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This guide details the international regulatory framework for the sea container security seal - ISO 17712:2013 standard, C-TPAT programme, TIR Convention - the three security grades (I, S, H), the seal types used including lead seals, the five-step installation procedure and the decision matrix by shipping route.
What is a sea container security seal and what is it for?
A sea container security seal is a single-use device that guarantees the tamper-evidence of a container between loading and delivery. Once installed on the door locking rods, any opening attempt destroys it irreversibly, leaving visual proof. ISO 17712:2013 governs its mechanical characteristics, traceability and marking.
The sea container security seal serves four simultaneous purposes: guarantee the integrity of goods between shipper and consignee, trace each logistical step through a unique number, provide legal proof in case of transport or customs dispute, and meet the regulatory requirements of shipping lines and international customs authorities. All major carriers (MSC, Maersk Line, CMA CGM, Evergreen, COSCO, Hapag-Lloyd) mandate an ISO 17712 compliant seal on every container in international circulation.
Why compliance matters in 2026. According to the World Shipping Council, more than 250 million TEU container movements are logged every year on the world's major maritime corridors. Every container in international circulation must carry a compliant seal. If a seal is missing, damaged or non-compliant, the goods are held at the dock, contractual liability automatically shifts from carrier to shipper, and the insurer may deny coverage.
Regulatory framework: ISO 17712, C-TPAT and the TIR Convention
The sea container security seal operates under three international regulatory frameworks: the ISO 17712:2013 standard (mechanical and security specifications), the C-TPAT programme (Customs-Trade Partnership Against Terrorism, US Customs) and the TIR Convention managed by the World Customs Organisation. All three apply cumulatively to any transatlantic or transpacific traffic.
The ISO 17712:2013 standard
Published in 2013 by the International Organisation for Standardisation, ISO 17712:2013 defines the mechanical, procedural and security requirements for mechanical seals used on ISO containers. It sets three non-negotiable requirements: uniqueness (each seal carries a unique traceable number), tamper-evidence (any opening attempt must be irreversible and leave proof), inspectability (visual inspection must detect any alteration). It classifies seals into three grades I, S and H, detailed below. The manufacturer must be ISO 17712 audited and certified, and provide a certificate of conformity for each batch shipped.
The C-TPAT programme (US Customs and Border Protection)
Established in 2001 by US Customs and Border Protection, C-TPAT is a voluntary partnership between US customs and the international supply chain community. It mandates a Grade H ISO 17712 high-security seal on every container bound for the United States. In return, C-TPAT members benefit from expedited clearance, fewer physical inspections, and mutual recognition with the European Union (AEO status) and 15 other partner customs administrations.
The TIR Convention and the World Customs Organisation
The TIR Convention, signed in 1975 under the UN Economic Commission for Europe, governs international road transit after port unloading. It requires a compliant customs seal on any container or TIR vehicle crossing multiple countries without a new inspection. The World Customs Organisation (WCO, based in Brussels), which coordinates 185 national customs administrations, regularly issues recommendations on the use of electronic and mechanical seals in the international supply chain.
The three ISO 17712 grades: indicative (I), security (S), high security (H)
ISO 17712:2013 classifies seals into three grades according to their resistance to tension, torsion, shear and impact. Grade H, mandatory for any container in international circulation and any C-TPAT traffic, withstands over 3,300 kg of tensile load. Grades I and S are reserved for secondary use or low-risk domestic routes.
Grade I (indicative): empty container, repositioning
The indicative seal signals an intrusion but does not mechanically prevent it. It typically consists of thin plastic, adhesive tape or a light lead seal, and opens by hand without tools. Its use is limited to empty container repositioning, low-risk zone marking and secondary side-door sealing. Not allowed on the main door of a container in international circulation.
Grade S (security): intermediate transport
The security seal prevents unauthorised opening and leaves visible evidence in case of tampering. It withstands moderate mechanical force on low-risk routes, intra-European transit or road trailers. It is not enough for C-TPAT traffic to the United States.
Grade H (high security): mandatory for international containers
The Grade H high-security seal withstands more than 3,300 kg of tension, over 400 kg of shear, and manual tool attack. It requires a hydraulic bolt cutter, an angle grinder or a heavy-duty pincer to be cut - loud, bulky and visible tools that are incompatible with a discreet theft. The only Grade H seals recognised in 2026 are hardened-steel bolt seals and braided-steel cable seals with a diameter above 3.5 mm. The "H" marking and the ISO certification number must be visibly engraved on the seal. Mandatory grade for any sea container in international circulation and any C-TPAT traffic.
