---
title: "Seal"
description: "A device used for containers  lockers  trucks or lorries to proof relevant parties that they have remained closed during transport."
url: "https://oceancargo.co.uk/shipping-terms/seal"
date: "2026-05-26T08:11:44+00:00"
language: "en-GB"
---

![Ocean Cargo](https://oceancargo.co.uk/images/GenPics/OCs-Customs-Brokerage.webp)

 # Container Seals: Your Guide to Supply Chain Security with Ocean Cargo

## What is a Container Seal (SEAL)?

In the intricate world of global freight, security and integrity are paramount. A container seal, often simply referred to as a "seal" or "SEAL," is a crucial, tamper-evident device used to secure shipping containers, truck trailers, rail wagons, and even aircraft cargo compartments. Its primary purpose is to provide proof that the cargo unit has remained closed and undisturbed from the point of sealing until it reaches its intended destination. For businesses relying on international trade, understanding the role and types of container seals is fundamental to safeguarding their goods.

At Ocean Cargo, we recognise that a robust security protocol, including the correct application and verification of container seals, is an integral part of a reliable supply chain. Our comprehensive [customs compliance services](https://oceancargo.co.uk/services/customs-compliance/) and meticulous operational procedures ensure that your cargo's integrity is maintained throughout its journey, whether by [sea freight](https://oceancargo.co.uk/services/sea-freight/), [air freight](https://oceancargo.co.uk/services/air-freight/), or [road freight](https://oceancargo.co.uk/services/road-freight/).

## Why are Container Seals So Important for Freight Forwarding?

The humble container seal plays a disproportionately large role in the security and efficiency of global logistics. Its importance extends far beyond a simple locking mechanism:

- **Tamper Evidence:** The most critical function. Seals are designed to show clear signs of tampering if an unauthorised attempt is made to open the container. This provides immediate visual evidence of a potential breach.
- **Security Against Theft:** While not impenetrable, seals act as a deterrent to opportunistic theft and make unauthorised access more difficult and time-consuming, increasing the risk for would-be thieves.
- **Customs Compliance:** Customs authorities worldwide often mandate the use of high-security seals for international shipments. A properly sealed container facilitates quicker [customs clearance](https://oceancargo.co.uk/services/customs-compliance "customs clearance") and reduces the likelihood of delays or inspections.
- **Cargo Integrity:** Ensures that the contents of the container match the shipping manifest, preventing the introduction of contraband or the removal of legitimate goods.
- **Liability Protection:** In the event of a dispute or claim, a properly intact seal provides strong evidence that the cargo was not tampered with during transit, helping to assign liability.
- **Supply Chain Visibility:** Each seal has a unique identification number, which is recorded on shipping documents. This number allows for tracking and verification at various points in the supply chain.

Ocean Cargo integrates stringent sealing protocols into all our freight forwarding operations, providing peace of mind that your valuable cargo is protected from origin to destination.

## Types of Container Seals and Their Applications

Not all seals are created equal. The type of seal used depends on the level of security required, the mode of transport, and regulatory standards. The International Organization for Standardization (ISO) sets standards for mechanical seals, particularly ISO 17712, which defines "high-security" seals.

### High-Security Seals (ISO 17712 Compliant)

These are the most robust seals, designed to withstand significant force and provide clear evidence of tampering. They are typically required for international shipping, especially for high-value goods or routes with elevated security risks.

- **Bolt Seals:** Comprising a metal bolt and a separate locking barrel, these are extremely strong and require bolt cutters to remove. They are widely used for shipping containers and are the most common type of high-security seal.
- **Cable Seals:** Made from braided aircraft cable, these seals are highly versatile and can be used on various locking points. They are also cut with cable cutters and are often used for containers, rail cars, and truck trailers.

### Indicative Seals

These seals are primarily for tamper-evidence rather than high physical security. They can typically be removed by hand or with simple tools.

- **Plastic Seals (Strap Seals):** Common for truck doors, airline cargo, and internal container doors. They are easy to apply and remove but clearly show if they've been broken.
- **Metal Strip Seals:** Similar to plastic seals but made of metal, offering slightly more resistance. Used for similar applications.

### Electronic Seals (E-Seals)

Representing the cutting edge of cargo security, e-seals incorporate RFID (Radio-Frequency Identification) or GPS technology. They provide real-time monitoring of a container's status, including whether it has been opened, its location, and even environmental conditions inside.

