Multi Leg Slings
The working load limit of any master link should be at least equal to that of the sling. The working load limit of any intermediate link fitted to a 3-leg or 4-leg sling should be at least equal to 1,6 times the WLL of the current chain.
WARNING! If the sling is to be used in an anticipated lift with a lifting angle less then (ß) 45° and with a higher working load limit than usual, it should be specified at time of order.
Length
Tolerance of length
The length (L) should be measured between the "bearing points" or the circumference for endless slings.
The length on each leg should be nominal length with a tolerance of -0/+2 chain link lengths.
The difference in length (usally the same for all legs) between the shortest and longest leg in a mulit-leg sling, assembled with connecting links, should not exceed 10 mm if the sling is 2 m or less, for longer slings a value of 5 mm per metre should be used.
Marking
Slings are provided with a marking plate with the manufacturer's identifying mark, working load limit (WLL), length, date of manufacture and CE-marking.
Dimensioning of Chain Slings
Calculation of working load limit (WLL) for chain slings
When the exact information about weight, lifting angle and position of the centre of gravity is known, you are able to calculate the working load limit using the trigonometric method as follows:
2-leg sling
WLL (ton) = 2 x WLL for single leg sling x cos ß.
3-4-leg sling
WLL (ton) = 3 x WLL for single leg sling x cos ß.
Note: If the load is unform on all 4 legs in a sling the following formula can be used in exceptional cases:
WLL (ton) = 4 x WLL for single leg sling x cos ß.
ß = the legs angle against the vertical surface.
Sharp edges
Edge protectors should be used to prevent sharp edges from damaging the lifting equipment. As a general rule the radius (R) of the edge should be > 2x the chain diameter. When lifting with chain directly on lugs it is recommended that lug diameter greater than 3x the pitch of the chain should be used. If a lug diameter is less than this, the WLL must be reduced by 50%.
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Edge R
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R > 2x chain Ø
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R > than chain Ø
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R = chain Ø
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Load factor
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1
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0,7
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0,5
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Working Load Limit (WLL) - Grade 10
General: Tables specify the maximum load for common chain dimensions in grade 10 for use in slings.
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Chain
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WLL in ton for chain grade 10
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Ø
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Single
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2-leg & Basket*
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3-4-leg*
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Endless
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mm |
Straight |
Choked |
Basket
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0°-45°
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45°-60°
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0°-45°
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45°-60°
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Choked |
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6
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1,4
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1,12
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2,8
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2
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1,4
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3
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2,12
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2,24
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7
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1,9
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1,5
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3,8
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2,65
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1,9
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4
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2,8
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3
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8
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2,5
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2
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5
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3,55
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2,5
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5,3
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3,75
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4
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10
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4
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3,15
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8
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5,6
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4
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8
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6
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6,3
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13
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6,7
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5,3
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13,4
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9,5
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6,7
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14
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10
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10,6
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16
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10
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8
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20
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14
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10
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21,2
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15
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16
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19
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14
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11,2
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28
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20
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14
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30
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21,2
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22,4
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22
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19
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15
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38
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26,5
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19
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40
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28
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30
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26
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26,5
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21,2
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53
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37,1
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26,5
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55,6
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39,7
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42,4
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Factor (KL)
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1
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0,8
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2
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1,4
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1
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2,1
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1,5
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1,6
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*When multi-leg chain slings are used in choke hitch - reduce value by 20%
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Working Load Limit (WLL) - Grade 12
General: Tables specify the maximum load for common chain dimensions in grade 12 for use in slings.
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Chain
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WLL in ton for chain grade 12
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Ø
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Single
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2-leg & Basket*
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3-4-leg*
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Endless
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mm |
Straight |
Choked |
Basket
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0°-45°
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45°-60°
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0°-45°
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45°-60°
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Choked |
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7
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2,36
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1,9
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4,72
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3,35
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2,36
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5
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3,55
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3,75
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8
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3
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2,36
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6
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4,25
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3
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6,3
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4,5
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4,75
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10
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5
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4
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10
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7,1
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5
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10,6
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7,5
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8
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13
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8
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6,3
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16
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11,2
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8
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17
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11,8
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12,5
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Factor (KL)
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1
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0,8
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2
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1,4
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1
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2,1
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1,5
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1,6
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*When multi-leg chain slings are used in choke hitch - reduce value by 20%
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Allmänt om kättingredskap
Chain slings
General: Chain slings are used when wear resistance and durability is required. A chain sling is flexible. It is possible to shorten, it has many components to choose from, it can withstand high temperatures, and is easy to store.
Material/Design: For manufacturing of chain slings, short link chain grade 8, 10 or 12 shall be used. In multi-leg slings the rope dimension and grade shall be the same for each leg. The working load limit for assembled forging shall be at least the same as working load limit for the current chain. Master link with intermidiate link should always be used to 3- and 4-leg slings.
Working temperature: See "Use and maintenance".
Safety factor: 4:1.
Use in Adverse Environments
Temperatureaffects on working load limit (WLL)
Account should be taken to the maximum temperature that can be reached by the chain sling in service. This is difficult in practice but underestimation of the temperature should be avoided. The table below summarises the necessary de-rated working load limit due to temperature.
Chain slings in grade 8 and 10 will not be negatively affected by temperatures down to -40 °C which result in the fact that no reduction of the working load limit are needed. When chain slings are to be used in temperatures below -40 °C CERTEX should be consulted.
The use of a chain sling in grade 8 and 10 within the permissible temperatures ranges given in the table does not require any permanent reduction in working load limit. Working load limit are valid again when the chain sling is used in normal temperature again. If the chain sling reach temperatures that highly exceed the maximal allowed according to the table it should be discard or be returned to CERTEX for measure.
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Grade
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Allowed load expressed in % of working load limit (WLL)
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temperature (t) Cº
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-40 - 200
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201 - 300
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301 - 400
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401 - 475
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8
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100
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90
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75
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Not allowed
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10
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100
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Not allowed
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Not allowed
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Not allowed
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10+
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100
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100
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100*
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Not allowed
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*Grade 10+ only allowed up t=380°C
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Acidic conditions
Chain slings in grade 8 and 10 should not be used either immersed in acidic solutions or exposed to acid fumes.
Chain slings should, for the same reason, not be warm-galvanized or exposed to electroytic finish without permisson from CERTEX.
Chemical affects
CERTEX should be consulted in case the slings is to be exposed to chemicals combined with high temperature.
