Shipping Container Seals 2024 Buying Guide

Have you ever thought about how shipping containers traveling all across the globe by air, sea, or land are secured?

There are 226 million containers that carry all kinds of cargo being shipped all around the world per year. What prevents thieves and smugglers from intercepting these containers?

The answer is container seals!

What are shipping container seals? Why are they important in securing shipping containers? This article will answer these questions and more, so stick around.

What Are Container Seals?

shipping container seals on empty containers

Container seals are specialized locks that are used to secure shipping containers. Each seal is a one-time-use lock that’s designed to withstand destruction attempts and the harsh conditions of the transportation process.

The container seal is placed on the cargo container’s doors at its origin locations and remains locked and intact for the whole voyage, ensuring that the cargo remains unopened during the journey. Once the container arrives at its destination, the seal is then unlocked by the buyer.

Container seals are a primary security procedure but do not guarantee an entry-proof container. Seals are essentially a way to deter theft and can be used as evidence in case of any tampering with the cargo goods.

Each container seal has a unique serial number that is used to identify it. The serial number on the seal is recorded into the container’s bill of lading before the transport to ensure the cargo hasn’t been opened or tampered with during the voyage. More on that further down the article.

What Are the Benefits of Container Seals?

barrier seals and metal strip seals
  • Securing the shipping containers and minimizing the risk of potential theft.
  • Preventing cargo goods from being tampered with or from undergoing any manipulation.
  • Allow for maintaining the container’s preset temperature and cleanliness.
  • Gives customers the guarantee that their goods haven’t been opened since loading.
  • Securing the containers against potential smugglers and transport of illegal cargo

Are Container Seals Legally Required to Ship Containers?

Container seals are legally required by government regulators, ports, importers, and exporters. This is especially the case when shipping from/to the US, in accordance with the C-TPAT.

Both Full Container Load (FCL) and Less Than Container Load (LCL) are obligated by law to lock their containers using at least one container seal during transport.

What Is Customs-Trade Partnership Against Terrorism (C-TPAT)?

container doors with multiple seals and lock rods

After the 9/11 attack in 2001, the US customs and border protection force set up the C-TPAT. C-TPAT is a program that’s responsible for creating better security systems for global trade and supply chains.

C-TPAT consists of most of the major US companies, cargo consolidators, carriers, and manufacturers. This includes many of the big names in container seal manufacturers worldwide.

The C-TPAT is tasked with setting security standards, improving safety practices, and helping fight terrorism. They also have the authority to suspend any member that breaches their security protocol.

Do Container Seals Guarantee the Container’s Security?

While container seals are a method of security, they’re not entry-proof and should not be solely relied on to prevent theft.

Container seals are mainly used to deter unauthorized access and to be used as evidence in case of theft or tampering with the shipped cargo.

However, to increase security, many shippers opt to use multiple container seals. Six is the maximum number of seals that can be used on a container door, as it only has six openings for seals to go through.

What Are the Different Types of Container Seals?

There are various different types of container seals on the market, including plastic seals, steel cable seals, steel bolt seals, and metal security seals.

In this section, we’ll shed light on each of these types of container seals and share with you our top pick from each category.

1. Plastic Cargo Security Seal

This is a type of seal which contains a metal or plastic lock at the end of its “flag.” The long side of the seal must be pulled through the lock and then pulled to the very end. The seal cannot be opened without being damaged, allowing for any tampering to be evident.

This seal is the most cost-efficient and is best suited for short-term use.

Best Plastic Seal: LeadSeals Tite-Lock

  • Made of a high-quality material that’s resistant to extreme weather conditions
  • Available in packs of 100, 500, or 1000 pieces
  • Very reasonable price
  • Available in different colors

2. Steel Cable Security Seal

This is a steel, heavy-duty type of seal. It acts as a self-locking seal, similar to the plastic one, but it’s more durable and must be removed using bolt-cutters.

This seal provides maximum security and high durability and it’s suitable for a wide range of applications, like water meters, cargo doors, and hazmat shipping containers.

