CA2509182A1 - Self-aligning stuffing box - Google Patents
Self-aligning stuffing box Download PDFInfo
- Publication number
- CA2509182A1 CA2509182A1 CA002509182A CA2509182A CA2509182A1 CA 2509182 A1 CA2509182 A1 CA 2509182A1 CA 002509182 A CA002509182 A CA 002509182A CA 2509182 A CA2509182 A CA 2509182A CA 2509182 A1 CA2509182 A1 CA 2509182A1
- Authority
- CA
- Canada
- Prior art keywords
- bore
- tubular housing
- stuffing box
- upper tubular
- rod
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000007789 sealing Methods 0.000 claims description 51
- 230000000717 retained effect Effects 0.000 claims description 5
- 238000012856 packing Methods 0.000 description 6
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 230000004308 accommodation Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B34/00—Valve arrangements for boreholes or wells
- E21B34/02—Valve arrangements for boreholes or wells in well heads
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/18—Sealings between relatively-moving surfaces with stuffing-boxes for elastic or plastic packings
- F16J15/187—Self-aligning stuffing-boxes
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/02—Surface sealing or packing
- E21B33/08—Wipers; Oil savers
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B2200/00—Special features related to earth drilling for obtaining oil, gas or water
- E21B2200/05—Flapper valves
Abstract
A self-aligning stuffing box having a spherical joint between the upper and lower portions of the housing permits universal movement of the upper portion relative to the lower portion to permit a rod to pass through the bore if the axis of the rod is misaligned relative to the axis of the bore in each of the upper and lower housing portions. An energized seal in the upper housing resides at or below the spherical joint due to a downwardly depending central portion of the upper housing which extends into a recess formed in the lower housing permitting the height of the stuffing box to be relatively short. A
second seal is positioned above the first seal and may be spaced sufficiently above the first seal to permit a flapper valve to be installed between the seals. The flapper valve is mounted through a port in the upper housing which is accessible without disassembly of the stuffing box, the seals or the wellhead.
second seal is positioned above the first seal and may be spaced sufficiently above the first seal to permit a flapper valve to be installed between the seals. The flapper valve is mounted through a port in the upper housing which is accessible without disassembly of the stuffing box, the seals or the wellhead.
Description
., 1 "SELF-ALIGNING STUFFING BOX"
2
3 FIELD OF THE INVENTION
4 Embodiments of the invention relate to wellhead assemblies and particularly to self-aligning stuffing boxes for a wellhead.
8 Conventionally beam pumps, or rod pumps, commonly known as 9 pumpjacks, reciprocate a polished rod extending axially through a stuffing box which contains packing to seal against the polished rod. Further, rotary pumps 11 rotate a rod within the stuffing box. In each case, the seal prevents wellbore 12 fluids from leaking from the wellhead during movement of the rod. If the rod is 13 not axially aligned within the bore of the stuffing box, excessive wear of both the 14 packing and the rod can occur. In extreme cases of wear the rod can fail and drop into the wellbore, leaving the wellbore open to the surface. Misalignment 16 may occur for many reasons such as resulting from settling of the pumpjack or 17 rotary drive on a base or due to misalignment of the wellhead or stuffing box 18 during assembly thereof.
19 Conventionally, it is known to provide a self aligning stuffing box to assist in preventing polished rod failure. US Patents 3,887,196 to Renfrow, US
21 Patent 4,889,184 to Lugtmeier and US Patent 6,412,783 to Finnestad all teach 22 self aligning stuffing boxes incorporating embodiments of a first tubular member 23 having a convex face for engaging a concave seat on a second tubular member 24 forming an alignment aspect therebetween, permitting limited universal movement of the first and second members relative to one another for aligning of 1 the polished rod therein while maintaining sealing of the packing about the 2 polished rod. In each of these examples, the alignment aspect is positioned 3 significantly below the packing in the stuffing box, necessitating a relatively tall 4 stuffing box. Height of the wellhead may become problematic if insufficient bridle clearance is available between a pumpjack bridle and the wellhead, resulting in a 6 shortened and less effective pumping stroke.
7 In the case of rod failure, many stuffing boxes are provided with a 8 valve for sealing off the wellbore in the event of catastrophic failure of the rod.
9 Typically, a valve, such as a flapper valve, is pivotally mounted in the bore of the stuffing box and is biased outwardly to engage the rod, such that if the rod drops 11 into the wellbore, the valve is freed to rotate and seal the bore.
12 As is the case in US Patent 6,412,783 to Finnestad, many valves 13 are positioned below the packing elements in the stuffing box and therefore, in 14 order to replace or service the valves, the wellhead and stuffing box must be disassembled which is costly and time-consuming.
16 Others such as US patent 4,889,184 to Lugtmeier have attempted 17 to resolve the problems associated with positioning the valve lower in the stuffing 18 box by positioning the valve adjacent the top of the stuffing box necessitating 19 additional height to the stuffing box to incorporate the valve thereabove.
Ideally, what is required is a stuffing box capable of self-alignment 21 for preventing undue wear of the packing and the rod moving therein that has a 22 lower profile for maximizing the space between the wellhead or stuffing box and 23 the pumpjack bridle in the case of a reciprocating pump or a rotary drive and the 24 stuffing box in the case of a rotary pump. Further, it would be ideal to equip the i 1 shortened stuffing box with a valve for sealing the wellbore in the event 2 catastrophic failure of the rod occurs.
A relatively low profile self-aligning stuffing box has a spherical joint 6 formed between and upper tubular housing and a lower tubular housing for 7 permitting misalignment of the upper housing relative to the lower housing for 8 passage of a rod therethrough preventing lateral loading of the stuffing box. A
9 first seal is housed in a bore in the upper tubular housing in a downwardly depending central cylindrical portion of the lower end of the upper tubular 11 housing formed within a concave spherical face which forms an upper surface of 12 the spherical joint. The downwardly depending central portion of the upper 13 housing protrudes into a recess formed in the upper end of the lower tubular 14 housing at a center of a convex spherical surface forming a lower surface of the spherical joint. Positioning of the first seal, at or below the spherical joint, permits 16 the height of the upper tubular housing to be reduced. A second seal is 17 positioned above the first seal in the bore of the upper housing.
