Note: Descriptions are shown in the official language in which they were submitted.
l~LZ47~;1
PAC~IN~ ASS~r~LY FOR A ~IOVABLE SHAET
This invention relates to a packing gland assembly for
a movable shaft, including a shutdown packing gland.
~ he packing gland assembly of this invention is designed
particularly for use ~ith a wellnead flow control device for
a producing oil well, where oil is produced from a formation
of asphaltic crude which includes highly toxic gases such as
hydrogen sulphide, and where the polished rod of a sucker rod
string passes through the flow control device.
Since the release to the atmosphere of a very small
amount of such toxic gases may be very dangerous, it is im-
portant that the packing gland assem~ly ~or such wellhead
flow control device provide an effective dynamic packing to
seal the reciprocating polished rod, and also an effective
static packing for sealing the idled polished rod in the event
of leakage at the dynamic packing, and to enahle repair or
replacement of the dynamic packing.
An object of this invention is to provide a novel packing
assembly for a movable shaft, including a dynamic shaft packing
and a static shutdo~n packing.
Another object of this invention is to provide such a
packing assembly ~herein the dynamic packing may be repaired
readily while the shutdown packing i5 effective to seal the
shaft.
A further object of this invention is to provide such
novel packing assembly including e~ternal operator means for
the shutdown packing.
Still another o~ject of this invention is to provide such
novel packing assembly which is readily removable from the
support housing, and wherein the several packing glands of the
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assembly are readily disassembled for repair, with the polished
rod in place.
A still further object of this invention is to provide .
such packing assembly including a shutdown packing gland wherein
the packing components are removable from either end of the gland
body.
Another object of this invention is to provide such
packing assembIy wherein the packing material for the shutdown
packing gland is fabricated as an integrated packing body.
A further object of this invention is to provide such
packing assembly ~Jherein the shutdown packing is adapted to
be closed by external power ~.eans.
These objects are accomplished in a packing assembly
for a movable shaft which projects from a housing to be sealed.
The assembly includes a gland body having threaded means at its
proximal end for sealing attachment to the housing, and pro-
viding a first packing chamber confronting the shaft adjacent
the proximal end. A first annular packing body is disposed in
the first packing chamber. An elongated tu~ular mandrel sur-
rounds the shaft with its proximal end disposed within the glandbody for compressing the first packing body ~ithin its packing
chamber. The gland body provides a second packing chamber con-
fronting the mandrel adjacent to its proximal end; and a second
annular packing body is disposed in the second packing chamber.
A packing cap threadedly mounted on the distal end of the gland
body effects the compressing of the second packing body within
its respective chamber. The mandrel provides a third packing
chamber adjacent to its distal end, confronting the shaft. A
third annular packing body is disposed in the third packing
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chamber; and a packing cap thxeadedly moun-ted on the distal
end of the mandrel effects compression of the third packing
kody within its chamber. ~ coupling means is provided between
the gland body and the mandrel for effecting axial compression
of the mandrel relative to the body for compressing the first
packing body.
The novel features and the advantages of the invention,
as well as additional objects thereof, will be understood more
fully from the following description when read in connection
with the accompanying drawings.
Draw nys
Fig. la is a view of the lower portion of a flow control
device, partially in elevation and partially in axial section;
Fig. lb is a view of the upper portion of the flow control
device of Fig. la,partially in elevation and partially in sec-
tion, including a packing assembly according to the invention;
Fig. 2 is a detail view of a shutdown packing body for
the packing assembly of Fig. lb; and
Fig. 3 is a view, similar to that of Fig. lb, illustra-
ting an alternative form of pac~ing assembly according to theinvention.
Description of the Preferred Embodiments
.
In the drawings packing gland assemblies, according to
the invention are illustrated as subassemblies for a wellhead
flow control device in association with the polished rod of a
well pump. Referr mg to Fig. la, a wellhead flow control device
2C is mounted on a wellhead 11 by a coupling assembly 12 which
consists of a lower flange 13, an upper flange 14 and a coacting
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ring seal 15. The ~ellhead 11 may consist, for example, of a
casing, a production casing bowl, well tubing, or other member;
and the lower flange is attached thereto by r.leans of welding,
for example. The flanges clamp the ring seal by means of
peripherally spaced nut-bolt assemblies 16. The upper flange
is threaded internally for suspending a string of well tubing 17.
The flow control device is designed for use with the polislled
rod 18 of a well pump.
