GB2163392A - Security seal - Google Patents

Abstract

A security seal comprises an elongate strip (2) of flexible material, having a plug (4) at one end and a socket (6) at the other. The socket is provided with two axially spaced rows of flexible tongues (38) and (42) which are engaged, in use, by respective barbs (16) on the plug (4). This provides double locking of the seal, so enhancing security. The seal may be broken by detaching the strap (2) from the plug (4) by breaking limbs (10) which provide a weakened connection. <IMAGE>

Description

SPECIFICATION Security seal This invention relates to a security seal. Such seals are increasingly used for detecting pilfering or unauthorised entry. For example, gas and electricity meters are provided with seals which must be broken to gain access to the meters. The intention is that unauthorised tampering with the meters can be detected. Also, cargo containers may be provided with seals in order to detect unauthorised opening of the container.

Hitherto, most security seals have been achieved by using a loop of wire which is secured by a crimped element of a malleable material, such as lead. During crimping, a code or other identifying marking is applied to the lead. A disadvantage of this type of seal is that its security depends significantly on how easy it is to copy the impression made by the crimping tool which is used. Lead is a very malleable material, and is comparatively easy to rework to remove evidence of tampering. Furthermore, not only is a special crimping tool required to fix the seal, but a cutting tool is required to remove it.

According to the present invention there is provided a security seal comprising a flexible elongate element having a plug at one end and a socket at the other end, one of the plug and the socket being connected to the elongate element by a weakened portion, the plug and socket being provided with cooperating barb means for preventing removal of the plug from the socket after insertion of the plug into the socket, the barb means comprising at least two sets of cooperating barb elements which are axially spaced from each other with respect to the direction of insertion of the plug into the socket.

Preferably, the plug has a fir-tree cross section to afford its barb means. The barb means of the socket preferably comprises two axially spaced rings of flexible tongues which can deflect to allow insertion of the plug, but which will prevent removal.

The socket is conveniently formed from two components, namely an outer sleeve and an inner sleeve. The outer sleeve may be integral with the elongate element. The rings of flexible tongues are formed one on the outer sleeve and one on the inner sleeve, and the inner sleeve may have an end wall to close one end of the socket.

In order to provide means for recording use of the seal, it may be provided with a serial number or other sequential marking or code, so that unauthorised removal and substitution of seals can be detected. It is useful for this purpose for the elongate element to be in the form of a strap, providing a flat surface for receiving such markings. For similar reasons, the seals may be produced in different colours, so as to provide an additional possibility of detecting unauthorised tampering.

For a better understanding of the present invention, and to show how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a side view of a security seal; Figure 2 is a view of the security seal of Figure 1 taken in the direction of the arrow II; Figure 3 is a sectional view taken on the line 111- 111 in Figure 1; and Figures 4to 8 show stages in the use of the security seal of Figures 1 to 3.

The security seal shown in Figures 1 to 3 is made from a thermoplastic material and comprises a flexible elongate element 2 in the form of a strap.

At one end, the strap 2 has a plug 4, and at the other end it has a socket 6. The plug 4 comprisesa cylindrical head 8 which is integrally connected to the strap 2 by two connecting limbs 10, so that the strap 2, the head 8 and the limbs 10 define a recess 12. Projecting away from the head 8 in alignment with the length of the strap 10 is a projection 14 which has a fir-tree cross-section so as to define barb means in the form of two axially spaced barbs 16. The head 8 is cylindrical as viewed lengthwise of the strap 2, and has a greater diameter than the projection 14. A small triangular fillet 18 is provided between the strap 2 and the head 8 on one side of the strap 2.

The socket 6, as shown in Figure 3, comprises an outer sleeve 20 within which is disposed an inner sleeve 22. The outer sleeve 22. The outer sleeve 20 is integral with the strap 2. It comprises a knurled portion 24 and a plain portion 26. The interior of the outer sleeve 20 comprises a cylindrical bore 28 and an inner chamber 30, in which the inner sleeve 22 is situated. The bore 28 is separated from the inner chamber 30 by a wall 32 having an opening 34. The portion of the outer sleeve 20 defining the inner chamber 30 is provided with two circumferential ribs 36 which engage the inner sleeve 22 to hold it in place. Three regularly distributed flexible tongues 38 extend from the wall 32 into the inner chamber 30, and are distributed regularly around the opening 34.Each tongue 38 extends from the wall 32 into the inner chamber 30, and is inclined slightly inwardly of the outer sleeve 20.

The outer sleeve 20 has an internal shoulder 40, against which the inner sleeve 22 abuts, The inner sleeve 22 has a ring of flexible tongues 42, similar to the tongues 38, which extend in substantially the same direction. The end of the inner sleeve 22 away from the tongues 38 is closed by a wall 44, which serves as an end wall for the entire socket 6.

The outer periphery of the wall 44 is bonded, for example by welding, to the outer sleeve 20, so as to retain the inner sleeve 22 in position.

Two reinforcing fillets 46 are provided, one on each side of the strap 2 at the junction between the strap 2 and the knurled portion 24 of the socket 6.

It will be appreciated from Figures 1 to 3 that the plug 4, the strap 2 and the outer sleeve 20 are formed integrally with each other as a single moulding, the inner sleeve 22 being subsequently inserted into the outer sleeve 20.

