Quick release sleeve retained split nut-bolt structure

A split nut structure provides the holding power of an ordinary nut on a bolt while allowing for quick release through removal of a retaining sleeve from containment alignment around the segments of the split nut. What could be in many respects like an ordinary hex nut is in three segments, with cuts in three faces of the hex nut to the center, put around a bolt in the same manner as though they were connected and retained in this state by a hexagonal sleeve, the hex inside of which snuggly fits the nut itself. The outside hexagon of the sleeve provides for a wrenching surface by which the nut may be adjusted and tightened much the same as any ordinary hex nut -- however, for quick release the sleeve is merely pulled straight up along the axis of the nut and the bolt.

This invention relates in general to nut and bolt structures, and in 
particular, to an improved quick release split nut structure allowing for 
quick release from a mating bolt through removal of a retaining sleeve. 
Nuts and bolts have been used as assembly fastening and holding devices for 
centuries. A quick release nut and bolt structure having the holding power 
along with the tightening and adjustability of a conventional nut and bolt 
combination would be an advantageous convenience and expand the usefulness 
of nut and bolt structures particularly in various adverse environmental 
application locations. This is particularly the case, for example, in 
under water installations such as with off-shore platforms. One such use 
designed for involves use of applicant's quick release nut and bolt 
structure with twelve of them holding a top plug closure on a top skirt 
sleeve of an off-shore platform. In this useage the bolt and nut units are 
tightened individually since clearances cannot, as a practical matter, be 
manufactured close enough to allow use of a fixed length connector having 
an ordinary quick disconnect structure on the end. The new quick 
disconnect nut and bolt units are tightened separately to their own 
individual optimum to attach the top plug structure to an annular top 
skirt ring structure welded to the top of a platform sleeve. A hexagon 
sleeve of each quick disconnect bolt nut is interconnected by a retainer 
pin with an annular lifting plate, circling the entire bolt circle, that 
when lifted, lifts nut retaining sleeves and releases all the quick 
disconnect nuts of the structure nut and bolts at the same time in one 
simple motion that also separates the top plug structure from the skirt 
sleeve. Through use of this release structure need for a diver is 
eliminated along with the extra expense and time requirements of such 
diving operations without considering the hazzards involved. Thus, release 
and lifting of a top plug closure from the surface with a reliable quick 
release provides many savings. Tests with some nut and bolt assemblies 
using some threads show at times that one or more nut segments may not 
release when tightened down against a flat surface as the retaining sleeve 
is removed from the nut. This is overcome by use of a beveled washer and a 
matching segmented conical surface on the nut segments at the bottom with 
the slope away from the bolt to augment separation force under high load 
and/or friction lock conditions. 
It is, therefore, a principal object of this invention to provide a 
reliable quick release nut and bolt structure. 
Another object is to provide such a quick release nut and bolt structure 
having the reliable holding power of an ordinary nut on a bolt, with the 
same ease of tightening and adjustment. 
A further object is to provide a sleeve plug release system using a 
plurality of quick release nut and bolt structures releasable either 
simultaneously or in a planned sequence. 
Another object is to provide a quick release segmented nut and bolt 
structure without any falling of released nut segments upon quick release. 
A further object is to provide a quick release segmented nut and bolt 
structure having positive nut segment release. 
Features of this invention useful in accomplishing the above objects 
include, in a quick release retained split nut-bolt structure, a hex nut 
in three segments put around a bolt in the same manner as though they were 
connected and retained in this state by a hexagonal sleeve the hex inside 
of which snuggly fits the nut itself. It is a structure with quick release 
provided by merely pulling the hex sleeve straight up along the axis of 
the nut and bolt until the nut sements are cleared to fall away from the 
bolt. The nut segments in some units are connected by flexable cable 
segments to the sleeve to prevent falling of released nut segments into 
other mechanism. The quick release segmented nut and bolt is incorporated 
into a removable top plug structure fastened on the top of an off-shore 
platform skirt sleeve for quick release under water without requiring a 
diver.