18 In an alternate embodiment of the invention, a valve such as a 19 flapper valve is pivotally mounted in the bore of the upper housing between the seals. The seals are spaced sufficient to accommodate the valve. In a preferred 21 embodiment, the addition of the valve does not increase the height of the stuffing 22 box significantly and preferably only about 2 inches. The valve is pivotally 23 mounted to a mounting plate which is fastened to the housing at a port extending 24 through a side wall of the upper housing. Preferably, the mounting plate is fastened to the housing using U-bolts and nuts and is readily removed to permit 1 access to the valve without disassembly of the stuffing box, the seals or the 2 wellhead.
3 Therefore, in a broad aspect of the invention a self aligning stuffing 4 box for a rod comprises: an upper tubular housing having a bore formed therethrough adapted for accepting the rod passing therethough along an axis, 6 the bore having a first axis; a lower tubular housing having a bore formed 7 therethrough adapted for accepting the rod passing therethrough, the bore 8 having a second axis; a spherical joint between the upper tubular housing and 9 the lower tubular housing having an upwardly recessed, substantially concave circumferential groove, having an outer spherical surface, formed about a lower 11 end of the upper tubular housing and defining a central, downwardly depending 12 portion therein; and an upwardly extending substantially convex spherical 13 surface formed at an upper end of the lower tubular housing having a central 14 recess formed therein for accepting the downwardly depending central portion of the upper tubular housing and permitting retained engagement of the concave 16 and convex spherical surfaces for sealed universal movement therebetween for 17 misaligning the first axis from the second axis and adapted for aligning the first 18 axis relative to the rod axis; and at least a first sealing means, the first sealing 19 means being housed within the bore of the downwardly depending central portion of the upper tubular housing and adapted for sealing about the rod.
21 Preferably, the seals are stacked circumferential chevron seals, 22 energized using biasing means such as a wave spring. The seals are retained in 23 the bore by retainers and are compressed against shoulders formed within the 24 bore of the upper housing for forcing the seals laterally outward to engage the rod passing therethrough.
,.
2 Figures 1a and 1b are longitudinal sectional views of prior art 3 stuffing boxes, the stuffing boxes having relatively high profiles;
4 Figure 2 is a side view of an outer housing of an embodiment of a self-aligning stuffing box, the stuffing box having a relatively low profile;
6 Figure 3 is a longitudinal cross-sectional view along section lines 7 A-A according to Fig. 2, illustrating mating spherical alignment surfaces 8 misaligned for accommodating a 2.5° deviation of a rod axis relative to an 9 aligned axis of the tubular housing and positioning of sealing means within the housing;
11 Figure 4 is a longitudinal cross-sectional view along section lines 12 B-B according to Fig. 3 illustrating alignment of the spherical alignment surfaces 13 for accommodating the rod axis along the aligned axis of the tubular housing;
14 Figure 5 is a side perspective view of an alternate embodiment of the stuffing box of Fig. 2, illustrating mounting means for a valve positioned in 16 the tubular housing;
17 Figure 6 is a rotated side perspective view according to Fig. 5;
18 Figure 7 is a front view of the embodiment according to Figs. 5 and 19 6, an upper portion of the tubular housing rotated relative to a lower portion of the tubular housing for accommodating a rod therethrough;
21 Figure 8 is a side longitudinal cross-sectional view along section 22 lines D-D according to Fig. 7, illustrating aligned spherical alignment surfaces 23 and positioning of a flapper valve between the sealing means;
24 Figure 9 is a longitudinal sectional view along section lines F-F
according to Fig. 8 illustrating misalignment of the spherical alignment surfaces
8 Conventionally beam pumps, or rod pumps, commonly known as 9 pumpjacks, reciprocate a polished rod extending axially through a stuffing box which contains packing to seal against the polished rod. Further, rotary pumps 11 rotate a rod within the stuffing box. In each case, the seal prevents wellbore 12 fluids from leaking from the wellhead during movement of the rod. If the rod is 13 not axially aligned within the bore of the stuffing box, excessive wear of both the 14 packing and the rod can occur. In extreme cases of wear the rod can fail and drop into the wellbore, leaving the wellbore open to the surface. Misalignment 16 may occur for many reasons such as resulting from settling of the pumpjack or 17 rotary drive on a base or due to misalignment of the wellhead or stuffing box 18 during assembly thereof.
19 Conventionally, it is known to provide a self aligning stuffing box to assist in preventing polished rod failure. US Patents 3,887,196 to Renfrow, US
21 Patent 4,889,184 to Lugtmeier and US Patent 6,412,783 to Finnestad all teach 22 self aligning stuffing boxes incorporating embodiments of a first tubular member 23 having a convex face for engaging a concave seat on a second tubular member 24 forming an alignment aspect therebetween, permitting limited universal movement of the first and second members relative to one another for aligning of 1 the polished rod therein while maintaining sealing of the packing about the 2 polished rod. In each of these examples, the alignment aspect is positioned 3 significantly below the packing in the stuffing box, necessitating a relatively tall 4 stuffing box. Height of the wellhead may become problematic if insufficient bridle clearance is available between a pumpjack bridle and the wellhead, resulting in a 6 shortened and less effective pumping stroke.
7 In the case of rod failure, many stuffing boxes are provided with a 8 valve for sealing off the wellbore in the event of catastrophic failure of the rod.
9 Typically, a valve, such as a flapper valve, is pivotally mounted in the bore of the stuffing box and is biased outwardly to engage the rod, such that if the rod drops 11 into the wellbore, the valve is freed to rotate and seal the bore.