The principal components of the flow control device are
a valve body consisting of a lower valve body 21 and an upper
valve body 22, a vertically reciprocible closure assembly in
the form of a ram 23, an operator sleeve 24 for coupling and
reciprocating the closure ram relative to the valve body, and a
polished rod pac~ing assembly 25 at the upper end of the ram
for providing a gas tight seal between the ram 23 and the
polished rod 18. The valve body, particularly the upper valve
body 22, includes a ram packing gland 26 for providing a gas
tight seal between the ram and the valve body. The lower valve
body defines a valve seat for the packing plug asse~bly associa-
ted with the closure ram.
The lower valve body 21 includes a lower externallythreaded nipple 30 for engagement with the upper flange 14
of the coupling assembly, and an upper externally threaded
nipple 31 for threaded engagement with the upper valve body,
the nipples being axially aligned and the body providing an
axial cha~ber for receiving the ram 23 and also for the passage
of the polished rod. This lower valve body is provided with
transverse internally threaded ports for the attachment of
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pipes defining a flow line 32 and a sampling line '3. The
body chamber defines an up~Jard facing annular valve seat 34.
The pipes for the flow line and sampling line open to the upper
cylindrical chamber 38 above the valve seat 34.
The closure ram 23 consists of a generally cylindrical
body 40, having an axial bore dimensioned for free sliding
reciprocation of the polished rod 18. The body has an upper,
externally threaded nipple 41 for attachment of the rod packing
assembly 25. The ram body has a principal outer diameter
dimensioned for a free sliding fit with the cylindrical chamber
portion 38 of the lower valve body. An annular packir.g plug 42
is secured to the lower end of the ram body. The packing plug
is retained on the ram body by an axially split annular retaining
ring 46, retained to the body by tie rods 47.
The upper valve body 22 is a generally cylindrical sleeve
having internal threads at its lower end for joining it to
the lower valve body 21, and having internal and external
threads at its upper end. The principal internal diameter of
the sleeve 22 is larger than that of the body chamber 38 and
of the ram body 40 to accommodate the ram packing gland 2~ opera-
tive between the valve body and the ram ~ody. This ram packing
- gland includes an annular packing material 52, and an externally
threaded packing nut 54 threaded into the upper end of the
sleeve 22. The exposed upper end of the packing nut is pro-
vided, at its outer periphery, with a plurality of peripherally
spaced indentions 55 to enable the rotation of the packing nut
without disassembly of the flow control device.
The operator sleeve 24 is a generally cylindrical member
having internal square threads throughout most of its length
for coaction with the external square threads on the upper end
of the upper valve body 22. The operator sleeve is coupled to
the ram body by means of a thrust coupling 60, which transfers
axial thrust rorces from the operator sleeve to the ram body.
P~otation of the operator sleeve is effected by an operator
handle 65, in the form of an elongated bar extending through
transversely aligned holes in the operator sleeve.
To enable tightening of the packing nut 54, o the ram
packing gland, the operator sleeve is provided with several
axially and rotationally spaced access holes 67. These access
holes are disposed generally in the area of the exposed portion
of the packing nut 54, when the valve is open, to enable rota-
tion o the paclcing nut by engaging the indentions 55 with a
suitable tool through an access hole.
A safety vent passage is provided in the lower valve
body 21 above the val~e seat. This consists of a vent passage
including an internally threaded bore opening to the exterior
wall for receiving a rupture disk and vent fitting 5~ for con-
necting a vent conduit to the valve housing.
The flow control device 25, which has been described
briefly herein, is the subject of a separate copending patent
application o the inventor.
Figs. lb and 2 of the drawing illustrate ~e preferred
form of rod packing assembly 25 according to the invention,
which includes a paclcing leak saety shutdown system. Fig. lb
illustrates portions of the flow control device 20 including
the operator sleeve 24 and associated operator handle 65, and
the nipple 41 at the upper end of the ram body 40. The packing
assembly 25 is secured to the nipple 41 of the ram by means of
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1 a union consisting of a union body 101 threaded onto the ram
nipple, a union ring 102 and the externally threaded lower
flange of a packing gland body 103. A mandrel 104 is a gener-
ally tubular member having a lower or proximal reduced diameter
poxtion dimensioned to be received within the gland body, and
having an enlarged upper or distal portion defining a gland
body for the rod packing gland.
The packing assembly 25 includes three packing glands, a
static shutdown packing gland, a static mandrel packing gland,
and a dynamic rod packing gland.
The mandrel is the operator for the shutdown packing
gland which consists of the following components. A rod guide
bushing 106 is an axially split sleeve having its proximal end con-
fined within a recess in the ram nipple 41. This bushing is fabri-
cated from a suitable bearing metal, and functions in part to guide
and center the polished rod 18 relative to the ram 40 and to the
packing assembly 25. The distal end of this bushing is provided
with an internal, inwardly converging conoid surface defining a
packin~ wedge; and this distal end is received within the lower
end of the gland body 103. The bushing 106 is pro~ided with notches
107 to enable prying of the bushing segments from the nipple 41.
