A SAFETY ARRANGEMENT IN GAS-CUTTING LANCES

Abstract: A safety arrangement in a so-called gas-cutting lance (1) arranged to be connected at one end (2) thereof, the attachment end, to a gas-supply handle (3) or like means for causing gas, primarly oxygen gas, to flow through the lance. The lance comprises a hollow tube (5) which preferably houses a core (6) of, for example, closely packed filaments (7). The tube and the core comprise a material having a high iron content and are intended to melt progressively at the free end of the lance and to burn, to oxidize, at least in part. The arrangement is characterized in that preferably at least the lance (1) includes at least one substantially tubular sleeve (8, 9) or like member in the vicinity of the attachment end (2) of the lance. The lance in the aforesaid vicinity of the attachment end (2) is devoid of any core material, and each sleeve (8, 9) is made of a material which will arrest or prevent the melting and burning process, the arrangement being such that the lance (1) will be extinguished when the melting and burning process reaches the sleeve or sleeves (8, 9).

Description: A safety arrangement in gas-cutting lances The present invention relates to a safety arrangement in so-called gas-cutting lances in which the lance is connected at one end thereof to a gas-supply handle or like device for the supply of gas therethrough, primarily oxygen gas, and in which the other end of the lance is progressively consumed. Cutting lances of this kind are used, inter alia, for making holes in concrete structures and truncating heavy metal pieces, and comprise a hollow tubular casing, normally made of iron or non-alloyed steel, which often has arranged therein a core of tightly packed, axially extending steel wires. Embodiments are known in which this core comprises a powderous mixture. One problem with such cutting lances is that the whole of a lance can be consumed, resulting in injury to the workman and the handle or like device, and in the release of gas to the surroundings, which in many cases may have serious consequences. An object of the invention is therefore to provide a safety arrangement, so as to eliminate this problem. Thus, the present invention relates to a safety arrangement in so-called gas-cutting lances of the kind in which the lance is connected at one end thereof, the attachment end, to a gas-supply handle or like device by which gas, primarily oxygen gas, can be caused to pass through the lance; in which the lance comprises a hollow tube having arranged therein a core preferably comprising eg. tightly packed filaments; and in which the tube and the core have a high iron content and are intended to progres- sively melt away at the free end of the lance, and to be at least partially combusted, oxidized. The invention is particularly characterized in that preferably at least said lance includes at least one - substantially tubular sleeve or like member arranged adjacent the attachment end of the lance; in that this CUREA ' &££ * attachment end is void of core material; and in that said at least one sleeve is intended and arranged to prevent or terminate melting and combustion of the lance and core. material, such that the lance is extinguished when melting and combustion of the lance has reached said at least one sleeve. The invention will now be described in more detail with reference to an embodiment thereof illustrated in the accompanying drawing, in which Figure 1 is a schematic longitudinal sectional view of part of a lance designed in accordance with the invention; Figure 2 is a sectional view taken on the line A-A in Figure 1 ; and Figure 3 illustrates a handle for a lance according to the invention. Figure 1 illustrates a so-called gas-cutting lance 1, which is arranged to be attached at one end 2 thereof, its attachment end, to a handle 3, shown in morse lines in Figure 1, by means of which gas, primarily oxygen gas, can be caused to flow through the lance 1, as indicated by the arrow 4 in Figure 1. The lance comprises a hollow tube or pipe 5. preferably having a core 6 of e.g. closely packed wire filaments 7 arranged therein. The tube 1 and the core are preferably made of low-carbon, substantially non-alloyed steel, i.e. a material of high iron content, and are intended to melt away progressively at the free end of the lance, not shown, and to be at least partially combusted, oxidized. In accordance with the invention, at least the lance 1 includes at least one substantially tubular sleeve or like member. The embodiment illustrated in Figures 1 and 2 includes two such sleeves, an internal sleeve 8 and an external sleeve 9. The sleeves 8,9 are located adjacent the lance- attachment end 2. At the lance-attachment end 2 the lance has extending from said end a region 10 which is void of core material, this region extending over a suitable