12 As is the case in US Patent 6,412,783 to Finnestad, many valves 13 are positioned below the packing elements in the stuffing box and therefore, in 14 order to replace or service the valves, the wellhead and stuffing box must be disassembled which is costly and time-consuming.
16 Others such as US patent 4,889,184 to Lugtmeier have attempted 17 to resolve the problems associated with positioning the valve lower in the stuffing 18 box by positioning the valve adjacent the top of the stuffing box necessitating 19 additional height to the stuffing box to incorporate the valve thereabove.
Ideally, what is required is a stuffing box capable of self-alignment 21 for preventing undue wear of the packing and the rod moving therein that has a 22 lower profile for maximizing the space between the wellhead or stuffing box and 23 the pumpjack bridle in the case of a reciprocating pump or a rotary drive and the 24 stuffing box in the case of a rotary pump. Further, it would be ideal to equip the i 1 shortened stuffing box with a valve for sealing the wellbore in the event 2 catastrophic failure of the rod occurs.
A relatively low profile self-aligning stuffing box has a spherical joint 6 formed between and upper tubular housing and a lower tubular housing for 7 permitting misalignment of the upper housing relative to the lower housing for 8 passage of a rod therethrough preventing lateral loading of the stuffing box. A
9 first seal is housed in a bore in the upper tubular housing in a downwardly depending central cylindrical portion of the lower end of the upper tubular 11 housing formed within a concave spherical face which forms an upper surface of 12 the spherical joint. The downwardly depending central portion of the upper 13 housing protrudes into a recess formed in the upper end of the lower tubular 14 housing at a center of a convex spherical surface forming a lower surface of the spherical joint. Positioning of the first seal, at or below the spherical joint, permits 16 the height of the upper tubular housing to be reduced. A second seal is 17 positioned above the first seal in the bore of the upper housing.
18 In an alternate embodiment of the invention, a valve such as a 19 flapper valve is pivotally mounted in the bore of the upper housing between the seals. The seals are spaced sufficient to accommodate the valve. In a preferred 21 embodiment, the addition of the valve does not increase the height of the stuffing 22 box significantly and preferably only about 2 inches. The valve is pivotally 23 mounted to a mounting plate which is fastened to the housing at a port extending 24 through a side wall of the upper housing. Preferably, the mounting plate is fastened to the housing using U-bolts and nuts and is readily removed to permit 1 access to the valve without disassembly of the stuffing box, the seals or the 2 wellhead.
3 Therefore, in a broad aspect of the invention a self aligning stuffing 4 box for a rod comprises: an upper tubular housing having a bore formed therethrough adapted for accepting the rod passing therethough along an axis, 6 the bore having a first axis; a lower tubular housing having a bore formed 7 therethrough adapted for accepting the rod passing therethrough, the bore 8 having a second axis; a spherical joint between the upper tubular housing and 9 the lower tubular housing having an upwardly recessed, substantially concave circumferential groove, having an outer spherical surface, formed about a lower 11 end of the upper tubular housing and defining a central, downwardly depending 12 portion therein; and an upwardly extending substantially convex spherical 13 surface formed at an upper end of the lower tubular housing having a central 14 recess formed therein for accepting the downwardly depending central portion of the upper tubular housing and permitting retained engagement of the concave 16 and convex spherical surfaces for sealed universal movement therebetween for 17 misaligning the first axis from the second axis and adapted for aligning the first 18 axis relative to the rod axis; and at least a first sealing means, the first sealing 19 means being housed within the bore of the downwardly depending central portion of the upper tubular housing and adapted for sealing about the rod.
21 Preferably, the seals are stacked circumferential chevron seals, 22 energized using biasing means such as a wave spring. The seals are retained in 23 the bore by retainers and are compressed against shoulders formed within the 24 bore of the upper housing for forcing the seals laterally outward to engage the rod passing therethrough.
,.
2 Figures 1a and 1b are longitudinal sectional views of prior art 3 stuffing boxes, the stuffing boxes having relatively high profiles;
4 Figure 2 is a side view of an outer housing of an embodiment of a self-aligning stuffing box, the stuffing box having a relatively low profile;
6 Figure 3 is a longitudinal cross-sectional view along section lines 7 A-A according to Fig. 2, illustrating mating spherical alignment surfaces 8 misaligned for accommodating a 2.5° deviation of a rod axis relative to an 9 aligned axis of the tubular housing and positioning of sealing means within the housing;
11 Figure 4 is a longitudinal cross-sectional view along section lines 12 B-B according to Fig. 3 illustrating alignment of the spherical alignment surfaces 13 for accommodating the rod axis along the aligned axis of the tubular housing;
14 Figure 5 is a side perspective view of an alternate embodiment of the stuffing box of Fig. 2, illustrating mounting means for a valve positioned in 16 the tubular housing;
17 Figure 6 is a rotated side perspective view according to Fig. 5;
18 Figure 7 is a front view of the embodiment according to Figs. 5 and 19 6, an upper portion of the tubular housing rotated relative to a lower portion of the tubular housing for accommodating a rod therethrough;
21 Figure 8 is a side longitudinal cross-sectional view along section 22 lines D-D according to Fig. 7, illustrating aligned spherical alignment surfaces 23 and positioning of a flapper valve between the sealing means;
24 Figure 9 is a longitudinal sectional view along section lines F-F
according to Fig. 8 illustrating misalignment of the spherical alignment surfaces
5 1 for accommodating a 2.5° deviation of a rod axis relative to an aligned axis of the 2 tubular housing;
3 Figure 10 is an exploded view of a mounting apparatus according 4 to Figs. 5 and 6 for mounting a valve in the bore of the tubular housing;
Figure 11 a is a sectional view of an upper tubular housing having a
3 Figure 10 is an exploded view of a mounting apparatus according 4 to Figs. 5 and 6 for mounting a valve in the bore of the tubular housing;
Figure 11 a is a sectional view of an upper tubular housing having a
6 valve in a first position for passing a rod thereby; and
7 Figure 11 b is a sectional view of the upper tubular housing having
8 the valve biased outwardly to a second position for sealing a bore therein.