Seal types used in sea shipping
The Grade H sea container security seal comes in two main families: bolt seal (container standard) and cable seal (flexibility). Lead seals and adhesive seals are never used as the primary seal on an international sea container, but they complement the device on side doors, internal compartments and customs documents.
Grade H bolt seals: the container reference
The bolt seal is the most widely used format on standard 20 and 40-foot sea containers. It consists of a numbered hardened-steel bolt locked into a steel body. Installation takes one press, removal requires a hydraulic bolt cutter. Measured resistance: over 3,300 kg tensile load, over 400 kg shear. This is the format chosen by nearly every international shipper on the China-Europe corridor and transpacific traffic.
Grade H cable seals: flexibility and versatility
The cable seal uses a braided steel cable (1.5 to 5 mm diameter) inserted into a lockable housing. It fits atypical containers (open-top, flat-rack, tank), tanker trailers, refrigeration units and reefer containers. It is also used when the sea leg is followed by TIR road transit. The SBE Direct padlock seals range covers this requirement for any international traffic.
Lead seals: secondary use, never as the primary seal
Lead seals - natural lead, coloured plastic lead, aluminium lead, stem lead - belong to grade I or S depending on their material. They are never used as the primary seal on an international container. Their role: seal an intermediate compartment, a customs bag, a case inside the container, a diplomatic pouch, an electricity meter on shipped equipment, a parcel in transit. The SBE Direct lead seals range covers all these uses.
Anti-fraud adhesive seals: essential complement
Anti-fraud adhesive seals with total or partial transfer complement the primary mechanical seal. They protect the interior doors of a multi-compartment container, high-value cartons, sensitive-goods pallets (electronics, pharmaceuticals, luxury). They reveal any opening attempt through an indelible VOID pattern that stays either on the substrate or on the removed adhesive.
Comparison table: sea container security seals
| Seal type | ISO 17712 grade | Material | Tensile resistance | Indicative price | Target use |
|---|---|---|---|---|---|
| Bolt seal | H (high security) | Hardened steel | Over 3,300 kg | 1.30 to 2.60 GBP | Standard 20/40-foot international container |
| Cable seal | H (high security) | Braided steel Ø 3.5 to 5 mm | Over 3,300 kg | 0.90 to 2.20 GBP | Atypical container, reefer, TIR trailer |
| Heavy plastic seal | S (security) | Reinforced polymer | 200 to 800 kg | 0.20 to 0.70 GBP | Intra-European traffic, trailer |
| Anti-fraud adhesive seal | Complement (out of grades) | VOID transfer adhesive | Not applicable | 0.10 to 0.45 GBP | Internal doors, cartons, pallets |
| Natural lead seal | I (indicative) | Lead | Under 50 kg | ≈ 90 GBP per 1,000 | Meters, customs bags, secondary compartments |
| Aluminium lead seal | I (indicative) | Aluminium | Under 100 kg | 65 to 100 GBP per 1,000 | Engraved personalisation, postal bags, parcels |
How to install a sea container security seal in 5 steps
Installing a Grade H sea container security seal takes under one minute and always follows the same procedure. Incorrect installation can void ISO 17712 compliance and shift claim liability to the shipper. The rule: right-hand door systematically, primary locking rod, visual check and number recorded on transport documents before closing.
- 1Fully close both container doors and engage the locking rods. The two doors must remain in continuous contact, the sealing gasket compressed over the full height, and the four locking rods fully engaged in their upper and lower housings.
- 2Select the primary locking rod on the right-hand door. The right-hand door is opened first at unloading, so it is sealed as a priority. If the container is single-door or if the right door is blocked, use the left door and document it on the bill of lading.
- 3Install the seal on the right-hand door locking rod. For a bolt seal, insert the bolt into the body and press firmly until a mechanical click. For a cable seal, thread the cable through the rod's eyelet and insert it into the locking housing until it snaps.
- 4Verify the fixing with a firm pull. Pull on the seal by hand. No slack, no slip, no click. A seal that moves indicates incomplete installation: restart immediately, never leave a doubtful seal on a container in circulation.
- 5Record the seal number on the bill of lading, CMR and any customs document. Photograph the installed seal if possible. The number must match the physical seal and every transport document. Any discrepancy holds the container on arrival and puts the liability on the shipper.
