PRESSURE VESSEL

RECIPIENT SOUS PRESSION

English Abstract

A pressure vessel having a relief area onto which a flange of a side port can be attached. The relief area includes a planar mating surface raised from the cylindrical sidewall of the vessel. A method for forming the pressure vessel includes providing a cylindrical mandrel provided with a side port spacer. Fiberglass is wrapped onto the mandrel and space. The fiberglass is impregnated with resin and the resin is cured. A metallic insert ring is embedded in a full bore open end of the pressure vessel. The ring has a cross-section having a height to width ratio of less than 0.7.

French Abstract

Appareil à pression doté d'une zone en relief sur laquelle la bride d'un orifice latéral peut être fixée. La zone en relief comprend une surface de contact planaire faisant saillie par rapport à la paroi latérale cylindrique de l'appareil. Une méthode de formage de l'appareil à pression consiste à prévoir un mandrin cylindrique pourvu d'un orifice latéral séparateur. Le mandrin et l'espace sont recouverts de fibre de verre. La fibre de verre est imprégnée de résine, et la résine est durcie. Un anneau à insertion métallique est intégré à une extrémité libre à passage intégral de l'appareil à pression. L'anneau comporte une section transversale ayant un rapport hauteur-largeur de moins de 0,7.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A pressure vessel comprising:
a cylindrical side wall formed from resin impregnated reinforcing fibers;
a generally cylindrical side port having an annular flange and an outside
thread;
a relief area onto which the flange can be attached, the relief area extending
outward from the cylindrical side wall;
a planar mating surface at an inside face of the relief area; and
a threaded bore in the mating surface threadedly receiving the port and
cooperating with the outside thread of the port.
2. The pressure vessel according to claim 1, wherein the flange
comprises an annular groove for accommodating an o-ring.
3. The pressure vessel according to claim 1, further comprising:
an open end of the vessel;
a closure inserted within the open end; and
an insert ring imbedded within a wall of the vessel at the open end, the
insert
ring comprising a generally annular body and a cross section of the body
having a height extending radially to the body and a width extending axially
to
the body, wherein a ratio of the height to the width is less than 0.7.
4. The pressure vessel of claim 3, further comprising a locking ring that
retains the closure within the vessel, wherein an annular groove in the insert
ring accommodates the locking ring.
5. The metallic insert ring of claim 3, wherein an outside surface of the
annular body is tapered inward along an axial direction of the body.
6. A pressure vessel comprising: a cylindrical side wall formed from resin
impregnated reinforcing fibers;
a generally cylindrical side port having an annular flange and an outside
thread;
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a relief area onto which the flange can be attached, the relief area extending
outward from the cylindrical side wall;
a planar mating surface at an inside face of the relief area;
a threaded bore in the mating surface threadedly receiving the port and
cooperating with outside thread of the port; an open end of the vessel;
a closure inserted within the open end; and
an insert ring imbedded within the side wall of the vessel at the open end,
the
insert ring comprising a generally annular body and a cross section of the
body having a height extending radially to the body and a width extending
axially to the body, wherein a ratio of the height to the width is less than
0.7.
7. The pressure vessel according to claim 6, wherein the cylindrical side
wall and the relief area are formed as a unitary structure from the resin
impregnated fibers.
8. The pressure vessel according to claim 6, wherein the flange
comprises an annular groove for accommodating an o-ring.
9. The pressure vessel of claim 6, further comprising a locking ring that
retains the closure within the vessel, wherein an annular groove in the insert
ring accommodates the locking ring.
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Description