9 .....p.... ~ .,~ , 2 Having reference to Figs. 1 a and 1 b, prior art self-aligning stuffing 3 boxes 1 typically have a relatively high profile due to positioning of the 4 components housed within the stuffing boxes 1 significantly above the alignment surfaces 2,3. Further, valve means 4 pivotally mounted within a bore 5 of the 6 stuffing box 1 for sealing the bore 5 in the absence of a rod 6 are conventionally 7 mounted either above or below sealing means 7 housed within the bore 5.
8 Access to the valve means 4 for servicing or replacement is typically through 9 disassembly of at least a portion of the stuffing box 1.
As shown in Figs. 2 - 4, a low profile stuffing box 10 comprises a 11 housing 11 for connection to a wellhead (not shown). The housing 11 comprises 12 and upper tubular housing 12 and a lower tubular housing 13, each of the upper 13 and lower tubular housings 12, 13 having bores 14, 15 formed therein. A
lower 14 end 17 of the upper tubular housing 12 is coupled to an upper end 21 of the lower tubular housing 13. The upper housing bore 14 has a first axis X and the 16 lower housing bore 15 has a second axis Y. When the upper and lower housings 17 12,13 are aligned, the first and second axis X,Y form a common axis.
18 Between the upper tubular housing 12 and the lower tubular 19 housing 13 is a spherical joint in order to permit misalignment of the upper housing 12 and first axis X relative to the lower housing 13 and second axis Y
for 21 accommodating a misaligned rod (not shown) to pass therethrough without 22 laterally loading the stuffing box 1. A lower end of the upper housing 12 has a 23 lower concave spherical surface 17 formed in an upwardly recessed, 24 substantially concave circumferential groove 18 formed in the upper housing 12.
1 The groove 18 defines a central downwardly depending cylindrical portion 19 2 about the bore 14.
3 The lower housing 13 has an upwardly extending substantially 4 convex spherical surface 20 formed at an upper end 21. the lower concave spherical surface 17 of the upper housing 12 and the convex spherical surface 6 20 of the lower housing 13 are compatible surfaces. The convex spherical 7 surface 20 has a central recess 22 formed therein for accepting the downwardly 8 depending central portion 19 of the upper tubular housing 12 and permitting 9 engagement of the compatible concave and convex spherical surfaces 17, 20.
Once engaged, the upper housing 12 is capable of limited universal movement 11 relative to the lower tubular housing 13, the spherical surfaces 17, 20 permitting 12 the limited universal movement therebetween.
13 A connector portion 16 engagingly retains the upper housing 12 to 14 the lower housing 13 at second corresponding spherical sliding surfaces 23, to accommodate the universal movement of the upper housing 12 relative to the 16 lower housing 13. Preferably, the connector portion 16, such as a hammer nut, is 17 threadedly connected to an outer extent 25 of the lower housing 13 and positions 18 the spherical sliding surfaces 23,24 adjacent one another for movement 19 therebetween.
Preferably, the bore 15 of the lower tubular housing 13 is larger in 21 diameter than the bore 14 of the upper tubular housing 12. The lower tubular 22 housing 13 is fixed to the wellhead (Fig. 9) and thus, the larger bore 15 permits 23 accommodation of deviation of the rod (not shown) therein while, at the same 24 time, the upper tubular housing 12 moves at the engaged spherical surfaces 17,20, misaligning the first axis X relative to the second axis Y to align the first 1 axis X to a rod axis R (Figs. 4 and 9). Typically, a maximum deviation of the rod 2 would be about 2.5°.
3 Having reference again to Figs. 3 and 4, at least a first sealing 4 means 30 is housed within the bore 14 of the upper tubular housing 12. The first sealing means 30 is housed in the downwardly depending central portion 19 of 6 the upper housing 12. In a preferred embodiment therefore, the first sealing 7 means 30 is effectively seated at or below the spherical alignment surfaces 17, 8 20 which permits the upper housing 12 to have a lower profile than conventional 9 prior art stuffing boxes. The upper housing 12 comprises a lower stuffing box 70 and an upper stuffing box 71 to permit installation of the first sealing means 30 in 11 the downwardly depending central portion 19.
12 The first sealing means 30 is retained in the upper housing's bore 13 14 by a first retainer 31. The first tubular retainer 31 has a bore 32 and 14 preferably a tab 33 formed about a lower edge 34 which engages a profiled recess 35 formed in the upper housing's bore 14 for engaging the first retainer 16 31 therein. The profiled recess 35 prevents upward movement of the first 17 retainer 31 within the bore 14. A first shoulder 36 is formed at a lower end 37 of 18 the upper housing's bore 14. The first sealing means is retained between the first 19 retainer 31 and the first shoulder 36.
Preferably, the first sealing means 30 is a plurality of stacked 21 circumferential seals 38, the seals 38 preferably being chevron seals. A
biasing 22 means 39, preferably a wave spring, is housed in the bore 14 between the first 23 retainer 31 and the first shoulder 36 for energizing the seals 38 to engage a rod 24 passing therethrough. The biasing means 39 may be positioned above or below ....p.... , . ,.... w ..
1 the seals 38 and acts to compress the seals 38 between the first retainer 31 and 2 the first shoulder 36 forcing them laterally outward into engagement with the rod.
3 At least a second sealing means 40 is housed in the upper tubular 4 housing's bore 14, above the first sealing means 30. A second shoulder 41, a second retainer 42 and a second biasing means 43 act to retain and energize 6 the second sealing means 40 in the bore 14 as described above. In a preferred 7 embodiment, the second sealing means 40 is housed at a top end 44 of the 8 upper tubular housing 12. Preferably, a profiled top cap 45 or hammer nut 9 threadedly engages the upper tubular housing's top end 44 for retaining the second retainer 42 and sealing means 40 therein.