How to choose your seal by shipping route and destination
The choice of a sea container security seal depends on three variables: destination (United States, European Union, Asia, Africa), container type (standard, reefer, open-top, post-unloading TIR road) and customs or goods risk level. Here is the decision matrix by international shipping route.
| Route | Destination | Recommended primary seal | Complements |
|---|---|---|---|
| Transatlantic | United States, Canada (C-TPAT) | Grade H bolt seal | Adhesive on internal doors |
| Transpacific | China, Japan, South Korea | Grade H bolt seal | Reinforced numbered marking |
| Intra-European maritime | Baltic and Mediterranean feeders | Grade H bolt seal | Grade S plastic seal as secondary |
| Trans-African | North and sub-Saharan Africa | Grade H bolt seal | Anti-fraud adhesive |
| Reefer container | All destinations | Grade H cable seal | Temperature-check seal |
| Open-top or flat-rack container | All destinations | Grade H cable seal | Tarpaulin marking |
| Post-unloading TIR road | Multi-country transit | Grade H cable seal | Customs lead seal |
| Internal compartment or bag | All routes | Engraved aluminium lead seal | VOID adhesive |
Traceability, numbering and alert procedure
Every sea container security seal carries a unique laser-engraved number recorded by the manufacturer. This number appears on the bill of lading, the CMR waybill, the customs declaration and the loading report. Any mismatch on arrival triggers an immediate alert procedure that holds the container until an expert inspection.
On arrival, the consignee or customs agent verifies three elements before opening: physical presence of the seal, mechanical integrity (no signs of tampering), and exact number match with the bill of lading. Any discrepancy - seal missing, damaged, or number different - halts reception, triggers a contradictory expertise with the insurer, and shifts the burden of proof. In this case, immediately notify the shipping line, the freight forwarder and the transport insurer before any opening. Opening a non-compliant container without prior expertise almost always voids insurance coverage.
SBE Direct approach. Since 1992, SBE Direct has supported B2B players in transport, logistics and customs with a complete range of seals covering every ISO 17712 grade and use case, from container main door to compartment lead seals. Our General Catalogue No. 33 lists over 2,000 references. Lead seal and mechanical seal customisation is available from 500 units with laser engraving and custom numbering. This guide draws on our field feedback in 2024 and 2025 international traffic.
Securing your sea container flows effectively
Sea container flow security rests on three complementary layers: a Grade H ISO 17712 primary seal on the container's right-hand door, secondary lead or adhesive seals for internal compartments, and a documented procedure to record the number on every transport document. A compliant and correctly installed sea container security seal neutralises nearly all tampering attempts, while ensuring customs admissibility and insurance coverage.
Before any rollout, frame three points: the destination and applicable regulatory framework (C-TPAT, TIR, ISO 17712), the container type to secure (standard, reefer, open-top, post-unloading TIR) and the grade required by the shipping line handling the traffic.
Updated in September 2026.
Secure your sea containers
Grade H ISO 17712 bolt and cable seals, customisable lead seals, anti-fraud adhesive seals.
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Sea container security seal FAQ
Is a Grade H seal mandatory on every sea container?▾
Yes, for any container in international circulation. Every major shipping line (MSC, Maersk, CMA CGM, Evergreen, COSCO, Hapag-Lloyd) mandates an ISO 17712:2013 Grade H compliant seal on the main door of each container in transatlantic, transpacific or intra-European maritime traffic. The C-TPAT programme makes Grade H mandatory for any container bound for the United States, and the TIR Convention requires it on any multi-country transit after unloading. A lower-grade seal (I or S) is refused at loading.
What to do if the seal number does not match the transport document?▾
Never open the container. Immediately notify the shipping line, the freight forwarder and the transport insurer, photograph the physical seal and the transport document, and request a contradictory expertise before any handling. Opening a container with a mismatched seal without prior expertise voids insurance coverage in nearly all standard contracts.
Can a lead seal be used as the primary seal of a sea container?▾
No, never on a container in international circulation. A lead seal (natural, plastic, aluminium) is Grade I indicative and withstands under 100 kg of tension. It is only used for secondary sealing: internal container compartment, customs bag, sealed case, embedded electricity meter, multi-modal transit parcel. The primary seal of a sea container must be Grade H (hardened-steel bolt or braided-steel cable).
How long should a container seal be kept after reception?▾
The standard rule of transport insurers and international shippers is to keep the physical seal and its photograph for the full claim period, generally 12 months for international sea transport under the Hague-Visby Rules. In case of loss or damage, the installed and removed seal is direct evidence that can be examined by an accredited lab. Shippers of sensitive goods (pharmaceuticals, defence, luxury) keep seals for up to five years.
How to obtain C-TPAT certification for your seals?▾
C-TPAT certification applies to the shipper company, not directly to the seal. The seal must be ISO 17712:2013 Grade H compliant and supplied by an ISO 17712 certified manufacturer. The shipper company joins the C-TPAT programme via an application to US Customs and Border Protection, committing to supply chain security procedures (personnel screening, physical site security, training, documented seal installation procedure). Membership grants expedited clearance and fewer physical inspections.