Trailer Seals and Cargo Security for Dry Van Carriers

Trailer seals are cheap pieces of metal or plastic, but on a dry van they're the line between "the freight arrived as loaded" and a shortage claim you can't defend. Here's how seals work, how to record them, what to do when one is wrong, and the habits that keep a loaded van from being stolen.

Types of trailer seals

The international standard for mechanical seals is ISO 17712, which classes seals as indicative, security or high-security. U.S. Customs and Border Protection requires ISO 17712 high-security seals on loaded containers and trailers in its CTPAT and FAST programs, and plenty of domestic shippers use the same bolt seals.

Recording truck trailer seals

The seal only protects you if the number is written down in the right places. At pickup:

1. Watch it go on if you can. If the shipper seals it after you're out of the dock, check it before you leave the yard.
2. Check the number on the seal against the number written on the bill of lading. Both halves of a bolt seal carry the number; they should match each other too.
3. Tug and twist the seal to make sure it's locked, and look at the door hardware it's attached to.
4. Photograph it with the number readable.
5. Note "shipper load and count" on the bill of lading if you didn't see the freight loaded and counted.

Then check the seal at every stop: fuel, breaks and before you back into the receiver's door. A ten-second look with a photo can settle a dispute months later.

What to do with a broken or wrong seal

If the seal is cut, missing, or the number doesn't match the paperwork:

• Don't move on as if nothing happened, and don't open the doors yourself.
• Take photos of the seal, the doors and the area around the trailer.
• Call the broker and the shipper right away and follow their instructions.
• Call the police if you suspect theft, and get a report number.
• Write it down on the bill of lading: time, place, what you found and who you notified.

If an officer opens the trailer for an inspection, ask them to record it, note their name or badge number and any new seal number on the bill of lading, and tell your broker. The new number is now the one that has to match at delivery.

Cargo theft prevention for dry vans

A loaded 53 ft van is a target because it's anonymous and full. Practical habits that make your truck a harder target:

• Leave loaded, don't park loaded. Plan the trip so you don't sit loaded in a high-theft area for a 34-hour restart if you can avoid it.
• Park in secure, lit lots with cameras, and back the doors against a wall or another trailer.
• Use a kingpin lock and a door lock when the trailer is dropped or the truck is parked for a long time.
• Don't talk about the load. Not on the CB, not at the fuel island, not on social media.
• Check for followers after pickup, especially near ports and big distribution hubs.
• Know who you're dealing with. Fake brokers and fictitious pickups are a growing form of theft. Our guide to dry van brokers covers how to vet a broker and spot a fake one.

For fleets, the same habits need to be written down and followed by every driver. Our dry van fleet dispatch service plans parking and pickup times for each truck, so loaded trailers spend less time sitting.

Seals, claims and your liability

Under the Carmack Amendment, a carrier is liable for actual loss or damage to the goods it's carrying (49 U.S.C. 14706). A matching, intact seal and a "shipper load and count" note are some of the best evidence you have when a receiver reports a shortage on a load you never saw. Our dry van cargo claims guide covers the claim process.

Seals also connect to how the trailer is loaded and built. A load that's counted pallet by pallet at pickup is easier to defend than one you couldn't see, and the 53 ft trailer pallet calculator tells you whether a pallet count even fits the trailer. Door hardware varies by van too; see types of dry van trailers.

Where dispatch helps

Our dry van dispatch desk works with vetted brokers, confirms pickup details through official channels and keeps a record of every load. Read more dry van guides on running a safe operation.

Trailer seal questions

What are truck trailer seals for?

They prove the doors weren't opened between pickup and delivery. Each seal has a unique number recorded on the bill of lading. If the number at delivery matches and the seal is intact, it supports that the load arrived as it left. If not, it's evidence something happened in transit, which matters in a cargo claim.

What is an ISO 17712 high-security seal?

ISO 17712 is the international standard for mechanical freight container seals. A high-security (H) seal, usually a steel bolt seal, takes bolt cutters to remove. U.S. Customs and Border Protection requires ISO 17712 high-security seals on loaded containers and trailers in its CTPAT program, and many domestic shippers use them too.

Can a driver cut a seal?

Only with permission and a record. If a scale officer or inspector needs to see the load, write down who opened it, their badge or inspection number, the time and the new seal number if one is applied, and call your broker. Otherwise only the receiver should cut the seal.

What do I do if the seal is broken?

Stop and don't continue as if nothing happened. Take photos, call the broker and the shipper, note it on the bill of lading, and follow their instructions. If you suspect theft, call the police and get a report number. Don't put on a new seal of your own without instructions and a written record.

Sources

1. U.S. Customs and Border Protection, CTPAT and FAST lane requirements (ISO 17712 high-security seals on loaded containers and trailers), checked October 2026
2. 49 U.S.C. 14706, liability of carriers under receipts and bills of lading, checked October 2026