanced (see annex A);

g) the load is raised ot lowered steadily nvr)lrlirly snatchloadtng;

4.2 Fitting the sling

When fitt;ng the sling, it is necessary to ensure that

a) sling legs are free of any tendency to kink;

b) the terminations are properly seated wtthout over-crowding;

h) the sling IS not trapped under the load it ncccssi3rv.place suitable battens, etc. In posItIon so that the load :.a ~be put down without damage to Itself and without tropr,lnrlthe sling;

i) there are no free swinging legs; even wherl hooked backthese might constitute a danger and should Ix: sllblr?c:f PJcareful control.

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IS 12735 : 1994ISO 8792 : 1986

4.4 Precaufions

The following precautions shall be taken :

5

a) no one shall be allowed to ride on the load;

b) the load shall not be allowed to be carried over anyonewithout due care being exercised;

c) a suspended load shall not be left unattended;

d) slings shall not be dragged along the floor;

e) the slings shall not be unnecessarily exposed to cor-rosive liquids, solids or vapours;

f) if the sling is to be used in an environment where thetemperature exceeds 100 OC, advice of the sling manufac-turer shall be sought.

Inspection, thorough examination and

discard criteria

5.1 General

During service, slings are subjected to conditions which affecttheir safe working characteristics. It is necessary therefore toensure, as far as is reasonably practicable, that the sling is safefor continued use.

The sling shall be inspected for damage or deterioration beforeeach period of use and thereafter shall be checked for obviousdefects at suitable intervals during service.

In addition, thorough routine examinations shall be carried outby a competent person.

If at any time there is reason to doubt the safe condition of thesling, it shall be withdrawn from service and subjected to athorough examination (see 5.3).

5.2 Inspection (for details, see 5.4)

An inspection is a visual check on the condition of the sling toidentify damage or deterioration which might affect its fitnessfor use, such as:

a) broken wires;

b) distortion of the rope (crushing, kinking, etc.);

c) distortion of ferrules, splicing or fittings:

d) excessive wear:

e) heat damage;

f) corrosion

5.3 Thorough examination

A thorough examination is a visual examination carried out by acompetent person and, where necessary, supplemented byother means, such as non-destructive testing, in order to detectdamage or deterioration which might affect the fitness for use

of the sling.

A thorough routine examination shall be carried out at intervalsnot exceeding six months and this interval shall be less wheredeemed necessary in the light of service conditions or where re-quired by statutory requirements.

Records of such tests shall be kept in accordance with nationalstandards and regulations.

5.4 Assessment of the condition of the slingand discard criteria

5.4.1 Broken wires

54.1 .l General

Broken wires are detrimental because of

a) the possrbrlrty of injury to user’s hands;

b) the loss of strength in the rope.

Broken wires are usually caused by mechanical damage,although corrosion may be a significant factor.

The appearance of well distributed broken wires may have nomarked effect on the strength of the sling, but it might beindicative of mechanical or corrosive damage. In general, theloss of strength caused by the mechanical or corrosive actionon the rope as a whole is more critical than the loss in strengthresulting from the actual wire breaks.

To prevent injury to the user’s hands, protruding wires shall bebroken off in the gusset by reverse bending until fractureoccurs.

5.4.1.2 Randomly distributed breaks

If the total number of visible broken wires in any length of sixrope diameters exceeds 5 % of the number of wires in the rope,the sling shall be withdrawn from service and referred to acompetent person for thorough examination.

5.4.1.3 Localized breaks

If there are three or more broken wires closely grouped, thesling shall be discarded.

5.4.2 Excessive wear

If surface wear reduces the measured diameter of the rope atany point to less than 90 % of the nominal diameter, the slrngshall be discarded.

54.3 Corrosion

Corrosion may occur where slings have been improperly storedor have been used in particularly corrosive conditions, such asin moving loads in and out of acid/alkali baths. The effect isreadily identified through the loss of flexibility and roughness tothe touch. While slight surface rusting is unlikely to affect therope strength, it may be indicative of rnternal corrosion, the

effect of which is not predictable.

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IS 12735 : 1994IS0 8792 : 1986

Where internal corrosion or corrosion beneath the serving of ahand splice is suspected, the sling shall be withdrawn from ser-vice and referred to a competent person for thorough examination.

5.4.4 Significant distortion of the rope

The sling shall be discarded when distortion due to kinking,crushing, core collapse, or knotting is identified. However, incertain circumstances, permanent deformation may occurwithout necessarily affecting the strength of the sling, e.g. flat-tening when the rope is bent around a small diameter underheavy loading.

In cases where it is difficult to distinguish between detrimentaldistortion and acceptable deformation, the sling shall bewithdrawn from service and referred to a competent person forexamination.

5.4.5 Heat damage

Discolouration of the wires and other evidence of overheating,such as loss of lubrication or pitting of the wires caused by elec-trical arcing, etc., may be detrimental.

A sling which has been exposed to excessive temperatures foran excessive length of time may have a significantly reducedstrength.

Where such conditions are identified, the sling shall bewithdrawn from service and referred to a competent person forexamination.