Best Steel Cable Seal: LeadSeals Pull Tight

  • Adheres to the International Standard ISO 17712: 2013
  • Very hard to break, allowing for more security
  • Available in packs of 50, 100, 200, 500, 1000 pieces
  • Can be ordered in customizable lengths and printing content

3. Steel Bolt Security Seal

These security seals consist of a heavy-duty steel pin inserted into an anti-corrosive steel barrel that’s plastic-coated. A unique code number is shown on the steel pin and the barrel to ensure that the seal isn’t tampered with, making it a one-time-use lock.

This is the most commonly used seal for securing cargo containers and is considered the primary go-to option. It is the standard seal for high-security locks and can only be removed using bolt-cutters.

Best Steel Bolt Seal: AVG Bolt Seals

  • High-quality construction that can handle harsh weather conditions
  • Anti-spin feature to prevent tampering
  • Adheres to the International Standard ISO 17712: 2013
  • Reasonable price considering the build quality

4. Metal Security Seal

This is the highest-level container seal available in the market in terms of security. It’s known for its corrosion resistance properties and is mainly used by customs and the military.

How to Lock a Container Using Container Seals?

lock rods on shipping container doors

A regular container has two doors, each with two lock rods that run vertically from top to bottom and that are used to lock the door in place.

Attached to these rods are handles with small holes through which the seals are inserted to lock the door.

Here’s how to lock the container using container seals:

1.     Close the door on the left-hand side first, then close the one on the right.

2.     Use the vertical lock rod to anchor the doors in place.

3.     Check that the numbers on both parts of the seal (pin and barrel) match each other.

4.     Separate the pin from the steel by snapping the plastic connector that holds them together.

5.     Insert the pin’s end through the opening on the lock rod and firmly into the barrel.

6.     Hear a soft click to ensure that the seal is locked. Ensure that the seal is properly locked by making sure it doesn’t open with your hands.

How to Remove a Container Seal?

1.     Make sure that the container seal shows no signs of any tampering or damage. If you find any of these signs, immediately notify the cargo handler and any other concerned parties.

2.     Make sure that the numbers of the pin, barrel, and bill of lading all match. If any numbers mismatch, immediately notify all the concerned parties.

3.     Use a heavy-duty bolt cutter to remove the seal, cutting it from the metal pin.

What Do the Colors and Numbers on Container Seals Indicate?

The colors are merely there to indicate different shipping lines, but they’re irrelevant to the types of cargo within the containers.

As far as the numbers, container seals of all different types come with a unique identification serial number.

These numbers are used to confirm that the container seal was not broken or changed during the transport. In the case of a bolt seal, both the steel pin and the barrel should carry the same number.

The port authorities, customs, and the receiving customer use the bill of lading, which contains the container seal’s number, to verify that the container hasn’t been opened or tampered with during the transport voyage.

It’s worth noting that, on some rare occasions, container seals of different types might carry the same serial number. This is why checking the bill of lading information is essential.


What is the standard for container seals?

The international standard for container seals is ISO 17712:2013. This sets the standards for mechanical seals used to lock cargo shipping containers.
While certain countries, such as the US, mandate that all inbound containers be sealed with high-security ISO container seals, other countries set different requirements according to their security standards.

What to do if your container seal parts are mismatched?

In case of a mismatch between the serial number on your seal and in your bill of lading, then you should immediately notify your shipping line.
You should not remove the seal or open your container until the shipping line representative is present, as the seal is used as evidence in the investigation process.

What should you do if your container seal has been broken?

A broken container seal doesn’t necessarily mean that theft has been committed. Sometimes, it means that a custom inspection has taken place. In this case, customs will usually put a specific seal on your container, and they also return the original seal back to you.

If your container seal has been broken and you don’t find a customs seal on your container, you should suspect that there was unauthorized entry and notify the authorities immediately. It’s also important not to open your container until a representative of the shipping line is present.

In Summary

Shipping container seals are the primary method of securing cargo shipping containers. They’re serialized one-time use locks that help minimize the risk of theft or smuggling. They’re also used to prevent cargo from being tampered with.

While container seals come in many types, the steel bolt seal is the one most commonly used for securing cargo shipping containers. It’s the worldwide standard for high-security seals and can only be removed using heavy-duty bolt cutters.

It’s essential that you pick the right container seal and that you properly place it on the container to ensure the security of your cargo. Depending on your needs, you can choose between plastic cargo seals, steel cable seals, steel bolt seals, and metal security seals.

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