Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a method of
forming a joint between a structural tubular member and a
sleeve.
According to the present invention there is pro-
vided a method of repairing a damaged structural tubularmember including the steps of providing a sleeve which is
divided longitudinally and has cylindrical end portions and
an enlarged central portion, placing the said divided sleeve
around said structural tubular member with said enlarged
portion around said damaged part, so that there is a space
between each cylindrical end portion oE the sleeve and the
adjacent part of the tubular member, closing the ends of at
least the said spaces between the cylindrical end portions
and the tubular member, injecting a hardenable composition
through the wall of the sleeve into the space between the
closed ends, and maintaining the composition under pressure
until set. Preferably the composition is a high-friction
epoxy resin composition such as for example the composition
sold under the trade mark "Araldite" SW404 which includes
carborundum powder in the epoxy resin.
According to another aspect of the invention there
is provided a method o forming a joint between a structural
tubular member and a sleeve which comprises placing the
sleeve around a part of the structural tubular member so that
there is a space between the sleeve and the adjacent part of
the tubular member, closing the ends of at least a part
o the space between the tubular member and the sleeve, in-
jecting a hardenable composition through the wall of the
sleeve into the space between the closed ends, and maintaining
3~ the composition under pressure until set, the sleeve serving to
couple two structural members inclined to one another and
bein~ connected to one of the structural members by a hinge
pin .
According to yet another aspect of the invention
there is provided a method of forming a joint between two
structural tubular members inclined to one another including
providing a coupling memberl which is secured to one of the
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tubular members and has a sleeve; placing said sleeve around
a part of said other structural tubular member so that there
is a space between the sleeve and the adjacent part of the
tubular member, closing the ends of at least a part of the
space between the tubular member and the sleeve, injecting
a hardenable composition through the wall of the sleeve into
the space between the closed ends, and maintaining the com-
position under pressure until set.
The invention will now be further described by way
of example with reference to the accompanying drawings, of
which:-
Figure 1 shows a longitudinal section through arepair joint between a sleeve and a structural tubular member
of an oil production platform; .............................
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Figure 2 shows an end elevation of the sleeve of
Figure l;
Figure 3 shows an o~'fshore structure including a tower
supporting the framework of a drilling platform and constructed
using the joint of the present invention;
Figure 4 shows a vertical section on an enlarged scale
through a joint of the tower of Figure 3;
Figure 5 shows a horizontal section through the joint of
Figure 4;
Figure 6 shows a vertical section through an alternative
form of joint which may be used constructing framework structures
according to the invention;
Figure 7 shows a horizontal section through the joint of
Figure 6;
Figure 8 shows a joint between two aligned tubular members
which may be used in a modification of the tower of Figure 3; and
Figure 9 shows a nodal joint between cross-bracing members.
Referring to Figures 1 and 2 of the drawings, these show
a joint according to the invention as applied to the permanent
2~ repairing of a structural member 11 of an underwater part of an
oil production platform. The structural member 11 has been
damaged with a bend 12 and a buckle 13. A steel sleeve 14 is
placed around the damaged part of the structural member 11 and
~ecured to the membe'r to reinforce the damaged part.
The sleeve 14 comprises two cylindrical sections 15 which
are located on each side of the damaged part of the tubular member
and a flared central part of a size great enough to span the
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damaged part formed by two frusto-conical sections 16 with
their ends of larger diameter joined together and their ends
of smaller diameter joined to the inner ends of the respective
cylindrical sections 15. At each end of each cylindrical
section 15 is a flange ring 17 which has a groove 18 on its
inner side to accommodate a hollow nitrile rubber tyre 19.
The flange rings, cylindrical sections and conical sections
are secured together by welding. Insulated electrical heating
tape (not shown) is wound on the inside of the cylindrical
sections.
Each nitrile rubber tyre 19 has a filling pipe and
an exhaust pipe (not shown) which communicates with the
interior of the tyre. The filling and exhaust pipes pass
through radial bores through the wall of the flange ring.
Filling bores 20 are provided through the wall of the
cylindrical sections 15 and filling bores 21 are provided
through the wall of one of the conical sections.
The sleeve 14 is divided along a diametrical plane
and bolting flanges 22 are welded along the edges of each
half of the sleeve.
