Container Seal Verification and Seal Logs

What ISO 17712 covers

ISO 17712 is the international standard for mechanical freight container seals. It classifies seals by their barrier strength into three classes:

Class	Name	Typical examples	What it means
I	Indicative	Plastic strap seals, labels	Shows tampering; can be broken by hand or with simple tools
S	Security	Light metal or cable seals	Some resistance; needs tools to remove
H	High security	Bolt seals, heavier cable seals	Designed to need heavy-duty cutters to remove

CBP's published seal procedures for CTPAT participants call for seals that meet the ISO 17712 standard for high security seals on loaded containers and trailers, with documentation of that compliance kept on file. Ask your seal supplier for the certificate that covers the seal model you buy, and check it names the current edition of the standard.

VVTT: the four-step check

CBP's seal procedures describe the View, Verify, Tug and Twist method, often shortened to VVTT. It is used when a seal is applied and again before it is cut.

View the seal and the container's locking mechanism. Look for scratches, glue, paint, cuts, signs of heating, and damage to the door hardware, hinges and rivets.
Verify the seal number against the shipping documents, character by character.
Tug the seal firmly to make sure it is locked.
Twist and turn the seal to make sure its parts do not unscrew or separate.

The same procedures call for a trained person to apply the seal with a witness, and for the check to be done, with a witness, before a seal on an inbound shipment is cut.

Where to check the seal

Point	Who checks	Record
Stuffing and sealing at origin	Trained shipper staff, with a witness	Seal number, applier, witness, time, photo of the applied seal
Pickup	Driver	Seal number matches the bill of lading; condition
Each handover	Receiving party	Seal number, condition, any change
Border or customs examination	Carrier or broker	New seal number if the seal was removed, and who removed it
Delivery	Receiver, with the driver	VVTT result before cutting; photo; cut seal retained or destroyed as policy says

Keeping a seal log

A seal log connects each physical seal to the shipment it was used on. CBP's procedures describe logging seals on receipt, recording their use when issued, and inventorying them at least once a year.

On receipt from the supplier: seal number range, quantity, date received, who received them.
Storage: locked, with access limited to named people.
On issue: seal number, date and time, issued to, trailer or container number, shipment reference.
On application: applied by, witnessed by, time, photo reference.
Voided or damaged seals: number, reason, and what happened to the seal.
Audit: periodic count of unused seals against the log.

A log can be kept on paper or electronically. What matters is that entries are made at the time and not altered afterward.

When the seal does not match

Do not cut the seal or open the doors until you have recorded what you found, unless safety requires it.
Photograph the seal, its number, and the door hardware.
Note the discrepancy on the delivery receipt before signing, with both numbers.
Notify the shipper, carrier and, where relevant, your customs broker. CBP's procedures also call for compromised seals and containers to be reported to CBP or the appropriate foreign authority.
Open with a witness, count and inspect, and complete an OS&D report.
Keep the seal as evidence until the question is settled.

Not every mismatch means theft. Customs examinations and carrier inspections can require a seal to be removed, and a replacement seal should then be applied and recorded. The difference between an innocent seal change and a suspicious one is whether the change was recorded, by whom, and when.

Choosing a seal type

Seal type	Where it fits	Watch for
Bolt seal	Loaded ocean containers and trailers on the container door's locking bar	Needs cutters to remove; keep cutters at receiving docks
Cable seal	Doors or fittings a bolt will not suit	Pull the cable tight; slack makes tampering easier to hide
Plastic or indicative seal	Internal movements, totes, cages and low-risk uses	Shows tampering but offers little resistance
Electronic seal	Loads where an opening event should be reported as it happens	Still record the physical seal number; batteries and coverage vary

Whatever you use, buy seals with unique numbers from a supplier who can document the standard they meet, and never reuse a number.

Seals and chain of custody

An intact seal with the right number at each handover is strong evidence that nothing was added or removed on that leg. That is why the seal number belongs in every handover entry of a chain of custody record, and why a broken or changed seal is one of the first things a claims handler looks for in a freight claim. Seals also help against some forms of cargo theft, mainly by making pilferage in transit evident.

Common questions

What does VVTT stand for?

View, Verify, Tug and Twist: a four-step seal inspection described in CBP's seal procedures, used when applying a seal and before cutting one.

What is an ISO 17712 H class seal?

A high security seal under ISO 17712, such as a bolt seal, designed so that removing it needs heavy-duty cutting tools.

Does a domestic truckload need a high security seal?

Not by any single rule for all domestic freight. Many shippers seal full truckloads as a matter of policy or contract, and CTPAT participants follow CBP's seal requirements across their supply chain. Check your customer and program requirements.

What should happen to cut seals?

CBP's procedures describe keeping cut seals in a separate, inaccessible container and destroying them, so they cannot be reused to disguise tampering. Keep any seal involved in a dispute until it is resolved.