Container lashing capacity is not determined by strap strength alone. The correct rating depends on the lashing’s usable securing capacity and the overall restraint arrangement.
Lashing Capacity (LC), Maximum Securing Load (MSL), Working Load Limit (WLL), and breaking strength or Minimum Breaking Strength (MBS) describe different characteristics of a restraint system, and they should not automatically be treated as interchangeable.
For exporters and container packers, the distinction matters even more because cargo may travel by road, rail and sea, with different forces acting on it during each leg of the journey.
The lashing itself is also only one part of a larger system. Friction, lashing angles, securing points, edge protection, blocking, pre-tension and the cargo configuration can all influence the restraint required.
This guide explains what the main container lashing ratings mean, how the CTU Code treats LC and MSL, and what exporters should consider when developing a repeatable cargo restraint system.
| Rating | What it tells you |
|---|---|
| Breaking Strength/Breaking Load (BL) | The force at which the lashing ultimately fails in testing |
| LC – Lashing Capacity | The rated securing capacity of the lashing for the intended cargo restraint application |
| MSL – Maximum Securing Load | The maximum force that should not be exceeded when the lashing is used for cargo securing |
| WLL – Working Load Limit | A specified working limit for equipment under defined conditions; it should not automatically be treated as LC/MSL |
| Pre-tension | The initial force applied through the tensioning device; this is not the same as lashing capacity |
The CTU Code and Container Cargo Securing
For cargo packed and secured inside shipping containers and other intermodal Cargo Transport Units (CTUs), the key international reference is the IMO/ILO/UNECE Code of Practice for Packing of Cargo Transport Units, commonly known as the CTU Code.
The published 2014 CTU Code is a non-mandatory global code of practice covering the packing and securing of cargo across intermodal transport, including sea and land.
For Australian exporters, this is different from AS/NZS 4380:2001, which relates to cargo restraint on motor vehicles and has been withdrawn. The NHVR Load Restraint Guide 2025 remains a useful reference for the road-transport leg.
The key takeaway is that road and sea restraint requirements shouldn’t be treated as interchangeable. The CTU Code states that multimodal transport should be considered when identifying the most demanding conditions for the journey.
Read X-Pak’s article on the 2026 NHVR changes for Australian exporters
Click to read the section:
- What Is Lashing Capacity (LC)?
- What Is Maximum Securing Load (MSL)?
- What Is Working Load Limit (WLL)?
- What Is Breaking Strength or Minimum Breaking Strength (MBS)?
- Where Are Container Lashing Ratings Marked?
- How Required Securing Capacity Is Calculated for Container Cargo
- How Transport Mode Changes the Forces on Your Cargo
- A 25-Tonne Example: DSI Underground Case Study
- Lashing Angles and Forces: Why Configuration Matters
- Friction and Anti-Slip Materials
- Protect Lashings From Sharp Edges
- What Exporters Should Check Before Choosing Container Lashing
- Choosing the Right X-Pak Container Lashing System
- Why Correct Lashing Ratings Matter
- Secure Your Export Cargo With the Right Lashing Solution
What Is Lashing Capacity (LC)?
Lashing Capacity (LC) is the rated securing capacity of a lashing for its intended cargo restraint application.
It should not be confused with the force at which the lashing itself breaks.
The CTU Code distinguishes between breaking strength – the force at which the lashing fails – and Maximum Securing Load (MSL), the force that should not be exceeded during securing. Where national or regional standards use the term Lashing Capacity, it corresponds to MSL. These values are expressed as units of force, such as kilonewtons (kN) or dekanewtons (daN).
In practice, container lashing capacity needs to be considered as part of the complete restraint arrangement, including:
- The cargo weight and dimensions
- Lashing configuration
- Lashing angles
- Attachment points
- Friction between surfaces
- Transport mode and route
- Other blocking or securing methods
For example, X-Pak’s Cargo-Lash system has published system strengths of:
- 32 mm: 4,450 kg
- 40 mm: 7,250 kg
X-Pak also states that the system can be used to secure loads of up to 30 tonnes, depending on the application and restraint configuration.
These figures should be interpreted within the relevant application and restraint configuration, rather than treating them as the amount of cargo one strap can secure.
For an exporter securing a heavy load inside a container, the question is therefore not simply “How strong is the strap?” It is “What rated restraint capacity is required for this cargo, configuration, and journey?“
What Is Maximum Securing Load (MSL)?
Maximum Securing Load (MSL) is the maximum force that should be applied to a securing device while it’s in service.
For container restraint, this is a very useful rating because it represents the usable securing force rather than the point at which the lashing fails.
The CTU Code defines MSL as a specified proportion of breaking strength, with the percentage varying according to what type of material is being secured.
For web lashings, the Code gives:
- Single-use web lashing: MSL = 75% of breaking strength
- Reusable web lashing: MSL = 50% of breaking strength
Breaking Strength to MSL Example
Consider an illustrative single-use polyester web lashing with a breaking strength of 8,000 kg-force, or approximately 78.5 kN.
Using the CTU Code:
78.5 kN × 75% = approximately 58.9 kN MSL
This is equivalent to approximately 6,000 kg-force.
The key point is that breaking strength is not the same as usable securing capacity. A lashing with an 8,000 kg-force equivalent breaking strength should not automatically be treated as having 8,000 kg-force of available securing capacity.
The applicable MSL or LC should always be confirmed for the specific lashing system and restraint application.
What Is Working Load Limit (WLL)?
Working Load Limit (WLL) is a manufacturer’s specified working limit for equipment under its intended conditions of use.
You may encounter WLL across lifting, rigging, and load restraint equipment. However, the WLL figure should not be automatically treated as another name for Lashing Capacity (LC) or Maximum Securing Load (MSL).
When comparing lashing products, check:
- What the stated rating represents
- Whether the equipment is intended for lifting, tie-down, or direct restraint
- How the rating was established
- Whether the rating relates to the complete system or an individual component
- What the manufacturer specifies for the intended application.
A 5:1 safety factor, for example, should not be presented as a universal conversion between breaking strength and every type of working load or lashing rating. Safety or design factors depend on the equipment, application, and applicable requirements.
For container exporters, the safest approach is to use the manufacturer’s specified rating for the intended application and avoid assumptions based on terminology alone.
What Is Breaking Strength or Minimum Breaking Strength (MBS)?
Breaking strength, also called breaking load (BL) in the CTU Code and sometimes described by manufacturers as Minimum Breaking Strength (MBS), relates to the force at which the lashing or component fails under specified test conditions.
It’s a failure-strength measurement, not a normal operating limit.
This explains why a lashing with a high MBS does not mean you can use the same force as its working or securing capacity. The applicable MSL or LC may be lower.
This is also why comparisons between products should be based on equivalent ratings rather than comparing the breaking strength of one product with the LC or WLL of another.
Where Are Container Lashing Ratings Marked?
The location of the rating depends on the lashing system.
Ratings may be printed directly onto the webbing, included on an identification label, marked on a component or specified in the manufacturer’s technical documentation.
For X-Pak’s container lashing, the relevant information is printed directly onto the strap rather than carried on a separate tag.
Whatever marking system is used, confirm that you are checking the rating that applies to the complete restraint application rather than assuming that every strength figure represents usable securing capacity.
How Required Securing Capacity Is Calculated for Container Cargo?
Calculating the required restraint for a container load involves more than simply dividing cargo weight by strap strength.
For a container load, you need to consider the forces acting on the cargo and how those forces are resisted. Depending on the restraint method, this can involve friction, pre-tension, direct lashing forces, blocking, lashing angles, and the equipment’s rated capacity.
For tie-down restraint, the tension from the tensioning device contributes to the clamping force on the cargo, which can increase the friction available to resist movement. X-Pak’s calculation methodology uses approximately 500 kg of tension per tie-down, subject to the equipment and applicable calculation method.
For direct lashing, the lashing’s rated securing capacity contributes directly to resisting cargo movement. The effectiveness of that capacity also depends on factors such as the lashing angle, direction of restraint and strength of the securing points.
