Korean Used Car Container Seal: ISO 17712 Bolt Seals & Verification Guide (2026)

A Korean used car container seal is a uniquely numbered mechanical lock — almost always an ISO 17712 high-security steel bolt seal — fitted to the container doors after your car is loaded, so the box cannot be opened in transit without visibly destroying it. Its serial number is recorded on your Bill of Lading, cargo manifest, and packing list, and at the destination port you verify that the physical seal is intact and its number matches the documents before you accept the container and break the seal.

That small numbered bolt is the single clearest piece of physical evidence in the whole shipment: a matching, undamaged seal proves nobody entered the container between Korea and your port. This guide explains what the seal is, the ISO 17712 grades, the seal types, where the number appears, and exactly how to check it on arrival. It sits alongside our container loading guide, which covers how the car is lashed inside the box before that seal ever goes on.

What a Korean Used Car Container Seal Is

When your Korean car is stuffed into a shipping container and the doors are closed, the last physical act before the box leaves the yard is sealing. A seal is a small, uniquely numbered device fitted through the container's right-hand door locking bar. Its job is not to be an unbreakable lock — a bolt cutter will always defeat it — but to be tamper-evident: once fitted, it cannot be opened and re-fitted without leaving proof, and its serial number cannot be forged onto a fresh seal.

Think of the seal as a numbered witness. As long as the same numbered seal is intact on arrival, the container has not been opened since Korea. The moment it is cut, altered, or swapped, the record breaks — and that broken record is exactly what a buyer, a carrier, and a marine cargo insurer rely on. This is why the seal is inseparable from the paperwork: the number on the doors and the number on your Bill of Lading must be the same.

For a used car — a high-value, theft-attractive cargo — the seal is one of the strongest reasons buyers on theft-prone lanes choose container shipping over open RoRo decks. The car travels invisible and inaccessible inside a locked steel box, and any breach announces itself. SH GLOBAL fits a high-security bolt seal on every car container and sends the buyer the number and a photo of the sealed doors before the vessel sails.

The Three ISO 17712 Seal Security Grades

ISO 17712 is the international standard that governs mechanical seals for freight containers. It does two things: it defines the physical strength a seal must survive, and it sets the tamper-evidence and audit rules a seal manufacturer must follow. Crucially, it sorts every seal into one of three grades by a single letter:

Only High-Security ("H") seals — the hardened steel bolt seal and the high-tension cable seal — meet the strength threshold demanded by customs security programmes worldwide, including the U.S. C-TPAT (Customs–Trade Partnership Against Terrorism) and the Container Security Initiative (CSI). An "I"-grade plastic indicative seal will show if it was snapped, but it offers almost no resistance and is unsuitable for a car. For an exported vehicle, the only sensible choice is an ISO 17712 "H" bolt seal, and a serious exporter treats that as non-negotiable.

Bolt Seal vs Cable Seal vs Indicative Seal

Three seal types show up in container shipping. For a Korean used car, one is the norm, one is occasional, and one should never be your only seal. The table below sets them side by side.

The bolt seal is the workhorse of car export: a two-part hardened steel pin and locking barrel that snaps together through the container's door handle bars. It cannot be pulled apart, twisted off, or picked; a thief needs a bolt cutter and time, and even then the numbered seal is destroyed, not defeated silently. The cable seal is common on some lanes and is fine when it is a genuine "H"-grade high-tension unit. The plastic indicative seal has its place — sealing sample bags or low-value goods — but on a car container it belongs, at most, as a secondary marker, never as the primary seal.

Customs Seal vs Carrier Seal — Who Applies It

Not every seal is fitted by the same party, and knowing the difference prevents a needless panic at the destination. There are two categories a buyer will meet:

Carrier seal (shipper's seal)

This is the ordinary seal fitted by whoever stuffs and closes the container. In a Korean car export that is the exporter or the loading yard, acting on behalf of the shipping line, immediately after the car is lashed and photographed. The carrier seal's number is the one that goes onto your Bill of Lading and is the number you expect to see on the doors when the container reaches you.

Customs seal

A customs authority may apply its own seal. In Korea this happens if the container is examined or moved under bond; at the destination it happens if customs opens the box for inspection and then re-seals it. When customs re-seals, the number changes — and that is normal, provided there is a customs examination note or re-seal record explaining it.

The Seal Number Chain — Where It Appears

The power of the seal comes from its number appearing on every core document, so the whole chain can be cross-checked against one physical object. When SH GLOBAL seals a container, the same alphanumeric serial flows onto each of the following, in order:

The four documents that carry the seal number are the Bill of Lading, the cargo manifest, the packing list, and (often) the shipping instructions and export declaration. The number is also tied to the container's own number and, separately, to the container's Verified Gross Mass (VGM) — three independent facts about one sealed box that together make substitution or tampering hard to hide. For the buyer, the practical point is simple: hold the seal number in writing before the ship sails, so you can check it yourself on arrival rather than taking the terminal's word.

