CA1321574C - Valve stem seal - Google Patents
Valve stem sealInfo
- Publication number
- CA1321574C CA1321574C CA000587630A CA587630A CA1321574C CA 1321574 C CA1321574 C CA 1321574C CA 000587630 A CA000587630 A CA 000587630A CA 587630 A CA587630 A CA 587630A CA 1321574 C CA1321574 C CA 1321574C
- Authority
- CA
- Canada
- Prior art keywords
- base
- exterior
- interior
- axially
- extending
- 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.)
- Expired - Fee Related
Links
Abstract
Abstract The present invention relates to an improved metal-to-metal seal for a moving stem of a valve and includes a U-shaped ring having a base, an inner leg extending from the inner portion of the base and an outer leg extending from the outer portion of the base. The sealing surface of each leg is flattened and in its free position has a slight angle with respect to the axis of the seal. Each of the legs includes a support enlargement on its sealing side at a point toward the base from the sealing surface and preferably at the position of maximum deflection of the leg. The diameter of such supports is preselected so that in its free state they each are spaced a short distance from the walls against which their leg seals.
The end of the outer leg is turned inwardly at an angle.
The end of the outer leg is turned inwardly at an angle.
Description
Valve Stem Seal DESCRIPTION
Backqround The present invention relates to an improved metal-5 to-metal stem seal for sealing between the exterior of a movable valve stem and the interior of the bore through which the stem extends.
Prior to the present invention there have been many stem seals which have been tried but they have suffered 10 from some disadvantage. For example, some of the prior seals have caused galling of the stem. Others have not provided a continuous seal either due to losing their preferred configuration when exposed to excess pressure either in testing or in service or have worn prematurely 15 so that the metal surfaces no longer were in sealing contact.
An example of a metal-to-metal seal which has been used both in stem sealing applications and in the sealing of the annulus between a casing hanger and the surrounding 20 housing is disclosed in Paper No. OTC 4371 presented at the 14th Annual Offshore Technology Conference in Houston, Texas, May 3-6, 1982 and entitled 'IFire Resistant Wellhead Equipment for Statfjord 'B' Platform". The specific metal seal ring which is referred to above is that seal labelled 25 "Primary Seal" in Figure 7 of such paper. The seal has inner and outer legs extending from a midpoint in the seal ring base portion and diverging from each other. The seal legs end in a reverse curve so that their outer end are convergent with respect to each other. The seal ring 30 labelled "Secondary Seal" us a U shaped seal ring having an energizing ring which urges the outer ends of the seal 2 ~ ~ 2 ~ r 7 ~ 65~45-367 legs into sealing engagement with the walls of the annulus against which they are to seal.
Another similar shaft seal is disclosed in U.S. Patent No. 4,471,965 in which the seal ring is U-shaped in section and the two legs each have an outer rounded projection which is intended to make the sealing contact with the surface against which it is to seal.
Summar~
According to a broad aspect of the present invention, there is provided a seal for sealing between the exterior surface of a movable valve stem and the interior surface of the bonnet bore through which the stem extends, comprising:
an annular metal ring being U-shaped in section and having an annular base extending transversely to the axes of the stem and bore, an inner leg extending axially from the inner peripheral portion of the base and an outer leg extending axially from the outer peripheral portion of the base in the same direction as said inner leg, said outer leg being longer than said inner leg, said inner leg and outer leg extending axially away from said base to 0 distal ends, said outer leg having an exterior cylindrical surface extend-ing axially away from said annular base, an exterior cylindrical support surface connected to the outer axial end of said exterior cylindrical surface away from said base, an exterior arcuate recess extending from the outer portion of said exterior support surface, a first tapered exterior surface connecting to said arcuate recess and extending radially outwardly and axially away from said base, an exterior frusto-conical sealing surface 1~
~4;;,~,,, , ,. .~ , ~h 3 - ~32~ rO7l~ 65845-367 connecting to the axially outer end away from said base of said tapered exterior surface and having a diameter slightly larger than said exterior support surface, a second exterior tapered surface extending from the axially outer portion of said exterior sealing surface radially inward and axially away from the base, said outer leg having an interior cylindrical surface extending axially away from said base, a tapered interior surface extending from the axially outer portion of said interior cylindrical sur-face away from said base and commencing at a point radially inward of the start of said first exterior tapered surface, said interior tapered surface extending radially outward and axially away from said base, and an arcuate interior surface extending from the axially outer end of said interior tapered surface away from said base and ending at the distal end of said outer leg with the sur-face extending generally radially inwardly and axially away from said base, said inner leg having an interior cylindrical surface extend-ing axially away from said annular base, an interior cylindrical support surface connected to the axially outer end of said inte-rior cylindrical surface away from said base, an arcuate interiorconcave surface extending from the axially outer portion of said interior support surface away from said base, an interior tapered surface extending radially inwardly and axially away from said base from the outer portion of said arcuate interior surface, an interior frusto-conical sealing surface having a diameter slightly smaller than said interior support surface of said inner leg extending from the axially outer end of said interior tapered surface away from said base and ending in the distal end of said ~4~
Backqround The present invention relates to an improved metal-5 to-metal stem seal for sealing between the exterior of a movable valve stem and the interior of the bore through which the stem extends.
