Container Sealing
Securing a container with a seal to ensure contents are tamper-proof during transit.
Definition
Container sealing involves attaching a unique seal to a shipping container to prevent unauthorized access and maintain security.
Overview of Container Sealing
Container sealing is the process of affixing an authorized, tamper-evident device to a shipping container's door lock rod to verify that the container has not been opened between the point of stuffing (loading) and the point of devanning (unloading) at destination. The seal creates a documented chain of custody: the seal number is recorded on the bill of lading, packing list, and customs documentation, and any discrepancy between the declared seal number and the seal physically present at destination is a flag for customs inspection, carrier investigation, or cargo claims. Sealing is mandatory for most international shipments and is a core security compliance requirement for programs like C-TPAT and ISO 28000. There are several seal types used in commercial and customs-controlled operations. High-security bolt seals meeting ISO 17712 "H" classification are required by many trade lanes and customs authorities — they are steel, resistant to bolt cutters, and numbered with a visible identifier. Cable seals offer flexibility for odd-shaped door hardware. Indicative seals (plastic or wire) are lower-security options used for internal handling, such as sealing a container moving from a stuffing warehouse to a port terminal within a bonded zone. For C-TPAT and AEO-certified shipments, ISO 17712 high-security seals are mandatory, and sealing must be performed by an authorized employee at the stuffing location, not at the terminal. On WareMatch, warehouse operators offering stuffing and export preparation services must have documented seal control procedures to serve exporters and 3PLs with customs compliance requirements. A warehouse with ISO 17712 high-security seals on hand, an auditable seal issuance log, and trained staff who know how to properly apply and record seals is a meaningful differentiator for clients shipping to markets with strict import security requirements. For importers, asking a prospective WareMatch-listed 3PL or customs-bonded facility how they handle seal verification at devanning and how discrepancies are escalated tells you a great deal about their import compliance maturity.
Role
Securing a container with a seal to ensure contents are tamper-proof during transit.
Focus
Container sealing is the process of affixing an authorized, tamper-evident device to a shipping container's door lock rod to verify that the container has not been opened between the point of stuffing (loading) and the point of devanning (unloading) at destination. The seal creates a documented chain of custody: the seal number is recorded on the bill of lading, packing list, and customs documentation, and any discrepancy between the declared seal number and the seal physically present at destination is a flag for customs inspection, carrier investigation, or cargo claims. Sealing is mandatory for most international shipments and is a core security compliance requirement for programs like C-TPAT and ISO 28000. There are several seal types used in commercial and customs-controlled operations. High-security bolt seals meeting ISO 17712 "H" classification are required by many trade lanes and customs authorities — they are steel, resistant to bolt cutters, and numbered with a visible identifier. Cable seals offer flexibility for odd-shaped door hardware. Indicative seals (plastic or wire) are lower-security options used for internal handling, such as sealing a container moving from a stuffing warehouse to a port terminal within a bonded zone. For C-TPAT and AEO-certified shipments, ISO 17712 high-security seals are mandatory, and sealing must be performed by an authorized employee at the stuffing location, not at the terminal. On WareMatch, warehouse operators offering stuffing and export preparation services must have documented seal control procedures to serve exporters and 3PLs with customs compliance requirements. A warehouse with ISO 17712 high-security seals on hand, an auditable seal issuance log, and trained staff who know how to properly apply and record seals is a meaningful differentiator for clients shipping to markets with strict import security requirements. For importers, asking a prospective WareMatch-listed 3PL or customs-bonded facility how they handle seal verification at devanning and how discrepancies are escalated tells you a great deal about their import compliance maturity.
Example
See the definition above for context.
Benefits
- Creates a tamper-evident chain of custody from stuffing location to destination devanning
- Mandatory for C-TPAT, AEO, and other supply chain security certification programs
- Reduces cargo theft and tampering risk during transit and terminal dwell
- Documents seal numbers on shipping records, enabling rapid customs and carrier verification
- ISO 17712 high-security bolt seals are resistant to common tools, raising the effort threshold for tampering
- Proper seal procedures reduce the probability of targeted customs inspections at destination ports
FAQs
Q: What seal type is required for C-TPAT certified shipments?
A: C-TPAT requires ISO 17712 high-security bolt seals for all container shipments crossing into the United States. These seals must be applied by a C-TPAT member or their verified business partner at the point of stuffing, not at the terminal. The seal number must appear on all shipping documentation. Plastic indicative seals do not meet this requirement.
Q: What should happen if a seal discrepancy is discovered at the destination?
A: Do not open the container until the discrepancy is documented. Photograph the seal and door hardware. Notify the carrier, customs broker, and cargo insurer immediately. File a note of protest with the carrier and request a joint survey before devanning. A seal discrepancy does not automatically mean cargo has been tampered with — seals are sometimes changed by customs authorities during inspection — but the change must be documented with a customs seal applied in its place.
Q: Who is responsible for applying the seal — the shipper, the 3PL, or the carrier?
A: For C-TPAT compliance, the stuffing entity (shipper or their authorized 3PL) is responsible for applying the seal at the point of stuffing before the container enters the port terminal. The carrier typically applies a secondary or indicative seal at the terminal gate. The bill of lading should reflect the shipper-applied seal number as the primary security seal.
Q: How are seal numbers tracked and audited in a compliant operation?
A: Compliant operations maintain a seal log that records each seal's unique number, the date issued, the employee who applied it, the container number, and the shipment reference. This log is reconciled against shipping documents and available for audit during C-TPAT validations. Some WMS and export documentation platforms include seal number fields that automatically populate the bill of lading, reducing transcription errors.