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Alloy lifting chain
Alloy chain slings
Find out about types of alloy chain slings and how to select the correct ones to use.
Alloy chain slings are manufactured and tested in accordance with Australian Standards AS3775 and AS3776 using quality lifting chain and components.
Refer to:
- AS 3775.1 Chain Slings for lifting purposes T (80) & V (100)
- AS 3775.2 Chain Slings for lifting purposes T (80) & V (100).
All slings come with a Working Load Limit tag and a test certificate.
Alloy chain slings are made from components matched to suit a variety of applications.
Alloy chain slings are used when:
- the load may be unbalanced and requires an adjustable sling, or
- the load may be subject to cut, sharp edges or shock loading.
Alloy chain slings can be made to any configuration and are always made from short link lifting chains to AS2321.
Variations include:
- the number of legs
- the length of legs
- the fittings attached to the chain.
Typical alloy chain assemblies to AS3775
Below are common types of alloy chain slings:
Single leg chain sling
Two leg chain sling
Alloy lifting chain and components. All alloy chain slings should be supplied with NATA test certificates and safe use data sheets.
There are regular and large series oblong links (also known as Head Links or Master Links). The ring will have a number stamped to correlate with other components.
The connector, commonly known as a 'Hammerlock' connects to the ring as well as the chain and shortener (of which there are two types shown).
The hooks (of which there are a variety of types) are connected to the chain as either a clevis connection or alternatively with a hammerlock.
Three leg chain sling
Four leg chain sling
Sling selection
The following factors should be considered when making a sling selection:
Load: mass, shape balance and need for adjustment
You can't select the correct sling for the job unless you know the weight or mass. See packing notes, transport notes or labels on packages. Or calculate the weight of the load.
Also check if the load is balanced or equally distributed. If not, you may need “adjustable type slings” achieve a balanced and safe lift.
Headroom
Always consider head room when selecting a sling length. You may run out of usable room unless the sling is adjustable in length.
If using a serial hoist, they may need the chain block to be “close-coupled". This removes the top hook assembled and saves on headroom. For example, if headroom is limited inside a structure or building.
Frequency of use: life of sling
The life of a sling can be severely impacted by the number of cycles of use. Being used 8-10 times per day may require protective sleeves or higher grade fittings.
The "periodic inspection frequency" is different depending on the frequency of use. For example, 1-5 lifts per week is 12 monthly inspections. 26-200 lifts per week is 3 monthly inspections.
Type of load: steel, machinery, timber, shipping, containers, crates, steel fabricated sections, fragile or items subject to marring
Depending on the type of material being lifted you may need lower or higher grades of alloy chain for durability. Be aware of slippery surfaces, such a steel. This can limit safe angles of use.
Length of sling
Leg length can be fixed or adjustable with shortening hooks. The length can impact on workspace. Normally, chains are supplied as effective length from top head ring to the hook, not just the length of the chain leg itself.
Method of slinging (direct, choke hitch or basket hitch)
Depending on information gathered before selecting the attachment method (weight, shape, balance, surface finish and headroom), you need to consider how to attach to the load. This will impact on leg length, type of end fittings and top links.
Environment: acid or alkaline corrosion, heat and other factors
Alloy should never be used in acid or alkaline environments. Use in these environments can cause hydrogen embrittlement. Work areas should never be above 400 degrees Celsius, as derations will apply. Take extreme care.
Available storage for slings
Alloy chains, like all lifting gear, should be stored in racks, shelves and cupboards. They should be stored up off the ground away from mobile plant and dirt.
End fittings required
Depending on the aperture or connection points on the load, different hooks or shackle end fittings may be required. Always match to the working load limit (WLL) of the leg.
Some example of hooks are as shown below.
Some examples of Masterlinks or head links are as shown below.
Working Load Limits and sling selection
To decide what assembly is needed for the job, a competent person will:
- use the working load limit chart
- risk asses the load
- review AS3775 grade 80 or 100 WLL charts (or similar).
Some manufacturers do produce grade 120 alloy chain assemblies. These currently sit outside Australian or international standards. Refer to manufacturer's advice.
See WLL charts below:
Alloy chain slings - single & multi-leg assemblies - AS3775 - Grade T(80)
Grade 80 WLL chart
Notes:
- Some shortening devices, such as grab hooks may derate the WLL. Advice regarding the appropriate deration should be sought from the manufacturer.
- The determination of the angle of the multi-leg sling is the largest included angle at the apex of the configuration.
- Reeved slings and basket slings, in a two leg configuration have a maximum angle for use of 60°.
| Temperature °C = deration | -40° to + 200° = none | +200° to 300° = 10% | +300° to 400° - 25% |
Alloy chain slings - single & multi-leg assemblies - AS3775 - Grade V(100)
Grade 100 WLL chart
Notes:
- Some shortening devices, such as grab hooks may derate the WLL. Advice regarding the appropriate deration should be sought from the manufacturer.
- The determination of the angle of the multi-leg sling is the largest included angle at the apex of the configuration.
- Reeved slings and basket slings, in a two leg configuration have a maximum angle for use of 60°.
| Temperature °C = deration | -40° to + 200° = none | +200° to 300° = 10% | +300° to 400° - 25% |