Prior to the present invention there have been many stem seals which have been tried but they have suffered 10 from some disadvantage. For example, some of the prior seals have caused galling of the stem. Others have not provided a continuous seal either due to losing their preferred configuration when exposed to excess pressure either in testing or in service or have worn prematurely 15 so that the metal surfaces no longer were in sealing contact.
An example of a metal-to-metal seal which has been used both in stem sealing applications and in the sealing of the annulus between a casing hanger and the surrounding 20 housing is disclosed in Paper No. OTC 4371 presented at the 14th Annual Offshore Technology Conference in Houston, Texas, May 3-6, 1982 and entitled 'IFire Resistant Wellhead Equipment for Statfjord 'B' Platform". The specific metal seal ring which is referred to above is that seal labelled 25 "Primary Seal" in Figure 7 of such paper. The seal has inner and outer legs extending from a midpoint in the seal ring base portion and diverging from each other. The seal legs end in a reverse curve so that their outer end are convergent with respect to each other. The seal ring 30 labelled "Secondary Seal" us a U shaped seal ring having an energizing ring which urges the outer ends of the seal 2 ~ ~ 2 ~ r 7 ~ 65~45-367 legs into sealing engagement with the walls of the annulus against which they are to seal.
Another similar shaft seal is disclosed in U.S. Patent No. 4,471,965 in which the seal ring is U-shaped in section and the two legs each have an outer rounded projection which is intended to make the sealing contact with the surface against which it is to seal.
Summar~
According to a broad aspect of the present invention, there is provided a seal for sealing between the exterior surface of a movable valve stem and the interior surface of the bonnet bore through which the stem extends, comprising:
an annular metal ring being U-shaped in section and having an annular base extending transversely to the axes of the stem and bore, an inner leg extending axially from the inner peripheral portion of the base and an outer leg extending axially from the outer peripheral portion of the base in the same direction as said inner leg, said outer leg being longer than said inner leg, said inner leg and outer leg extending axially away from said base to 0 distal ends, said outer leg having an exterior cylindrical surface extend-ing axially away from said annular base, an exterior cylindrical support surface connected to the outer axial end of said exterior cylindrical surface away from said base, an exterior arcuate recess extending from the outer portion of said exterior support surface, a first tapered exterior surface connecting to said arcuate recess and extending radially outwardly and axially away from said base, an exterior frusto-conical sealing surface 1~
~4;;,~,,, , ,. .~ , ~h 3 - ~32~ rO7l~ 65845-367 connecting to the axially outer end away from said base of said tapered exterior surface and having a diameter slightly larger than said exterior support surface, a second exterior tapered surface extending from the axially outer portion of said exterior sealing surface radially inward and axially away from the base, said outer leg having an interior cylindrical surface extending axially away from said base, a tapered interior surface extending from the axially outer portion of said interior cylindrical sur-face away from said base and commencing at a point radially inward of the start of said first exterior tapered surface, said interior tapered surface extending radially outward and axially away from said base, and an arcuate interior surface extending from the axially outer end of said interior tapered surface away from said base and ending at the distal end of said outer leg with the sur-face extending generally radially inwardly and axially away from said base, said inner leg having an interior cylindrical surface extend-ing axially away from said annular base, an interior cylindrical support surface connected to the axially outer end of said inte-rior cylindrical surface away from said base, an arcuate interiorconcave surface extending from the axially outer portion of said interior support surface away from said base, an interior tapered surface extending radially inwardly and axially away from said base from the outer portion of said arcuate interior surface, an interior frusto-conical sealing surface having a diameter slightly smaller than said interior support surface of said inner leg extending from the axially outer end of said interior tapered surface away from said base and ending in the distal end of said ~4~
4 ` ~3 ~ ~ ~ 7 ~ 65845-367 inner leg, the exterior portion of said inner leg having a first exterior cylindrical surface extending from said base and a tapered exterior surface extending from the axially outer portion of said first exterior cylindrical surface away from said base of said inner leg from a point radially outward from said arcuate concave interior surface to the distal end of said inner leg, said seal ring adapted to be positioned between the exterior stem surface and the interior surface of the bonnet bore with its inner and outer legs extending in the direction toward the source of pressure from the valve.
With reference to preferred embodiments of the present invention there is provided an improved metal-to-metal seal for sealing around a moving stem of a valve and includes a U-shaped ring having a base, an inner leg extending from the inner portion of the base and an outer leg extending from the outer portion of the base. The sealing surface of each leg is flattened and in its free position has a slight angle with respect to the axis of the seal. Each of the legs includes a support enlargement on its - sealing side at a point toward the base from the sealing surface and preferably at the position of maximum deflection of the leg.
The diameter of such supports is preselected so that in its free state they each are spaced a short distance from the walls against which their leg seals. The end of the outer leg is turned inward-ly at an angle.
An object of the present invention is to provide an improved valve stem seal which will withstand substantial test pressures without any reduction in the metal-to-metal seal provid-ed by the seal ring.
o~
-' ' .
.
1 3 2 ~ L 65845-367 Another object is to provide an improved valve stem seal which provides a metal-to-metal seal around a moving valve stem without any galling.
A further object is to provide an improved metal valve stem seal which can maintain its sealed position through heightened pressures and movements of the valve stem.
Brief Descri~tion of the Drawin~s These and other objects and advantages of the present invention are hereinafter set forth and explained with reference to the drawings wherein:
FIGURE 1 is a sectional view through the bonnet and valve stem of a moving stem valve with the improved seal installed around the stem and within the bore through the bonnet.