Referring to the drawings: 
The top plug assembly 10 is shown in FIG. 1 to be fastened in place as a 
closure structure at the top of an off-shore platform skirt sleeve 11 that 
is a submerged portion of an off-shore platform when the platform is in 
place resting on the ocean floor. An annular bolt holding mount member 12, 
welded to the top of skirt sleeve 11, has a conical segment surface 13 
that together with guide member 14 forms a truncated conical guide for 
locating the top plug assembly 10 as it is being positioned for bolt 15 
fastening on mount member 12 at the top of sleeve 11. The top plug 
assembly 10 has a metal disc 16 welded at the outer periphery to annular 
member 17 having a seating surface 18 that rests on shoulder 19 of mount 
member 12. An annular plate 20, welded on the top of annular member 17, 
mounts a plurality of lifting bolts 21 threaded thereinto and provides an 
annular flange with through openings 22 through which bolts 15 extend. 
Bolts 15 also extend through openings 23 in mount member 12 to clamp top 
plug assembly 10 on the top of skirt sleeve 11 with bolt heads 24 below 
mount member 12 and split nuts 25 tightened down on bolts 15 to exert 
clamping force against the upper surface of annular plate 20. 
Referring also to FIGS. 2, 3 and 4, split nut 25 is like a hex nut but in 
three segments 26, with cuts in three faces of the hex nut to the center, 
positioned around the threaded end 27 of a bolt 15 as though they were 
connected and normally retained in this state by hexagon sleeve 28. 
Hexagon sleeve 28 provides a hexagon wrenching surface the hex inside of 
which is a snug sliding fit on the split nut 25 itself. Hexagon sleeve 28 
is provided with an end cap 29 that mounts an upper hexagon extension 30 
by which the split nut 25 may be adjusted by wrenching tool action. The 
quick release split nut 25 and bolt 15 structure as used in a release 
structure for the top plug assembly 10 is positioned with the upper 
hexagon extension 30 extended through respective openings 31 in lifting 
plate 32 an annular plate also provided with openings 33 through which 
lifting bolts 21 are a sliding fit. Lifting plate 32 is provided with a 
plurality of tubular lift members 34 interconnecting the plate 32 with a 
hoist connection 35. When shear pins 36 in lifting bolts 21 are sheared 
with lifting force applied from hoist connection 35 through members 34 to 
lifting plate 32 the plate 32 is lifted through a range of movement from 
the position shown in FIG. 1 to a position in engagement with the bottom 
side of bolt heads 37. This range of movement is sufficient to lift the 
hexagon sleeves 28, lifting through retainer pins 38 extended through 
upper hexagon extensions 30, vertically clear of the respective split nuts 
25 to a quick release state such as shown in FIG. 4. This results in 
release of all quick release split nuts 25 from bolts 15 such that with 
continued lifting force of sufficient magnitude being exerted on hoist 
connection 35 as transmitted through lifting plate 32 to lifting bolts 21 
the top plug assembly 10 is lifted from the top of skirt sleeve 11 even 
though the structure is in the submerged state. A secondary pickup 
structure is provided from hoist connection 35 through cable assembly 39 
to the top plug assembly metal disc 16 and via connective member 40 to 
lower structure to be removed, such as a diaphragm support (not shown), 
from the skirt sleeve 11. 
In the off-shore platform under water installation of FIG. 1 and some 
installations where it is important that loose parts and nut segments be 
retained from falling into other mechanism each of the nut segments 26 is 
tied to its sleeve 28 with individual lengths of flexible cable 41. Each 
length of flexible cable 41, that extends from an enlarged end fitting 42 
outside of the hex sleeve 28 through a sleeve opening 43 to connection 
with a nut segment 26, is long enough to allow the sleeve 28 to clear the 
nut before they become taut. The top plug 10 installation of FIG. 1 in one 
design uses twelve of the quick disconnect split nut and bolt structures 
for holding the top plug closure on the top of a skirt sleeve in an 
off-shore platform. The design is such as to permit adjustment of split 
nut and bolt units individually since in such a structure clearances are 
difficult to hold so close as to allow use of fixed length connectors with 
an ordinary quick disconnect structure on the end. Each of the twelve 
split nut and bolt units is tightened separately to its own optimum 
tautness even though covering sleeves 28 are connected to a common lifting 
plate 32 circling the entire bolt circle. Raising lifting plate 32 
separates the top plug from the skirt sleeve 11 in one simple motion such 
as to eliminate need for a diver (a fairly expensive operation). The 
reliable quick release saves money not only in eliminating need for a 
diver, but also by making release operations quicker through operational 
time savings as well. 
In the alternate quick disconnect segmented nut and bolt embodiment of FIG. 
5 the nut segments 26' are modified to accommodate a hardened beveled 
washer 44 therebeneath. This structure is provided since tests with some 
nut and bolt assemblies with shallow angled threads have shown that, at 
times, one or more nut segments may not release when tightened down 
against a flat surface when they should release as the retaining sleeve 28 
is removed. The problem is overcome through use of a beveled washer 44 
having an upper beveled surface sloping away from the bolt and with the 
nut segments 26' having matching segmented conical surfaces 45 at the 
bottom to cooperatively augment separation force under high load and/or 
friction lock conditions. 
Whereas this invention is illustrated and described with respect to a 
plurality of embodiments thereof, it should be realized that various 
changes may be made without departing from the essential contributions to 
the art made by the teachings hereof.