A packing body 108 is confined between the packing wedge and an
upper split packing ring 109, which define the packing chamber.
The packing ring i5 engaged by the proximal end of the mandrel 104.
The packing body 108 may be fabricated from any suitable
material such as metallic wool, metallic felt or metallic tape, and/or
ceramic fibers, which will act as a bulk sealing material under
the e~tant conditions and which is chemically inert with respect
to hydrogen sulfide or other corrosi~e gases. This packing
body is preferably formed into a unitary body of defined shape. Fig. 2
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is a detail view of this packing body 108, illustrating the
shape which includes an upper cylindrical portion and a lower
external conoid which coacts with the conoid surface of the ;
packing wedge. In preferred foxm the packing body may be
fabricated in the form of a one piece spiral, as illustrated
in Fig. 2, so that it may be assembled around the polished
rod 18. In assembled relation, as seen in Fig. lb, the packing -
body will not be maintained in engagement with the rod, but
is a standby shutdown packing to be employed, for example, in
the event of a leak in the rod packing to be described. In
this event the mandrel 104 will be moved downward to effect
radially inward compression of the packer body by coaction
with the conoid of the packing wedge. This seating of
the body will occur only after reciprocation o~ the polished
rod is stopped.
The mandrel packing gland includes a packing chamber 110
disposed in the distal end of the gland body 10" a split lower
~acking ring 111, gland pac~ing material 112, a split upper
packing ring 113, a split pusher sleeve 114 and a packing cap
115 threadedly coupled to the gland body 103. The packing rings
and pusher sleeve are preferably formed as diametral halves to
enable assembly around the polished rod 1~. ~he packing material
112 may be a wrap-around packing or other suitable gland packing
material~
The rod packing gland consists o~ the gland body and pac~ing
chamber defined by the distal end of the mandrel 104, a lower
metallic, split pacl:ing ring 116, gland pac~inq ~aterial 117,
an upper metallic split packing ring 118, and a split guide
bushing 119 functioning as a pusher sleeve retained within the
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upper gland cap 12G. Again, the packing rings and pusher
sleeve are preferably formed as diametral halves to enable
asse~nbly around the polished rod 18. The gland cap 12~ is
threadedly coupled to the upper end of the mandrel 104.
This rod packing gland is subject to considerable wear because
of reciprocation of the rod; and the pac~ing material and
packing rings should be chosen for wear resistance as well as
for sealing against the leakage of toxic gases. Suita~le
material for this packing gland may be a strand of the above
described material identi ied as me~allic materials.
The guide bushing 119 functions as a centering bushing for
centering the rod relative to the packing assembly at the upper
end, and is preferably fabricated from a suitable bearing material
resistant to corrosive gases and fumes.
The gland cap 12C is provided with a suitable vent
passage and sniffer itting 121 for connecting the upper end
of the rod pac]iing to a suitable ~as detector for the purpose
of warning and/or for automatic control of the safety shutdown
mechanism.
The safety shutdown mechanism consists of a pair of
oppositely disposed, double acting, hydraulic cylinders 124,
connected between lower and upper yokes 125 an~ 126 ~ounted
respectively on the union ~ody 101 and the mandrel 104. The
lower yoke 125 is seated against t'ne lower face of the union
ring 102 by a nut 127. The upper yoke 126 is seated against
the upper face o a flange 128 of the mandrel by a nut 129.
It will ~e seen then that the double acting hydraulic cylinders
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124 function as part of the safety shutdown system. An auto-
matic control may respond to detection of a leak at the snifrer
fittlng 121 and effect automatic operation of the cylinders
to n-~ove the upper yoke 126 downward and effect compression
of tne packing body 10~ against the polished rod 18. Such
automatic control would effect simultaneous shutdown of the
pump and accompanying reciprocation of the polished rod. This
enables saFety shutdown o the system and prevents any leak-
age of gas until the rod packing gland can be suitably adjusted
or repaired.
Figure 3 illustrates a modified form of rod packing assem-
bly according to the invention, wherein the rod shutdown pack-
ing gland is operated manually rather than by hydraulic power
means. This assembly is shown mounted on the same ram body 40
and ram nipple 41; and the components of the assembly which are
identical to those described above are identified by the same
reference num~ers, and the components which are modified but
e~uivalent to those described above are identified by the saTde
reference numbers with the subscript a. Inis assembly is
secured to the nipple ~1 by means of a union consisting of a
union body lOla threaded onto the ram nipple, a union ring 102,
and the externally threaded lower flange of a packing gland body
lQ3a. The gland body is provided with a short length of in-
ternal threads 105 intermediate its ends. The mandrel 104a is
a generally tubular member having a lower or proximal reduced
diameter portion dimensioned to be received within the gland
body, and having an enlarged upper or distal portion defining
a gland body for the rod packiny gland. The proximal end of
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the mandrel is provided with e~ternal threads for coaction
with the threads 105 of the first named gland body. The
packing assembly 13C also includes three packing glands: a
static shutdo~ln packing gland, a static mandrel packing gland,
and a dynamic rod packing gland.