FIGURE 2 is an enlarged sectional view of the seal shown in FIGURE 1.
FIGURE 3 is a detail sectional view of the improved seal.
FIGURE 4 is an enlarged cross section of the seal ring with the remainder of the ring being omitted for clarity.
Descri~tion of the Preferred Embodiment Valve 10 illustrated in the drawings is a gate valve having a body 12 which defines a gate chamber 14 and having gate 16 positioned therein to control flow through valve 10 in the usual manner. Valve 10 is a rotating stem gate valve and stem 18 is threaded into gate 16 so that rotation causes gate 16 to move in chamber 14 between positions closing flow through valve body 12 or ~ opening flow through valve body 12. Stem threads 20 engage ; threads 22 within gate 16 so that rotation of stem 18 causes the ~, ",, ~;~! r*q~
6 1c~ 4 65845-367 desired movement of gate. In the position illustrated in FIGURE 1 gate 16 is iIl its upper position and such position may either close or open flow through valve body 12 depending on the place-ment of the opening in gate 16. From this position, the rotation of stem 18 by suitable means (not shown) engaging its outer end causes gate 16 to move away from bonnet 24 to its opposite posi-tion. Thereafter, rotation of stem 16 in the opposite direction causes it to return to the illustrated position.
Bonnet 24 includes flange 26 through which suitable connecting means extend, such as studs 28 and nuts 30, to secure bonnet 24 to the exterior of valve body 12 in covering relation-ship to the opening of chamber 14. Central bonnet bore 32 extends through bonnet 24 and counterbore 34 extends into the inner end of bonnet 24 and ends in backseat shoulder 36. The outer interior of bonnet 24 includes inner threads 38, counterbore 40 and counter-bore 42 which defines the recess 44 in which improved seal assem-bly 46 is positioned. Exterior threads 48 surround the outer end of bonnet 24 and enlargement 50 is positioned in surrounding relationship to the sealing area of seal 46. Port 52 extends through enlargement 50 and communicates into central bore 32 immediately below recess 44. Fitting 54 is secured within the opening of port 52 and may be suitable for lubricating the inte-rior within bonnet 24 or for pressure testing.
The outer end of stem 18 includes suitable bearing means 56 providing the rotary mounting of stem 18 and fusible material 58 which provides for the backseating of stem shoulder 60 on back-seat shoulder 36 when the valve is subjected to excess heat. Stem extension 62 is secured to the outer end of stem 18 by pin 64 and ,,~j,,"",, ~
7 ~ 7~ 65845-367 extends outwardly through cap 66 which is threaded onto external threads 48 on the outer exterior of bonnet 24. Seal assembly 46 is positioned within recess 44 and is held therein by retaining means including a follower ring or packing gland 68 which is threaded into internal threads 38 of bonnet 24 as shown in FIGURE
1. The packing gland constitutes a means of limiting the outward movement of ring seal 70 from its desired position, as explained below. The outer end of stem extension 62 is provided with a suitable shape to allow connection of a suitable means (not shown) to cause the rotation of stem 18, either manually as with a hand-wheel or mechanically with a suitable power drive.
Seal assembly 46 which is shown in greater detail in FIGURE 2, includes seal ring 70 as hereinafter described, backup ring 72, which is positioned between the inner end of packing gland 68 and seal ring 70, and locating ring 74. Backup ring 72 is metal and annular in shape with suitable inner and outer dia-meters so that it fits easily into recess 44. The thickness of backup ring 72 is selected so that when packing gland 68 is threaded completely into threads 38 in bonnet 24, seal ring 70 is positioned within recess 44 so that the sealing portions of its inner and outer legs 84, 86 are in engagement with sealing surface 76 on the interior of bonnet 24 and with sealing surface 78 on the : exterior of stem 18. The backup ring is positioned between the surface of the base portion 88 of the seal ring 70 which is opposite from its inner and outer legs and the packing gland 68.
Locating ring 74 is positioned within recess 44 at a position so that its inner end engages the shoulder between the end of recess 44 and bore 32. Locating ring 74 includes a base portion 80 and ~fh ,'. ~
. ~
8 ~ 65845-367 upstanding rim or central projection 82 which extends upwardly between inner leg 84 and outer leg 86 of seal ring 70 and engages the base portion 88 oE seal ring 70 to further ensure that seal ring 70 is properly positioned within recess 44.
Seal ring 70 is best seen in FIGURES 3 and 4. The seal ring 70 is an annular metal ring being U-shaped in section. It includes an annular base portion 88, extending transversely to the axes of the stem and bore, and from which inner leg 84 outer leg 86 extend axially in the same direction as shown, respectively from the inner and outer peripheral portions of the base. The outer leg 86 is longer than the inner leg 84 and both legs extend axially away from the base 88 to distal ends. The diameters of base portion 88 are such that it can be inserted within recess 44 and have a small clearance from the walls of the bonnet interior and the stem exterior. As shown in FIGURE 3, diameter C will always be greater than the outer diameter of stem 18 and diameter F will always be less than the inner diameter of sealing surface 32 within bonnet 24.
Inner leg 84 has its interior cylindrical surface extending axially away from the inner surface of base portion 88 to its approximate mid point where it extends inwardly to interior cylindrical support surface 90 which is parallel to the axis.
Interior cylindrical support surface 90 is therefore connected to the axially outer end of the interior cylindrical surface away from the base. An arcuate interior concave surface extends and curves outwardly and back inwardly from the outer portion of the interior support surface away from the base 88. An interior tapered surface extends radially inwardly and axially away from ;'i jJ .
,r,~ t,, "
g ~ r~ 65845-367 the base 88 from the outer portion of the arcuate interior sur-face. An interior frusto-conical sealing surface 92, having a diameter A slightly smaller than the diameter B of the interior support surface of inner leg 84, extends from the axially outer end of the interior tapered surface away from the base 88 and ending in the distal end 94 of inner leg 84. Sealing surface 92 is at a slight angle to the axis of the seal ring as hereinafter described.
The outer surface or exterior portion of inner leg 84 has a first exterior cylindrical surface extending from the base 88 axially to a point beyond support surface 90. The exterior portion of inner leg 84 also has a tapered exterior surface extending and tapering inwardly from the axially outer portion of the first exterior cylindrical surface away from the base of the inner leg from a point radially outward from the arcuate concave interior surface of the leg to the distal end 94 of the leg.
Outer leg 86 has its outer or exterior cylindrical sur-face extending axially away from the outer surface of base portion 88 to its approximate mid point. There, the outer axial end of the exterior cylindrical surface away from the base 88 is connec-ted to an exterior cylindrical support surface 96. The support surface 96 is parallel to the axis of the seal ring. An exterior arcuate recess extends from the outer portion of the exterior support surface, first curving inwardly and then outwardly. A
first tapered exterior surface connects to said arcuate recess and extends radially outwardly and axially away from the base 88. An exterior frusto-conical sealing surface 98 connects to the axially outer end of the first tapered exterior surface away from the base ~,....
10 ~ 65845-367 of said surface and has a diameter D slightly larger than the dia-meter F of the exterior support surface. Sealing surface 98 is at a slight angle outwardly to the axis of the seal ring as herein-after described. A second exterior tapered surface extends from the axially outer portion of the exterior sealing surface 98 radially inward and axially away from the base.
The outer leg 86 has an interior cylindrical surface which extends axially from the base 88. A tapered interior sur-face extends from the axial outer portion of the said interior cylindrical surface away from the base and commencing at a point radially inward of the start of the first exterior tapered sur-face. The interior tapered surface tapers and extends radially outward and axially away from the base to a position near distal end 100 of outer leg 86. An arcuate interior surface extends from the axially outer end of the interior tapered surface away from the base and ends at distal end 100 of the outer leg 86, with the surface extending generally radially inwardly and axially away from the base. Separate surfaces 90 and 96 preferably are located at the point of maximum deflection of their respective seal legs 84 and 86.
The seal ring 70 is adapted to be positioned between the exterior stem surface 78 and the interior surface 76 of the bonnet bore 32 with its inner and outer legs 84,86 extending in the direction toward the source of pressure from the valves.
As shown in FIGURES 2, 3, and 4 diameter A of inner sealing surface 92 is preferably less than the diameter of the exterior of stem 18 and diameter D is preferably larger than the diameter of sealing surface 76 on the interior of bonnet 24. Dia-~, ~, ~ 2~ ~7l~ 65845-367 meter B, which is the diameter of support surface 90, is greater than diameter A and also slightly greater than the diameter of the exterior of stem 18. Diameter E, which is the diameter of support surface 96, is less than diameter D and also is slightly less than the diameter of sealing surface 76 on the interior of bonnet 24.
Diameter C, which is the diameter of the interior of base portion 88 and inner leg 84, is larger than the exterior of stem 18.
Diameter F, which is the diameter of the exterior of base portion 88 and of outer leg 86, is less than the diameter of the interior of bonnet 24. Sealing surface 92 on inner leg 84 is tapered with respect to the axis inwardly by the angle b and sealing surface 98 on outer leg 86 is tapered with respect to the axis outwardly by the angle a. The radial difference between support surface 96 and sealing surface 98 on outer leg is dimension d and the radial difference between support surface 90 and sealing surface 92 is dimension c, all as shown in FIGURE 4.
~, : In the following chart suggested relationship of dimen-sions for a 3 inch diameter stem which is positioned within a :~ 3-3/4 inch diameter bore .
A 2.992" B 2.999" C 3.042 D 3.762" E 3.755~' F 3.712 , ~ ~
a 1 35' b 1 35' c 0.0035"
~; d 0.035" e 15 Preferably, then, the frusto-conical sealing surface 98 of the outer leg 86 before installation tapers radially inwardly and axially toward the annular base 88 at an angle a of approxi-: mately one and one-half degrees. The frusto-conical sealing sur-":~
. :~ face 92 on inner leg 84 before installation is preferably tapered , ~ ~
: 7, L, "' . ,~' ,' ' , ': :
:
12 1 ~ 2 ~ ~ ~7 l~ 65845-367 radially outwardly and axially toward the annular base at an angle b of approximately one and one~half degrees. From the foregoing it can be seen that the improved seal provides a positive metal-to-metal seal against the exterior of the stem and the interior of the bonnet bore which is designed so that each of the seal legs is provided with a support surface so that even when they are exposed to test pressures of substantial magnitude, such as 10,000 psi, the pressure urging the legs against their sealing surfaces will not cause permanent deformation of the legs.
With reference to preferred embodiments of the present invention there is provided an improved metal-to-metal seal for sealing around a moving stem of a valve and includes a U-shaped ring having a base, an inner leg extending from the inner portion of the base and an outer leg extending from the outer portion of the base. The sealing surface of each leg is flattened and in its free position has a slight angle with respect to the axis of the seal. Each of the legs includes a support enlargement on its - sealing side at a point toward the base from the sealing surface and preferably at the position of maximum deflection of the leg.
The diameter of such supports is preselected so that in its free state they each are spaced a short distance from the walls against which their leg seals. The end of the outer leg is turned inward-ly at an angle.
An object of the present invention is to provide an improved valve stem seal which will withstand substantial test pressures without any reduction in the metal-to-metal seal provid-ed by the seal ring.
o~
-' ' .
.
1 3 2 ~ L 65845-367 Another object is to provide an improved valve stem seal which provides a metal-to-metal seal around a moving valve stem without any galling.
A further object is to provide an improved metal valve stem seal which can maintain its sealed position through heightened pressures and movements of the valve stem.
Brief Descri~tion of the Drawin~s These and other objects and advantages of the present invention are hereinafter set forth and explained with reference to the drawings wherein:
FIGURE 1 is a sectional view through the bonnet and valve stem of a moving stem valve with the improved seal installed around the stem and within the bore through the bonnet.
FIGURE 2 is an enlarged sectional view of the seal shown in FIGURE 1.
FIGURE 3 is a detail sectional view of the improved seal.
FIGURE 4 is an enlarged cross section of the seal ring with the remainder of the ring being omitted for clarity.
Descri~tion of the Preferred Embodiment Valve 10 illustrated in the drawings is a gate valve having a body 12 which defines a gate chamber 14 and having gate 16 positioned therein to control flow through valve 10 in the usual manner. Valve 10 is a rotating stem gate valve and stem 18 is threaded into gate 16 so that rotation causes gate 16 to move in chamber 14 between positions closing flow through valve body 12 or ~ opening flow through valve body 12. Stem threads 20 engage ; threads 22 within gate 16 so that rotation of stem 18 causes the ~, ",, ~;~! r*q~
6 1c~ 4 65845-367 desired movement of gate. In the position illustrated in FIGURE 1 gate 16 is iIl its upper position and such position may either close or open flow through valve body 12 depending on the place-ment of the opening in gate 16. From this position, the rotation of stem 18 by suitable means (not shown) engaging its outer end causes gate 16 to move away from bonnet 24 to its opposite posi-tion. Thereafter, rotation of stem 16 in the opposite direction causes it to return to the illustrated position.
Bonnet 24 includes flange 26 through which suitable connecting means extend, such as studs 28 and nuts 30, to secure bonnet 24 to the exterior of valve body 12 in covering relation-ship to the opening of chamber 14. Central bonnet bore 32 extends through bonnet 24 and counterbore 34 extends into the inner end of bonnet 24 and ends in backseat shoulder 36. The outer interior of bonnet 24 includes inner threads 38, counterbore 40 and counter-bore 42 which defines the recess 44 in which improved seal assem-bly 46 is positioned. Exterior threads 48 surround the outer end of bonnet 24 and enlargement 50 is positioned in surrounding relationship to the sealing area of seal 46. Port 52 extends through enlargement 50 and communicates into central bore 32 immediately below recess 44. Fitting 54 is secured within the opening of port 52 and may be suitable for lubricating the inte-rior within bonnet 24 or for pressure testing.
The outer end of stem 18 includes suitable bearing means 56 providing the rotary mounting of stem 18 and fusible material 58 which provides for the backseating of stem shoulder 60 on back-seat shoulder 36 when the valve is subjected to excess heat. Stem extension 62 is secured to the outer end of stem 18 by pin 64 and ,,~j,,"",, ~
7 ~ 7~ 65845-367 extends outwardly through cap 66 which is threaded onto external threads 48 on the outer exterior of bonnet 24. Seal assembly 46 is positioned within recess 44 and is held therein by retaining means including a follower ring or packing gland 68 which is threaded into internal threads 38 of bonnet 24 as shown in FIGURE
1. The packing gland constitutes a means of limiting the outward movement of ring seal 70 from its desired position, as explained below. The outer end of stem extension 62 is provided with a suitable shape to allow connection of a suitable means (not shown) to cause the rotation of stem 18, either manually as with a hand-wheel or mechanically with a suitable power drive.
Seal assembly 46 which is shown in greater detail in FIGURE 2, includes seal ring 70 as hereinafter described, backup ring 72, which is positioned between the inner end of packing gland 68 and seal ring 70, and locating ring 74. Backup ring 72 is metal and annular in shape with suitable inner and outer dia-meters so that it fits easily into recess 44. The thickness of backup ring 72 is selected so that when packing gland 68 is threaded completely into threads 38 in bonnet 24, seal ring 70 is positioned within recess 44 so that the sealing portions of its inner and outer legs 84, 86 are in engagement with sealing surface 76 on the interior of bonnet 24 and with sealing surface 78 on the : exterior of stem 18. The backup ring is positioned between the surface of the base portion 88 of the seal ring 70 which is opposite from its inner and outer legs and the packing gland 68.
Locating ring 74 is positioned within recess 44 at a position so that its inner end engages the shoulder between the end of recess 44 and bore 32. Locating ring 74 includes a base portion 80 and ~fh ,'. ~
. ~
8 ~ 65845-367 upstanding rim or central projection 82 which extends upwardly between inner leg 84 and outer leg 86 of seal ring 70 and engages the base portion 88 oE seal ring 70 to further ensure that seal ring 70 is properly positioned within recess 44.
Seal ring 70 is best seen in FIGURES 3 and 4. The seal ring 70 is an annular metal ring being U-shaped in section. It includes an annular base portion 88, extending transversely to the axes of the stem and bore, and from which inner leg 84 outer leg 86 extend axially in the same direction as shown, respectively from the inner and outer peripheral portions of the base. The outer leg 86 is longer than the inner leg 84 and both legs extend axially away from the base 88 to distal ends. The diameters of base portion 88 are such that it can be inserted within recess 44 and have a small clearance from the walls of the bonnet interior and the stem exterior. As shown in FIGURE 3, diameter C will always be greater than the outer diameter of stem 18 and diameter F will always be less than the inner diameter of sealing surface 32 within bonnet 24.
Inner leg 84 has its interior cylindrical surface extending axially away from the inner surface of base portion 88 to its approximate mid point where it extends inwardly to interior cylindrical support surface 90 which is parallel to the axis.
Interior cylindrical support surface 90 is therefore connected to the axially outer end of the interior cylindrical surface away from the base. An arcuate interior concave surface extends and curves outwardly and back inwardly from the outer portion of the interior support surface away from the base 88. An interior tapered surface extends radially inwardly and axially away from ;'i jJ .
,r,~ t,, "
g ~ r~ 65845-367 the base 88 from the outer portion of the arcuate interior sur-face. An interior frusto-conical sealing surface 92, having a diameter A slightly smaller than the diameter B of the interior support surface of inner leg 84, extends from the axially outer end of the interior tapered surface away from the base 88 and ending in the distal end 94 of inner leg 84. Sealing surface 92 is at a slight angle to the axis of the seal ring as hereinafter described.
The outer surface or exterior portion of inner leg 84 has a first exterior cylindrical surface extending from the base 88 axially to a point beyond support surface 90. The exterior portion of inner leg 84 also has a tapered exterior surface extending and tapering inwardly from the axially outer portion of the first exterior cylindrical surface away from the base of the inner leg from a point radially outward from the arcuate concave interior surface of the leg to the distal end 94 of the leg.
Outer leg 86 has its outer or exterior cylindrical sur-face extending axially away from the outer surface of base portion 88 to its approximate mid point. There, the outer axial end of the exterior cylindrical surface away from the base 88 is connec-ted to an exterior cylindrical support surface 96. The support surface 96 is parallel to the axis of the seal ring. An exterior arcuate recess extends from the outer portion of the exterior support surface, first curving inwardly and then outwardly. A
first tapered exterior surface connects to said arcuate recess and extends radially outwardly and axially away from the base 88. An exterior frusto-conical sealing surface 98 connects to the axially outer end of the first tapered exterior surface away from the base ~,....
10 ~ 65845-367 of said surface and has a diameter D slightly larger than the dia-meter F of the exterior support surface. Sealing surface 98 is at a slight angle outwardly to the axis of the seal ring as herein-after described. A second exterior tapered surface extends from the axially outer portion of the exterior sealing surface 98 radially inward and axially away from the base.
The outer leg 86 has an interior cylindrical surface which extends axially from the base 88. A tapered interior sur-face extends from the axial outer portion of the said interior cylindrical surface away from the base and commencing at a point radially inward of the start of the first exterior tapered sur-face. The interior tapered surface tapers and extends radially outward and axially away from the base to a position near distal end 100 of outer leg 86. An arcuate interior surface extends from the axially outer end of the interior tapered surface away from the base and ends at distal end 100 of the outer leg 86, with the surface extending generally radially inwardly and axially away from the base. Separate surfaces 90 and 96 preferably are located at the point of maximum deflection of their respective seal legs 84 and 86.
The seal ring 70 is adapted to be positioned between the exterior stem surface 78 and the interior surface 76 of the bonnet bore 32 with its inner and outer legs 84,86 extending in the direction toward the source of pressure from the valves.
As shown in FIGURES 2, 3, and 4 diameter A of inner sealing surface 92 is preferably less than the diameter of the exterior of stem 18 and diameter D is preferably larger than the diameter of sealing surface 76 on the interior of bonnet 24. Dia-~, ~, ~ 2~ ~7l~ 65845-367 meter B, which is the diameter of support surface 90, is greater than diameter A and also slightly greater than the diameter of the exterior of stem 18. Diameter E, which is the diameter of support surface 96, is less than diameter D and also is slightly less than the diameter of sealing surface 76 on the interior of bonnet 24.
Diameter C, which is the diameter of the interior of base portion 88 and inner leg 84, is larger than the exterior of stem 18.
Diameter F, which is the diameter of the exterior of base portion 88 and of outer leg 86, is less than the diameter of the interior of bonnet 24. Sealing surface 92 on inner leg 84 is tapered with respect to the axis inwardly by the angle b and sealing surface 98 on outer leg 86 is tapered with respect to the axis outwardly by the angle a. The radial difference between support surface 96 and sealing surface 98 on outer leg is dimension d and the radial difference between support surface 90 and sealing surface 92 is dimension c, all as shown in FIGURE 4.
~, : In the following chart suggested relationship of dimen-sions for a 3 inch diameter stem which is positioned within a :~ 3-3/4 inch diameter bore .
A 2.992" B 2.999" C 3.042 D 3.762" E 3.755~' F 3.712 , ~ ~
a 1 35' b 1 35' c 0.0035"
~; d 0.035" e 15 Preferably, then, the frusto-conical sealing surface 98 of the outer leg 86 before installation tapers radially inwardly and axially toward the annular base 88 at an angle a of approxi-: mately one and one-half degrees. The frusto-conical sealing sur-":~
. :~ face 92 on inner leg 84 before installation is preferably tapered , ~ ~
: 7, L, "' . ,~' ,' ' , ': :
:
12 1 ~ 2 ~ ~ ~7 l~ 65845-367 radially outwardly and axially toward the annular base at an angle b of approximately one and one~half degrees. From the foregoing it can be seen that the improved seal provides a positive metal-to-metal seal against the exterior of the stem and the interior of the bonnet bore which is designed so that each of the seal legs is provided with a support surface so that even when they are exposed to test pressures of substantial magnitude, such as 10,000 psi, the pressure urging the legs against their sealing surfaces will not cause permanent deformation of the legs.
Claims (8)
1. A seal for sealing between the exterior surface of a movable valve stem and the interior surface of the bonnet bore through which the stem extends, comprising:
an annular metal ring being U-shaped in section and having an annular base extending transversely to the axes of the stem and bore, an inner leg extending axially from the inner peripheral portion of the base and an outer leg extending axially from the outer peripheral portion of the base in the same direction as said inner leg, said outer leg being longer than said inner leg, said inner leg and outer leg extending axially away from said base to distal ends, said outer leg having an exterior cylindrical surface extend-ing axially away from said annular base, an exterior cylindrical support surface connected to the outer axial end of said exterior cylindrical surface away from said base, an exterior arcuate recess extending from the outer portion of said exterior support surface, a first tapered exterior surface connecting to said arcuate recess and extending radially outwardly and axially away from said base, an exterior frusto-conical sealing surface connecting to the axially outer end away from said base of said tapered exterior surface and having a diameter slightly larger than said exterior support surface, a second exterior tapered surface extending from the axially outer portion of said exterior sealing surface radially inward and axially away from the base, said outer leg having an interior cylindrical surface extending axially away from said base, a tapered interior surface extending from the axially outer portion of said interior cylindrical sur-face away from said base and commencing at a point radially inward of the start of said first exterior tapered surface, said interior tapered surface extending radially outward and axially away from said base, and an arcuate interior surface extending from the axially outer end of said interior tapered surface away from said base and ending at the distal end of said outer leg with the sur-face extending generally radially inwardly and axially away from said base, said inner leg having an interior cylindrical surface extend-ing axially away from said annular base, an interior cylindrical support surface connected to the axially outer end of said inte-rior cylindrical surface away from said base, an arcuate interior concave surface extending from the axially outer portion of said interior support surface away from said base, an interior tapered surface extending radially inwardly and axially away from said base from the outer portion of said arcuate interior surface, an interior frusto-conical sealing surface having a diameter slightly smaller than said interior support surface of said inner leg extending from the axially outer end of said interior tapered sur-face away from said base and ending in the distal end of said inner leg, the exterior portion of said inner leg having a first exterior cylindrical surface extending from said base and a tapered exterior surface extending from the axially outer portion of said first exterior cylindrical surface away from said base of said inner leg from a point radially outward from said arcuate concave interior surface to the distal end of said inner leg, said seal ring adapted to be positioned between the exterior stem surface and the interior surface of the bonnet bore with its inner and outer legs extending in the direction toward the source of pressure from the valve.
an annular metal ring being U-shaped in section and having an annular base extending transversely to the axes of the stem and bore, an inner leg extending axially from the inner peripheral portion of the base and an outer leg extending axially from the outer peripheral portion of the base in the same direction as said inner leg, said outer leg being longer than said inner leg, said inner leg and outer leg extending axially away from said base to distal ends, said outer leg having an exterior cylindrical surface extend-ing axially away from said annular base, an exterior cylindrical support surface connected to the outer axial end of said exterior cylindrical surface away from said base, an exterior arcuate recess extending from the outer portion of said exterior support surface, a first tapered exterior surface connecting to said arcuate recess and extending radially outwardly and axially away from said base, an exterior frusto-conical sealing surface connecting to the axially outer end away from said base of said tapered exterior surface and having a diameter slightly larger than said exterior support surface, a second exterior tapered surface extending from the axially outer portion of said exterior sealing surface radially inward and axially away from the base, said outer leg having an interior cylindrical surface extending axially away from said base, a tapered interior surface extending from the axially outer portion of said interior cylindrical sur-face away from said base and commencing at a point radially inward of the start of said first exterior tapered surface, said interior tapered surface extending radially outward and axially away from said base, and an arcuate interior surface extending from the axially outer end of said interior tapered surface away from said base and ending at the distal end of said outer leg with the sur-face extending generally radially inwardly and axially away from said base, said inner leg having an interior cylindrical surface extend-ing axially away from said annular base, an interior cylindrical support surface connected to the axially outer end of said inte-rior cylindrical surface away from said base, an arcuate interior concave surface extending from the axially outer portion of said interior support surface away from said base, an interior tapered surface extending radially inwardly and axially away from said base from the outer portion of said arcuate interior surface, an interior frusto-conical sealing surface having a diameter slightly smaller than said interior support surface of said inner leg extending from the axially outer end of said interior tapered sur-face away from said base and ending in the distal end of said inner leg, the exterior portion of said inner leg having a first exterior cylindrical surface extending from said base and a tapered exterior surface extending from the axially outer portion of said first exterior cylindrical surface away from said base of said inner leg from a point radially outward from said arcuate concave interior surface to the distal end of said inner leg, said seal ring adapted to be positioned between the exterior stem surface and the interior surface of the bonnet bore with its inner and outer legs extending in the direction toward the source of pressure from the valve.
2. A seal according to claim 1, wherein said support sur-faces of said inner and outer legs are positioned at the point of maximum deflection of said legs.
3. A seal according to claim 2, including means for retain-ing said seal ring in its desired position between the exterior surface of the stem and the interior surface of the bonnet bore.
4. A seal according to claim 3, wherein said retaining means includes means secured to said bonnet and limiting the out-ward movement of said seal ring from its desired position.
5. A seal according to claim 4, including a backup ring positioned between the surface of said base opposite from said inner and outer legs and said movement limiting means.
6. A seal according to claim 5, including a locating ring positioned in the annular space between the exterior surface of the stem and the interior surface of the bonnet bore and having a central projection extending into a position engaging the base between the inner and outer legs of said seal ring.
7. A seal according to claim 1, wherein the frusto-conical exterior sealing surface of said outer leg before installation, tapers radially inwardly and axially toward said annular base at an angle of approximately one and one-half degrees.
8. A seal according to claim 4, wherein the interior frusto-conical sealing surface of said inner leg before instal-lation, tapers radially outwardly and axially toward said annular base at an angle of approximately one and one-half degrees.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP88302541.3 | 1988-03-23 | ||
| EP88302541A EP0333943B1 (en) | 1988-03-23 | 1988-03-23 | Valve stem seal |
| US18902788A | 1988-05-02 | 1988-05-02 | |
| US07/189,027 | 1988-05-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1321574C true CA1321574C (en) | 1993-08-24 |
Family
ID=26115932
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000587630A Expired - Fee Related CA1321574C (en) | 1988-03-23 | 1989-01-06 | Valve stem seal |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP2619946B2 (en) |
| CA (1) | CA1321574C (en) |
| NO (1) | NO170439C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9863551B2 (en) | 2014-12-22 | 2018-01-09 | Ge Oil & Gas Pressure Control Lp | Dynamic stem packing |
-
1989
- 1989-01-06 CA CA000587630A patent/CA1321574C/en not_active Expired - Fee Related
- 1989-02-10 JP JP1032514A patent/JP2619946B2/en not_active Expired - Fee Related
- 1989-03-16 NO NO891138A patent/NO170439C/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9863551B2 (en) | 2014-12-22 | 2018-01-09 | Ge Oil & Gas Pressure Control Lp | Dynamic stem packing |
| US10302222B2 (en) | 2014-12-22 | 2019-05-28 | Ge Oil & Gas Pressure Control Lp | Dynamic stem packing |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2619946B2 (en) | 1997-06-11 |
| NO891138L (en) | 1989-09-25 |
| NO170439C (en) | 1992-10-14 |
| JPH01242890A (en) | 1989-09-27 |
| NO170439B (en) | 1992-07-06 |
| NO891138D0 (en) | 1989-03-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5031923A (en) | Valve stem seal | |
| US6655658B2 (en) | Plug valve assembly and fluid flow control method with improved low pressure sealing | |
| US7249751B2 (en) | Ball valve with shear bushing and integral bracket for stem blowout protection | |
| US5979491A (en) | Valve arrangement adaptable to meet different leakage requirements | |
| US4113268A (en) | Extended temperature range valve seal | |
| EP0046663B1 (en) | Fluid flow control valve with fire-safe seal | |
| US4750709A (en) | Diaphragm valve | |
| US3515371A (en) | Valve and valve seat | |
| JP3653279B2 (en) | Valve assembly with improved valve seat | |
| GB2032583A (en) | Heat responsive back seat arrangement for valve stems | |
| US3988000A (en) | Seals for a gas service butterfly valve | |
| US5259590A (en) | Valve seat for high temperature valve | |
| JP2002509230A (en) | Ball valve stem seal | |
| US3450385A (en) | Grooved valve disc | |
| US4356997A (en) | Flow control mechanism for high pressure wells | |
| CA1321574C (en) | Valve stem seal | |
| CA1284978C (en) | Stem seal for tapered lubricated plug valves | |
| CA1055005A (en) | Single double backseat | |
| CA1208191A (en) | Bidirectional valve seal | |
| US5209256A (en) | Sealing arrangements | |
| JPH03157574A (en) | Valve having freely detachable inserting body | |
| GB2074294A (en) | Plug Valve for Reduced Leakage | |
| JPS6218788B2 (en) | ||
| EP0135284A2 (en) | Valve | |
| US5601276A (en) | Retrofit valve stem seal assembly |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |