Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This is a division of Patent Application 288,452,
filed October 11, 1977.
The present invention relates to access ports for
pipes or pressure vessels and to seals for closures therefor.
We have previously developed a closure member for a
pipe or pressure vessel comprising a door adapted to fit an
aperture in the body of pipe or the pressure vessel, a plurality
of blocks slidably mounted adjacent the periphery of the door
and movable from a position at least substantially wholly within
the said periphery to a position in which a part of each block
protrudes beyond the periphery for engagement with the said body,
the said parts of the blocks together forming a protrusion ex-
tending substantially entirely around the periphery of the door,
and means for moving the blocks from the withdrawn to the pro-
truding position.
The closure member of this previous development was
particularly designed for relatively large apertures in pipes
and pressure vessels which are subject to high pressures. The
complexity of the construction of the closure member prevents a
similar design from being readily used in closures for small
apertures.
According to the aforementioned Patent Application
288,452 we provide a closure for a pipe or pressure vessel com-
prising a door adapted to fit into an aperture in the pipe or
pressure vessel, and an arcuate locking member disposed around
the periphery of the door for locking the door to the pipe or
pressure vessel, the ends of the locking member being movable
towards and away from each other to cause radial expansion and
contraction of the locking member, whereby the locking member
may be brought into and out of locking engagement with the pipe
or pressure vessel.
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It is an object of the present invention to provide
a pressure seal which is particularly adapted for use with the
closure of Patent Application 288~452O
The pressure seal of the present invention comprises
a support of relatively rigid material having first and second
flanges having remote surfaces adapted to engage respective
opposed faces of elements between which a seal is to be formed,
the first flange having a greater surface area than the second
flange and being less flexible than the second flange and the
support defining an inwardly open channel, and a lining of rela-
tively flexible material carried by the support in the channel
and extending beyond the terminal edges of the flanges.
The shape of the seal will usually conform to the
shape of the aperture and closure. In most cases annular seals
will be used.
The disposition of the flanges of the seal relative
to the plane of the seal will depend upon the relative disposi-
tions of the faces between which the seal is interposed. Thus,
where the two faces extend at right angles to the axis of the
aperture, the flanges of the seal will, in use, extend in planes
parallel to the plane of the seal.
The materials from which the support and lining are
made will depend upon the pressures to which the seal is to
be subjected. Thus, where the seal is to be subjected to com-
paratively low pressures, the support and the lining may be
composed of elastomers of different flexibilities. Where how-
ever the seal is to be subjected to relatively high pressures,
the support is preferably composed of metal and the lining is
preferably composed of an elastomeric material.
Preferably the two flanges of the support diverge from
each other towards the tips of the flanges so that, in use, the
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tips of one or both of the flanges make first contact with the
faces against which the seal is disposed.
Where the flanges extend in planes generally parallel
to the plane of the seal, the flanges are preferably connected
by a wall which has an external surface which tapers in the axial
direction of the seal, the said surface converging in adirection
from the first flange to the second flange. The seal can then
be housed in a recess which is provided with a similarly con-
verging surface as a result of which the seal will be pressed
into position between the closure and a body portion of an access
port when the closure is inserted into the aperture in the access
port.
In order that the invention may be better understood a
preferred embodiment of an access port for a pipe or pressure
vessel and incorporating a seal and closure embodying the present
invention will now be described by way of example only with
reference to the accompanying drawings in which:-
Figure 1 is a side view, partly in section, of theaccess port, the upper and lower parts of the drawing illustra-
ting the access port in its unlocked and locked conditions
respectively;
Figure lA illustrating a detail thereof on an enlarged
scale; and
Figure 2 is a partial front view, partly in cross-
section of the access port, the upper and lower parts of the
drawing illustrating the port in its unlocked and locked con-
ditions respectively.
The access port is symmetrical about the horizontal
centre line of Figures 1 and 2.
The access port illustrated in the drawings is an out-
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let for a fluid pipeline and comprises a body portion 1 in the
form of a socket which is welded to the end of the pipeline 2.
The socket 1 is reinforced by a generally rectangular rib 3
which is mounted adjacent the mouth of the socket.
A closure indicated generally at 5 is mounted in the
mouth of the socket 1 and comprises a door 6 which is mounted
on the rib 3 by means of a hinge assembly indicated generally
at 7.
The hinge assembly 7 includes a main bracket 8 pivot-
ally mounted upon the rib 3 for movement about a vertical axis,and a secondary bracket 8a pivotally mounted at one end of the
main bracket 8 for movement about a vertical axis. The secondary
bracket 8a carries two supporting pins 9, 10 which releasably
engage in sockets 11, 12 on the door 6 and may be retained
therein by a manually rotatable lock nut 13 threaded into the
sockets 11, 12.
A C-shaped locking member 14 is disposed around the
periphery of the door 6. As best seen in Figure 2, the locking
member 14 is generally annular in shape, one segment of the
annulus having been cut away. A series of recesses in the form
of radial slots 15 extend from the internal peripheral surface
of the locking member 14 and terminate in axial bores 16 of
larger diameter than the width of the slot 15.
The locking member 14 terminates in two parallel end
faces 17, 18. These two end faces may be brought into contact
with each other, thus causing radial expansion and contraction
of the locking member 14, by means of a locking mechanism best
illustrated in Figure 2. The locking member 14 is mounted
adjacent one face o~ the door 6 so that the locking
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member 14 and the door 6 define a recess 19 within which the
locking mechanism and the sockets 11, 12 for the pins 10 of the
hinge assembly 7 are mounted.
The locking mechanism comprises two levers 20, 21
which are pivotally mounted in the door 3 for movement about
axes which coincide with the centres of curvature of the loci of
the ends 17, 18 of the locking member 14, thus minimizing move-
ment, and therefore wear, between the levers 20, 21 and the lock-
ing member 14. One end 24, 25 of each lever is shaped to form a
ball which is received in a respective socket 26, 27 adjacent
each end of the locking member 14. The other ends of the levers
20, 21 are pivotally connected to internally threaded blocks
27, 28 which are mounted on respective ends of a double ended
lead screw 29, which is itself rotatably mounted in a bracket on
the door 6. The ends of the lead screw 29 are provided with
opposite-handed threads so that rotation of the lead screw causes
the blocks 27, 28 to move towards or away from each other. The
lead screw may be rotated by a ratchet spanner 65 which is
permanently connected to the lead screw 29 and may be housed
horizontally within the recess 19 when not in use, as illustrated
in Figure 2.
When the locking member 10 is in its expanded position,
illustrated in brocken lines in the upper and lower parts of
Figure 2, a block 30 may be inserted between the end faces 17, 18
of the locking member 14 so that the locking member 14 and the
block 30 completely surround the periphery of the closure 5. The
block 30 is secured to the door 6 by means of a bolt which is
captively mounted in a bolt-hole 31' in the door 6. The bolt-
hole 31 communicates with the interior of the socket 1 through a
pressure vent (not shown) which is closed when the bolt is fully
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tightened. Removal of the bolt to release the block 30 will thus
give the operator a visible or audible warning that the pipeline
2 is pressurized.
As best seen in Figure 1, the peripheral surface of
the locking member is provided with five peripheral ribs 32 to
36. Each of the ribs includes a bearing surface 37 which ex-
tends approximately at right angles to the axis of the locking
member 14. Each of the bearing surfaces of the ribs 32 to 36
engage with a corresponding bearing surface 38 formed on the in-
terior surface of the socket 1 adjacent the mouth of the socket.As seen in Figure 1, the maximum diameters of the ribs 32 to 36
decrease in the axial direction of the locking member, the rib
32 which is located furthest within the socket 1 when the closure
is in position, as illustrated in Figure 1, being of smallest
maximum diameter.
The door 6 engages a shoulder 40 formed on the internal
surface of the socket 1, and a seal 41 is positioned between two
sealing faces 42, 43 on the door and the socket 1 respectively
adjacent the shoulder 40. These faces are flat annular surfaces
extending in planes parallel to the plane of the door. They are
therefore easily manufactured and cleaned. If desired the seal-
ing faces could be formed as conical surfaces on the door and/or
socket but this would involve additional manufacturing diffi-
culties.
The seal 41 comprises an annular metal support 44
(Figure la) generally U-shaped cross-section comprising a wall
45 and first and second flanges 46, 47 respectively which extend
generally parallel to the plane of the annular seal 41 and abut
the opposed sealing faces 42, 43 on the door 6 and socket 1. In
their natural, uncompressed condition, the two flanges 46, 47
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diverge from each other towards the centre of the seal. In the
illustrated seal, the first flange extends parallel to the plane
of the seal, the second seal extending in a conical surface. It
will be appreciated that in alternative constructions, the first
flange or both flanges could be arranged to extend along conical
surfaces.
The first flange 46 is of greater radial length than
the second flange 47. The first flange 46 is also axially
thicker than the second flange 47 and is therefore less flexible
than the second flange 47. An annular groove 48 is formed in
one face of the first flange 46 allowing the first flange to be
deflected inwardly towards the second flange 47.
An elastomeric lining 49 is mounted within the support
44 and is also of generally U-shaped cross-section. The lining
49 extends along the inner walls of the support 44 and beyond
the terminal edges of the flanges 46, 47 in the radial direction
and also, to a lesser extent, in the axial direction so that the
ends of the lining 49 abut the sealing faces of the door and
the socket.
Although the seal may be mounted on either the door 6
or the socket, it is preferably attached to the door 6 so that
it is less susceptible to damage or displacement during loading
or unloading of the pipeline 2 through the open access port.
The seal is loosely secured to the door 6 by a set of spring
clips 50 bolted on to a raised circular boss 51 on the internal
face of the door 6 of smaller diameter to the internal diameter
of the first flange 46. The seal can therefore be easily re-
moved from and mounted on the door 6 for cleaning. When mounted
on the door 6, the first flange 46 of the seal overlies a circu-
lar array of bolt-holes 52 each of which contains a respective
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set screw 53. The set screws 53 are of greater length than the
bolt-holes 52 so that, when the ends of the set screws 53 are
disengaged from the first flange 46, their heads project beyond
the outer face of the door 6, immediately adjacent the internal
surface of the locking member 14. The set screws 53 must there-
fore be threaded into the bolt holes 52 before the locking member
can be contracted, thus deflecting the first flange 46 away from
the sealing face 42 of the door, this deflection being facili-
tated by the groove 48 in the first flange 46. As a result, the
seal between the door and socket will be broken, drawing the
operator's attention to the presence of pressurized fluid in
the pipeline 2.
A cover or weather door 60 carrying a flexible weather
seal 60' is hinged to the rib 3, and, when the hinge assembly 7
is disengaged from the door 6 can be swung into engagement with
the locking member 14, thus enclosing the sockets 11, 12 and the
operating mechanism for the locking member 14 within the recess
19. A series of keys 61 on the internal face of the cover 60
are positioned to engage between the locking member 14 and a
circular boss 62 on the external surface of the door 6 when the
locking member 14 is in its expanded condition, thus preventing
the cover 60 from being closed whilst the locking member 14 is
contracted.
The cover 60 is secured to the door 6 by means of a
bolt 63 mounted in a threaded bore in the door 6 which communica-
tes with the interior of the pipeline 2 through a pressure vent.
When the bolt 63 is withdrawn by rotating a hand wheel 64 (see
Figure 2) any fluid under pressure will emerge through the bore
thus giving the operator a visible or audible indication that
the pipeline is pressurized.
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When closed, the access port of the present invention
will occupy the position illustrated in the lower parts of
Figures 1 and 2. If it is desired to open the access port, the
hand wheel 64 on the cover 60 is rotated, thus withdrawing the
bolt 63 from the door 6 and releasing the cover. The cover is
then swung into its open position as illustrated in the upper
part of Figure 2. At this moment, any pressurized fluid in the
pipeline 2 would leak through the bore for the bolt 63 and would
be observed by the operator.