CA 02416987 2008-10-14
PRESSURE VESSEL
BACKGROUND OF THE INVENTION
(0002) This invention relates to pressure vessels having at least one open end
and to end
closures and side ports therefor. More specifically, it relates to cylindrical
pressure vessels
designed for reverse osmosis pressure driven filtration operations,
particularly to vessels which
provide full-bore access to accept elongated, cylindrical filtration media
cartridges. Even more
particularly, it relates to improved end closure arrangements for such
pressure vessels. It also
relates to methods for making such pressure vessels of this general type and
particularly to those
designed for pressure driven filtration operations, especially filtration
using filter cartridges, and
more particularly to making vessels suited f6r sidewall porting to provide
fluid flow couplings
through the cylindrical sidewall of the pressure vessel.
100031 Cylindrical pressure vessels have many industrial applications,
including use in
the field of filtration. Vessels used in filtration are often of the type made
from a resin-coated
fiberglass shell and having a fully open end that must be closed by a separate
closure. Further,
one or more side ports are often attached to a cylindrical side wall of such a
vessel.
100041 There are a variety of approaches used in the industry to anchor these
side ports
into vessels with fully open ends. They include threading into the body wall,
counterboring a
relief from the inside into which a flange of the port can reside, forming a
concentric relief during
the winding which will serve to pocket the port flange, and overmolding
sealing material onto
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the vessel.
100051 It is desirable to seal the port flange against the inside wall of the
pressure vessel.
The inside wall is rich in resin and provides a good seal. However, since the
wall cylindrical, a
special ring or other sealing means is necessary to provide an adequate seal,
thus adding to the
overall cost of production.
100061 Counterboring creates a flat surface allowing standard o-rings or other
less-
expensive sealing means to be used. However, counterboring cuts into
structural glass fibers
which weakens the vessel.
100071 Providing a concentric relief can require a difficult to produce side
port flange
design, also adding to the overall cost of production.
10008] Further, regarding high pressure vessels, it is conunon in the industry
to imbed
a metallic ring in the composite shell of a full-bore opening vessel to
provide a place to anchor
the end closure. An example is shown in U.S. Patent No. 5,720,411, wherein a
metallic annular
element is fixedly imbedded in a shell. Low-pressure units can be fabricated
without such an
insert ring.
(0009] As the burst test pressure requirements elevate considerably, in those
configurations with the end closure seal adjacent to the insert ring, the
exact configuration of the
insert ring becomes crucial. That is, for 8" diameter vessels that must only
survive test pressures
up to 3600 psig there are a variety of configurations that function
satisfactorily. These same insert
rings have been shown to be inadequately retained as test pressures approach
6000 psig, in
vessels of the same inside diameter.
SUMMARY OF THE INVENTION
(0010] The present invention provides a pressure vessel comprising a
cylindrical side
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wall formed from resin-coated fiberglass and a relief area onto which a flange
of a side port can
be attached, the relief area extending outward from the cylindrical side wall.
The vessel further
comprises a planar mating surface at an outside extent of the relief area, and
a bore in the mating
surface for accommodating a cylindrical port having a flange.
100111 According to another aspect, the present invention provides a method of
forming
a resin-coated fiberglass pressure vessel having a relief area in a
cylindrical sidewall of the
vessel. The method comprises the steps of: providing a mandrel having a
cylindrical forming
surface; providing a side port spacer on the mandrel, the side port spacer
having a proximate end
that conforms to and mates with the cylindrical forming surface of the mandrel
and having a
planar distal end for forming a mating surface of the relief area; winding a
fiberglass material
around the mandrel and the spacer to form a cylindrical pressure vessel having
a relief area;
impregnating the fiberglass material with a resin; and curing the resin.
According to yet another aspect, the present invention provides a metallic
insert ring for
imbedding in the full bore open end of a composite pressure vessel. The insert
ring comprises
a generally annular body, a cross section of the body having a height
extending radially to the
body and a width extending axially to the body, and an annular groove in an
inside surface of the
body. A ratio of the height to the width is less than 0.7.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
100121 FIG. IA is a front elevational view of a pressure vessel according to
the present
invention;
[00131 FIG. 1B is a side elevational view of the pressure vessel of FIG. ]A;
100141 FIG. 2A is bottom view of a side port spacer according to the present
invention;
10015] FIG. 2B is a perspective view of the side port spacer of FIG. 2A;
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[0016] FIG. 2C is a front elevational view of the side port spacer of FIG. 2A;
[0017] FIG. 2D is a side elevational view of the side port spacer of FIG. 2A;
[00181 FIG. 3A is a front elevational view of a side port for a pressure
vessel according
to the present invention;
[0019] FIG. 3B is a side elevational view of the side port of FIG. 3A;
[0020] FIG. 3C is a rear elevational view of the side port of FIG. 3A;
[0021] FIG. 4 is an additional embodiment of a side port spacer according to
the present
invention;
[0022] FIG. 5 is a cross-sectional view of an insert ring for a pressure
vessel according
to the present invention; and
[0023] FIG. 6 is a cross-sectional view of a pressure vessel according to the
present
invention.
DETA]LED DESCRIPTION OF THE INVENTION
[0024] Referring to FIGS.1 A,1 B, 2A-2D, 3A-3 C, and 6, the present invention
provides
a method and apparatus for forming a pressure vessel 10 having a relief area
12 onto which a
flange 14 of a side port 16 can be attached. Examples of pressure vessels of
the type used in the
present invention are disclosed in commonly owned U.S. Patent Nos. 6,165,303
and 5,720,411
to Darby et al. The present method and apparatus provides a more efficient,
lower cost
approach to providing a relief area than known methods. The present invention
results
in a configuration which more effectively utilizes the glass fibers of the
pressure vessel
shell 18 than known configurations.
[0025] According to the present invention,.a cylindrical mandrel (not shown)
of a known
design is used as a form upon which to build the pressure vessel shell 18. A
side port spacer 20
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is provided having a concave surface 22 of a shape which is complementary to
the cylindrical
surface of the mandrel. Thus, the side port spacer 20 is designed to conform
intimately to the
cylindrical mandrel. Further, the side port spacer has a flat surface 24
opposing the concave
surface 22.
[0026] To form the pressure vessel 10, the side port spacer 20 is placed on
the mandrel.
Then, reinforcing fibers combined with a resin, such as fiberglass wound with
thermoplastic resin
fibers or a thermosetting impregnating resin, are wound around the mandrel and
side port spacer
20. The resin is then hardened, fonning a rigid pressure vessel shell 18. In
the case of fiberglass
wound with thermoplastic resin fibers, the resin is sintered or melted under
the influence of heat
and then cooled, allowing the heat-softened thermoplastic to harden. Other
reinforcing fibers,
' TM
such as glass, carbon, KEVLAR (available from Dupont), metal, aramid, silicon
carbide and
boron may also be used. Suitable thermoplastic fibers include, for example,
polyethylene,
polybutylene terephthalate, polyethylene terephthalate and nylon.
Alternatively, thennoset
plastics, such as epoxy, vinyl ester and polyester, can be used in place of
the thermoplastic fibers.
[0027] The finished pressure vessel shell 18 is removed from the mandrel and
the side
port spacer 20 is removed from the shell 18. A flat surface 26 formed on the
inside of the
cylindrical shell side wall corresponds to the flat surface 24 of the side
port spacer 20.
[0028] A port hole is formed in the flat surface 26 of the pressure vessel
shell 18. The
side port 16 having an annular flange 14 is inserted through the port hole.
The side port flange
14 bears and seals against the flat surface 26 in the relief area 12
surrounding the port hole.
[0029] Further, the port hole is provided with an inside thread 27. The side
port 16 is
provided with a corresponding outside thread 28. Thereby, the side port 16 can
be inserted and
threaded into the port hole. An annular groove 30 in the side port flange 14
accommodates a
standard o-ring 31. When the side port flange 14 is tightened against the flat
surface 26 by way

