US2262445A - Safety bomb for submarine blasting - Google Patents

Description

1941 w. B. ALFORD 2,262,445-

' SAFETY BOMB FOR SUBMARINE BLASTING Filed April 26, 1939 2 Shee (.s-Sheet l Q4 #016 INVENTOR.

A TTORNEY New. 111, 1941, w. B. ALFORD SAFETY BOMB FOR SUBMARI NE BLAS'IING.

v Filed April 26, 1939 2 Sheets-Sheet 2 Defend/927 M? ig. Z

IN V EN TOR.

A TTORNEYS.

Patented Nov. ll, 124i UNE?E@ STAT S PAT I; GFFEQE SAFETY norm FOE SUBMARINE BLASTHG Application April 26, 1939, Serial No. 270,145

4 Claims.

The present invention relates to the art of submarine blasting and, in particular, to a safety blasting assembly especially adapted to submarine demolition operations.

The large scale flood control operations recently undertaken by the U. S. Government have done much to emphasize the importance of submarine blasting operations and to call attention to the many hazards involved therein.

Among the many practical problems involved in these and other related submarine blasting operations may be listed the demolition and removal of sunken boats, the removal of concrete or wooden pilings, the breaking up of log jams, the demolition of bridge piers, the shooting of new cut-offs on the river, the removal of shale and shell beds in tidal water, the shooting of river crossings for pipe lines and oil feeds, the removal of fallen trees from river banks, the making of boat landings in the marsh, and the like. For these and other submarine blasting operations, the blasting assemblies heretofore known, have many defects and disadvantages. This is especially true from the standpoint of safety and certainty of successful shooting. For instance, operators in the field of submarine blasting know how difilcult it is to drop a case or bundle of dynamite on a sunken barge, particularly in a current flowing from 10 to 13 feet a second.

The object of my invention is a new and improved safety blasting assembly especially adapted to submarine blasting operations. Further objects will be apparent from the following detailed description of my invention.

I have found that these objects may be accomplished and the disadvantages overcome by means of the safety submarine blasting assembly of my invention, also referred to by me as a snag grapnel safety bomb. My submarine blasting assembly or bomb comprises containing means for retaining the explosive, means for attaching a towing cable whereby the bomb may be towed along under the surface of the water, and grapnel means for fastening said bomb into place against the submerged object which is being blasted.

The containing means for retaining the ex plosive may be in the form of a single water-tight metal container, or it may take the form of a rigid framework adapted to support and retain one or more units of canned explosives. Although any blasting explosive may be employed in my device, I find that remarkably superior results may be obtained from the standpoint of safety in submarine blasting by using explosives which have a sensitiveness of no greater order of magnitude than that of trinitrotoluene. Among the explosives of this type, to which I will hereinafter refer as "safety explosives, I may list: trinitrotoluene, pentaerythritol tetranitrate, certain picrates, comparatively insensitive compositions comprising ammonium nitrate sensitized with aromatic hydrocarbons and the like, and similar explosives within the foregoing sensitiveness range. It is desirable, of course, to employ at least a primer charge which is sensitive to a commercial blasting cap and to a commercial detonating fuse.

It should be understood, however, that while it is highly advantageous to employ water-tight metal containers for many of these explosives, especially those containing appreciable amounts of ammonium nitrate, my invention is not limited to such an assembly. Instead, I may employ certain explosives having a high degree of water resistance such as gelatin dynamites, for example. These could be employed without necessitating a water-proof container for the explosive.

The details of my invention may be more readily appreciated by referring to the accompanying drawings which disclose preferred embodiments thereof, but which are not to be taken as limiting the scope of the invention.

Referring generally to the several views of the drawings, Figure l is a view of my safety bomb being employed to blast a log jam. Figure 2 is a view in vertical elevation of a preferred embodiment of my safety bomb. Figure 3 is a section of Figure 2 taken through the region AA. Figure 4 is a view in vertical elevation of the retaining frame with grapnels attached. Figure 5 is a plan view of the same.

Referring in greater detail to the various figures of the drawings, the preferred embodiment of my invention, as shown in Figure 4, comprises the steel frame consisting of the central bar I, preferably of seamless steel mechanical tubing and the supporting base 2. Mounted on either or both ends of the central bar are the grapnels 3. Four cans of explosive 5 are placed on the base, grouped about the central bar. These cans are held in place by means of steel bands 6 and l clamped about the top and bottom of the cans, as shown in Figure 2. Preferably one can contains a booster charge and serves as the primer. This primer can is provided with the confining tunnel 8' adapted to retain a length of detonating fuse 9 against the side of the can. This length of fuse preferably extends upward out of the water to a blasting cap, as indicated by the legends in Figure 2. The central bar is provided with a drill hole l at its upper end for fastening thereto a towing cable II which may be held in the form of a loop by the clips l8.