11 Having reference to Figs. 5 -11 b and in another embodiment of the 12 invention, the second sealing means 40 is spaced sufficiently above the first 13 sealing means 30 to permit pivotally mounting a valve 50, such as a flapper 14 valve, therebetween in the bore 14 of the upper tubular housing 12. Note that ports 49 are typically fitted with plugs 48 (Figs. 2-5) or instrument lines (not 16 shown). In a first position (Fig. 11a), the valve 50 permits passage of the rod 51 17 through the upper tubular housing's bore 14. In the absence of the rod 51, such 18 as through catastrophic failure of the rod 51, the valve 50 is biased to a second 19 position (Fig. 11 b) wherein the valve 50 seals the bore 14 of the upper tubular housing 12. In this embodiment, a height of the upper tubular housing 12 is only 21 increased by about 2 inches to accommodate mounting of the valve 50.
22 As shown in Fig. 8, a mounting port 52 is formed in the upper 23 tubular housing 12 between the first and second sealing means 30,40. The port 24 52 extends through a side wall of the upper housing 12 for positioning the valve 50 in the bore 14. A mounting plate 53, to which the valve 50 is pivotally * , __,2, , 1 mounted, is positioned in the mounting port 52 and fastened therein using 2 fasteners 54. As shown in a rotated view in Fig. 9, misalignment of the upper 3 housing 12 relative to the lower housing 13 aligns the first axis X to the rod axis 4 R as described above. The valve 50, mounted in the upper housing bore 14, remains operational regardless the misalignment, the first axis X being aligned 6 with the rod axis R.
7 Preferably, as shown in Fig. 7, the mounting plate 53 extends 8 laterally from the mounting port 52 to facilitate fastening of the mounting plate 53 9 to the upper tubular housing 12. Best seen in Fig. 10, the fasteners 54 preferably comprise at least two U-bolts 55 which extend around the upper tubular housing 11 12 for engaging the mounting plate 53. The U-bolts are passed through bolt 12 holes 56 formed in the portion of the mounting plate 53 which extends laterally 13 from the mounting port 52 and is fastened thereto by nuts 57 threaded thereon.
14 The flapper valve 50 is mounted to a hinge plate 58 which is pivotally mounted to the mounting plate 53 using a hinge block 59. A seal 60, 16 such as an O-ring, seals between the mounting plate 53 and the upper tubular 17 housing 12. Best seen in Fig. 11 b, in the second position a seal 61 such as an 18 O-ring positioned about the valve 50, seals the valve 50 to an upper spherical 19 seat 62 formed at the lower end 63 of the downwardly depending central portion 19 of the upper tubular housing 12 for sealing the upper housing bore 14. The 21 valve 50 is normally biased to the second position, such as by a clip spring 64.
22 Thus mounted, the valve 50 is readily accessible by removing the U-bolts 55 and 23 mounting plate 53 without need to disassemble the stuffing box, the sealing 24 means 30, 34 or other wellhead assemblies.
8 Access to the valve means 4 for servicing or replacement is typically through 9 disassembly of at least a portion of the stuffing box 1.
As shown in Figs. 2 - 4, a low profile stuffing box 10 comprises a 11 housing 11 for connection to a wellhead (not shown). The housing 11 comprises 12 and upper tubular housing 12 and a lower tubular housing 13, each of the upper 13 and lower tubular housings 12, 13 having bores 14, 15 formed therein. A
lower 14 end 17 of the upper tubular housing 12 is coupled to an upper end 21 of the lower tubular housing 13. The upper housing bore 14 has a first axis X and the 16 lower housing bore 15 has a second axis Y. When the upper and lower housings 17 12,13 are aligned, the first and second axis X,Y form a common axis.
18 Between the upper tubular housing 12 and the lower tubular 19 housing 13 is a spherical joint in order to permit misalignment of the upper housing 12 and first axis X relative to the lower housing 13 and second axis Y
for 21 accommodating a misaligned rod (not shown) to pass therethrough without 22 laterally loading the stuffing box 1. A lower end of the upper housing 12 has a 23 lower concave spherical surface 17 formed in an upwardly recessed, 24 substantially concave circumferential groove 18 formed in the upper housing 12.
1 The groove 18 defines a central downwardly depending cylindrical portion 19 2 about the bore 14.
3 The lower housing 13 has an upwardly extending substantially 4 convex spherical surface 20 formed at an upper end 21. the lower concave spherical surface 17 of the upper housing 12 and the convex spherical surface 6 20 of the lower housing 13 are compatible surfaces. The convex spherical 7 surface 20 has a central recess 22 formed therein for accepting the downwardly 8 depending central portion 19 of the upper tubular housing 12 and permitting 9 engagement of the compatible concave and convex spherical surfaces 17, 20.
Once engaged, the upper housing 12 is capable of limited universal movement 11 relative to the lower tubular housing 13, the spherical surfaces 17, 20 permitting 12 the limited universal movement therebetween.
13 A connector portion 16 engagingly retains the upper housing 12 to 14 the lower housing 13 at second corresponding spherical sliding surfaces 23, to accommodate the universal movement of the upper housing 12 relative to the 16 lower housing 13. Preferably, the connector portion 16, such as a hammer nut, is 17 threadedly connected to an outer extent 25 of the lower housing 13 and positions 18 the spherical sliding surfaces 23,24 adjacent one another for movement 19 therebetween.
Preferably, the bore 15 of the lower tubular housing 13 is larger in 21 diameter than the bore 14 of the upper tubular housing 12. The lower tubular 22 housing 13 is fixed to the wellhead (Fig. 9) and thus, the larger bore 15 permits 23 accommodation of deviation of the rod (not shown) therein while, at the same 24 time, the upper tubular housing 12 moves at the engaged spherical surfaces 17,20, misaligning the first axis X relative to the second axis Y to align the first 1 axis X to a rod axis R (Figs. 4 and 9). Typically, a maximum deviation of the rod 2 would be about 2.5°.
