Hole cutting tool and method

#The present invention relates to a tool for cutting holes in container walls, such as in tanks, cisterns, reservoirs, pipelines, vehicles, boats, production lines or the like that contain inflammable, explosive or other hazardous gases and liquids.

#In connection with accidents involving for example tank cars, gas tanks, cisterns, pipelines, production lines and the like it is often necessary to evacuate their contents before normal safety measures can be initiated. The work involved in the evacuation of inflammable, explosive or other hazardous and perilous gases and liquids constitutes a considerable hazards both to persons actively taking part in the rescue work and to persons present in the immediate surroundings.

#Rescue methods according to prior-art technology therefore often involve vacating people from the immediate surroundings, which could be quite an extensive operation in case the accident occurs for example in a densely populated area.

#The invention will be further described in the following by way of one embodiment and with reference to the accompanying drawings, wherein

#FIG. 1 is a schematic view of an arrangement of means for cutting holes in a tank with a view to evacuate its contents.

#FIG. 2 is a principle sketch showing the manner in which the hole-cutting tool is applied against a container wall.

#FIG. 1 illustrates schematically an arrangement of means for evacuation of the contents of a tank 20. A tank car 22, comprising a control centre 25 for controlling a hole-cutting tool 1, is positioned at a point spaced from the tank 20 concerned. The control of the hole-cutting tool 1 may be effected by transfer of signals between the control centre 25 and the hole-cutting device 1 wireless-fashion or via a cable 14.

#In accordance with the preferred embodiment shown and described herein, the pressure source preferably is a motor-driven high-pressure pump 24. The motor could be a hydraulic motor, which in turn is powered by a pump or an engine, not shown, such as a combustion engine. The motor as well as the high-pressure pump 24 are of more or less conventional design and are installed in the tank car 22 shown in the drawing figure. The capacity of the high-pressure pump 24 is such as to enable it to discharge the pressurised medium at a pressure in the range of 100-300 bars, preferably about 200 bars and a flow rate in the range of 10-50 l/min, preferably about 40 l/min. In some applications the pressure of the cutting medium as it leaves the nozzle could, however, be as high as up to 600 bars, which shows that other embodiments are not restricted to only the pressure interval of 100-300 bars. Also the flow rate could exceed the value defined above, depending on the area of application, and could amount to more than 100 l/min.

#Normally, the cutting medium 19 is ordinary water, to which preferably is added one or several liquid and/or particulate additives to increase the hole-cutting ability. One additive of this kind is an abrasive, such as a blasting agent containing particles of iron, sand, or some other abrasive substance that increases the speed of cutting through the container wall. For cutting holes in a container wall made from stainless steel aluminium oxide is advantageously used as the abrasive. Depending on the contents of the container to be evacuated, water sometimes is an unsuitable cutting medium 19 and in such cases it may be replaced by for instance oil.