The joint is assembled as follows. Two halves of
the sleeve 14 are placedaround the damaged part of the
structural member with a compression gasket between each
pair of flanges 22 and the flanges 22 are bolted together
using hydraulic bolts 28 such as are described in our United
Kingdom Patent No. 991,783. The hydraulic bolts are
simultaneously tensioned using a common .....................
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pressure source and an epoxy resin composition as the
hydraulic fluid. The pressure used may be 25,000 psi and
this pressure is maintained until the resin has set.
The spaces 23 between the cylindrical sections and
the structural member and the space 24 between the conical
sections and the structural member are then blown down with
air through pipes connected to the filling bores 20 and 21
to eject the salt water. This is followed by an injection
of fresh water into the spaces 23 and 24 and then a cleaning
of the spaces 23 with alcohol. Finally the spaces 23 and 2
are blown down with air and the heating tapes are connected
to a source of electricity to leave the spaces clean and dry.
The sealing tyres 19 are then pressurized with
water through the filling pipes to provide temporary seals
between the tubular member and the sleeve. The spaces 23
are brought to a test pressure with compressed air and then
the pressures in the spaces 23 and 24 are monitored to see if
there are leaks in the seals. If there are no leaks the water
is blown out of the seals through the exhaust pipe with
compressed air applied through the filling pipe after which
the tyres are filled with an epoxy resin composition (trade
mark "Araldite" SW404) and maintained at a pressure of about
80% of the yield strength of this pipe until set.
The spaces 23 are then filled with the epoxy resin
composition to a pressure of about 60% the yield strength of
the structural member or some other appropriate value. The
electrical heating tapes are connected to a source of elec-
tricity ......................................................
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and the current loading noted. The heating of the tapes
accelerates the curing of the epoxy resin composition. After
about an hour, when the current drops indicating that resin
has set, the currént is switched off.
Finally the space 24 is ~illed with a mixture of Portland
cement and sharp sand.
An example of the invention as used to join together 1
structural members.will now be described.
Figure 3 shows an offshore structure comprising a tower
111 standing in water 112 with its feet on the sea bed 113 and
supporting the framework o~ an oil-drilling platform 114 above
the surface 115 of the wate.r. The tower..lll comprises four .
tubular corner legs 116 which are continuous from top to bottom .`
and are cross-braced with horizontal tubular cross-bracing
members 117 and diagonal tubular cross-bracing members 118.
The nodal joints 119 between the cross bracing members 117 and
118 and the legs 116 are shown in detail in Figures 4 and 5.
~he joint 119 comprises a ductile cast iron sleeve 120
that is split longitudinally. The two parts of the sleeve
120 are secured together around the tubular leg 116 by means of
sel~straining bolts 121:such as are described in U.K. Patent No.
1~382~192, which pass through flanges 122 along the longitudinal
ed~es of one part of the sleeve and are secured in flanges 123
on the longitudinal edges of the other part. The use of
sel~-straining bolts enables precisely-controlled bolting loads
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in the axial and radial directions to be achieved.
The sleeves are temporarily located in place on the tubular
legs during the construction of the tower by tapered dowel
pins 124 which àre inserted into appropriately placed
holes in the sleeves 1~0 and the legs 116.
Cast on one part of the sleeves 120 are two sets of
lugs 125 spaced at 90 abou~ the axis of the sleeve 120. The
lugs are spaced apart by vertical slots which receive corresponding
lugs 126 on the ends of the cross-bracing member 117 and 118, so
that when the joint is assembled and hinge pins 127 are inserted,
the cross bracing members are hinged about a horizontal axis
to the sleeve 120.
The ends 128 of the cross-bracing members 117 and 118
adjacent the sleeve 120 are flattened to increase the inertia
of the member in a plane transverse to the hinge plane. The
lugs 126 on the end of each cross-bracing members are formed
as part of a steel casting 129 which is welded at 130 to the
flattened end 128 of the cross-bracing members and stress-
relieved in the factory before the structure is assembled.
The hinge pins 127 comprise self straining tapered pins
with a l/~40 taper. Holes 131 are drilled!in th~e interleaving
lugs of the sleeves and cross-bracing members and rearned to a
corresponding 1/40 taper. The pins 127 are inserted in the
bores in the stressed condition and subsequently the stress is
relieved so that the pin expands to provide a firm connection
between the sleeve and the cross-bracing members.
