What Is a 2 Leg Lifting Chain Sling?
2 Leg Lifting Chain Sling WLL and Specifications
How Does the Sling Angle Affect WLL?
What Sling Angle Is Safe for a 2 Leg Chain Sling?
How to Set Up a 2 Leg Lifting Chain Sling Safely
Safety Requirements for Double Leg Chain Slings
Inspection and Maintenance of a 2 Leg Lifting Chain Sling
Common Mistakes When Using a 2 Leg Lifting Chain Sling
Choosing a TOPONE 2 Leg Lifting Chain Sling
Frequently Asked Questions
Conclusion
A 2 leg lifting chain sling is widely used for lifting heavy machinery, structural steel, industrial components, and loads with two approved lifting points. Its double-leg configuration allows the load to be connected at two locations, making it useful for many industrial lifting and rigging applications.
However, using a two-leg chain sling safely requires more than selecting the correct chain diameter. The Working Load Limit (WLL), sling angle, load distribution, connection fittings, and lifting procedure all affect the performance of the complete assembly.
This guide explains how to select a double-leg lifting chain sling, understand angle-related tension, check the correct WLL, and follow essential safety procedures before and during lifting.
A 2 leg lifting chain sling, also called a double leg chain sling, consists of two alloy steel chain legs connected to a common upper master link.
Each leg typically has an end fitting, such as a sling hook, self-locking hook, or another approved lifting connector.
A typical assembly includes:
Master Link: Connects the sling to the crane or hoist hook.
Alloy Steel Chains: Grade 80 or Grade 100 lifting chains designed for the approved sling configuration.
End Fittings: Connect the chain legs to suitable lifting points.
Connecting Components: Provide compatible connections between the chain and fittings.
Identification Tag: Displays the information required to identify the sling and its rated capacity.
Double-leg chain slings are commonly used in construction, machinery installation, manufacturing, and heavy equipment maintenance.
For available product configurations, explore TOPONE's Chain Lifting Slings.
The Working Load Limit (WLL) represents the maximum load permitted for the complete sling assembly under its rated operating conditions.
For a two-leg lifting chain sling, the rated capacity depends on the chain grade, diameter, number of legs, end fittings, sling angle, and approved configuration.
The following selected values are taken from TOPONE's published Grade 80 double-leg chain sling metric specifications.
Chain Diameter | Single-Leg Reference WLL | 2-Leg WLL (0°–45° from Vertical) | 2-Leg WLL (45°–60° from Vertical) |
6 mm | 1.12 t | 1.60 t | 1.12 t |
8 mm | 2.00 t | 2.80 t | 2.00 t |
10 mm | 3.15 t | 4.25 t | 3.15 t |
13 mm | 5.30 t | 7.50 t | 5.30 t |
Important: These are reference values from the published TOPONE Grade 80 product table. They apply to the stated configuration and angle ranges, not to every two-leg chain sling. Boundary angles, applicable standards, end fittings, and final ratings must be verified against the selected product's identification and approved load chart.
The table demonstrates why a double-leg sling cannot be selected from chain diameter alone.
For complete specifications and available sizes, see TOPONE's Grade 80 Double Leg Chain Sling with Self-Locking Hooks.
Configuration | Main Components | Typical Selection Consideration |
Double Leg with Sling Hooks | Master link, two chains, sling hooks with latches | Approved lifting points and hook compatibility |
Double Leg with Self-Locking Hooks | Master link, two chains, self-locking hooks | Compatible positive-locking hook arrangement |
Double Leg with Grab Hooks | Master link, two chains, compatible grab hooks | Rated connection and approved shortening arrangement |
Customized Double Leg Sling | Selected chain grade, length, and fittings | Specific lifting geometry and application |
Grade 80 and Grade 100 are common lifting chain grades. The chosen grade and fittings must meet the complete assembly's required rating.
Sling angle is one of the most important factors in the safe use of a 2 leg lifting chain sling.
When two sling legs support a load, each leg carries tension. As the legs move farther away from vertical, the tension in each leg increases even though the suspended load remains unchanged.
This occurs because only the vertical component of each leg's tension supports the weight of the load.
Lifting charts may describe angles in different ways.
Angle from Vertical
This is the angle between one sling leg and a vertical reference line.
Angle from Horizontal
This is the angle between one sling leg and the horizontal plane.
Included Angle
This is the angle formed between the two sling legs.
For a symmetrical two-leg sling, the included angle is twice the angle measured from vertical.
These angle measurements must not be confused when using lifting charts.
Angle from Vertical | Angle from Horizontal | Included Angle (Symmetrical Sling) | Leg Tension Relative to Vertical Setup |
0° | 90° | 0° | 1.00× |
30° | 60° | 60° | 1.15× |
45° | 45° | 90° | 1.41× |
60° | 30° | 120° | 2.00× |
The factors above illustrate ideal symmetrical loading and do not replace the manufacturer's sling WLL chart.