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of the threads 28, the o-ring 31 is captured between the flat surface 26 and
the flange 14 to
provide a seal.
100301 In addition to cost reduction, another advantage of the present
invention over the
prior art concentric relieved region is that the flat surface 26 permits the
glass filaments that are
capturing the port flange 14 to approach the loaded area at a steeper angle,
and therefore carry
a greater load.
j00311 FIG. 4 shows an alternative embodiment of a side port spacer according
to the
present invention.
100321 FIGS. 5 and 6 show a metallic insert ring 32 for imbedding in the
composite shell
18 of a full-bore opening vessel 10. The ring 32 acts to reinforce the shell
18 where a closure 33
is attached. An inside annular groove 34 of the ring 32 also supports a
locking ring 35 that holds
the closure 33 in place.
100331 The insert ring 32 has a cross-sectional radial height (H) to axial
width (W) ratio
of less than 0.7, as compared to prior art ratios of greater than 1Ø The
lower ratio configuration
moves the centroid of the insert ring's cross-sectional area 36 to a point
which permits a reversal
of the direction of the torque applied to the composite shell 18 by the loaded
insert ring 32. The
conventional insert ring, when loaded by the pressurized fluid within the
vessel, applies a torque
to the shell which concentrates a compressive bearing stress load adjacent to
the inner diameter
of the shell wall. Reversing the direction of the torque applied by the insert
ring 32 on the shell
shifts the maximum loading to the interior of the composite wall, i.e. the
region adjacent to the
outer diameter of the insert ring 32.
100341 Another feature of the insert ring 32 is that it is shaped to minimize
or eliminate
the region adjacent to the ring 32 which would inherently be devoid of
fiberglass due to the
bridging of the fiberglass strands as they traverse the insert ring 32.
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100351 It should be evident that this disclosure is by way of example and that
various
changes may be made by adding, modifying or eliminating details without
departing from the fair
scope of the teaching contained in this disclosure. The invention is therefore
not limited to
particular details of this disclosure except to the extent that the following
claims are necessarily
so limited.
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Representative Drawing