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sefore each sleeve is located in position on the
legs 116, the inner surface of the sleeve and the site on the
legs where the sleeve will lie are both roughened, for example,
by using a rotary chipping hammer. The sleeve is then located
in position with the dowel pins 124.
The sleeve has on its inner side near each end an
annular groove 132 which accommodates a hollow annular sealing
tyre 133. The interior of the tyre communicates with the out-
side of the sleeve through filling and exhaust stem pipes 134
which pass through bores in the wall of the sleeve.
When the sleeve is in position, the tyres are
inflated with hydraulic fluid or an epoxy resin composition
to a suitable pressure applied through the filling pipe, air
being bled off through the exhaust pipe until -the tyre is com-
lS pletely filled. The inflated tyres seal the interface 135between the sleeve and the leg 116. The interface is then
washed down with carbontetrachloride (CTC) applied through
radial bores 136 in the sleeve 120. Air is bled off through
a radial bore 137 until the interface 135 is completely
filled with CTC after which the pressure is raised to say 50
psi to test the seals. Once the seals have been found to be
effective the CTC is drained out and the interface is filled
with a high-strength high-friction epoxy resin composition,
for example, a resin composition that is loaded with
carborundum powder such as is sold under the trade mark
"Araldite" SW404, the air once again being allowed to bleed
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through the bore 137 until the composition ooze~ out through
it. The hole is then plugged and the pressure is raised to
a suitable pressure at which pressure the composition is allow-
ed to cure.
The strength of the joint thus made is many times the
strength of the tubular leg.
Figures 6 and 7 show an alterna~ive form of coupling
sleeve 120' which may be used for the nodal joints 119 of he
tower of Figure 3.
The sleeve 120' has two set of lugs 125' spaced at 90
about the axis of the sleeve. Each set of lugs is connected
by a hinge pin 127' to a single set of lug~ 126' on a casting
129'. The casting has three tubular limbs 140 their axes
inclined to one another in a common plane. ~he cross-braces
117' and 118' have plain tubular ends which can fit around
the tubular limbs. The middle limb can be joined to the
horizontal cross-brace 117' in the factory. The other cross-
braces 118' may be joined to the outer limbs on site during
ere~tion of the structure. The joints between the limbs 140
and the cro~s-braces may be made u~ing the method according
to the present invention.
To acilitate erection of the structure each cross-bracing
member 117 or 118 may be formed in two half-lengths with a
sleevc spanning the division by about 1/2 tube diameter so that
as each level o~ the tower is completed, the hinge pin~ inserted
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and the distances between the legs is set, the interfaces
between sleeves of the cross-braces can be filled with epoxy
composition according to the method of the invention.
The legs of the structure may also be made in sections
joined together by sleeves. Figure 8 shows a vertical
section through a part Or a leg 116'. The leg is formed in
tubular sections 150. The ends of the sections 150 fit in a
tubular casting 151. The ends of the sections 150 are seated
against rubber 0 rings 152 in grooves 153 on opposite sides
of a central internal flange 154 on the casting 151. The
inter~ace between the sections 150 and the casting 151 are
filled with resin composition again using the method of the
invention.
Similarly the nodal joints 160 of the structure at the
points where the cross-bracing members meet may be formed as
shown in Figure 9 by a star-shaped casting 161 with four
tubular limbs 162. Each limb fits around the end of a diagonal
cross-bracing member and may be secured to it when the members
are aligned in their final positions, with an epoxy resin
~0 composition using the method according to the invention.
The method of the invenkion may be used for erecting
other,tubular framework structures such as for example road or
rail bridges or for the framework of high-rise buildings. The
method enables the structures to be erected in situ without
-~he use of welding and without penetrating the tubular stressed
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member. The structure described above uses pin joints
and thus avoids bending and racking stresses which would
otherwise be induced in the structure. It thus promotes
the most economic use of materials.
In order to reduce costs further and yet provide
versitility in using the method for any large structure, a
standard range of joint members may be mass produced and
catalogued. Structures of various shapes and sizes can then
be constructed using the joint members and lengths of standard
size tubing.
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