Shipping Container Seals
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Security Levels of Seals and HMRC Classes

There are three main security levels of seals that are recognised by HM Revenue and Customs for import and export. Long distance transport for high value cargo have regulations and requirements which must be fully compliant to successfully (and quickly) pass through border control. Not all seals are created equally, and the degree of protection varies depending on the seal components, assembly and material. Seal protection grades are often broken down to high-security, security and indicative.

Breakdown by Strength Category

For import and export purposes, there are three main protection gradings that customs use to categorise the security level of cargo by sealing.

The global standard for seal grading is ISO 17712 and defines three types of classes of security seal strength, or barrier capacity: “I” for Indicative; “S” for Security; and “H” for High Security. C-TPAT requires the use of “H” class seals. HMRC also implements this standard grading system but categorises them in strength as Group 1, 2 and 3.

  1. High Security Seals ‘H’ (HMRC Group 1 Barrier Seal): they basically include seals for maritime shipping containers. They may be in the form of a bolt seal but may also be metal seals with an adjustable cable. These seals often required specialised tools to cut through the seal and their tensile strength is often in excess of 1000kg.
  2. Security Seals ‘S’ (HMRC Group 2 Barrier Seal): These seals are a less specialized type of security seal than the previous ones, suitable for a wide variety of applications. Whilst they offer a good level of strength protection, they would not be classified as provided optimal protection against tampering. The tensile strength starts at around 231 kg.
  3. Indicating ‘I’ (HMRC Group 3 Seal): The main function of this type of seal is identification and only provide tamper-evident security. They are usually made of reduced strength metal or plastic. They may be in the form of security seals with metallic cable or ring type seals or adjustable strap seals. The tensile strength is usually about 50kg.

Indicative (I) and Security (S) Seals

  • Application: They are used mainly for international shipping transport, often referred to as border and customs seals. However, the application of the seals are varied and cover all types of transport, including trucks, lorries and tankers…
  • Products by security level: The function of these seals are for to provide tamper-evident identification rather than tamper-proof security. The level of security they offer is lower than those in Barrier Class 2 and 1.
    • Tensile breaking strength less than 231 kg.
    • Special shearing tools are needed for opening them.
  • Pieces that comprise it: the metallic indicative ‘I’ seals are made from a plated steel alloy. The standard security seals ‘S’ (Class 2) are made from a steel aircraft cable. They provide a good level of security but are more prominently used as a deterrent to and provide clear identification of unauthorised entry.
    • They are formed from metal alloys that bend for movement and give varied levels of application.
    • They are easy to apply and are marked to show the correct closure to avoid manipulation of the goods.
    • The seals are engraved with a sequential number to prevent unauthorised removal and reapplication.

The following table compares the different models of JW Products indicative seals.

ModelTypeMaterialTensile strength
Guardlock – 210mmSeal with metallic cablePlated Steel45 kg
Ballseal – 216mmSeal with ball seal headPlated Steel50 kg
Metal Cable Seal – 2.5mmCable type sealSteel Aircraft Seal500 kg


High-Security Barrier Seal (H)

  • Application: used primarily for the transport of high-value goods in shipping containers. Their function is to avoid them being accessed or tampered with during maritime transport.
  • International Regulations: Because of their use in transport, the seals are approved internationally to ISO/PAS 17712 and to C-TPAT regulations (customs anti-terrorism security in the USA).
  • Bolt Seal Assembly: These high security seals are called bolt type because they usually consist of two parts:
    • A central steel tube covered with plastic with a stop on the bottom.
    • An upper bushing with a steel core that closes the seal once installed. It is usually supplied attached to the other piece to avoid it being lost.
  • Products by security level: Bolt and Cable seals meet border high security regulations due to:
    • Tensile breaking strength greater than 1000kg.
    • Industrial cutting tool required to remove seal.
    • Sequentially numbered for identification purposes which aids in preventing unauthorised removal and re-application of another seal.

The following table compares the various models of JW Products high security seals.

ModelTypeMaterialTensile strengthApproved as per regulations
HMRC Bolt SealBolt type barrier seal (H)Carbon Steel1000 kg+ISO/PAS17712 and C-TPAT
Cable Seal 3.5mmCable type barrier seal (H)Steel Aircraft Cable1000 kg+ISO/PAS17712 and C-TPAT
ForksealFork type barrier seal (H)Galvanised Steel1935 kg+ISO/PAS17712 and C-TPAT


You can view our range of indicative seals (HMRC Barrier Class 3) here:

You can view our range of HMRC Bolt Seals (HMRC Barrier Class 1) here:

You can view our range of 3.5mm Metal Cable Seals (HMRC Barrier Class 1) here:

You can view our range of Shipping Container Fork Seals (HMRC Barrier Class 1) here:

You can view our range of 2.5mm Metal Cable Seals (HMRC Barrier Class 2) here: 

If you require a more bespoke option, you can use contact us by visiting the quote page or alternatively you can call our sales team on +44 1252624305.


JW Products have been servicing the security seal requirements of the transport, haulage and aviation industry worldwide, for over 20 years. We have built a reputation for reliability, expertise and excellence since our conception in 2000 and we are ready to help your business thrive in a post Brexit world. You can rely on our dedicated team to identify your business’s security seal requirements and offer approved solutions to meet them. We offer high security tamper proof security seals, conforming to ISO 17712:2013 and effective tamper evident seals, to help your business meet regulatory standards and protect your assets. As a trusted supplier to Government Agencies, NHS and UK Police Forces, your business can engage with JW Products with confidence.

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