ANTI-THEFT MEASURES

Abstract: An article made of metal has in or on its structure a poison, which is any other material (e.g. metal, chemical compound) which, when the article is melted, will react, alloy or otherwise combine with the original metal to render it less valuable. Alternatively, the poison may make smelting dangerous in the absence of expensive counter-measures. The aim is to make the metal recovery process too expensive for anyone other than the original owner of the article who can remove the poison before smelting.

Description: Anti-Theft Measures This invention relates to measures which can be taken as a deterrent to theft of metallic articles. Articles made of metal, e.g. aluminium lead or gold, may be stolen not for the value of the articles themselves, but for the value of the metal. Although precious metal articles are usually kept secure, base.metal is used for commonplace articles of everyday utility. An example is aluminium beer barrels, which cannot be kept very secure. These are persistently stolen for the value of the aluminium, which is melted down for re¬ sale. The invention aims to provide a deterrent to this practice. Accordingly, the invention provides an article of metal which includes at a discrete position a poison as herein defined within the metal or within the structure of the article. Preferably, the position where the poison is included is invisible at least to the naked eye. in the context of this invention, a poison is any other material, such as another metal, chemical compound, or other material which, when the original metal of the article is melted, will react, alloy or otherwise combine with the original metal to render it less valuable. As an examplary embodiment of the invention, we can consider again beer barrels. These have a considerable volume of aluminium which is quite cheap to smelt for re-sale. This is an advantage to the true owner who may wish to do this when the barrel's useful life is over. However, it also makes barrels a target of theft. For a thief, it involves an economic decision. The cost of stealing, handling, smelting and re-selling has to be balanced against the price obtainable. If this balance can be upset by the invention, then theft of barrels may no longer be attractive. The invention achieves this by either rendering the smelted aluminium useless, or at least by making it too expensive to refine the aluminium melt which has been contaminated by the poison. For aluminium, a small quantity of mercury is sufficient. This in most cases will form a thin film at the grain boundary, lowering the mechanical and corrosion resistance properties of the metal. Thereafter, the cost of eliminating this makes the process uneconomical. For the true owner of the barrel, it is necessary that the position of the poison is known so that it can be removed before legitimate smelting can be undertaken. It must not be obvious on casual inspection, but it might be determined in a number of ways. If a record is kept on manufacture, no additional apparatus may be needed. For example, a serial numbered barrel may carry a visible locating mark, preferable stamped into the metal, and the position be recorded relative to the locating mark. This position can be random. Less satisfactory would be a regular position relative to the mark. If no record is kept, the position might be discoverable e.g. by x-ray or ultra-sound probe. This would be a sufficient deterrent to theft provided the cost of the equipment needed were high enough to make it uneconomical to purchase. The method of including the poison will vary according to circumstances. In the simplest form, a bore could be made, the poison introduced and the top of the hole re- closed by any method which would not be visible externally. It could be welded and the surface refinished. Depending on the materials involved, it may be necessary to isolate the poison, so a glass phial containing it might be introduced into the bore. In order to escape detection by sensing means, it may be advisable to use a poison, and if required a container, which is inert and/or non-responsive to the likely sensing means. In certain cases the poison could be introduced in addition as a constituent of a wet painting, dry powder coating, metal spraying, metal implantation or of an electro-chemical deposition (electro-plating) as a decorative coating. . This coating could, in addition, act as the warning that the articl is protected against unlawful/unauthorised melting. When legitimate smelting is to be undertaken, it is necessary to remove the poison by boring out or by some other form of cutting. The bulk of the barrel can then afterwards safely be melted. The melting of the metal having poison hidden in its body or/and in a decorative coating may give up harmful gases, initiate a spontaneous combustion or even a violent explosion unless special process control is employed. Such special process control will increase the cost and the risk of the thieves being found out. This technique is of most utility for base metal articles of considerable size. It might however be used for precious meta articles. It is of course important that a potential thief should know about the poison, so the article must carry a notice explaining the steps taken. The lawful owner of the metal/article must be prepared to pay for such measures.

Claims: Cl a ims 1. . An article made of metal which has in or on its structure a poison as herein defined. 2. An article as claimed in claim 1 wherein the poison is at a discrete position within the metal or within the structure of the article. 3. An article as claimed in claim 2 wherein the position of the poison is invisible to the naked eye. 4. An article as claimed in claim 3 wherein the article carries a mark which enables location of said position. 5. An article as claimed in claim 2, 3, or 4 wherein the poison is held in a container. 6. An article as claimed in claim 5 wherein the container is of a material which is inert or non- responsive to X-rays or sonic detection means. 7. An article as claimed in claim 1 wherein the poison is applied as a coating to the outside of the structure. 8. An article as claimed in claim 7 wherein the coating is applied by wet painting, dry powder coating, metal spraying, metal implantation or electro-chemical deposition (electro-plating) . 9. An article wherein the poison is of such a nature that a dangerous reaction is produced upon smelting of the article. 10. An article made of aluminium which includes in or on its structure a poison consisting of mercury.

Inventors: KARP STEFAN, KARP, STEFAN
Applicants: KARP STEFAN, KARP, STEFAN
Application year: 1989
Main classification: C22B7
IPC codes: C22B7