5.4.6 Damaged or defective fittings, ferrules or splices

Particular attention shall be paid to signs of

a) opening up, distortion or cracking of the hook;

b) distortion and wear of links or closinq of the thimble;

c) cracks in the ferrule;

d) severe crushing or abrasion of the ferrule or handsplice;

e) pulling out of splice or ferrule;

fl concentrations of broken wires near to the ferrule orsplice, or in the splice;

g) the effect of bursting stress at the throat of the eye due

to the use of a pin of excessive diameter or certain types ofthimble;

h) fractured wires on the outside surface of the eye, e.g.where a soft eye has been used with an excessively smallpin;

i) effect of friction on bearing surface of a soft eye

The conditions described under items a) and b) may be anindication of overloading and will usually be justification forwithdrawing the sling from service.

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IS 12735 : 1994IS0 8792 : 1986

Annex A

Load stability

(This annex forms an integral part of the standard.1

A.1 General

Before lifting with slings, i t is important to ensure that the loadwill be stable when it is raised clear of the ground. It isdangerous if a load can tilt or swing in an uncontrolled manner,or if it can topple over.

A load will not tilt, if, before lifting, the sling(s) is fare) arrangedso that the load is suspended with its centre of gravity aligneddirectly below the main point of attachment of the hook (seefigure 11. (The centre of gravity is the point about which theparts of a body, when left free, exactly balance each other.)

A.2 Effect of “out of balance”

If a load is out of balance when lifted, it will tilt and swingtowards the position of balance, until the centre of gravitysettles directly below the main point of attachment.

This movement can give rise to hazardous situations, such as :

al the swinging load might strike persons or obstacles;

b) the individual sling legs might become overloaded;

c) the load might move within the sling;

d) in severe cases, the load may topple or be displacedfrom the sling with consequent damage.

If there is uncertainty about the balance of a load, it may benecessary to have a series of trial lifts before the position ofbalance can be determined. The load shall be lifted only suf-ficiently for the degree and direction of any tilt and swing to bedetermined. The tendency to tilt and swing shall be correctedby moving the slinging poin ts and the supporting hook a little at

a time, each trme making a trial lift until the position of balanceis obtained (see figure 2).

A.3 Effect of a high centre of gravity

To minimize the risk of toppling, the points of attachment ofthe sling legs shall, where practicable, be above the centre ofgravity of the load (see figure 3).

Where the centre of gravity of the load is above the point ofsling attachment a greater stability will result where the angle (rbetween the’horizontal and the sling leg is substantially greaterthan the angle/I formed between the horizontal and a linebetween the centre of gravity and the attachment point (see

figure 4).

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I S 12735: 1994i so 8792: 1986

Figure 1 - Alignment of centreof gravity

Figure 2 - Example showing effect of centre of gravitymisalignment

Figure 3 - Example of stable load Figure 4 - Example of high centre of gravityrelative to attachment points


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IS 12735 : 1994IS0 8792 : 1986

Annex 6

Determination of load mass(This annex forms an integral part of the standard.)

The mass of a load, m, in kilograms, is determined using thefollowing formula :

m V

where

Y is the volume of the load, in cubic decimetres orlitres;

Q is the density of the material, in kilograms per cubic The densities for the most commonly used materials are listeddecimetre or in kilograms per litre. in table 3.

The volume of a load can be found by dividing it into singleelements (fundamental bodies), for which the volumes can becalculated using one of the formulae given in table 2, and bytotalling the volumes of the elements.

In the cases of complex volumes or heterogeneous material orin other cases where it is difficult to calculate the load mass, themass should be determined by a measuring device, such as adynamometer, which is interposed between the crane hookand the load.

Table 2 - Volumes of fundamental bodies

Fundamental bodies

Sheet (rectangular)

4za

Volume

v = lwr

Sheet (circular)

d--_~___-- __~___

ti

‘4

v= $- XI

0

2

Sheet (triangular)

8


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IS 12735 : 1994IS0 8792 : 1986

Table 2 - Volumes of fundamental bodies (continued)

Fundamental bodies

Prism, bar or profile

@

\

A ,‘I/’@,Y \

A

A i s the surface area of the base

Cylinder

rube

rhin-walled

rhick-walled

Volume

V= Al

nl

V = d n l t

v - r,l

9


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IS 12735 : 1994

IS0 8792 : 1986

Table 2 - Volumes of fundamental bodies konfinuedl

Fundamental bodies I Volume

Sphere

Spherical segment

----___

Spherical shell segmentI’ = d2 + 4h21r

.---

Torus (cylindrical ring)V : n2 Dd2

Cone

10


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IS 12735: 1994IS0 8792 : 1986

Table 2 - Volumes of fundamental bodies (concluded)

Fundamental bodies Volume

Frustum of cone V = (02 + Dd + d21

Table 3 - Densities of the most commonly used materials

Material

AluminiumBrassBronzeCast ironCopperSteel-- ~_~~~ ~~. ~___WoodGlass____ ~~_ -~-~~ ~~~_~ _~BrickConcreteMarbleStoneCement (loose or set)

Soil, drySoil, wetSand, drySand, wet_-_ ~~~~ -Coal

11

Densitykg/dm3

2.785

8.4 to 9,27.48,96

7.8- ._____ ~~0.4 to 0.82,4 to 2.6

1.4 o 2.01.6 to 2,4

2,82.7

1.5 to 3.0.-___ _ _~ ~~~~1.3 to 1.9

2.01,51,65

1.2 to 1.35


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12735 wire rope siling-safety criateria for inspection proc

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