3 Having reference again to Figs. 3 and 4, at least a first sealing 4 means 30 is housed within the bore 14 of the upper tubular housing 12. The first sealing means 30 is housed in the downwardly depending central portion 19 of 6 the upper housing 12. In a preferred embodiment therefore, the first sealing 7 means 30 is effectively seated at or below the spherical alignment surfaces 17, 8 20 which permits the upper housing 12 to have a lower profile than conventional 9 prior art stuffing boxes. The upper housing 12 comprises a lower stuffing box 70 and an upper stuffing box 71 to permit installation of the first sealing means 30 in 11 the downwardly depending central portion 19.
12 The first sealing means 30 is retained in the upper housing's bore 13 14 by a first retainer 31. The first tubular retainer 31 has a bore 32 and 14 preferably a tab 33 formed about a lower edge 34 which engages a profiled recess 35 formed in the upper housing's bore 14 for engaging the first retainer 16 31 therein. The profiled recess 35 prevents upward movement of the first 17 retainer 31 within the bore 14. A first shoulder 36 is formed at a lower end 37 of 18 the upper housing's bore 14. The first sealing means is retained between the first 19 retainer 31 and the first shoulder 36.
Preferably, the first sealing means 30 is a plurality of stacked 21 circumferential seals 38, the seals 38 preferably being chevron seals. A
biasing 22 means 39, preferably a wave spring, is housed in the bore 14 between the first 23 retainer 31 and the first shoulder 36 for energizing the seals 38 to engage a rod 24 passing therethrough. The biasing means 39 may be positioned above or below ....p.... , . ,.... w ..
1 the seals 38 and acts to compress the seals 38 between the first retainer 31 and 2 the first shoulder 36 forcing them laterally outward into engagement with the rod.
3 At least a second sealing means 40 is housed in the upper tubular 4 housing's bore 14, above the first sealing means 30. A second shoulder 41, a second retainer 42 and a second biasing means 43 act to retain and energize 6 the second sealing means 40 in the bore 14 as described above. In a preferred 7 embodiment, the second sealing means 40 is housed at a top end 44 of the 8 upper tubular housing 12. Preferably, a profiled top cap 45 or hammer nut 9 threadedly engages the upper tubular housing's top end 44 for retaining the second retainer 42 and sealing means 40 therein.
11 Having reference to Figs. 5 -11 b and in another embodiment of the 12 invention, the second sealing means 40 is spaced sufficiently above the first 13 sealing means 30 to permit pivotally mounting a valve 50, such as a flapper 14 valve, therebetween in the bore 14 of the upper tubular housing 12. Note that ports 49 are typically fitted with plugs 48 (Figs. 2-5) or instrument lines (not 16 shown). In a first position (Fig. 11a), the valve 50 permits passage of the rod 51 17 through the upper tubular housing's bore 14. In the absence of the rod 51, such 18 as through catastrophic failure of the rod 51, the valve 50 is biased to a second 19 position (Fig. 11 b) wherein the valve 50 seals the bore 14 of the upper tubular housing 12. In this embodiment, a height of the upper tubular housing 12 is only 21 increased by about 2 inches to accommodate mounting of the valve 50.
22 As shown in Fig. 8, a mounting port 52 is formed in the upper 23 tubular housing 12 between the first and second sealing means 30,40. The port 24 52 extends through a side wall of the upper housing 12 for positioning the valve 50 in the bore 14. A mounting plate 53, to which the valve 50 is pivotally * , __,2, , 1 mounted, is positioned in the mounting port 52 and fastened therein using 2 fasteners 54. As shown in a rotated view in Fig. 9, misalignment of the upper 3 housing 12 relative to the lower housing 13 aligns the first axis X to the rod axis 4 R as described above. The valve 50, mounted in the upper housing bore 14, remains operational regardless the misalignment, the first axis X being aligned 6 with the rod axis R.
7 Preferably, as shown in Fig. 7, the mounting plate 53 extends 8 laterally from the mounting port 52 to facilitate fastening of the mounting plate 53 9 to the upper tubular housing 12. Best seen in Fig. 10, the fasteners 54 preferably comprise at least two U-bolts 55 which extend around the upper tubular housing 11 12 for engaging the mounting plate 53. The U-bolts are passed through bolt 12 holes 56 formed in the portion of the mounting plate 53 which extends laterally 13 from the mounting port 52 and is fastened thereto by nuts 57 threaded thereon.
14 The flapper valve 50 is mounted to a hinge plate 58 which is pivotally mounted to the mounting plate 53 using a hinge block 59. A seal 60, 16 such as an O-ring, seals between the mounting plate 53 and the upper tubular 17 housing 12. Best seen in Fig. 11 b, in the second position a seal 61 such as an 18 O-ring positioned about the valve 50, seals the valve 50 to an upper spherical 19 seat 62 formed at the lower end 63 of the downwardly depending central portion 19 of the upper tubular housing 12 for sealing the upper housing bore 14. The 21 valve 50 is normally biased to the second position, such as by a clip spring 64.
22 Thus mounted, the valve 50 is readily accessible by removing the U-bolts 55 and 23 mounting plate 53 without need to disassemble the stuffing box, the sealing 24 means 30, 34 or other wellhead assemblies.
