Security Seals Guide
What is a Cable Seal?
Structure and use cases of steel cable seals.
Show contents
- Key Takeaways
- Structure: steel cable and body
- Wire diameter and length options
- Adjustable and fixed-length models
- Fraying when cut: visible tamper evidence
- Metal and plastic bodies, typical application points
- Cable seal selection variables
- Why is a cable seal different from a plastic seal?
- Cable seal selection parameters
- Applications where cable seals are strong
- Correct cable seal application
- A thicker cable does not solve every problem
- Frequently Asked Questions
Direct answer
A cable seal is a security seal made of a braided steel wire and a metal or plastic body, preferred for longer and more demanding closure points than plastic seals typically cover. When cut, the wire visibly frays and deforms, which practically rules out hiding any tampering.
What you will learn
The body is a locking head through which the wire passes; the wire itself is multi-strand braided steel.
Wire diameter and length are offered in different models depending on the size of the closure point.
In adjustable models the wire is tightened to a chosen length; in fixed models the length is set at production.
When the wire is cut, fraying and deformation occur; this is the seal's most visible tamper-evident trait.
The body can be metal or plastic; it is commonly used on tankers, valves and containers.
Structure: steel cable and body
A cable seal has two main parts: a multi-strand braided steel cable and a body where one end of the cable is fixed and the other end passes through to lock. The body can be made of metal or reinforced plastic and contains a one-way locking mechanism inside.
The wire shows higher bending resistance and cut resistance compared to a plastic seal's strap, which is why it is preferred for longer closure points and more demanding environmental conditions.
Wire diameter and length options
Cable seals are produced in different wire diameters, from thin wire to thicker braided cable, and different lengths, from short valve seals to long models spanning container door bars. The right diameter and length are chosen based on the size of the closure point and the gap the body needs to pass through.
Wire diameter and length details for this product family are provided in the manufacturer's technical documentation; specific strength or pull-force figures are not presented here as a basis for operational decisions.
Adjustable and fixed-length models
- In adjustable models, the wire passes through the body and is tightened to the desired length, adapting to points of different diameters.
- In fixed-length models the wire length is set during production; these are preferred for repeated, standardized applications.
- In both types, once the wire enters the body it cannot be pulled back out; removal is only possible by cutting the wire.
Fraying when cut: visible tamper evidence
When cut with a tool, the multi-strand braided structure produces frayed, splayed wire ends rather than a single clean cut. This appearance practically prevents the wire from being disguised as reassembled and gives the inspector a clear signal of tampering.
Metal and plastic bodies, typical application points
Metal-bodied models are generally preferred at points where resistance to harsher outdoor conditions such as moisture, temperature and mechanical contact is expected, while plastic-bodied models offer a lighter and more economical alternative.
Cable seals are widely used on longer or higher-risk points such as filling and discharge valves on fuel tankers, industrial valves, and container door bars.
Cable seal selection variables
| Wire diameter group | Body type | Typical application | Removal tool |
|---|---|---|---|
| Thin wire | Plastic body | Valves, meters, light equipment | Wire cutters / pliers |
| Medium wire | Plastic or metal body | Tanker valves, industrial equipment | Cable cutters |
| Thick braided wire | Metal body | Container door bars, heavy logistics | Heavy-duty cable cutters / bolt cutter |
Why is a cable seal different from a plastic seal?
In cable seals, the load-bearing element is a multi-strand steel cable rather than a plastic strap. This provides higher mechanical resistance while allowing the seal to route through long or awkward closure geometries. That flexibility is especially valuable on valves, tanker hatches, machinery and heavy logistics applications.
Once the cable enters the locking body it tightens in one direction. On many models, cut strands flare apart, making attempts to reconnect the cable more visible. Security evaluation therefore considers not only pull resistance but also cable construction and how it behaves after cutting.
Cable seal selection parameters
| Parameter | What it affects | Check question |
|---|---|---|
| Cable diameter | Strength and fit | Does it pass through the closure hole easily? |
| Cable length | Application flexibility | Does it cover all connection points without excessive slack? |
| Cable construction | Tamper visibility after cutting | Do the strands visibly fray after cutting? |
| Body material | Environmental resistance and marking | Does it match field conditions and marking needs? |
| Removal tool | Operational safety and speed | Is the correct cutter available at the authorized opening point? |
Applications where cable seals are strong
- Tanker valves and filling hatches
- Rail and road freight equipment
- Machinery, panels and industrial equipment
- Closures requiring routing through long or multiple points
- Demanding field conditions where plastic seals are mechanically insufficient
Correct cable seal application
- 1
Route the cable correctly
Route the cable so it actually secures every closure point rather than merely passing through a visible point.
- 2
Remove unnecessary slack
Tighten the cable in the lock body in a controlled way; a large loop can make tampering easier.
- 3
Record the serial number
Link the physical seal to the shipment or equipment record.
- 4
Inspect both number and cable at handover
Check not only the serial number but also the cable for crushing, cutting or signs of re-crimping.
Frequently asked questions
What is the main difference between a cable seal and a plastic seal?
In a cable seal the closing element is a multi-strand braided steel wire, while in a plastic seal it is a plastic strap. Cable seals are generally preferred for longer and more demanding closure points.
How is the wire diameter of a cable seal chosen?
Wire diameter is chosen based on the size of the closure point and the gap the body needs to pass through. For specific strength figures, the manufacturer's technical documentation should be consulted.
Why does the wire fray when cut?
The cable is not a single solid wire but many thin strands braided together. When cut with a tool, these strands separate and create a frayed, splayed appearance, which makes hiding the tampering much harder.
Does an adjustable cable seal fit every point?
Adjustable models fit different diameters within a certain length range, but every model has a maximum length limit; a different model may be needed for very large or very small points.
Should I choose a metal-bodied or plastic-bodied model?
If harsh outdoor conditions or higher durability expectations apply, a metal body may be preferred; if a lighter, more economical solution is wanted, a plastic body may be chosen. The choice depends on the conditions at the application point.
What pull force can a cable seal withstand?
The pull-force value varies from model to model and is provided in that specific product's technical documentation. Since a general figure would be misleading, it is recommended to consult the product-specific technical information before application.
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Open quote formThis content is prepared using Senkron Seals product and field experience.