As will be appreciated from Figure 4, a plurality of the seals may be interco. elected, before use, by connecting elements 48. The straps 2 and connecting elements 48 may be moulded integrally with each other. To detach an individual seal for use, the endmost seal is pulled in the direction of the arrow 50 with respect to the remaining seals. This movement causes breakage of the connecting elements 48 which connect that seal to the remaining seals, Any parts of the connecting portions 48 which come away with the detached seal are then removed from the strap 2.

Before use of the seal, the plug 4 is bent relatively to the strap 2 through approximately 90ain the direction of the arrow 52, as shown in Figure 5.

This movement takes place about the limbs 10, further weakening them. As shown in Figure 6, the plug 4 is then inserted into the socket 6 and pressed home as shown in Figure 7, in order to push the barbs 16 of the plug 4 into locking engagement, respectively, with the rings of flexible tongues 38 and 42. This provides a double-locking function, so that locking will be maintained even if one of the rings of tongues 38 and 42 should fail. It will be appreciated that, should the ring of tongues 38 fail, it would not be possible to pull the inner sleeve 22 through the outer sleeve 20, because of the abutment of the inner sleeve 22 with the shoulder 40 and the abutment of the outer periphery of the wall 44 with the outer sleeve 20.

When the plug 4 is fully inserted into the socket 6, the head 8 fits into the bore 28. This prevents any attempt to release the seal by introducing a tool between the projection 14 and the flexible tongues 38 and 42.

To break the seal, the socket 6 is held in one hand and the strap 2 is held in the other hand at a position near the plug 4, and the two parts are pulled sharply apart. Unless it has been tampered with, the seal will break at the limbs 10. It will be appreciated that Figures 6 to 8 show the seal in isolation. In actual use, of course, the seal would be passed through staples or other fixing means of an assembly which is to be secured. For example, the seal may be passed around latching elements provided on container doors, so that the doors can be opened only after breaking the seal.

One useful feature of the seal shown in the drawings is that the strap 2, being flat, provides a surface for receiving printed matter. For example, the seals may be provided with consecutive serial numbers, so that a record can be kept of the serial number used to seal any particular item. By noting the serial number of the seal on that item, for example before the seal is broken by an authorised person, a cheek can be made that the originally fitted seal has not been broken and replaced one not having the recorded serial number. By making the seal from thermoplastic material, it is possible for the seals to be supplied having different colours so that, for example, the different colours can be used in rotation with each other. This, again, makes tampering more difficult, since the replacement of a seal which has been broken without authority would be immediately detected if a replacement seal of the wrong colour were used.

A further feature of the seal described is that if the strap is bent sharply, the material of which the strap is made discolours permanently.

Another feature of the above seal is that the knurls on the socket 6 serve as tamper disclosing means in that if for example any attempt is made to disengage the plug from the socket by squeezing the socket with pliers, say, permanent evidence, or at least evidence which is extremely difficult to remove, will be left on the socket.

Additionally the printing on the seal is of hot foil stamping and is quite indelible.

Lastly the one piece construction of the seal is of course important to the security of the seal.

Claims (14)

1. A security seal comprising a flexible elongate element having a plug at one end and a socket at the other end, one of the plug and the socket being connected to the elongate element by a weakened portion, the plug and socket being provided with cooperating barb means for preventing removal of the plug from the socket after insertion of the plug into the socket, the barb means comprising at least two sets of cooperating barb elements which are axially spaced from each other with respect to the direction of insertion of the plug into the socket.

2. A security seal as claimed in claim 1, in which the barb means of the plug is afforded by a fir-tree cross-section of the plug.

3. A security seal as claimed in claim 1 or 2, in which the barb means of the socket comprises two axially spaced rings of flexible tongues, which, when unstressed, project inwardly and in the direction of insertion of the plug into the socket.

4. A security seal as claimed in claim 3, in which the socket comprises an outer sleeve and an inner sleeve, on which the two rings of flexible tongues are respectively provided.

5. A security seal as claimed in claim 4, in which, on insertion of the plug into the socket, the plug encounters first the ring of flexible tongues on the outer sleeve and next the ring of flexible tongues on the inner sleeve.

6. A security seal as claimed in claim 3 or 4, in which the outer sleeve is provided with a shoulder against which the inner sleeve abuts to limit displacement of the inner sleeve relatively to the outer sleeve in a direction opposite the direction of insertion of the plug into the socket.

7. A security seal as claimed in any one of the preceding claims, in which the socket is closed at one end.

8. A security seal as claimed in any one of the preceding claims, in which the socket has an inner chamber, in which the barb means is situated, and an outer bore which communicates with the inner chamber through an opening in a wall portion separating the outer bore and the inner chamber, the plug having a head and a projection, provided with the barb means, extending from the head, the head being received in the bore when the plug is fully inserted into the socket.

9. A security seal as claimed in claim 8, in which the periphery of the head is complementary to that of the bore.

10. A security seal as claimed in any one of the preceding claims, in which the weakened portion comprises two connecting limbs extending between the elongate element and the plug or socket, respectively, the total cross- sectional area of the limbs being less than the minimum cross-sectional area of the elongate element.

11. A security seal as claimed in any one of the preceding claims, in which the plug is initially aligned with the elongate element but is adapted to be bent about the weakened portion to a position substantially perpendicular to the elongate element before insertion into the socket, thereby to weaken further the weakened portion.

12. A security seal as claimed in any one of the preceding claims, in which the elongate element comprises a strap.

13. A security seal substantially as described herein with reference to, and as shown in, the accompanying drawings.

14. A set of security seals in accordance with any one of the preceding claims, the security seals being interconnected by breakable connectors and being respectively provided with sequential code markings.