Ocean Cargo continuously evaluates and implements the latest security technologies to enhance the protection of your shipments, from standard bolt seals for [sea freight to the USA](https://oceancargo.co.uk/countries/usa/sea-freight-usa) to advanced solutions for sensitive cargo destined for [Australia](https://oceancargo.co.uk/countries/australia/wind-turbine-components-blades-nacelles-tower-sections-australia).

## The Sealing Process: Best Practices for Freight Forwarders

A seal is only as effective as its application. Ocean Cargo adheres to strict best practices to ensure maximum security:

1. **Inspection:** Before sealing, the container doors and locking mechanisms are thoroughly inspected for any signs of damage or pre-tampering.
2. **Application:** The seal is applied correctly to the designated locking point (typically the right-hand door locking bar for containers). For bolt seals, the bolt and barrel must be fully engaged.
3. **Verification:** Once applied, the seal is tugged firmly to ensure it is securely fastened.
4. **Recording:** The unique seal number is immediately recorded on all relevant shipping documentation, including the Bill of Lading, manifest, and customs declarations. Photographs of the applied seal are often taken.
5. **Communication:** The seal number is communicated to all relevant parties, including the consignee, so they can verify it upon arrival.
6. **Removal:** Upon arrival at the destination, the consignee verifies the seal number against the documentation. Only if the numbers match and the seal is intact is it removed (usually with bolt cutters for high-security seals). Any discrepancy or sign of tampering triggers an immediate investigation.

Our meticulous approach to the sealing process is a cornerstone of our commitment to secure and reliable [sea freight services to Canada](https://oceancargo.co.uk/countries/canada/sea-freight-canada) and other global destinations.

## Common Challenges and How Ocean Cargo Mitigates Them

Despite their importance, container seals can present challenges:

- **Incorrect Application:** A poorly applied seal is a compromised seal. Our teams are rigorously trained to ensure correct application every time.
- **Seal Tampering:** Sophisticated methods exist to tamper with seals. We advise on the use of ISO 17712 compliant seals and recommend additional security measures where appropriate.
- **Documentation Errors:** Mismatched seal numbers on documentation can cause significant delays. Ocean Cargo's robust administrative processes minimise such errors.
- **Loss or Damage in Transit:** While rare for high-security seals, damage can occur. Our proactive communication and tracking systems help identify and address such issues swiftly.
- **Customs Requirements:** Different countries have varying regulations regarding seal types and documentation. Our [customs compliance experts](https://oceancargo.co.uk/services/customs-compliance/) ensure all requirements are met, whether you're shipping [excavators to the UAE](https://oceancargo.co.uk/countries/uae/excavators-diggers-uae) or general cargo elsewhere.

Ocean Cargo's 25+ years of experience in freight forwarding means we anticipate and mitigate these challenges, providing a seamless and secure shipping experience for our clients.

#### What is the difference between a high-security seal and an indicative seal?

A high-security seal (e.g., bolt or cable seal) is ISO 17712 compliant, meaning it's designed to withstand significant force and requires special tools (like bolt cutters) to remove, offering robust physical security. An indicative seal (e.g., plastic or metal strip seal) is primarily for tamper-evidence; it can be removed by hand or with simple tools and shows if the container has been opened, but offers less physical resistance.

#### Who is responsible for applying the container seal?

Typically, the shipper or their authorised agent (like Ocean Cargo) is responsible for applying the seal at the point of stuffing the container. This ensures the integrity of the cargo from the moment it's loaded. The unique seal number is then recorded on all shipping documents.

#### What should I do if a container arrives with a broken or missing seal?

If a container arrives with a broken, missing, or tampered seal, or if the seal number does not match the documentation, it is critical to immediately notify the carrier, your freight forwarder (Ocean Cargo), and customs authorities. Do not open the container until an official inspection has been conducted and the discrepancy documented. This is crucial for insurance claims and security investigations.

#### Are electronic seals (e-seals) mandatory for all shipments?

No, electronic seals are not mandatory for all shipments. While they offer advanced tracking and security features, they are typically used for high-value cargo, sensitive goods, or specific routes where enhanced monitoring is required or desired by the shipper. ISO 17712 compliant mechanical seals (bolt or cable seals) remain the standard for most international container shipments.

### Ready to simplify your global logistics?

Get advice and a quote for your next shipment. Contact the Ocean Cargo team to start shipping.

[Freight Quote](https://oceancargo.co.uk/contact-us)

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