The set screws 53 are then driven fully into the
threaded bores in the door 6 so that the first flange 46 of the
seal is lifted out of engagement with the sealing face 43 of the
door 6. Again, any fluid under pressure in the pipeline 2 would
reveal itself to the operator.
The bolt securing the block 30 to the door is then
withdrawn from bolt hole 31, again giving the operator a visible
or audible warning of pressure fluid in the pipeline 2. The
block 30 is then removed from between the end faces 17, 18 of the
locking member 14. The block is preferably chained or otherwise
attached to the cover 60 so that the cover 60 cannot be closed
unless the block 60 is in position between the ends 17, 18 of the
locking member 14. Preferably, the length of the spanner 65 is
such that the block 30 must be positioned wholly within the gap
between the ends 17, 18 of the locking member before the spanner
can be returned to its storage position in the recess 19, thus
permitting the cover 60 to be closed.
Using the ratchet spanner 65 the operator then rotates
the lead screw 29 so that the blocks 27, 28 move away from each
other. This in turn causes the ends 24, 25 of the levers 20, 21
to approach each other thus bringing the faces 17, 18 of the lock-
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ing member 14 into engagement with each other. As a result, thelocking member 14 is contracted radially by an amount sufficient
to disengage the ribs 31 to 35 from the corresponding recesses
in the socket 1.
In order to withdraw the closure 5 from the socket 1,
the operator inserts the pins 9, 10 of the hinge assembly 7 into
the sockets 11, 12 on the door 6 and secures the pins by means
of the lock nuts 13. He then pulls the door 6 axially out of
the socket 1. After completion of this axial motion, the door 6
can be swung on the hinge assembly to one side, as illustrated in
the upper part of Figure 2.
In order to close the access port, the reverse of the
above procedure is adopted. During the closing movement, the
seal, which is carried on the inner surface of the door 6 by the
clips 50, is first driven into the recess in the socket 1 ad-
jacent the shoulder 40. The tapering external surface of the
wall 44 assists in positioning the seal in its recess.
The first part of the seal 41 to contact the sealing
face of the socket 1 is the tip of the second flange 47. As the
door 6 is closed, the Elange is progressively deflected until the
second flange of the seal 41 occupies the position illustrated
in Figure 1.
When the door 6 is in place and locked in position,
with the set screws withdrawn, the flanges of the seal are held
in engagement with the respective sealing faces of the socket
and door by the elasticity of the support 44. When the pipeline
2 is pressurized, a greater force will be applied to the first
flange 46 by the fluid under pressure than to the second flange
47 since the first flange has a greater surface area than the
second flange. Consequently if the door 6 should move under the
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pressure, the first flange will remain firmly in contact with
the sealing face of the door. The initial compression of the
seal 41 between the socket and the door will cause the second
flange to move away from the door 6 to accommodate any initial
movement of the door under the fluid pressure. If the fluid
pressure should cause the door 6 to move even further out of the
socket 1, the second flange will deflect under the fluid pressure
and remain in engagement with the sealing surface on the socket
1. The seal 41 is therefore capable of accommodating movement
of the doors in the socket 1 without damage or leakage. Since
the support 44 is composed of metal the seal cannot extrude under
the pressure of the fluid in the ~ipeline 2 into the relatively
large gaps which may form between the door 6 and the socket 1
as a result of movement of the door 6. The elastomeric lining
49 extends radially beyond the tips of both the first and second
flanges and axially beyond the tip of the second flange, so that
any gaps which may develop between the first and second flanges
and the sealing surfaces on the socket 1 and the door 6 result-
ing from irregularities in the sealing surfaces will be closed
by the lining. The seai is therefore effective at low pressures
as well as at high pressures and can be used safely in pipelines
handling gases and toxic liquids.
The relatively narrow radial diameter of the seal 41
compared with the diameter of the door 6 ensures that the seal
does not appiy excessive thrust to the door 6 when under pressure.
Moreover the simple geometry of the sealing faces of the door 6
and socket 1 facilitates manufacture and cleaning.