distance, such as from 1-2 decimeters for example. The sleeves 8,9 are suitably placed at the coreless region 10 of the lance 1, contiguous with the core-filled region 11. thereof, and overlap each other in the manner shown in Figure 1. The sleeves 8,9 are suttj-ώJy.of nocticeable length,for example in the order of some few centimeters and are also of noticeable thickness. Each sleeve 8,9 is preferably made of a material which will arrest the melting and combustion of the lance. Suitable materials herefor are given hereinafter. As beforementioned, preferably at least the lance 1 is provided with a sleeve or sleeves in accordance with the aforegoing. It will be understood however, that one or more such sleeves can be arranged on the handle 3 in a corresponding manner. In this case the lance sleeves can either be omitted, or the lance may be provided with a sleeve or sleeves in addition to those on the handle. By way of example, there is illustrated in Figure 3 a handle 3 according to Swedish Patent... (Swedish Patent Application No. 8302651-8) , comprising a valve housing 12, a connect piece 13 for attachment of a lance 1 to the handle 3, and two gas pipes 14,15 which extend between . the valve housing 12 and the connector piece 13. In this embodiment, the pipe 14 is intended to convey ignition gas, the flow of which is controlled by means of a valve 16, while the pipe 15 is intended to convey cutting gas, the flow of which is controlled by means of a valve 17. Suitably, each pipe 14,15 is provided with at least a single sleeve of the aforesaid kind. In the illustrated embodiment, however, each sleeve has arranged thereon two sleeves 18,19, an internal sleeve 18 and an external sleeve 19, as shown in Figure 3. In the case of a conventional handle comprising only a gas pipe, i.e. having only one pipe, the sleeve or sleeves is or are, arranged on said pipe. Each sleeve 8,9; 18,19, irrespective of whether it is mounted on the lance 1 or on the handle 3, lies adja- - cent the through-flow passages 14,15 of the lance and/or the handle, and is bonded thereto in some suitable fashion, for example by means of a layer 20 of binding agent as illustrated in Figures 1 and 2, this binding agent comprising, for example, water-glass or some other appro¬ priate binder. The sleeve may also be secured in some other way, for example mechanically, by deforming the sleeve. The functional mode of the arrangement according to the invention will be fairly obvious from the aforegoing. Under normal working conditions, when ignited the lance 1 will burn and melt progressively at its free end during a cutting operation, with a continued supply of oxygen gas. Combustion, oxidation, is sustained, inter alia, by the core 6, the specific surface of which is large relative to its volume. When only a small part of the lance 1 remains adjacent the handle 3 or the like, the supply of gas is cut-off, thereby extinguishing the lance, which is then replaced with a fresh lance. With the arrangement according to the invention the lance is extinguished even if the supply of gas is unintentionally left on. The core-free region 10 of the lance, void of wire-like filaments or the like, impairs ' the melting and combustion conditions. The presence of sleeve or sleeves 8,9, which are made of a material poor in iron and having a high melting point and low oxidizing tendencies under the conditions in question, further impair the conditions for continued melting and combustion of the lance tube 5 to an extent such that burning ceases and the lance is extinguished. In the event, for example, that a lance according to the invention is -not used, and the lance is allowed to melt and burn up to the handle 3, the handle 3 is also liable to burn and melt progressively, which is highly undesirable of course and which may result in the release of a not-readily stopped stream of gas, therewith creating the risk of a serious accident. This melting and burning of the handle is arrested by means of the sleeve or sleeves fitted thereto, in the same manner as_ with the lance, the sleeve, or sleeves, being placed so as to arrest the aforesaid burning and melting process before it reaches the valve housing, or l ike fitting. The sleeves are preferably made from a material which will not tend to burn, be oxidized, under the conditions prevai ling at the point of the burning and self-consuming lance, despite the presence of oxygen gas. A metal l ic material suitable in this context and of attractive price is stainless steel of high chromium content. Other metal lic materials of high melting points, relatively low iron contents, and low oxidation tenden¬ cies can also be used, however. Other materials suitable in this context include ceramics, such as sintered metal oxides. It is also possible to use a composite material, such as metal with ceramic material, or sleeve