SH GLOBAL Hyundai inventory — every car container is closed with a high-security bolt seal and the number is sent to the buyer. Browse Hyundai inventory →

How to Verify Your Container Seal at the Destination

Verification is the buyer's job, and it takes two minutes. Whether you clear the container yourself or use a clearing agent, insist the following happens before the seal is cut. This is the moment the whole seal system pays off.

1. Locate the seal on the right-hand container door and read the number and any brand or logo stamped on it.
2. Compare it to your Bill of Lading. The number on the physical seal must match the seal number on the B/L exactly, character for character.
3. Inspect the seal for tampering — cuts, filing marks, glue, a re-joined bolt, or a seal that looks newer or different from the one photographed in Korea.
4. Check the container number too. Confirm the container's own ID (four letters + seven digits) matches the B/L, so you are opening the right box.
5. Photograph the intact seal and the container number together before anything is cut, as your dated record.
6. Only then break the seal — ideally with the clearing agent or terminal present — and keep the cut seal until the car is unloaded and checked.

If the Seal Is Broken or the Number Doesn't Match

A broken, missing, or mismatched seal is uncommon, but if it happens the way you respond decides whether you can recover anything. The one rule that governs everything: document before you open.

1. Photograph everything — the broken or wrong seal, its number, and the container number beside it, clearly and in focus.
2. Record the exception in writing on the delivery order, equipment interchange receipt (EIR), or arrival paperwork, so the carrier and terminal formally acknowledge it.
3. Notify your exporter and marine cargo insurer immediately. A broken or mismatched seal is the trigger event for a theft or tampering claim; delay undermines it.
4. Request a joint survey before unloading if theft is suspected, so an independent surveyor records the car's condition against the Korean baseline.
5. Keep the seal remains. A cut or altered seal is physical evidence; do not discard it.

This is where the whole documentation chain earns its keep. Your undamaged pre-shipment inspection photos establish the car's exact condition and contents in Korea; the sealed-door photo ties that to the seal number; and the B/L ties the number to the carrier. If the destination evidence differs, you hold a complete, time-stamped trail — the difference between a paid claim and a "your word against ours" dispute. A mismatched number with no customs note is treated exactly like a broken seal.

Container Seals and Car Theft — the Real Protection

Buyers on African and some Middle Eastern lanes worry, rightly, about theft and parts pilferage. The container seal is central to why sealed shipping answers that worry, and it works on two levels at once.

First, it is a genuine physical deterrent. A high-security bolt seal cannot be opened by hand; a thief needs a bolt cutter and enough uninterrupted time at a port or yard to use it. That friction alone turns away most opportunistic theft, which depends on being fast and quiet. Second, and more decisive, the seal is tamper-evident: even a determined thief who cuts it cannot restore the original numbered seal, so the intrusion is provable the instant the container is inspected. Undetectable theft — the kind that leaves the buyer with no claim — becomes almost impossible.

That is why sealed container shipping is the default recommendation for higher-value cars and theft-sensitive destinations, and why our Africa export guide leans on it for those lanes. The car travels sealed and invisible; the number on the doors is the promise that it arrives the way it left. Compare that with an open RoRo deck, where the car is under cover but accessible — a trade-off we break down in the container loading guide. The seal does not make theft impossible. It makes silent theft impossible, and that is what protects both the car and the buyer's claim.

Buyer Checklist for Container Seals

You will not fit the seal, but you can make sure it is done right and used to your advantage. Six things to confirm across the shipment:

1. Require a high-security ISO 17712 "H" bolt seal — not a plastic indicative strip — as the primary seal on your car container.
2. Get the seal number in writing before the vessel sails, together with a photo of the sealed doors with the number legible.
3. Confirm the same number is on the Bill of Lading and, ideally, the packing list and manifest.
4. Verify the physical seal against the B/L at the destination before it is cut, and photograph it intact.
5. Know the customs-reseal rule — a changed number is only acceptable with a customs examination note.
6. Keep the cut seal and all photos until the car is unloaded, inspected, and accepted.

How SH GLOBAL Handles Container Seals

SH GLOBAL Co., Ltd. treats the container seal as the final, documented link in a controlled handling chain — not an afterthought left to a yard. Our standard practice on every sealed car container:

• High-security bolt seal, always. An ISO 17712 "H" hardened-steel bolt seal is fitted to the container doors after the car is lashed and photographed — never a cheap indicative strip.
• Sealed doors photographed. The closed, sealed doors are photographed with the seal number clearly legible, and the photo goes to the buyer with the pre-shipment inspection report.
• One number, every document. The seal number is recorded on the Bill of Lading, the packing list, and the cargo manifest, so every document agrees and the buyer can cross-check.
• Buyer holds the number before sailing. The seal number reaches the buyer before the vessel departs, so it can be verified against the physical seal on arrival.
• Customs re-seals recorded. If customs examines and re-seals a container in Korea, SH GLOBAL records the new number and the examination note, so there is never an unexplained change of seal at the destination.

For availability, browse Hyundai inventory or Kia inventory, or see the current stock. To see where sealing sits in the wider purchase, walk through our step-by-step buying process.