Container Seal
A container seal is a tamper-evident locking device applied to a shipping container door after loading. Its unique alphanumeric seal number is recorded on shipping documents such as the Bill of Lading, allowing receiving teams to verify that the physical seal matches documentation. It serves as the control point linking packed shipment, documented identity, and receiving inspection, preserving chain of custody and cargo integrity.
After a container is stuffed at the shipper's dock or export consolidation point, the seal is applied to the closed doors and its number logged before dispatch. At receipt, warehouse staff compare the physical seal number against the manifest or Bill of Lading and inspect for signs of breakage or substitution. An intact matching seal supports clean acceptance. In raw material tracking, the seal confirms that inbound materials such as resins, metals, chemicals, or finished components have not been accessed in transit, reducing contamination, pilferage, and unauthorized substitution risk. In manufacturing logistics, a seal mismatch can trigger hold, quarantine, customs review, or claims processing, preventing suspect material from entering production and protecting line uptime and traceability. Container seals are one-time-use; once removed they are destroyed, making re-use or replacement visible. This control is especially important in international freight, supporting compliance and cargo security programs while deterring theft, smuggling, and tampering.
- Mistyped seal number at stuffing: If the seal number is entered incorrectly or left off the Bill of Lading, receiving cannot validate the shipment, forcing delays, manual investigation, and claim disputes.
- Broken or substituted seal at receiving: A missing, cut, or mismatched seal compromises chain of custody, so the container gets placed on hold for inspection or rejected until the issue is resolved.
- Wrong seal type or poor application: A seal that is not properly affixed to the container door, or is too weak for the voyage, can fail in transit and trigger a false tamper event or allow unauthorized access.
Is a container seal the same as a container number?
No. The container number identifies the physical box, while the seal number identifies the security device applied to the doors. The seal number is used to verify cargo integrity.
What does an intact seal prove?
An intact seal provides evidence that the container doors were not opened after sealing at origin, supporting chain-of-custody continuity from the shipper to the receiving dock.
Why do warehouses care if the seal is broken?
A broken seal can indicate pilferage, contamination, or substitution. Receiving must escalate to inspection, documentation, and exception handling before stock is released to inventory, protecting material quality and traceability.