Claims (21)
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:
1. A self-aligning stuffing box for a rod comprising:
an upper tubular housing having a bore formed therethrough adapted for accepting the rod passing therethough along an axis, the bore having a first axis;
a lower tubular housing having a bore formed therethrough adapted for accepting the rod passing therethrough, the bore having a second axis;
a spherical joint between the upper tubular housing and the lower tubular housing having an upwardly recessed, substantially concave circumferential groove, having an outer spherical surface, formed about a lower end of the upper tubular housing and defining a central, downwardly depending portion therein; and an upwardly extending substantially convex spherical surface formed at an upper end of the lower tubular housing having a central recess formed therein for accepting the downwardly depending central portion of the upper tubular housing and permitting retained engagement of the concave and convex spherical surfaces for sealed universal movement therebetween for misaligning the first axis from the second axis and adapted for aligning the first axis relative to the rod axis; and at least a first sealing means, the first seating means being housed within the bore of the downwardly depending central portion of the upper tubular housing and adapted for sealing about the rod.
an upper tubular housing having a bore formed therethrough adapted for accepting the rod passing therethough along an axis, the bore having a first axis;
a lower tubular housing having a bore formed therethrough adapted for accepting the rod passing therethrough, the bore having a second axis;
a spherical joint between the upper tubular housing and the lower tubular housing having an upwardly recessed, substantially concave circumferential groove, having an outer spherical surface, formed about a lower end of the upper tubular housing and defining a central, downwardly depending portion therein; and an upwardly extending substantially convex spherical surface formed at an upper end of the lower tubular housing having a central recess formed therein for accepting the downwardly depending central portion of the upper tubular housing and permitting retained engagement of the concave and convex spherical surfaces for sealed universal movement therebetween for misaligning the first axis from the second axis and adapted for aligning the first axis relative to the rod axis; and at least a first sealing means, the first seating means being housed within the bore of the downwardly depending central portion of the upper tubular housing and adapted for sealing about the rod.
2. The self-aligning stuffing box as described in claim 1 wherein the bore of the downwardly depending central portion further comprises a first shoulder formed at a lower end of the bore and wherein the first sealing means further comprises:
a plurality of stacked circumferential seals for sealing about the rod;
a first retainer positioned in the bore for retaining the stacked circumferential seals against the first shoulder; and biasing means positioned in the bore for compressing the stacked seals between the first retainer and the first shoulder.
a plurality of stacked circumferential seals for sealing about the rod;
a first retainer positioned in the bore for retaining the stacked circumferential seals against the first shoulder; and biasing means positioned in the bore for compressing the stacked seals between the first retainer and the first shoulder.
3. The self-aligning stuffing box as described in claim 2 wherein the stacked circumferential seals of the first sealing means are chevron seals.
4. The self-aligning stuffing box as described in claim 2 or 3 wherein the biasing means of the first sealing means is a wave spring.
5. The self-aligning stuffing box as described in any one of claims 1 - 4 further comprising at least a second sealing means housed in the bore of the upper tubular housing above the at least a first sealing means.
6. The self-aligning stuffing box as described in claim 5 wherein the bore of the upper tubular housing further comprises a second shoulder formed therein and wherein the at least a second sealing means further comprises:
a plurality of stacked circumferential seals for sealing about the rod;
a second retainer positioned in the bore for retaining the stacked circumferential seals against the second shoulder; and biasing means positioned in the bore for compressing the stacked seals between the second retainer and the second shoulder.
a plurality of stacked circumferential seals for sealing about the rod;
a second retainer positioned in the bore for retaining the stacked circumferential seals against the second shoulder; and biasing means positioned in the bore for compressing the stacked seals between the second retainer and the second shoulder.
7. The self-aligning stuffing box as described in claim 6 wherein the stacked circumferential seals of the at least a second sealing means are chevron seals.
8. The self-aligning stuffing box as described in claim 6 wherein the biasing means of the at least a second sealing means is a wave spring.
9. The self-aligning stuffing box as described in claim 5 further comprising a valve pivotally mounted within the bore of the upper tubular housing between the first and second sealing means, the valve adapted in a first position to permit passage of the rod through the bore of the upper tubular housing and, in the absence of the rod, to pivot to a second position for sealing the bore of the upper tubular housing.
10. The self-aligning stuffing box as described in any one of claims 1 - 9 wherein the bore of the lower tubular housing is larger than the bore of the upper tubular housing and the upper tubular housing is capable of misalignment at the engaged spherical surfaces adapted for accommodating misalignment of the rod therebetween.
11. The self-aligning stuffing box as described in claim 9 wherein the pivotal mounting further comprises:
a plate for pivotally mounting the valve thereon;
a mounting port extending through the upper tubular housing for mounting the plate therein and positioning the valve in the upper tubular housing bore;
fasteners for retaining the plate in the mounting port.
a plate for pivotally mounting the valve thereon;
a mounting port extending through the upper tubular housing for mounting the plate therein and positioning the valve in the upper tubular housing bore;
fasteners for retaining the plate in the mounting port.
12. The self-aligning stuffing box as described in claim 11 wherein the plate extends laterally beyond the mounting port and the fasteners comprise:
at least two U-bolts extending about the upper tubular housing for bolting to the portions of the plate extending beyond the mounting port.
at least two U-bolts extending about the upper tubular housing for bolting to the portions of the plate extending beyond the mounting port.
13. The self-aligning stuffing box as described in any one of claims 9, 11 or 12 wherein the valve is a flapper valve.
14. A self-aligning stuffing box for a rod comprising:
an upper tubular housing having a bore formed therethrough adapted for accepting the rod passing therethough along an axis, the bore having a first axis;
a lower tubular housing having a bore formed therethrough adapted for accepting the rod passing therethrough, the bore having a second axis;
a spherical joint between the upper tubular housing and the lower tubular housing having a upwardly extending, substantially concave circumferential groove, having an outer spherical surface, formed about a lower end of the upper tubular housing and defining a central, downwardly depending portion therein; and an upwardly extending substantially convex spherical surface formed at an upper end of the lower tubular housing having a central recess formed therein for accepting the downwardly depending central portion of the upper tubular housing and permitting engagement of the concave and convex spherical surfaces for sealed universal movement therebetween for misaligning the first axis from the second axis and adapted for aligning the first axis relative to the rod axis;
a first sealing means housed within the bore of the downwardly depending central portion of the upper tubular housing adapted for sealing about the rod;
a second sealing means adapted for sealing about the rod housed within the bore of the upper tubular housing above the first sealing means;
and a valve pivotally mounted in the bore of the upper tubular housing between the first and second sealing means the valve adapted in a first position to permit passage of the rod through the bore of the upper tubular housing and, in the absence of the rod, to pivot to a second position for sealing the bore of the upper tubular housing.
