In global logistics, a minor detail like a container seal carries immense operational weight.

Costing only a few dollars, this tamper-evident lock serves as the ultimate safeguard for international cargo and regulatory compliance. By matching the seal number directly to the Bill of Lading (B/L), it provides a verifiable chain of custody that builds trust among shippers, carriers, consignees, and customs. Conversely, a missing, broken, or illicitly replaced seal signals potential theft or smuggling, triggering immediate detentions, intense inspections, and severe financial penalties for the consignee. To eliminate these risks, supply chains must always deploy ISO-compliant, high-security seals alongside rigorous verification logging.

Container seals are mandatory, tamper-evident mechanisms used to secure shipping containers during international transit. Each seal features a unique identification number that is logged on shipping documents like the Bill of Lading to establish a secure chain of custody.

Three Main Types of Seals

• Bolt Seals
  Heavy-duty metal pins used for international ocean freight. They require bolt cutters to remove and must meet strict ISO 17712 high-security standards.
• Cable Seals
  Flexible steel cables that loop through irregular locking mechanisms. They offer high security and are highly resistant to pulling forces.
• Plastic/Indicative Seals
  Lightweight plastic strips used primarily for short-haul trucking or empty container repositioning. They only show evidence of tampering but offer no physical theft resistance.

The ISO 17712 Standard

To comply with global customs initiatives like C-TPAT, international shipments must use seals certified under ISO 17712:2013.

This standard classifies seals into three physical strength categories: Indicative (I), Security (S), and High Security (H). Ocean freight requires “H” class bolt or cable seals.

Proper Application Process

1. Inspect the Door: Check the container locking bars and handles for existing damage before sealing.
2. Left Door First: Close the left container door first, followed by the right door.
3. Placement: Insert the bolt or cable seal through the locking bar hash on the right door.
4. The Click: Push the bolt firmly into the locking cap until it clicks, then pull down to ensure it is locked.
5. Log the Number: Take a clear photograph and log the unique serial number on the shipping paperwork.