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UDC 621*86*065’3 : 677’72 IS : 2762 - 1982
Indian Standard
SPECIFICATION FOR WIRE ROPE SLINGS AND SLING LEGS
( First Revision )
1. Scope- Specifies dimensions, construction, loading, tests and marking of one-, two-, three- jnd four-leg slings for wire ropes of nominal diameter 8 to 44 mm, having legs of the following :ypes:
a) Single part spliced,
b) Double part spliced endless, and
c) Double part grommet.
!. Single Part Spliced Sling Legs
2.1 Rope -The wire rope used in the manufacture of single part spliced sling legs shall consist of six round strands over a fibre core, right-hand ordinary lay, un-galvanized or galvanized as-required b_y the purchaser, and shall conform to IS : 2266-1977 ’ Specification for steel wire ro~pes for general engineering purposes ( second revision ) ’ with wires of tensile designation 1770.
2.2 Construction of Rope -The rope shall be of one of the following constructions:
Rope Designation
6 x 19 Group
6 x 37 Group 8 x 26 Group 6 x 31 Group 6 x 36 Group 6 x 41 Group 6 x 19 Group
--
Construction
6 X 19 ( 12/6/l ) 6 x 19 (9/9/l ) 6 x 19 (12/6 + 6F/l ) 6 x 37 ( 18/12/6/l ) 6 X 26 ( IO/5 & 5/5/l ) 6 x 31 ( 12/6 & 6/6/l ) 6 x 36 ( 14/7 & 7/7/l ) 6 x 41 (16/S & 8/8/l ) 8x 19(9/9/l) 8 x 19 (12/6 + 6F/l )
Core
Fibre Steel
X X X X X X X X x X X X X X X X - X - X
2.2.1 For sling legs up to about 20 mm diameter, a rope in the 6 x 19 Group will generally provide sufficient flexibilty and will offer good wearing properties. is generally preferred on account of its increased flexibility.
For larger sizes, 6 x 37 Group
2.3 Minimum Length of Leg - To provide adequate flexibility and to allow splicing, the effective length of a single part spliced sling leg shall be not less than 70 diameters of the rope,
2.4 Safe Working Load-For normal conditions of service, the safe working load shal~l not exceed one-sixth of the minimum breaking strength of 6 X 37 construction wire rope with wires of tensile designation 1770 conforming to IS : 2266-1977 ( see also Appendix A ).
2.5 General Requirements
2.5.1 Thimbles - Each end of each single part spliced sling leg shall be fitted w~ith a galvanized thimble off the ordinary or reeving type conforming to IS : 231.51978 ‘ Specification for thimbles for wire rope/s (first revision 1’ appropriate for the size of the rope, and securely spliced thereto,
2.5.2 Sldlicing - Each splice shall have at least five tucks, three tucks with a whole strand of the ropeandltwo tucks with one-half of the wires, cut out of each strand. The tucks shall be over and under ag#nst the lay of the rope. The splice shall be tightly drawn and neatly made,
Adopted 26 November 1981 I
@ March 1983, ISI I
INDIAN STANDARDS INSTITUTION MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
Or 7
IS : 2762 - 1982
3
Note-The approximate length of a five-tuck splice exclusive of the thimble is 20 diameters of the rope. Alter- natively, the splicing may be done by mechanical means or swaging, subject to agreement between the supplier and the purchaser.
2.5.3 Serving-That portion of the splice which contains the wire ends shall be neatly and effectively served with spun yarn or seizing strand to give protection to the user in handling. Alter- natively, when required by the purchaser, the full length of the splice taper may be served.
3. Double-Part Spliced Endless Sling Legs
3.1 Rope - The wire rope used in the manufacture of double part spliced endless sling legs shall consist of six round strands over a fibre core, right hand ordinary lay, bright or galvanized as required by the purchaser.