an upper tubular housing having a bore formed therethrough adapted for accepting the rod passing therethough along an axis, the bore having a first axis;
a lower tubular housing having a bore formed therethrough adapted for accepting the rod passing therethrough, the bore having a second axis;
a spherical joint between the upper tubular housing and the lower tubular housing having a upwardly extending, substantially concave circumferential groove, having an outer spherical surface, formed about a lower end of the upper tubular housing and defining a central, downwardly depending portion therein; and an upwardly extending substantially convex spherical surface formed at an upper end of the lower tubular housing having a central recess formed therein for accepting the downwardly depending central portion of the upper tubular housing and permitting engagement of the concave and convex spherical surfaces for sealed universal movement therebetween for misaligning the first axis from the second axis and adapted for aligning the first axis relative to the rod axis;
a first sealing means housed within the bore of the downwardly depending central portion of the upper tubular housing adapted for sealing about the rod;
a second sealing means adapted for sealing about the rod housed within the bore of the upper tubular housing above the first sealing means;
and a valve pivotally mounted in the bore of the upper tubular housing between the first and second sealing means the valve adapted in a first position to permit passage of the rod through the bore of the upper tubular housing and, in the absence of the rod, to pivot to a second position for sealing the bore of the upper tubular housing.
15. The self-aligning stuffing box as described in claim 14 wherein the pivotal mounting further comprises:
a plate for pivotally mounting the valve thereon;
a mounting port extending through the upper tubular housing for mounting the plate therein and positioning the valve in the upper tubular housing bore;
fasteners for retaining the plate in the mounting port.
a plate for pivotally mounting the valve thereon;
a mounting port extending through the upper tubular housing for mounting the plate therein and positioning the valve in the upper tubular housing bore;
fasteners for retaining the plate in the mounting port.
16. The self-aligning stuffing box as described in claim 15 wherein the plate extends laterally beyond the mounting port and the fasteners comprise:
at least two U-bolts extending about the upper tubular housing for bolting to the portions of the plate extending beyond the mounting port.
at least two U-bolts extending about the upper tubular housing for bolting to the portions of the plate extending beyond the mounting port.
17. The self-aligning stuffing box as described in any one of claims 14 - 16 wherein the valve is a flapper valve.
18. The self-aligning stuffing box as described in any one of claims 14 -17 wherein the first and second sealing means further comprise:
a plurality of stacked circumferential seals for sealing about the rod;
a retainer positioned in the bore for retaining the stacked circumferential seals against a shoulder formed within the bore; and biasing means positioned in the bore for compressing the stacked seals between the retainer and the shoulder.
a plurality of stacked circumferential seals for sealing about the rod;
a retainer positioned in the bore for retaining the stacked circumferential seals against a shoulder formed within the bore; and biasing means positioned in the bore for compressing the stacked seals between the retainer and the shoulder.
19. The self-aligning stuffing box as described in claim 18 wherein the stacked circumferential seals are chevron seals.
20. The self-aligning stuffing box as described in claim 18 or 19 wherein the biasing means is a wave spring:
21. The self-aligning stuffing box as described in any one of claims 14-20 wherein the bore of the lower tubular housing is larger than the bore of the upper tubular housing and the upper tubular housing is capable of misalignment at the engaged spherical surfaces adapted for accommodating misalignment of the rod therebetween.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002509182A CA2509182A1 (en) | 2005-06-03 | 2005-06-03 | Self-aligning stuffing box |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002509182A CA2509182A1 (en) | 2005-06-03 | 2005-06-03 | Self-aligning stuffing box |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2509182A1 true CA2509182A1 (en) | 2006-12-03 |
Family
ID=37545632
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002509182A Abandoned CA2509182A1 (en) | 2005-06-03 | 2005-06-03 | Self-aligning stuffing box |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2509182A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10597968B2 (en) | 2015-07-09 | 2020-03-24 | Dreco Energy Services Ulc | Modified stuffing box |
| US10900313B2 (en) | 2016-07-26 | 2021-01-26 | Dreco Energy Services Ulc | Method and apparatus for production well pressure containment for blowout |
| US10920887B2 (en) | 2016-02-10 | 2021-02-16 | Dreco Energy Services Ulc | Anti-extrusion seal arrangement and ram-style blowout preventer |
| US10941628B2 (en) | 2017-09-25 | 2021-03-09 | Dreco Energy Services Ulc | Adjustable blowout preventer and methods of use |
| US11035198B2 (en) | 2017-01-16 | 2021-06-15 | Dreco Energy Services Ulc | Multifunction blowout preventer |
-
2005
- 2005-06-03 CA CA002509182A patent/CA2509182A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10597968B2 (en) | 2015-07-09 | 2020-03-24 | Dreco Energy Services Ulc | Modified stuffing box |
| US10920887B2 (en) | 2016-02-10 | 2021-02-16 | Dreco Energy Services Ulc | Anti-extrusion seal arrangement and ram-style blowout preventer |
| US10900313B2 (en) | 2016-07-26 | 2021-01-26 | Dreco Energy Services Ulc | Method and apparatus for production well pressure containment for blowout |
| US11035198B2 (en) | 2017-01-16 | 2021-06-15 | Dreco Energy Services Ulc | Multifunction blowout preventer |
| US10941628B2 (en) | 2017-09-25 | 2021-03-09 | Dreco Energy Services Ulc | Adjustable blowout preventer and methods of use |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |