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Safe use and maintenance of chain sling

1. The load should never exceed the working load limit (WLL). Visual inspection is a must before use, make sure that actual loading is matching with WLL of the chain sling.

2. The bigger the angle of sling leg to vertical, the bigger the load borne by the chain legs. In case of exceeding the limit, the chain slings will be overloaded. The recommended calculation charts for selecting chain sling, accessories and lifting round link chain don’t work in these case, other solution should be considered (such as using lifting beam or raising lifting point).
a. The angle of sling leg to vertical is within 0~60° (the angle between two legs is within 0~120°) .Relations between load of leg and angle when lifting 10t.

b. In choke hitch, natural angle is 120°, never change the natural states through force (such as hammer). Under no circumstance shall the included angle between the legs of multi-sling be allowed to exceed 120° in case of local overloading.
3. Ensure the lifting point is over center of gravity without twisting or tipping over.


4. For preventing load from tipping down or incline, the point of lifting must be above of center of gravity, the angle α between the leg and horizontal is large than angle β between joint line (from end fitting to gravity center) and horizontal. When using multi-leg sling, the angle between each leg and vertical should be large than 15°, the angle between legs should exceed 30°.

5. Multi-leg slings exert a gripping force on the load which increases as the angle between the legs increases and this must be taken into consideration. The angle should be reduced considering low strength and toughness of the load, avoiding possible damage to the load.

6. It is not allowed to assemble chains and components of different grades.

7. Ensure the chain is flexible, free from twist, knot or kink.

8. Special order should be made under working condition of impact and severe corrosion (such as caustic atmosphere or acid solution).
9. Working load limit will change with the variation of environmental temperature (see following table). If exceeding 400℃, special order should be made.
Temperature
-30-200℃
200-300℃
300-350℃
350-400℃
400-475℃
475℃以上
Grade of Strength
WLL at Above said temp / WLL at normal temp (%)
M(4)
100
100
85
75
50
--
S(6)
100
90
75
75
--
--
T(8)
100
90
75
75
--
--
10. Non-standard components are prohibited for lifting chain connecting.
11. The load should be fully lifted in bowl of hook (picture 1). Always position hooks facing outward from load (picture 2).

12. Never hanging or winding chain on the hook or hook tip directly.

13. Take the load steadily and slowly, avoid shock loads. Do not leave suspended loads unattended.
14. Single-leg, multi-leg sling or endless sling in choke hitch is recommended when suitable lifting point not available (see picture 1,2 3). If lifting bulk load such as pipe or timber, the chain can be wound one more cycle (see picture 4)


15. Pad sharp corners to prevent bending links and to protect load.
16. When lifting load in basket sling, if load is too huge or too heavy or load may cause damage to chain sling, two same grade and same-sized chains can be used for upper and lower part. It is more cost-efficient since the easily-damaged lower chain can be conveniently replaced if necessary.

17. Do not drag chains over floor or attempt to drag a trapped sling from under a load. Do not use a sling to roll a load.
18. Back hook free legs to the master link or upper connectors when part legs of chain slings are not used.
19. Handling chain slings carefully, never casting, dropping or dragging chain avoiding deformation, surface or inside damage.
20. Store chain slings on a rack and not lying on the ground. Applying some rust-proof oil on the dry chain if needed. The store area should be dry, clean and free from any contaminates which may harm the sling.

21.Inspection of chain slings

a.Before each check the sling should be cleaned thoroughly so that they are free of dirt, oil and corrosion. All cleaning methods are approved that do not affect the base material. Methods should be avoided that, e.g., may cause hydrogen embrittlement, abrasion of material or deformations through which cracks or other surface damage may be concealed.

b.Visual inspection and measurement is necessary before use of new chain slings. Keep a record of all chain slings in use. Regular inspection should be carried out by competent person at interval of six months, recording all finding in the log book and comparing with original data, deciding whether continually using, repairing, replacing or discarding.

22. Inspection Criterion for Lifting Chain

   a.Wear never exceeds 10% of link diameter or thickness of fitting.

   b.Bend or twist should not exceed 10° from normal plane. Otherwise discarding it.

   c.The sling must not be cracked, twisted, knotted or kinked in any way.

   d.Chain and single link stretch never exceed 5% of nominal length.

23. If the following defects occur,the sling must be taken out of service immediately for maintenance and repair:

  a. Deformation or damage on upper and lower terminal fitting.

  b. Individual link stretched too much or appeared local obvious wear.

  c. Cut, crack, discoloring through heat, excess corrosion, bend, deformation or other defects on the link or accessories.

24. Criterion for discarding hook

a. Crack

b. Wear or corrosion is more than 5% of nominal size.

c. The lateral bending of hook is over 10°.

d. The throat opening of the hook exceeds 10% of the nominal.

25.Any self-repairing or reprocessing (welding, heating, heat treatment, surface chemical treatment) is not allowed, may only be carried out by the manufacturer or under supervision of expert from the manufacturer.

26. Ensure carefully keeping all certificates, documents and identification tag. Uncompleted documents, missing identification tag or broken lead-sealing is beyond of the product liability of insurance company.

27. For safety, the company commits to carry out appraising and analyzing for defect and damaged chain sling in their working life. When in appraising or analyzing, all related documents, identification tag and damaged modular should be sent back to the manufacturer.

28. The manufacturer can not take any responsibility for damages occurred by user’s violating regulations and operation procedure.


 
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Add: 19 Diamond North Road, Zhangjiakou, Hebei Province, China
Enterprise E-Mail:postmaster@chaincom.com E-Mail: sales@chaincom.com
Phone: +86 313 2056564 Fax: +86 313 2028507 Post Code: 075025