As the angle from vertical increases, the tension in each chain leg rises.
A 60° angle from vertical produces approximately twice the leg tension of a vertical arrangement carrying the same total load with two equally loaded legs.
For a symmetrical two-leg sling with equally loaded legs:
T = W ÷ (2 × cos θ)
Where:
T = Tension in each sling leg
W = Total suspended load
θ = Angle of each sling leg measured from vertical
If the angle is measured from horizontal instead, the corresponding formula is:
T = W ÷ (2 × sin α)
Where α is the angle from horizontal.
These equations describe ideal static loading with symmetrical geometry and equal load sharing. They are not sufficient for an asymmetric or dynamically loaded lifting arrangement.
Consider a 4-ton load suspended from two equally loaded chain legs.
Angle from Vertical | Approximate Tension per Leg |
0° | 2.00 t |
30° | 2.31 t |
45° | 2.83 t |
60° | 4.00 t |
At 30° from vertical, each leg experiences approximately 2.31 tons of tension.
At 45° from vertical, the tension increases to approximately 2.83 tons per leg.
At 60° from vertical, each leg must carry approximately 4 tons of tension.
The suspended load has not changed. Only the sling geometry has changed.
This example explains why selecting a double-leg chain sling by dividing the load weight by two can be unsafe.
For more information about angle-related load changes, read Why Does Chain Sling WLL Change With the Sling Angle?.
There is no single angle that is suitable for every lifting operation.
However, lower angles from vertical generally reduce the tension in each chain leg.
In practical terms:
More vertical sling legs generally produce lower leg tension.
As the legs spread outward, the required tension increases.
The manufacturer's rated WLL must be checked for the actual operating angle.
Widely separated lifting points may require a different rigging arrangement.
OSHA guidance advises against using horizontal sling angles below 30° unless recommended by the manufacturer or a qualified person.
A horizontal angle of 30° is equivalent to 60° from vertical.
When the required lifting geometry falls outside the approved configuration, the lift must be reassessed rather than assuming a stronger chain alone will solve the problem.
The simplified angle formula assumes that both legs share the load equally.
In real lifting operations, the center of gravity may not be positioned halfway between the lifting points.
If the load is unbalanced, one chain leg may carry significantly more tension than the other.
This can occur when lifting:
Machinery with an offset motor or gearbox
Irregular steel structures
Uneven industrial assemblies
Components with asymmetrical lifting points
The load distribution must be evaluated before lifting, and the complete assembly must be rated for the actual forces acting on each leg.
Correct installation helps maintain the intended lifting geometry and reduces the risk of uncontrolled movement.
Determine the total suspended weight, including any attachments or below-the-hook equipment.
Identify the expected center of gravity and ensure that the selected lifting points are suitable for the intended loading direction.
Verify the sling identification tag, chain grade, rated capacity, and effective length.
Check the WLL for the intended sling angle and configuration.
Do not use a sling when its rating or identity cannot be reliably established.
Examine both chain legs, the master link, connecting components, and end fittings.
Look for deformation, cracks, abnormal wear, corrosion, twisted chain legs, and damaged hooks.
Confirm that the fittings operate correctly and are suitable for the lifting points.
Seat the master link correctly in the crane or hoist hook.
Attach each sling leg to its designated lifting point using compatible rated fittings.
Avoid point loading, side loading, or incorrect hook positioning.
Ensure that the chain legs are free from knots, twists, and unintended obstructions.
Measure or otherwise reliably establish the actual angle of each sling leg.
Compare the arrangement with the manufacturer's rated load chart.
If the angle is unsuitable, revise the rigging plan using an approved alternative, such as different sling lengths, lifting points, or an appropriate lifting beam.
Gradually take up the slack and carefully raise the load just enough to verify the balance and stability of the arrangement.
Check that:
Both legs are engaged as intended.
Hooks and connections remain correctly seated.
The load is stable.
The sling angles match the approved lifting plan.
No component is experiencing unexpected loading.
Lower the load and correct the arrangement if any problem is detected.
Lift and move the load smoothly without sudden acceleration, shock loading, or uncontrolled swinging.
Maintain a clear lifting area and keep personnel away from the suspended load.
Never allow personnel to stand beneath a suspended load.
A safe lifting operation depends on the condition and rating of the entire lifting arrangement.
The master link, hooks, connecting links, shackles, and other fittings must be suitable for the intended load and direction of loading.
A high-grade chain does not compensate for an underrated fitting.
The manufacturer's approved assembly rating must be followed.
The complete sling must remain within its rated capacity for the actual operating configuration.
The WLL of a single chain leg must not simply be doubled without considering sling angle, load distribution, fittings, and the complete assembly rating.
Direct contact with sharp edges can create local damage or unfavorable loading conditions.