The mandrel lG4a is the operator for the shutdown packing
gland which consists of the components previously described
including the wedge ring 106 and the packing body lG~. Again,
this shutdown packing is engaged by the proximal end of the
mandrel 104a, through the upper packing ring lG9, and the
packing body 10~ is compressed through rotation of the mandrel
104a and the operation OL the threads 105. The packing body
108 has the same configuration and construction as that pre-
viously described, and functions in the same manner.
The mandrel packing gland, disposed in the packing chamber
110 at the distal end of the gland body 103a, also includes the
same components including the packing body 112. -Similarly,
the rod packing gland consists of the same components including the
packing hody 117 and the guide bushing 11~, and functions in
the same manner. The gland cap 120 is provided with a suitable
vent passage and sniffer ~itting 121 for connecting the upper
end of the rod packing to a suitable gas detector; and for this
embodiment the gas detector will trigger a suitable warning
device such as an audible or visble signal device or both; and
this will alert the operator personnel to close the shutdown
gland by rotating the mandrel 10~a.
Operation
The operation of the above descrihed packing assemblies
from the standpoint of the packing functions, is believed to be
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apparent from the foregoing description; and the following is
a discussion of maintenance and repair operation.
In order to disassemble the pac~ing assembly 25 from
the ram body 40, it is first necessary to disconnect the power
cylinders 124 from either or both of the yokes 125 and 126.
The nut 127 is then loosened to release the yoke 125 from the
union body 101; and the union ring102 may then be loosened to
release the gland body 103 along the remainder of the assembly
to be slipped upward on the polished rod lS. Preferably the
rod packing gland cap 120 would first be loosened to reduce the
friction of the packing body 117 on the polished rod.
Should the rod guide bushing 106 re~uire replacement,
the union body 101 may be unthreaded from the ram nipple 41,
allowing the removal and replacement of the split sleeves of
this bushing.
Should the shutdo~m packing require replacement, the -
split members of the packing wedge 106 may be removed from the
gland body by engaging a prying tool in the notches 1~7; and
the packing body 10~ and pac~ing rings 109 ma~ then be pushed
from the lower end of the sland body either by the mandrel 104
or by another suitable implement.
With the shutdown packing components removed, removal o
the components of the mandrel packing are also readily accom-
plished after first separating the gland cap 115.
For removing the components of the rod packing, the gland
cap 120 is first unthreaded and separated from the ~andrel,
and the mandrel may then be separated from the gland body 103.
After removal of the split guide bushing halves 119, the packing
body 117 and packing rings 116 and 118 may be removed by a
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suitable elongated pushing tool which may be passed through
the clearance space between the mandrel and the shaft 18.
The packing assembly is designed so that the dynamic rod ;
packing may be removed and replaced while the shut down packing
is effective to seal the rod 18. This involves unthreading
of the gland cap 120, removal of the guide bushing halves 119
and removal of the upper packing ring halves 118 and of the
packing body 117 f~om the top of the assembly. While this
packing removal and replacement is more difficult, it can be
accomplished with safety.
An important feature of this invention is the construction
of a packing assembly, for association with a movable rod or
shaft such as the polished rod of a well pump, which facilitates
the maintenance and/or repair of the several packing glands of
the assembly and therefore minimizes unnecessary down time.
Another important feature of the invention is the provision
of a packing assembly including a dynamic rod packing gland and
a static shutdo~m packing gland for the;rod, wherein the shut-
down packing may be operated by external power means in the
event of leakage detected at the dynamic gland.
Another feature of the invention is the configuration of
the wedge-shaped packing chamber for the packin~ material of
the shutdown packing gland, and of the wedge-shaped configuration
of the packing body coacting with that! chamber.
Still another important feature of the invention is the
provision of the guide bushing 106 consisting of split members
seated within xam nipples to center the polished rod relative to
both the ram and the attached packing assembly. A related advan-
tage is the provision of the prying notches 107 which coact with
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the union structure to enable ready separation of the packing
assembly from the ram, and the ready removal of a worn guide
bushing with a prying took, utilizing the prying notches. '
While preferred embodiments of the invention have been
illustrated and described, it will be understood by those skilled
in the art that changes and modifications may be resorted to
without departing from the spirit and scope of the invention.
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