Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to pressure vessels and their manufacture and,
more particularly, relates to a split tank closure assembly.
B`ag-molded glass fiber reinforced tanks or pressure vessels are dis-
closed, for example, in United States Reissue Patent No. 25,241 to Randolph and
United ~tates Patent No. 3,138,507 to Wiltshire. Split tank assemblies of the
general class to which the present invention is directed are shown in United
States Patents 2,709,524 to RusseLl et al and 3,388,823 to Fleming et al.
Split tanks of the type herein disclosed provide full access to the interior
of the tank for placement and removal of rigid filter elements and various
other purposes.
In United States Patent No~ 4133,442, granted January 9, 1979, there
is disclosed a fiber-reinforced split tank assembly. Two basic arrangements are
set forth in that patent for clamping the tank sections together. In one such
arrangement~ grooves are cut into the tank sections to accommodate clamping
members. However, in order to minimize weakening of the tank sections, the
interior of the tank must be provided with additional reinforcement in the area
where the grooves are cut. This necessitates extra resin and glass and adds
further steps to the manufacturing operation. In another embodiment, there is
disclosed an arrangement where plastic members are adhered to the tank sections
to provide clamping flanges. The plastic clamping flanges are expensive and
fit only a given size tank. Therefore, if a manufacturer makes tanks of
different diameters, the manufacturers must provide plastic flanges to accommo-
date various diameters.
According to one aspect of the present invention there is provided a
fiber-reinforced plastic split tank assembly comprising a pair of tank sections
having mating faces, each of said sections being provided with an external
circumferential flange adjacent its mating face, each said flange comprising
bands of filament-wound, resin-impregnated fibers encircling circumferential
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portions of said tank sections, said circumferential portions having an abraded
surface, sealing means between said flanges, and clamping means clamping said
flanges together.
According to another aspect of the invention there is provided a
fiber-reinforced plastic split tank assembly comprising a pair of tank sections,
each with an open mouth, the open mouth of a first one of said sections having
a multiplicity of resin-impregnated wound fibers encircling an abraded portion
of said first one of said sections adjacent said open mouth which comprises a
first clamping flange, said first clamping flange having an outwardly facing
recess extending circumferentially around the flange, a circumferentially
extending groove in said recess, an O-ring in said groove, the open mouth of
a second one of said sections having a multiplicity of resin-impregnated
wound fibers encircling an abraded portion of said second one of said sections
adjacent said open mouth which comprises a second clamping flange, said
second clamping flange having an inwardly facing recess extending circumfer-
entially around the flange, the inner diameter of the inwardly facing recess
being slightly greater than the outer diameter of the outwardly facing recess
so that the first clamping flange may be telescoped into the second clamping
flange with the O-ring forming a seal between the flanges and means to clamp
said flanges together.
According to a further aspect of the invention there is provided a
method for forming a fiber-reinforced plastic split tank assembly comprising
the steps of providing a hollow fiber-reinforced plastic pressure vessel,
rotating said pressure vessel about its longitudinal axis, level winding
resin-impregnated filaments on the sidewall of the vessel while confining
the filaments to a relatively narrow band, curing the resin and the filaments,
cutting the band and vessel in two at a plane perpendicular to such axis and
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passing through the approximate midpoint of said band so that a band half
is provided adjacent each open mouth~ machining a circumferential outwardly
facing shelf in one band half~
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machining an 0-ring groove in said outwardly facing shelf, machining a circum-
ferential inwardly facing shelf in the other band half, providing an 0-ring in
said groove, telescoping the band halves together to form a pressure vessel withthe 0-ring pressed between said shelves, and clamping said half-bands together
to form said assembly.
An embodiment of the invention will now be described, by way of
example, with reference to the accompanying drawings, in which:
FIGURE 1 is an elevational view of a completed assembly;
FIGURE 2 is a fragmentary, cross sectional view of the tank after the
filament winding operationJ illustrating a technique for confining the resin-
impregnated filaments to a predetermined location on the sidewall of the tank;
FIGURE 3 is a fragmentary, cross sectional view similar to FIGURE 2,
but showing the tank after a severing operation;
FIGURE 4 is a fragmentary, cross sectional view of the complete joint
assembly; and
FIGURE 5 is a perspective view of one of the clamps employed in the
invention.
Referring initially to FIGURE 1, there is illustrated a split tank
assembly 10 constructed in accordance with the principles of the invention. The
assembly 10 includes a pair of mating tank sections 11 and 12 formed by trans-
versely splitting an elongated tank having generally cylindrical sidewalls and
domed end walls. Preferably, the tank is originally an integral, bag-molded,
glass-reinforced, closed tank such as that shown in the aforementioned United
States Reissue Patent No. 25,241. Each tank section 11 and 12 is provided with
a clamping band 13 and 14 so that C-clamps may be applied to hold the assembly
together during use. The clamping bands 13 and 14 are initially fabricated as a
single unit or band 15 by a conventional filament winding technique. In such a
typical technique, the tank would be mounted in a hori~ontal position for rota~
tion about its longitudinal axis in a filament winding machine which is similar
to a lathe. To provide a stronger bond between the filaments and tank sidewall,
the sidewall is slightly abraded in the area to be wound. Resin-impregnated
fiber filaments are then laid up on the sidewall by a guide which moves back andforth at a predetermined rate which is geared to the rate of rotation of the
vessel between end guides 16 and 17. The rate of traverse is such that the
filaments are laid down in a level-wound pattern where there is substantially noside-to-side overlap of the filaments. When the band 15 is built up to a suit-
able thickness, the resin is cured (by heat, a suitable catalyst, or both) and
the guides 16 are removed.
Referring now to FIGURP 3, the tank sections 11 and 12 are formed by
rotating the unitary tank about its longitudinal axis while severing the band 15and the tank with a suitable tungscen carbide or diamond cutting tool.
To complete the assembly, the clamping bands 13 and 14 are further
machined in the following manner. The clamping band 13 is machined along the
dotted line 17 to provide a shelf 18 and a circumferential 0-ring groove 19.
This operation may be done with a single cutting tool shaped to conform to the
shape of the shelf 18 and the 0-ring groove 19.
A portion 20, together with a portion 21 of the band 14, is machined
away to form an inwardly facing shelf 22 which has a diameter slightly greater
than the diameter of the shelf 18.
After the machining operations are completed, an 0-ring 28 is inserted
in the 0-ring groove 19 and, as is indicated in FIGURE 4, the tank sections are
brought together by telescoping the shelf 18 into the shelf 22 so that the
0-ring 28 is firmly pressed between the band halves. The ends of the band
halves are undercut slightly to provide a gripping surface for the clamps.
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As indicated in FIGURES 4 and 5, clamps 23 are provided. Each clamp
23 has a C-shaped configuration and is provided with raised stiffening portions
24 at the legs of the C. The clamps 23 are held in place by a band 25 which ex-
tends through struck-out tab portions 26 on each clamp. The band is fastened
together by a nut and bolt 27 or other suitable fastener~ As may be appreci-
ated, the bands may be employed on tanks of various diameters, as opposed to
prior art techniques wherein integral bands were employed as the clamping means.
As is evident in FIGURE 4, the legs of the clamps are slightly in-
clined toward each other so that they conform to the undercut portions of the
bands. To assemble the tank sections, the tank sections must be abutted to per-
mit the legs to clear the band ends. When the tank is pressurized, the sections
part slightly, as is indicated in FIGURE 4, so that the clamps cannot be re-
moved while the tank is under pressure.
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