Use suitable protection or a different approved lifting arrangement where necessary.
The protection system must be appropriate for the load and lifting geometry.
Twisted chain legs and sudden loading can create unintended stresses or affect the stability of the lift.
Arrange the sling correctly before loading and use smooth, controlled movements.
High temperatures, corrosive environments, chemical exposure, and severe abrasion may affect sling performance.
Consult the manufacturer's instructions for material compatibility, temperature limitations, and any required reduction in rated capacity.
Surface coatings should not be assumed to make a sling suitable for every environment.
ASME B30.9, OSHA 29 CFR 1910.184, and applicable EN 818 requirements provide relevant requirements or guidance for chain slings within their respective scopes.
The exact requirements depend on the region, sling specification, and intended use.
These standards do not replace the manufacturer's product-specific rated load information or a suitable lifting plan.
Both chain legs and all associated fittings should be inspected before use.
Common warning signs include:
Missing or illegible sling identification
Cracked, distorted, or stretched links
Excessive chain wear
Damaged weld areas
Corrosion or pitting
Bent or twisted chain components
Damaged hooks or abnormal hook opening
Missing or damaged hook latches
Deformed master links or connecting components
If damage is found, remove the sling from service and arrange assessment by a qualified person.
Periodic inspections must follow applicable regulations, manufacturer instructions, operating frequency, and service conditions.
For example, U.S. OSHA guidance requires periodic inspections of alloy steel chain slings at intervals no greater than 12 months, with more frequent inspections appropriate for severe service.
Inspection records should identify the sling and support traceability of its condition.
Proof testing should follow the applicable sling standard, manufacturer requirements, and circumstances such as initial manufacture or qualifying repairs.
A routine inspection does not automatically require a new proof-load test.
Damaged slings must not be returned to service merely because they appear visually acceptable after repair.
For additional guidance on selecting sling length and maintaining suitable lifting angles, see How to Choose the Right Chain Sling Length.
Using a horizontal-angle WLL chart as though it measured angles from vertical can produce incorrect ratings.
Always identify the reference direction before performing any calculation.
Uneven load geometry or an offset center of gravity can cause one leg to carry more tension.
The lifting arrangement must account for actual load distribution.
Chain diameter alone does not determine the rated capacity of a completed sling.
Grade, components, angle, and assembly configuration must also be considered.
Incompatible fittings may be loaded in ways they were not designed to withstand.
All connection components must match the approved rigging arrangement.
A sling that has experienced deformation, severe corrosion, excessive wear, or other defects may no longer be suitable for lifting.
Correct inspection and timely removal from service are essential.
TOPONE supplies Grade 80 and Grade 100 chain lifting sling configurations for industrial applications.
Available two-leg arrangements include different hook styles, master links, chain grades, and working lengths.
For example, the Grade 80 Double Leg Chain Sling with Self-Locking Hooks features an oblong master link and two self-locking end hooks.
Customers should confirm the complete assembly rating and compatibility with the planned lifting operation.
When discussing a two-leg sling configuration, provide:
Total suspended load weight
Required WLL
Chain grade and diameter
Sling angle and lifting point spacing
Required effective sling length
Preferred hook configuration
Operating environment
Quantity and documentation requirements
Product-specific WLL tables, available configurations, and technical information are provided in the corresponding product pages.
The WLL depends on chain grade, diameter, fittings, sling angle, and the complete approved configuration. A two-leg sling must be selected using its rated load chart rather than simply doubling the capacity of a single chain leg.
When the angle is measured from vertical, a symmetrical two-leg sling at 45° experiences approximately 1.41 times the per-leg tension of the same load supported by two vertical legs.
The actual permitted WLL must be confirmed from the manufacturer's approved load chart.
It may be possible with an appropriately engineered lifting arrangement, but the load distribution must be evaluated. An offset center of gravity can cause one leg to carry more tension.
Grade 100 generally provides a higher rated capacity at the same nominal chain size under comparable standards and conditions. The complete assembly rating, compatible components, and intended application remain essential.
A pre-use inspection is required as part of safe lifting practice. Periodic inspection frequency depends on the applicable regulations, manufacturer instructions, service conditions, and lifting frequency.
A 2 leg lifting chain sling provides a practical lifting arrangement for machinery, structural components, and loads with two suitable lifting points. However, safe lifting depends on understanding how chain grade, WLL, sling angles, load distribution, and connection fittings work together.
The most important principle is that widening the sling angle increases the tension carried by each chain leg. Correct angle measurement, manufacturer-approved ratings, proper setup, and thorough inspection are therefore essential.
For industrial lifting applications, explore TOPONE's Chain Lifting Slings or review our Grade 80 Double Leg Chain Sling.
Contact TOPONE with your lifting load, sling angle, required length, and preferred hook configuration to discuss a suitable two-leg chain sling assembly.
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