means which include a metallic and a ceramic sleeve. As wi l l be understood from the aforegoing, the arrangement according to the invention affords an i n- creased safety measure with the use of particularly simple and inexpensive means. Although the invention has been described with reference-: to particular embodiments thereof, it wi l l be understood that other embodiments are conceivable and that minor modifications can be made without departing from the spi rit of the invention. Thus, several sleeve materials can be chosen which fulfi ll the aforesaid pur¬ pose. It is conceivable to use sleeves with high i ron content, such as cast iron or low-al loyed or non-alloyed steel, although in this case the sleeves must be given a wal l thickness which wi l l ensure the arresting function of the sleeves, this wal l thickness being greater than that of sleeves made from material poor in i ron and pos¬ sessing low oxidation tendencies. The sleeves may also have the form of a sol id, J! £A OMPI * * sintered body or of a body comprising turns of wire or strip. The invention may also be applied with lances which have no core, or in which the core comprises a sintered body or a core of some other form. The sleeves may also conceivably be produced , from board, preferably impregnated board, ' or like material. In the aforegoing water-glass and glue have been mentioned as a suitable binder. Other binders can also be used, however, for example other silicates, suitably glass or the like. Suitably, there is chosen a binder which will itself tend to arrest the melting and burning process. It is also possible, of course, to secure the sleeves both with the aid of a combination of binder and mechanical -means. The invention is thus not restricted to the afore- described embodiments, but that modifications can be carried out within the scope of the following claims.

Claims: CLAIMS 1. A safety arrangement in a so-called gas-cutting lance in which one end of the lance, the attachment end, is connected to a gas-supply handle or like means through which gas, preferably oxygen gas, can be caused to flow through said lance; in which said lance comprises a hollow tube in which there is preferably arranged a core of, for example, closely packed filaments; and in which said tube and said core comprise material of high iron content and are intended to melt progressively at the free end thereof and to combust, oxidize, at least partially, characterized in that at least the lance (1) has at least one substantially tubular sleeve (8,9) or like member located in the vicinity of the attachment end (2) thereof; in that the tube (5) is devoid of core material (6) in said vicinity of said attachment end; and in that each sleeve (8,9) is intended and arranged to prevent or arrest said melting and burning process, such as to extinguish the lance when said melting and burning thereof reaches said at least one sleeve (8,9) . 2. An arrangement according to Claim 1, characteri¬ zed in that the lance (1) presents at its attachment end (2) a coreless region (10) which extends from said attachment end along a.suitable distance, such as 1-2 dm; and in that at least one sleeve (8,9) is located at said coreless region (10) in connection with the core-filled portion, (11) of the lance (1). 3. An arrangement according to Claim 1 or Claim 2, including a handle having connector means for connecting a lance thereto; a valve housing which incorporates at least one valve for regulating the flow of gas; and at least one gas-supply pipe extending between the valve housing and the connector means, characterized in that said gas-supply pipe 0M5) includes at least one sleeve (18,19) ' for arresting or preventing said melting and burning process. . An arrangement according to Claims 1 , 2 or 3,. characterized in that the sleeved portion includes two sleeves (8,9; 18,19), an internal sleeve (818) and an external sleeve (9,19), said sleeves preferably over- lapping one another. 5. An arrangement according to Claims 1, 2, 3. or k, cha- - racterized in that said sleeve or sleeves (8,9;18,19) comprises, or comprise, a material which is poor in iron relative to the lance material and which has a high melting point and low oxidation tendencies, such as stainless steel of high chromium content or a ceramic material, such as sintered metal oxide. 6. An arrangement according to any one of the preceding Claims, characterized in that each sleeve (8,9; 18,19) joins with the part (10,14,15) on which it is arranged and is fixed thereto with the aid of a binder (20) , such as water-glass or some other silicate, an adhesive or the like and/or mechanically by deforma¬ tion or with the aid of mechanical fasteners.

Inventors: LARSSON ARNE, LARSSON, ARNE
Applicants: SVENSK TERMO EKONOMI AB, SVENSK TERMO-EKONOMI AB
Application year: 1984
Main classification: E21B7
IPC codes: E21B7