The CTU Code therefore considers factors including MSL, securing angle and pre-tension when assessing the overall securing arrangement
How Transport Mode Changes the Forces on Your Cargo
Export cargo may travel by road, rail and sea, and the forces acting on the load can differ depending on the transport leg.
For example, for a 12-tonne load:
| Transport mode | Forward | Sideways |
|---|---|---|
| Road | 12,000 × 0.8 = 9,600 kg-force | 12,000 × 0.5 = 6,000 kg-force |
| Sea Area A | 12,000 × 0.3 = 3,600 kg-force | 12,000 × 0.5 = 6,000 kg-force |
The example above shows why the transport route matters: the same cargo can be exposed to different design forces during different stages of its journey.
The CTU Code stresses that the applicable acceleration factor depends on the transport mode and route, and that multimodal transport should be considered when identifying the most demanding leg.
This is particularly relevant to exporters whose cargo may leave a warehouse by truck, travel to a port, then continue by vessel.
These figures illustrate horizontal inertial forces only and are not, by themselves, a complete calculation of the number or capacity of lashings required. Factors such as vertical acceleration, friction, lashing angles, blocking and securing-point capacity also need to be considered.
A 25-Tonne Example: DSI Underground Case Study
A practical example of load restraint engineering comes from X-Pak’s work with DSI Underground, where loads of up to 25 tonnes were tested for transportation by flat rack, truck, and vessel.
For a 25-tonne load, using the stated 0.8G forward and 0.5G sideways forces:
- Forward: 25,000 × 0.8 = 20,000 kg-force ≈ 196 kN
- Sideways: 25,000 × 0.5 = 12,500 kg-force ≈ 123 kN
The DSI case study shows why cargo weight alone does not determine restraint requirements. X-Pak’s testing involved tilting the loaded flat rack to simulate the required restraint forces, including 54° lengthways for 0.8G forward and 30° sideways for 0.5G lateral movement.
The strongest strap isn’t automatically the safest solution. Effective cargo restraint comes from matching the right lashing capacity to the load, the securing arrangement, and every stage of the transport journey.” – Gareth Sanderson, Load Containment Specialist, X-Pak Global
Read the DSI Underground case study
Lashing Angles and Forces: Why Configuration Matters
A lashing’s rating cannot be considered in isolation from its installation.
The direction and angle of a lashing influence how the force it exerts on the cargo acts. The CTU Code recommends keeping direct lashings as close as practicable to the direction of the intended restraining effect. It also notes that securing assessments should consider the lashing’s MSL together with application parameters such as securing angle and pre-tension.
When assessing a container restraint arrangement, consider:
- Direction of potential cargo movement
- Lashing angle
- Lashing length
- Position and strength of securing points
- Number of lashings
- MSL/LC of the equipment
- Pre-tension
- Friction
- Blocking or other restraint methods
A higher-rated lashing does not automatically make an incorrectly configured restraint system safe.
Friction and Anti-Slip Materials
Friction can play a major role in preventing cargo from moving inside a container.
The CTU Code notes that greater friction between cargo and the stowage surface can reduce the additional securing effort required. The friction force depends on factors including cargo mass, vertical acceleration, and the applicable friction factor.
Where the actual friction factor cannot be verified, the CTU Code specifies a maximum allowable factor of 0.3 for calculations. For oily or greasy surfaces, or where slip sheets have been used, 0.1 applies. By comparison, the Code gives 0.6 for rubber anti-slip material where the contact surfaces are clean.
This creates a significant practical difference.
A clean contact surface with an appropriate anti-slip material can provide substantially greater resistance to movement than an oily or slippery surface.
That is why you should consider anti-slip matting, surface condition, and friction assumptions alongside the lashing equipment itself, rather than treating them as separate concerns.
Protect Lashings From Sharp Edges
Even correctly rated lashings can lose strength if the webbing is damaged where it passes over the cargo.
The CTU Code notes that its MSL relationships assume lashings pass over smooth or smoothed edges. Sharp edges and corners can substantially reduce the available strength, so suitable edge protection should be used where required.