The device when assembled with towing cable and a length of cap fuse, attached as indicated, is submerged beneath the surface of the water and towed along thereunder by any suitable means; for example, by means of the tow-boat i3 shown in Figure 1. Finally, the grapnels hook into the log jam or other obstruction I4, as shown. Then, it is time to shoot. In Figure 1, the grapnels are shown disposed at the lower end of the bomb in a position inclined toward the upper end. However, they may be placed at either or both ends of the bomb.

Although I have described my invention in the foregoing with particular reference to initiation by means of a detonating fuse and cap, it should be understood that my invention is not limited thereto. For instance, under some conditions, I may employ an electric blasting cap of the conventional type, with leg wires of sufficient length to meet the operating conditions.

More generally, it is found that the log jam has started from the key-log leaning up against some old, submerged stump, bridge pier, or the like. In this case, the bomb'can be pulled up stream until it is fastened close to this obstruction, and then set off. If the entire jam does not move with this first shot, I then continue to work upstream, and in this Way all debris moves downstream until it clears the entire channel.

Alternatively, the bomb can be used in what I would call a strung shot, making the first one with a nose turned up to protect it, and keeping it from hanging up on the bottom; and the other sections made without grapnels, making them plain so that as many as from 100 to 200 linear feet can be made. It can be dropped overboard and pulled upstream until it straightens out and reaches the exact place where the shot is to be made.

The bomb can be used for removing large stumps sitting or hanging on the river banks by throwing the cable over the outside of the stump and pulling the bomb until it hooks itself under the inside, assuming the channel is pretty well filled with water as it is in most cases in river work.

I have been given to understand, by those employed in flood-control operations, that the bomb of my invention has contributed greatly to the increased safety of these operations, since less shots are misplaced under water, and for the reason that the bomb is, in its preferred form, charged with such safety explosives as to render it innocuous if it is misplaced or lost under water, since it is practically impossible to set it oif by shock alone. Accordingly, it is to all practical purposes relatively harmless if it breaks away from the capped portion of the fuse, which is maintained above the water where it can be kept in sight.

It should be understood, of course, that the foregoing description refers to only a preferred embodiment of my invention. Many variations can be made without departing from the scope of the invention. For instance, the grapnels could be attached to a single large container of explosive instead of having four separate cans, or

be bound only by the following patent claims.

I claim:

1. A safety blasting assembly especially adapted to submarine blasting, which comprises a central bar, a supporting frame attached to the lower end of said bar, four water-tight containers resting on said frame and retained about said bar, said containers being charged with a safety explosive, at least one of said containers including a booster charge, a length of commercial detonating fuse in initiating relationship with said booster charge, means disposed at the upper end of said bar for attaching a tow line thereto, and grapnel means disposed at an end of said bar.

2. A safety blasting assembly especially adapted to submarine blasting, which comprises a central bar, a supporting frame attached to the lower end of said bar, four water-tight containers resting on said frame and retained about said bar, said containers being charged with a safety explosive, at least one of said containers including a booster charge and having a confining tunnel adapted to retain a length of commercial detonating fuse therein, means disposed at the upper end of said bar for attaching a tow line thereto. and grapnel means disposed at an end of said bar.

3. A safety blasting assembly especially adapted to submarine blasting, which comprises a central bar, a supporting base attached to the lower end of said bar, a plurality of water-tight'containers charged with blasting explosive resting on said frame and retained adjacent to said bar at least one of said containers including a booster charge and being provided with a tunnel adapted to retain a length of commercial detonating fuse in initiating relationship with said booster charge, means at the upper end of said bar for attaching a tow-line thereto, and grapnel means disposed at at least one end of said bar.

4. A safety blasting assembly especially adapted to submarine blasting, which comprises a central bar, a supporting frame attached to the lower end of said bar, a container charged with gelatin dynamite, said container resting on said frame and retained about said bar and being provided with means for retaining a water-impervious initiator adjacent to said gelatin dynamite, means at one end of said bar for attaching a towing cable, and grapnel means for snagging a submerged object.

WALTER BOSWELL ALFORD

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