3.2 Construction of Rope - The wire rope shall be of one of the constructions specified in 2.2.
3.3 Minimum length of Leg- To provide adequate flexibility and to allow splicing, the effective length of a double part endless sling leg shall be nof less than 70 diameters of the single part of the spliced endless sling leg when using ordinary thimbles, and not less than 80 diameters when using reeving thimbles.
3.4 Safe Working Load -For normal conditions of service, the permissible working load on a single part of a spliced endless sling ~leg shall not exceed one-eighth of the minimum breaking load of a 6 x 37 construction wire rope conforming to IS : 2266-1977.
3.5 General Requirements
3.5.1 Thimlbles -Each end of each double part spliced endless sling leg shall be fitted with a galvanized thimble of the ordinary or reeving type conforming to IS : 2315-1978. Ordinary thimbles shall be two (and where necessary, three ) sizes larger and reeving thimbles one size larger~than the nominal size specified in IS : 2315-1978. The scores ( rope grooves ) of these thimbles may be closed in to suit the diameter of the rope and hits serving ( see 2.5.3 ).
3.5.2 Splicing - The initial length of straight rope shall be circled with two ends overlapping. The ends shall then be spliced, each to each, with a five-tuck splice, making the complete splice ten tucks overall. Each five-tuck splice shall be made ~with three tucks with a whole strand of the rope and two tucks with one-half the wires cut out ofeach strand. The tucks shall be over and under against the lay of the rope. The splice shall be tightly drawn and neatly made.
Note -The approximate length of a ten-tuck splice is 40 diameters of the single part rope. Alternatively, the splicing may be done by mechanical means of swaging, subject to agreement between the supplier and the purchaser.
3.5.2.1 Unless specified otherwise by the purchaser, one end of the ten-tuck served splice shall be adjacent to, but clear of, the thimble in the finished sling leg.
3.5.3 Serving - At those portions of the spliced endless rope which will seat in the thimble grooves (see 3.5.1 ), the single part of the rope shall be served with spun yarn to suit the grooves in the oversize thimbles, and to provide a foundation for the throat seizing ( see 3.5.4 ). The length of each serving shall be such that in addition to the portion in contact with the thimble groove, it underlies and projects three rope diameters beyond the throat seizing (see 3.5.4 and Fig. IB). Those portions of the splice~which contain the wire ends shall be neatly and effectively served with spun yarn or seizing strand to give protection to the user in handling. Alternatively, when required by the purchaser, the full length of the splice taper may be served.
3.5.4 Seizing - The spliced endless rope shall have its two parts brought into parallel contact with the two served portions forming the bight at each end. A thimble shall be throat seized close up to its point into each bight of the rope by means of annealed quality galvanized seven-wire seizing strand in accordance with Table 1. The overall length of each throat seizing shall be not less than six diameters of the single part rope. The seidng shall be tightly~drawn and neatly made, free frorn projections liable to cause injury when handling the sling. Where the sling leg exceeds 100 diameters of the single part rope in length, a central seizing equal In length to three diameters of the single part rope shall also be provided. In the case of longer sling legs, such intermediate seizing shall be provided at intervals not greater than 72 diameters of’the single part of the sling leg.
2
IS : 2762 -1982
TABLE 1 SIZES OF GALVANIZED ANNEALED SEVEN-WIRE STRAND FOR THROAT SEtZING OF DOUBLE PART SLING LEGS SPLICED ENDLESS AND GROMMET
(Clauses 3.5.4 and 4.4.4 )
Single Part Rope Diameter
mm
Size of Strand, Seven Wires Each of Dia
mm
Up to and~including 8 0.46 Over 8 up to and including 12 0.71 Over 12 up to and including 18 0.91 Over 18 up to and including 24 t-02 Over 24 up to and including 29 1’22 Over 29 up to and including 33 1.42 Over 38 up to and including 44 1.63
4. Double Part Grommet Sling Legs
4.1 Strand
4.1.1 The strand used in the fabrication of double part grommet sling legs shall be left-hand lay, bright or galvanized as required by the purchaser.
