Metallurgical apparatus – Means for cutting solid metal with heat – e.g. – blowpipes
Patent
1983-06-13
1984-10-16
Stallard, W.
Metallurgical apparatus
Means for cutting solid metal with heat, e.g., blowpipes
B23K 700
Patent
active
044770600
DESCRIPTION:
BRIEF SUMMARY
The instant invention relates to an underwater cutting tool for steel, concrete, or the like, comprising a tubular oxygen lance adapted to be connected to an oxygen source and having at its one end a pistol grip-like handle or the like and at its other, free end an igniter unit for igniting the oxygen flowing out of the lance.
Such so-called burner bars or thermal lances are used to cut steel and concrete. The diameter of those bars or lances is approximately 3/8". However, lances having smaller or greater diameters are used as well (e.g. 1/2" and 1/4").
The conventional thermal lances (cf. e.g. U.S. Pat. Nos. 4,050,680 and 4,055,322) normally are used only above water. However, under certain conditions they may be employed under water too, although in shallow waters only as they must be ignited above the water surface in order to be brought to the job site by a diver. This premature igniting above the water level causes substantial loss of oxygen. Loss of oxygen, however, is nothing to worry about, since it is rather inexpensive. However, a considerable length of lance is consumed on its way down to the diver. Loss of lance is critical since it means loss of time. Furthermore, the risk of the diver becoming injured is very great. The maximum working depth of the known thermal lances is about 30 m.
It is another disadvantage of the known designs that igniting the torches above water means that the diver must carry the entire apparatus to the place where the work is to be done. In this connection please note that normally all the oxygen cylinders are on the surface and never put under water. The battery is also normally kept on the surface. For deep-water applications, however, it is obvious that the gas bottles should be brought to the worksite under water and the ignition should take place under water. This apparatus is rather heavy and cumbersome to handle as it includes not only the lance or bar but also oxygen cylinders, oxygen hoses and corresponding valves. In the case of a lance to be ignited electrically, the weight of the battery must be considered in addition.
It is, therefore, the object of the invention to provide an underwater cutting tool of the kind specified initially which is ignitable safely under water, even in greater depths, thereby avoiding the above mentioned disadvantages of the conventional underwater cutting tools or torches.
This object is met in surprisingly simple manner, in accordance with the invention, in that before being made use of, the lance is sealed to be water-tight, the seal being adapted to be blasted off or fused under water by the igniter unit upon simultaneous ignition of the oxygen flowing out of the lance.
Before igniting the lance, the whole apparatus can be transported to the place of work. There is no hazard for the diver by an ignited lance. The sealing of the lance in accordance with the invention prevents water from entering into it before the seal has been removed by igniting the igniter unit. The seal preferably is so dimensioned that it will withstand the water pressure down to a depth of 400 m. Additionally the seal and the lance itself are to resist internal elevated pressure of 5 to 10 bars as compared to the external water pressure, caused by the burner gas, preferably oxygen flowing into the lance.
A particularly advantageous structure is characterized in that the seal is formed by a plug which tightly seals the free end of the lance and is made of a material which is easily inflammable or contains such a substance. The priming or firing substance preferably is iron thermite.
In another structural further development the lance is sealed also at the end adjacent the pistol grip. This seal is adapted to be opened mechanically so that oxygen may flow into the lance at a predetermined or preadjusted elevated pressure as compared to the external water pressure. The seal at the end adjacent the pistol grip is opened before the seal is removed which closes the free end of the lance. As regards the structural embodiment of the opening mechanism for the se
REFERENCES:
patent: 3507230 (1970-04-01), Seib
patent: 4050680 (1977-09-01), Sweeny
patent: 4182947 (1980-01-01), Brower
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