Australian guidance reinforces the same point. The NHVR Load Restraint Guide 2025 warns that webbing straps can be cut by sharp edges and recommends using corner protectors, protective sleeves or other suitable packing where lashings contact sharp or abrasive surfaces.
This is particularly important when securing steel, machinery, fabricated components or other cargo with hard edges. Lashings should also be checked for cuts and abrasion, especially where the webbing contacts the load.
A NSW load-restraint case study documented a 3-tonne item secured with webbing where the strap rubbed against the load during transport and eventually sheared, leaving the cargo inadequately restrained.
Using appropriate edge protection helps preserve the integrity of the lashing and reduces the risk of damage to both the restraint system and the cargo.
What Exporters Should Check Before Choosing Container Lashing
Before selecting container lashing, container restraint, or lashing for containers, consider the full application rather than a single rating.
Exporter checklist
- Lashing capacity: Is the rated capacity suitable for the restraint application?
- MBS/breaking strength: What is the tested failure strength?
- MSL: What maximum securing force applies?
- WLL/SWL: Is this rating relevant to the particular equipment and application?
- Cargo weight and dimensions: What forces could the cargo experience?
- Transport route: Will the cargo travel by road, sea, or both?
- Lashing configuration: How many lashings are required and where will they be positioned?
- Lashing angles: Will the arrangement provide restraint in the required direction?
- Friction: What surfaces are in contact and what friction factor can be justified?
- Attachment points: Are the lashing points suitable for the forces involved?
- Equipment condition: Is the lashing free from damage, excessive wear, or other defects?
- Documentation: Can the restraint procedure and equipment ratings be consistently documented?
A properly designed restraint system should account for the cargo, CTU, route, securing method, and equipment together.
Choosing the Right X-Pak Container Lashing System
Choosing the right container lashing system is about more than selecting a product with the highest strength rating.
X-Pak specialises in container and flat-rack lashing, with experience in the container loading industry, on-site training, and an understanding of lashing applications and technical properties. The business also develops custom lashing systems and solutions for larger projects with engineering support.
Depending on the application, support can include:
- Custom lashing systems
- Load testing
- Site visits
- Tailored calculations and guides
- SOP development
- Engineered certification
- Load certificates
- On-site demonstrations
- Container lashing accessories
X-Pak’s broader approach is to provide specialist product knowledge and practical support rather than operate as a general packaging supplier. Its brand positioning centres on safety, expertise, and quality, including tested and certified products and support with tailored guides and calculations.
For exporters, this means they can focus on developing a complete, appropriate, and repeatable cargo restraint solution.
Why Correct Lashing Ratings Matter
For businesses that regularly pack containers, understanding lashing ratings is about more than securing a single shipment.
A properly assessed restraint arrangement can form the basis of a repeatable, documented loading procedure.
A documented procedure can specify:
- Which lashing equipment to use
- Required LC/MSL
- Number and positioning of lashings
- Lashing angles
- Friction assumptions
- Anti-slip requirements
- Cargo configuration
- Applicable transport conditions
- Inspection requirements
This reduces reliance on guesswork and makes it easier for different members of a packing team to follow the same process.
The principle aligns with X-Pak’s emphasis on providing tailored guides, calculations, site training, and practical demonstrations.
Secure Your Export Cargo With the Right Lashing Solution
Understanding LC, WLL, and MBS is an important starting point. Effective container cargo restraint requires the right equipment, configuration, and calculations for the cargo and its transport journey.
For exporters, the key is to distinguish between:
- Breaking strength: when the lashing fails
- MSL/LC: the applicable securing capacity
- WLL: a specified working limit that should not automatically be equated with LC/MSL
- Pre-tension: the force applied through the tensioning device
The CTU Code, transport conditions, lashing angles, friction and cargo characteristics all need to be considered when developing the restraint system.
X-Pak brings specialist experience in container and flat-rack lashing, including load testing, custom solutions, site support, SOPs and load certification. This approach reflects X-Pak’s wider focus on safety, compliance and education rather than simply supplying packaging products.
Need help selecting the right container lashing system?
Contact us to request a quote or book a free site assessment with X-Pak.