4.1.2 The strand shall be one of those specified for the ropes in 2.2.
4.1.3 Strength of sfrand - The single wires of the strand shall be subjected to the tests specified in IS : 6594-1977 ‘ Technical supply conditions for steel wire ropes and strands ( first revision )’ and thestrand itself to a tensile test. The minimum breaking load of the strand shall be not less than one-sixth of the minimum breaking load of ropes made up from similar strands with wires of tensile designation 1770 for the particular construction plus 5 percent.
4.1.4 Fabricafion -The left-hand lay strand shall be laid into a grommet of uniform right-hand lay, the cross-section of which shall be six strands over one central strand. The maximum length of lay of the strand in the grommet when measured in the straight shall not exceed 8 times the diameter of the grommet made rope. The two ends of the strand shall ~butt in the centre of the rope. The crossing of the tucks shall be well and neatly made, due care being taken not to bruise or damage the wire.
Note-While the finished grommet has a central wire strand, this strand is not considered to add to the strength of the rope.
4.2 Minimum Lengfh of Leg - To provide adequate flexibility, the effective length of a double-part grommet sling leg shall be not less than 40 diameters of the single part of the grommet when using ordinary~thimbles, and not less than 50 diameters when using reeving thimbles.
4.3 Safe Working Load - For normal conditions of service, the permissible working load of a single part of the grommet which complies with 4.1.1 and 4.1.2 shall not exceed one-eighth of the minimum breaking load of 6 x 37 construction rope of similar size with wire of tensile designation 1770 conforming to IS : 2266-l 977.
A4 General Requiremenfs
4.4.1 Thimbles - Each end of each double~part grommet sling leg shall be fitted with a galvanized thimble of the ordinary or reeving type in accordance with IS : 2315-1978. Ordinary thimbles shall be two ( and where necessary, three) sizes larger and reeving thimbles one size larger than the minimum size s-pecified in IS : 2315-1978. The scores ( rope grooves) of these thimbles may be closed in to suit the diameter of the rope and its serving (see 4.4.2).
4.4.2 Serving - Atthose portions of the grommet which wit1 seat in the thimble grooves (see 4.4.3), the single part of the rope shall be served with spun yarn to suit the grooves in the oversize thimbles, and to provide a foundation for the throat seizing (see 4.4.4). The length of each serving shall be such that, in addition to the portion in contact with the thimble groove, it underlines and projects three rope diameters beyond the throat seizing (see 4.4.4 and Fig. lC_).
4.4.3 Posit/on of tuck -The crossing of the tucks shall be adjacent to, but clear of, one thimble and under the throat seizing in the finished sling leg.
IS : 2762 - 1982
4.4.4 Seizing - The finished grommet shall have its two parts brought into parallel contact with the two served portions forming the bight at each end. A thimble shall be throat seized close up to its point into each bight of the rope by means of annealed quality seven-wire seizing strand in accordance with Table 1. The overall length of each throat seizing shall be not less than six diameters of the single part of the grommet. The seizing shall be tightly drawn and neatly made, free from projections liable to cause injury when ‘handling the sling. Where the sling leg exceeds 100 diameters of the single part in length, a ~central seizing equal fin length to three diameters of the single part shall be provided. in the case of longer sling legs, such intermediate seizing shall be provided at intervals not greater than 72 diameters of the single part of the sling leg.
5. Components
5.3 Thimbles - Thimbles shall be either ordinary or reeving and shall conform to 4s : 2315-1978.
5.2 Hooks - Eye hooks shall be of mild steel in accordance with IS : 2758-1969 ‘Specification for mild steel point hooks for use with wire rope thimbles’ or of high tensile steel according to IS : 2759-1969 ‘ Specification for higher tensile steel point hooks for use with wire rope thhnbies’.
5.3 Rings
5.3.1 Mild steel rings - Mild steel rings shall be made from steel C20 of IS : 1570-1961 ‘Schedules for wrought steels-for general engineering purposes ‘. The rings may be either weldless or welded.
5.3.2 When welded, the mild steel rings shall be made by one of the following methods :
a) Electrical resistance butt welding
b) Flash-butt welding
c) Atomic hydrogen welding 1 d) Inert-gas shielded-arc welding 1
Suitable for sizes above 50 mm diameter. e) Submerged-arc welding
f) Covered electrode welding 1
J
5.3.3 The rings shall be smoothly finished ail round, and if they are welded, care shall be taken to avoid porosity and to ensure penetration and fusion throughout.
5.3.4 When inspection by radiography is required by the purchaser, this shall be specified at the time of enquiry and order.
5.3.5 The mild steel rings shall be normalized by heating uniformly in a furnace until the whole of the metal has attained a temperature between 880°C and 910°C. The rings shall then be withdrawn from the furnace and allowed to cool in still air.
5.3.6 in all other respects, the mild stee~l rings shati comply with the req~uirements specified in IS : 2760-1972 ‘ Specification for mild steel chain slings ‘.
5.3.7 Higher tensile steel rings -Higher tensile steel rings shall comply with the requirements specified in IS : 2760-1972.
The dimensions of the rings, whether mild steel or higher tensile steel, shall be in accordance with Table 2 for main rings and with Table 3 for intermediate rings.
Note -Where rings which differ In dimensions from those given in Table 2 Dr 3 are required, this selection shall be done having regard to safe working load and required internal diameter. The following formula gives relationship between safe working load, internal diameter and the nominal diameter of the material in the ring:
Safe working load = 0.062 x f x d3
D + 04 d
When $ Is less than 2.55, the above value is to be multlplisd by VP2 ( $1
2 +
where
f = nominal extreme Abre (tensile) stress at the safe working load in MPa,
= 186’3 MPa for wrought Iron and mild steel rings,
= 265-O MPa for higher tensile steel rings,
d = nominal diameter of material in ring in mm, and
D = internal diameter of ring In mm.
+roof load = 2 x safe working load.
4
t
IS : 2762 - 1962
TABLE 2 lIlAIN RINGS FOR SLINGS, WROUGHT IRON, MILD STEEL AND HIGHER TENSILE STEEL
(Clauses 6.3.7, 6.2 and 6.4)
Safe Ring Dimensions Load Working
Load Internal Diameter of Material E;P;;;;
Diameter on Crane ot Ring Wrought Iron and Higher Tensile
Mild Steel Steel kN mm mm mm kN
(1) (2) (3) (4) (5)
5 100 18 16 30
7 100 22 18 30
IO 100 22 22 30
15 125 26 24 50
20 125 29 26 50
25 125 32 29 50
30 125 35 29 50
40 150 41 38 75
50 150 44 38 75
60 175 48 44 75
80 200 54 51 100
100 200 60 54 100
125 225 67 60 125
150 250 14 61 150
Note 1 -Each ring in the above table is suitable for a one-leg, two-leg or four-leg sling when the safe working load of the combined legs (at 0” ) is equal to that of the ring (see Appendix A ).
Note 2-Standard thimbles can be used with att the rings for single leg slings and with the 125 and 150 kN rings for two-leg stings. Smaller two-leg slings and all three- and four-leg slings will require thimbles larger than the nominal size in IS : 2315-1978. In such cases, the rope shalt beserved with spun yarn to suit the groove of the oversize.
TABLE 3 DIMENSIONS FOR INTERMEDIATE AND MAIN RINGS FOR FOUR-LEG SLING, MILD STEEL AND HIGHER TENSILE STEEL
( Clauses 5.3.7 and 6.2)
Safe Working Load of Four-leg
Sling
kN
(1)
20
30
40
60
80
100
125
150
.-
-
-
Main Rings for Four-leg Sling
i Diameter of Material Internal Diameter
of Ring
mm
(2)
125
125
150
175
200
200
225
a 250
Mild steel mm
-
. -
-
Higher tensile steel mm
(3) (4)
30 27
35 30
41 37
47 44
54 50
61 54
67 61
73 67
7-
I- Intermediate Rings for Two-Leg Sling
internal Diameter of Ring
mm
(5) -~-
63
75
75
100
112 . 125
140
150
i Diameter of Material
- _
--
Mild steel mm
Highytesnsile
mm
(6) (7)
20 17
22 21
25 24
32 29
37 34
41 - 37
44 41
50 44
IS 8 2762 - 1982
6. Sling Assemblies
6.1 The assembled slings shall be of one of the forms shown in Fig. 1 to 6.
6.2 Components Attachment - The components fdr all slings shall be splic;ed or seized ( as may be appropriate) directly to the slHng leg, with the exception of four-leg slings, which shall comp_rise 2 two-leg assemblies complete with intermediate rings ( see Table 2 or 3 ) and main ring ( see Table 2 ). The welding and heat treatment of the rings (see 5.3 ) shall be completed before the wire~rope legs are attached.
6.3 Effective Length - The effective length of all slings and sling legs shall be the length between the bearing points of their terminal components, whether thimble, ring or hook ( see Fig. 1 to 6 ).
j
EFFECTIVE LENGTH
1A 1B 1c
1 A Single Part SpUced
1 B Double Part Spiked Endless
4C Double Part Grommet ’
FIG. 1 ONE-LEG WIRE ROPE SLINGS WITH ORDINARY THIMBLES AT BOTH ENDS
6
EFF .LE
2A -?B 3A 38 2A Ordinary Thimble at One End,
Reeving Thimble at Other End 3A Ring at One End, brdinary
2B Reeving Thimbles at Both Ends Thimble at Other End
3B Ring at One End, Hook at
EFFE LE
FIG. 2 OkE-LEG WIRE ROPE SLINGS Other End
FIG. 3 ONE-LEG WIRE ROPE SLINGS FIG. 4 TWO-LEG WIRE ROPESLING WITH MAIN RING
AT ONE END, HOOKS AT OTHER ENDS E
c IS : 2762 - 196i
7. One-Leg Slings
.7.1 One-leg sling shall comprise one of the three types of leg as follows:
a) Single part spliced ( see Z),
b) Double part spliced endless-( see 3 ), and
c_) Double part grommet ( see 4 ).
7.1.1 Single part spliced sling legs shall be fitted with the following components:
Ref to
Fig. 1A
Fig. 2A
a) Ordinary thimble at both ends
b) Ordinary thimble at one end, reeving thimble at other end
c) Reeving thimble at both ends
d) Ordinary thimble at both ends, ring at one, and
e) Ordinary thimble at both ends, ring at one end, hook at other end
Fig. 2B
Fig. 3A
Fig. 3B
7.1.2 Double part spliced endless or grommet sling legs shall be ~provided with the following components:
a) b)
cl d) e)
Ordinary thimble at both ends
Ordinary thimble at one end, reeving thimble at other end
Reeving thimble at both ends
Ordinary thimble at both ends, ring at one end
Ordinary thimble at both ends, ring at one end, hook at other end
Ref to
Fig. 1B or 1C
Similar to Fig. 2A
Similar to Fig. 28
Similar to Fig. 3A
Similar to Fig. 3B
8. Two-, Three- and Four-leg Slings
8.1 Each sling shall consist of two or more of one of the following types of legs:
a) Single part spliced ( see 2 ),
b) Double part spliced endless ( see 3 ), and
C) Double part grommet ( see 4 ).
8.2 Terminal Ends - The extremities of the legs shall be thimbled and spliced over the eye of the hook in accordance with IS : 2758-1969 or in accordance with IS : 2759-1969.
8.3 Pairing - The legs of a sling shall be as nearly as possible of equal .effective lengths ( see 6.3 ), and the discrepancy between the legs of any sling shall not exceed that given by the following formula:
Maximum discrepancy = 6 + d/3 + 3’4 L Min ( in mm )
where
d - diameter of single part rope in the leg in mm, and
L = length of leg in metres.
Note-Where smaller discrepancies than those given by the formula are required by the purchaser, these shall bethe subject pf agreement between the purchaser and the manufacturer.
8.4 Two-Leg Slings -The two-leg with the terminal hooks ( see 8.2), shall at their other ends be each thimble’d and spliced over a ring ( see Table 2 ) having a permissible working load of not less
.I_ than twice the permissible working load of one leg in accordance with Tables 4 and 5.
i
i
IS : 2762 - 1982
8.5 Three-Leg Slings - Each three-leg sling shall comprise three-leg with the terminal hooks at one end as in the case of two-leg slings, each of the other ends being thimbled and spliced over a ring which has a permissible working load of not less than three times the permissible working load of one leg, in accordance with Table 4 or Table 5.
8.6 Four-Leg Slings - Each four-leg sling shall comprise two complete two-leg_slings, with ring and terminal hooks assembled with a main ring which has a permissible working load of not less than four times the permissible working load of one leg in accordance with Table 4 or Table 5.
Note -SShack/es- While standard two-, three- and four-leg strngs are specified to be provided with a terminal hook on each leg, there are instances whare such hooks can be omitted with advantage, and the thimble end of the legs attached direct to the load by means of shackles.
Where sling legs terminating in thimbles are to be used with detachable shackles having the eye ends and pin outwards, it may be necessary to use a thimble larger than the nominal size given in IS: 2315-1978 to enable the shackle eyes to pass through the thimble.
It is permissible, if so desired, to close in the scores ( rope grooves ) ef the oversize thimbles, but allowance must be made for the thickness of the serving when such serving is specified.
TABLE 4 NOMINAL BIZES OF WIRE ROPE FOR SINGLE PART SPLICED SLING LEGS
Safe Wo;$ing Load Nominal Rope Die mm
5 . 8 9
:8 14 ;: 28 18 33 20 38 :: 43 82 28
1:: 36 40 126 40 150 44
.I^&^ P-1- . ..^_ I.!__ ,^^A I- ---l:-^LI_ Z_-..-_.?__I LIA_L
Minimum Effective Length mm ’
550 775
1 880 000 1 200 1 340 1 460 1660 2.000
2 2 450 660 2 900 3120
1 TABLE 5 NOMINAL SIZES OF WIRE ROPES FOR THE SINGLE PART OR DOUBLE PART SLING LEGS SPLICED ENDLESS AND GROMMET
Safe Working Nominal Load of Com- Single piete Double Part Rope
Part Single Diameter Leg
kN mm
(1) (2) (3) (41 (5) (6)
f-5 10
;: 25
:: 50 60 80
100 125 150
8
lo” :‘4 16 18 20
:
:: 36 40
560 560 650 890
1000 1 120 1 220 1 330 1560 1660 2 000 2 220 2430 2 670
630 630 760
1 020 1140 1 270 1 400 1530 1780 1900 2 280 2 540 2 800 _ ___ 3 osu
315 315 380 510 570 635 700 765 890 950
1 140 1 270 1 400 1525
410 410 480 635 710 800 880 950
1 120
: :03: 1 590 1 750 1900
Minimum Effective Length I
Spliced Endless I Grommet I
Ordinary Reeving Ordinary thimbles thimbles thimbles
mm mm mm
Note - Safe working load is appiidabie for vertical hitch.
Reeving thimbles
mm
10
c IS : 2762 - 1982
9. Marking
9.1 Each completed sling shall be permanently marked by the maker, so that it can be identified with the warranty (see Appendix B )*
a.2 Warranfy -With -each consignment of slings the manufacturer shall furnish a warranty in the form shown in Appendix B.
1
Y APPENDIX A
( Clause 2.4 )
RECOMMENDATION ON WORKING LOAD
A-l. Two-Leg Slings
A-l.1 The load lifted by two-leg slings shall be reduced as the angle between the legs increases. An included angle of 60” is the most easily visualized, as the distance between the extremities of the legs is equal to the length of the leg. An included angle of 120” is the maximum which should be permitted, and when the legs are 120’ apart, the permissible working load is one-half of that at O”, and reduces the load capacity of the sling to that of one leg.
A-1.2 The loads given in Table 6 are the greatest which can be lifted without exceeding the specified safe working load of the sling leg.
A-2. Safety Precautions (Applicable to All Slings )
A-2.1 It is recommended that whenever possible, the angle between the legs of a two-leg sling should not exceed 90”.
A-2.2 Snatch or shock loading is detrimental; steady application of the load at the start of each lift will avoid risk and prolong the life of the sling. corners or small radii.
The sling legs should not be bent round sharp The practice of placing a hook or shackle round the rope to provide a bight
is also to be deprecated. Slings should not be dragged along the floor or ground and should never be pulled from under a load which has to be lowered and is resting on the sling.
A-2.3 When in use, it is essential that there be free articulation of components, and that they be in correct position and alignment.
A-2.4 The slings should be put into a dry store after use, but should be inspected before so doing. If any malformation-has taken:place, it should be remedied and if it cannot be remedied, the sling should be scrapped. Bending around sharp corners must be avoided. With loads that have sharp corners, any acute bend can be eliminated by packing over the corners with wooden battens or a thick canvas or some other similar arrangements. When reeving slings, care must be taken to ensure that all legs have a direct toad. It should be made sure that all shackles, ring links and hooks have a direct bearing and a true lead and are not bending or wedged up. Such errors in reeving should be corrected in time, because when the weight is taken, there may be a shock load and this can be sometimes suffXeritly serious to cause some part to break.
A-3. Three-Leg Slings
A-3.1 Three-leg slings are often used for lifting articles which do not lend themselves to lifting by single Or two-leg slings. Owing to the variety of conditions under which such slings may be used, it Is not possible to specify safe working loads, Users are recommended to draw up their own tables of safe working loads with due regard to the particular conditions of service.
A-3.2 Assuming equal load distribution on each leg of a three-leg sling (a condition rarely operative), the table of safe working loads for two-leg slings can be used to deduce the load for a three-leg sling for any given angle between the legs and the vertical, for example, for an angle of
30” between any leg and the vertical F= 30” ( see Fig. 7 1, the load is 50 percent greater than for a
two-leg sling with an included angle of 60”.
Eii AS load distribution may be unequal, caution is advisable in fixing appropriate safe working .
IS : 2762 - 1962
A-4. Four-Leg Slings
A-4.1 In making allowance for the angle of four-leg slings, assuming equal load distribution, the angle which applies is that between the diagonally opposite legs ( see Fig. 7 ).
FIG. 7 INCLUDED ANGLE a, BETWEEN THE LEGS OF THREE-LEG AND FOUR-LEG SLINGS
A-4.2 They are also used for lifting rigid articles, such as structures, castings, etc, where the centre of gravity of the load is not central with the four points of suspension. Also, the slinging points may be at different levels, resulting in unequal angles and loading of the sling legs. In such instances, users should evaluate the appropriate safe working loads to suit the particular conditions of service, care being taken that the tension in the heaviest loaded leg does not exceed the safe working load of one leg, as given In col 1 of Table 6 of safe working loads for two-leg slings, the table being used to deduce the proportionate effect due to sling angularity. It is essential in the case of any multiple-leg sling that the safe working load of any leg is not exceeded.
(1)
5
7.5
10
15
20
25
30
40
50
60
75
TABLE 6 SAFE WORKING LOADS FOR TWO-LEG SLING
( Clauses A-l .2 and A-4.2)
i-
00
kN
(2) ~(3)
10 10 00
15 15.00
20 20.00
30 30.00
40 40.00
50 50’00
60 60.00
80 80.00
100 1 oo*oo
120 120*00
150 150*00
1 Lower Reduction Facto!
Approximate Reduction Percent
1.000
0
-
-_
- _
-_
Included Angle between Legs, CL
3o” 60”
kN kN
(4) (5)
9.65 8.65
14’50 13.15
19.60 17.50
29.00 26.30
38.60 35.00
48.30 43.80
58.00 52.50
77.80 70.00
96.60 86.60
116.00 105.00
145~00 131.50
OS966 0,866
3.5 13.5
Note- Safe working load is for vertical hitch.
- 9o” 1200
kN N
(6) (7)
7.05 5.00
10.00 7.50
14’10 15.00
21.20 19~00
28’30 20.00
35.30 25.00
42.40 30.00
65.50 40.00
70.70 50.00
84,80 60.00
106.00 75.00
0’707
29.5
0.500
50
-_
12
IS : 2762 - 1982
APPENDIX 6
( Ckfuses 9.1 and 9.2 )
FORM OF WARRANTY
Number of Slings *Description of Slings tMaterial of l-looks Identification ~Mark on and Rings Slings
We hereby warrant that the slings described above comply in all respects with IS : 2762 - 1981.
The rope and components have been tested and are found to comply with the relevant Indian Standards.
We hold test certificates for the rope and for the hooks and rings from which the slings have been assembled.
Signature ,..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l . .
Date . . . . . . . . . ._ . ..i . . . . . . . . . . . . . . . . . . . . . . . . . .
*State type, size and length of sling. @tate whether hooks and rings. are made of wrought iron, mild steel, or higher tensile steel.
EXPLANATORY NOTE
This standard was originally published in 1964 and has been revised to incorporate latest developments in the field.
This standard is limited to three types of sling legs, that is, single part, double part spliced endless and double part grommet, made of construction of wire ropes all of which are of w’rre of one tensile strength, that is 1 770 N/mm2, assembled with appropriate terminal fittings suitable for most of the normal purposes. The effect of the foregoing limitations is to standardize the size of the rope for any given working load and to facilitate the correct selection by the slinger.
Plain loops without thimble reinforcement are not recognized in this standard.
ln this standard, the splice taper is shown as served for the entire length (see Fig. 1 to 6 ). This is not mandatory.
It is realized that the minimum effective lengths for double part ropes fitted with reeving thimbles (see Table 5) are such that the reeving of one end through the other is impracticable; this information is given to provide for those cases where a thimble larger than the ordinary is required, for engaging in large iron works, for example, two thimbled ends having to connect to a ramshorn or ordinary hook, where headroom is restricted.
In the case of doublepart sling legs and multiple-leg slings, it has been necessary to specify oversize thimbles to provide effective strength or to allow assembly with a ring of the specified size and safe working load. It is, however, permissible, if SO desired, to close in the scores (rope grooves) of the oversize thimbles, but allowance shall be made for the thickness of the serving when such serving is specified.
The following rope constructions are not included, as they are not commonly used in engineer- ing operations.
Designation Construction of Strand
6 x 24 Group 15 wires over 9 wires over fibre ( 15/9/Fibre )
6 x 37 Group 14 wires over 7 plus 7 filler wires over 7 over 1 (14/7 + 7F/7/1 )
15 wires over 15 wires over 6 over 1 ( 15/15/6/l )
16 wires over 8 plus 8 filler wires over 6 over 1 (16/8 + 8F/6/1)
An Indian Standard on methods for splicing of w~ire ropes ( IS : 5245 - 1969 in two parts ) is available and hence it is suggested that the methods as given in this standard should be followed for splicing of wire ropes.
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Printed at New India Printing Press, Khurla, India
