Understanding Seal Tampering to Reduce Theft

Understanding Seal Tampering to Reduce Theft

Posted by Steve Diebold

There are two important aspects of seal tampering. Both are of equal importance.

First is recognizing there is something wrong with a seal you are examining. The other is using that information to detect, counter and prevent theft.


Here are things that typically might be wrong with a seal:

“The seal is broken.”

This is often obvious, but sometimes it’s necessary to physical check to find it.

“This does not look like the right seal.”

To know this this the responsible person must be well informed about their seals.

“The mechanism does not operate as expected.”

To detect this requires knowledge of the seal plus physical and visual inspection.

Any of these things can be a sign of theft but broken seals should first be looked at to determine if the breakage was accidental through normal use or is unauthorized access. If it is from normal use a stronger seal may be the solution. If the opening was unauthorized or a seal was tampered, then the user should have a plan of action.

Seal violation takes various forms including hiding the opening and closing to fool the untrained observer, substitution of parts, modification of markings, or substitution of whole (clone) seals.

An initial discovery of tampering may occur when the seal is cut and taken out of use. It may also be found on site by scheduled inspection, or on examination of the seal after it is opened by the user and checked at another location. If a seal is never examined by an informed person, tampering or violation of the seal may not be discovered at all.

It is important that users of the seal are familiar with them and trained in proper inspection or test procedure. Proper tracking records of seals and numbers are also important. Ideally a photo of the seal would be accessible either near the seal, on the shipping document, or online. This is a not a common practice yet but highly effective and recommended.


General practices regarding handling tampered seals are referenced in our guide to seals. https://seals.com/guide-to-tamper-evident-security-seals/ We do not specify or publish detailed procedures for seals that are tampered because of the many variables and unique situations each user has. Some companies have internal policies for reporting and handling seals found to be tampered, opened without authorization, or suspected to be tampered by unknown persons.

Once discovered, the process is normally to systematically narrow the time and/or place the violation occurs. This may take several cycles of use, but can tell an investigator who potentially is violating (or attempting to violate) a secured container or device, when it happened, as well as where it happened (if it is a moving application like rail or truck)

If you need help establishing a policy or program for that, we can provide general guidance, but would not get involved in a customer’s internal policies. To assist we need to know the type of seal, and all details and circumstances regarding the suspected or known tampering. We also need the seal or seal(s) involved to identify the issue. We also encourage users to closely examine locking procedures before assuming it was tampered. Proper locking is critical.


With cable seals they must be pulled as tightly as possible for secure closure. Leaving loose cable is a common error and can invite problems. Either with the seal remaining in place, or with potential for forcing the seal open using tools.

Most seals have a specific sound when properly locked and often there is an amount of movement or inspection point to check if a seal is fully locked. AC&M is an experienced manufacturer, and we can provide information or help with all details of how seals should be properly locked and inspected. Even if that requires direct personal assistance from one of our experienced staff.

If you need advice or assistance when tampered seals are found, then returning the seal(s) to us (the manufacturer) is one recommendation. We are available and best qualified to inspect any of our seals that are found tampered or suspected of tampering. When a customer submits a seal for examination, we can offer informed reporting of the tampering evidence found. But the solution can only be offered in broad terms. It also requires control samples from the same batch of seals to verify there is no defect. A rare occurrence, but it is possible.

We encourage customers to contact an expert at American Casting & Mfg. for information or help with anything related to seals and maximizing their effectiveness in finding and stopping losses from theft. We have been in this business since 1910 and our mission is to help our customers get the most from our seals.

Find complete contact information on the website www.seals.com