CA2077266A1 - Hollow metal sealing rings - Google Patents
Hollow metal sealing ringsInfo
- Publication number
- CA2077266A1 CA2077266A1 CA 2077266 CA2077266A CA2077266A1 CA 2077266 A1 CA2077266 A1 CA 2077266A1 CA 2077266 CA2077266 CA 2077266 CA 2077266 A CA2077266 A CA 2077266A CA 2077266 A1 CA2077266 A1 CA 2077266A1
- Authority
- CA
- Canada
- Prior art keywords
- ring
- radially
- section
- cross
- regions
- 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 title claims abstract description 36
- 239000002184 metal Substances 0.000 title claims abstract description 20
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 20
- 230000006835 compression Effects 0.000 claims abstract description 17
- 238000007906 compression Methods 0.000 claims abstract description 17
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 12
- 238000003466 welding Methods 0.000 description 10
- 238000003754 machining Methods 0.000 description 8
- 229910001026 inconel Inorganic materials 0.000 description 6
- 229910052759 nickel Inorganic materials 0.000 description 6
- 239000012530 fluid Substances 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 229910000990 Ni alloy Inorganic materials 0.000 description 4
- 238000003483 aging Methods 0.000 description 4
- 238000010894 electron beam technology Methods 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 239000004810 polytetrafluoroethylene Substances 0.000 description 4
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910000816 inconels 718 Inorganic materials 0.000 description 2
- 239000011133 lead Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000013011 mating Effects 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 229910001235 nimonic Inorganic materials 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- ODPOAESBSUKMHD-UHFFFAOYSA-L 6,7-dihydrodipyrido[1,2-b:1',2'-e]pyrazine-5,8-diium;dibromide Chemical compound [Br-].[Br-].C1=CC=[N+]2CC[N+]3=CC=CC=C3C2=C1 ODPOAESBSUKMHD-UHFFFAOYSA-L 0.000 description 1
- 101150034533 ATIC gene Proteins 0.000 description 1
- 239000005630 Diquat Substances 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 241000613130 Tima Species 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000007788 roughening Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- 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
- F16J15/02—Sealings between relatively-stationary surfaces
- F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
- F16J15/08—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with exclusively metal packing
- F16J15/0887—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with exclusively metal packing the sealing effect being obtained by elastic deformation of the packing
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Gasket Seals (AREA)
- Sealing Devices (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
Abstract
ABSTRACT
A self-energizing metal sealing ring has a generally C-shaped cross section open on its radially inner side, with limbs (9) which are convergent at least on their axially outer surfaces (11). The radially outermost region (13) is of increased thickness; and is shaped to provide a broad cylindrical outer rim or heel surface (15). The free ends of the limbs have axially outwardly projecting tips (31), the axial distance over which is the maximum axial dimension (A) of the ring in its relaxed state. The limb regions have, adjacent to the said projections, regions (27) of reduced thickness at which the limbs flex during axial compression.
A self-energizing metal sealing ring has a generally C-shaped cross section open on its radially inner side, with limbs (9) which are convergent at least on their axially outer surfaces (11). The radially outermost region (13) is of increased thickness; and is shaped to provide a broad cylindrical outer rim or heel surface (15). The free ends of the limbs have axially outwardly projecting tips (31), the axial distance over which is the maximum axial dimension (A) of the ring in its relaxed state. The limb regions have, adjacent to the said projections, regions (27) of reduced thickness at which the limbs flex during axial compression.
Description
2 1~ 7 ~
:
:
HOLLOW METAL SEALING RINGS
This invention relates to hollow metal sealing rings, and in particular to sealing rings of the so called low-ioad self-energizing s~atic kind, as used for example in valves, pumps, motors and other apparatus to form leakproof seals between opposed, usually plane, parallel surfaces.
One known form of sealing ring has a radial cross section of C shape, with the open side of the C facing the centre of the ring. Another known seal is that known as the "Ellipseal" ~Trade Mark), described in British patent specification 2187805, comprising a radial cross section of modified parabolic form with convergent margins. A further known seal is that of GB
2038961, in which the limbs of the seal cross section have out-turned lips, forming an n-shaped cross section.
The above-mentioned seals have been very suacessful in numerous stat1c sealing applications, but are not always entirely successful in meeting the demands o sealing equipment and pipelines used in natural gas fields, where pressures are commonly in the region of 10Q00 PSI~
;:
' .
': i' ' `': ' ~' ~ ~ ~ 2 ~ ~ 7 6~ .3 .
~ and may exceed 30000 PSI
`
A reason for the lack of success with these known seals when sealing extremely high pressures, is their lack of hoop strength. Because of this, the seal rings can expand under the applied internal fluid pressure until they can expand no further ~eeause of the restriction imposed by the recesses in which tha seals sit. During this change of diameter of the seal ring, the areas of the seal ring surfaee in contact with the mating faees to be sealed are subjected to a galling aetion whieh roughens the surfaees, and in many eases it beeomes impossible to establish a satisfactory seal. If the thiekne~s of the ~eal ring metal is increassd, to inerease the hoop strength,~ the flexibility of the seal is substantially reduced, as the seals are made of metal ., .
of eonstan~ thiekness. This then requires larger bolts and increased torque to compress the seal, and makes the seal less able to cope with rotation of the flanges to be sealed, i.e. loss of paralellism, whieh can occur under the action of the pressure of a contained fluid.
:~ , Our GB-A-2239496 (8928648.8) describes self-energizing metal seals eapable of overeoming the described shortcomings of the known seals, and in partieular ;` ' 2 ~ 3 ~
capable of providing reliable sealing against a fluid at very high pressure.
``'' - .
According to G~-A-2239496 a metal sealing ring has a cross section which is hollow and open on its radially inner side and has convergent limb regions at this side, ~ .
and the radially outermost region is provided with reinforcement locally increasing its hoop strength.
Preferably the reinforcement of this outermost region is provided by a greater thickne~s of material than radially inner limb regions which in use engage the surfaces to be sealed.
. ~
The increased material thlckness in the radially outermost reglon and resulting increased hoop strength resist expansion of the seal in use, whereas the smaller thickness o~ inner regions, comprisi~g the flexible limbs which contact the surfaces to be sealed, provides ample flexibility. Relative movement of the seal and sealed surfaaes is therefore reduced or eliminated, so that the seal is not subjected to galling and roughening, but the load required to compress the seal is not substantially~increased and the seal remains sufficientIy flexible to accommodate misalignment and lack of parallelism of the surfaces to b~ sealed.
: ~7Pd~2~
;~ - 4 :; .
In this the present seal contrasts significan~ly with the conventional seals, which are made of metal of constant thickness.
.
` The hoop strength of the sealing ring can be further increased by broadening (in the axial direction) the outer rim or heel region of the seal ring that is of increased radial thickness.
The hoop strength and limb fle~ibility can be ~elected within wide ranges, independently of one another.
According to another aspect of GB-A-2239496, a hollow self-energizing metal seal ring and its seating are provided with complementary aross sectional shapes which - cooperate to limit rotation of the seal cross section when compressed.
The present invention concerns a further improved hollow metal sealing ring, applicable to situations in which there is exceptionally high pressure to seal, and/or a tendency to separation of the.flanges or o~her surface6 to be sealed owing to the extremely high pressures.
According to the present invention, in a metal sealing ,, :, ,, . . :,. :., . : , '': ,: -: , ~ . . ,; - . , 2 ~ ~
s .
ring of the kind generally set forth in GB-A-8928648.8, the said rein~orcement of the radially outermost region is provided by an increase of the thickness of the ring material in this region; this thicker region is shaped to provide an axially broad outer rim or heel surface generally parallel to the axis of the ring; the radially innermost free ends of the limb regions have axially outwardly projecting tips which provide the maximum axial dimension of the ring in its relaxed state; and the limb regions preferably have, radially external to the said projections, regions of reduced axial thickness providing points of preferential flexing of the inner ends of the limb regions during axial compression.
Preferably the maximum axial dimension is no greater than, preferably less than the radial dimension of the ring cross section between its radially innermost and outermost surfaces.
In one form of ring embodying the invention, the limb regions are convergent on their axially outer surfaces, for example along circular or other arcs blending into the regions of lea t thickness, whereas the internal profile of the ring cross section comprises axially inner limb surfaces which, in the relaxed condition, are substantially parallel to 8 ach other, being interconnected at their radially outer sides by a :: ' ':' ' '~ ,,'~':, : ,'., ! ': ' . , `~ :
~ ~ 7 '~ 2 ~ ~
.~ .
~ smoothly blended part-circular or other arc.
;,'` .
One form of seal ring embodying the present invention will be described, by way of example only, with reference to the accompanying drawing, which is a cross section on a radial and axial plane of one side of a sealing ring seated in a recess.
The drawing shows part of a lower flange 3 to be sealed ~ .:
against an upper flange (not shown), for example pipe end flan~es in a natural gas pipeline. The upper flange has a plane surface, the lower flange has a rectangular recess S at the end of the plpeline bore 1, and a hollow metal sealing ring 7 is seated i~ this rece~s. The overall axial dlmension A of the sealing ring in its relaxed condition is greater than the axial depth of the recess, so that one axial side of the ring stands proud of the flange surface and is compressed by the opposite flange in use. In the lllustrated case, the depth of the recass is 0. sa A.
With the exception of the radial extent B of the ring cross section, all of the dimensions of the ring cross section are related to the maximum axial dimension A, and a preferred set of relationships between the ring ., i ~ .....
~ ~ rl~ 7 2 ~ ;~
.
dimensions is illustrated in the drawing. B may be equal to A, or greater than A to give greater strength.
The present illustrated ring combines certain aspects of the rings shown in Figures 4 and 9 of GB-A-2239496 but is modified to cope with higher pressures and greater flange separations.
The seal ring is of metal with a hollow cross section, open on its radially inner side, that i8 to say, towards the pipeline bore so that the fluid being conveyed has access to the interior of the seal ring cross section and the pressure of this fluid therefore acts on the interior of the seal ring to force its limbs 9 into contact with the flange surfaces. The limbs 9 have arcuate convergent external margins 11, so that the external surface of the ring is convex whsre it meets the flange surfaces.
.
The internal surface of the seal ring cross section is ; U-shaped with parallel surfaces 21 joined by a semi circular surface 23. The external surface of the seal ring cross section is non-circular and is such that " " , ,,,, " ~,", ,., ~ "., ;,.,," ,~
'.. ' 7 ~
the thickness of the metal of the seal ring is increased progressively into the radially outermost heel or rim region 13.
: ' ' The thicker heel region 13 enhances the hoop strength of the seal ring, without reducing the flexibility of the l l mbs 9 . ' ~he relaticnship between the thickness of the heel and -;the limbs is selected according to the required hoop strength and flexlbility in relation to the intended use.
The thicker heel region has an effectively cy1indr1cal outermost surface 15, joined to the circular arcs 11 ~: :
deflning the 11mbs by frusto-conical surfaces 17 tangential to the limbs, and radiused transitions 19.
This profile substantiaIly increases the hoop strength of the heeI region. In the illustrated seal the heel surface lS has an axia1 extent of 0.6 A.
It is desirable that rotation of the seal ring cross section within its seat be prsvented. The cylindrical outermost surface 15 cooperates directly with the sylindrical radially outer surface o~ the recess or seat S to prevent rotation.
.
' `:
~ .
\` `
~7 ~ 9 The inner ends o the limbs have axially outwardly turned lips 31, so that the profile is approximately that of the greek letter Q.
These outwardly turned lip8 also prevent the seal from rotating in its 5 eat.
The outwardly turned lips 31 have axially ~acing flat surfaces 25, which converge with one another in the radially outward direation. ~hus, when these lip~ are put under compression between the flanges, it is the radially innermost edges or angles o~ the lips 31 which first come under compression, as these define the maximum axial dimension A of the sealing ring.
Because the internal surfaces ~1 of the ring cross section are plane radial surfaces whereas th~ outer surfaces 11 are convergent arcuate surfaces, regions 27 of minimum thickness of the limbs are defined, immediately radially outside the lips 31.
:;
When the illustrated sealing ring is compressed axially, the points E at the r~dially innermost extremities of ~-~ the lip surface6 25, are the first to contact the mating ;~
faces of the flanges. Vnder compression, initially the :: : , . :. : . : i;, - ' :
'' : ' ' " ,', ', .,,' - ::' ' ,, .. : :., :. :.:. :- . - .
: , .: . : . .: : .-, 2~7726~
lips 31 are compressed, flexing about the regions 27 of least thickness, until the flanges make contact with the next widest part of the ring cross section, at the positions C on the convex portion o:E the ring profile.
At this time, the surfaces 25, having rotated under the initial compression, lie substantia:Lly flat against the flange surfaces.
.
Accordingly, at this tima there is a primary seal at positions E (surfaaes 25) and a secondary seal at : ~ positions C. Because the limb thickness at points C is greater than in regions radially inwards from these points, and increases furthe.r, radially outwards of the points C, the contact pressure at the point~ C is much greater than that at the points E. During further comprAssion of the sealing ring, now effecting compression at the points C, the limbs flex at the radiused diameter of surface 23 of the internal groove 29 in the sealing ring.
To cope with extremes in flange separation or rotation, as may occur in the seallng of pressure vessels, the radial distance between points C and E can be increased ~' as necessary.
:
~:: ., ~ : :: .~ . . .
,~ ~ r~l ~7 2 $
ll It will be seen that the present ring provides a two-stage sealing action, in which sealing contact is initially made only at the relatively flexible lip8 31, forming a primary seal, and after initial compression a further, stronger, secondary seal is formed at the position C. This, together with the increased radial extent of the seal ring cross section and in particular of the flattsned heel region, enable the sealing ring to cope wi~h the most extreme sealing conditions.
Preferably, the surfaces 25 are tangential to the convex arcuate secondary seal regions, in the relaxed state;
this is indicated by broken lines in the drawing. As already stated, surfaces 25 will be tangential to regions C after compression when they lie againt the sealed surfaces.
The surfaces 25 should be given a high surface finish and close tolerances, for example by machining and lapping.
~ .
The present seals can he manufactured for example by machining firom solid; by a combination of machining and rolling; or by initially manufacturing two ring halves and then welding these together on a radial surface perpendicular to the seal ring axis.
In the case of a seal ring of welded construction, the individual ring halves can be made by machining from plate, by pressing, or in any other convenient way.
Welding can for example be by TIG or micro-plasma welding, but electron beam wslding is preferred owing to :
'~
:
.. . ...
. . .: . . . , , ~:
:, ~, .. , - ::-. . .: :
, :.:,., .: .:: . i: ,. .: :.: . ::::
2~7~2~
its lower heat input, maXing it posstble to weld without difficulty sèctions having a heel thickness up to 35mm.
Particularly in the case of a seal made by electron beam welding, it may be desirable to heat treat the seal after welding, for example by re-solution heat treatment, before any subsequent age hardening treatment Sea1s embodying the invention can be made of any suitable metal. High nickel alloys are particuIarly suitable, for example Nimonic (registered trade mark) and Inconel (registered trade ntark). A suitable alloy for sub-sea sour well applications is Inconel 718.
The spring ¢haracteristics of the seal and therefore its recovery factor after compression can be greatly improved by age-hardening.
:`~
, ~
The seals may be coated before use with a protective and/or low friction coating for example lead, silver, ~, gold, nickel, PTFE, or a combination of nickel or other metal and PTFE. The last mentioned combination is ,:~
valuable for reducing gall1ng during compression, when an Inconel seal i6 compressed between Inconel flanges, : ~ ~
or more generally, when nickel alloy seals are used in conjunction with nickel-containing or coated flanges.
' '~: :
'~
.,., ~, , . :: : :. :; : : :~: :, , :::, :.. , :
~ ~ r~ P~
It will be seen that the present ring provides a two-stage sealing action, in which sealing contact is initially made only at the relatively i`lexible lips 31, forming a primary seal, and after initial compression a further, stronger, secondary seal is formed at the position C. This, together with the increased radial axtent of the seal ring cross section and in particular of the flattened heel region, enable the sealing ring to cope with the most extrsme sealing conditions.
Preferably, the surfaces 25 are tengential to the convex arcuate secondary seal regions, in the relaxed state;
this i8 indicated by broken lines in the drawing. As already stated, surfaces 25 will be tangential to regions C after compression when they lie agaisnt the sealed surface.
By providing that the primary seal surfaces 25 are tangsntial to the secondary seal surfaces, we ensure the optimum progression of sealing action from initial contact at the corners of the surfaces 25, to the condition in which the surfaces 25 lie flat against the sealed surfaces and the secondary sealed regions are in contact with the sealed surfaces. This also ensures particularly good sealing in the final compressed condition.
::
' :::
, . , ~ ~ . , ~ .. , ,. . ", .
~ ~7~
In the illustrated embodiment, the limbs of the seal ring cross section have minumum thickness at the positions 27, immediately adjasent the outwardly turned lips. This has the important advantage that the lip regions flex ahout the regions of minimum thickness, relative to the portions of the limbs which are of greater radius from the centre of the ring.
this design in which the tip regions of the limbs flex preferentially at the adjacent regions 27, provides particularly high elestic recovery after compression, typically a recovery of 43% is achieved with the illustrated ring profile, which enables the sealing ring to be re-used.
However, it is also possible to use a seal ring in . .
~. accordance with the present invention, having a constant ; limb thickness, in the region between the outwardly A' turned lips 31, and the secondary seal regions. In this case the internal surfaces 21 are not paralle to each other, but instead, each is parallel to the respective outer surface 11 of the same limb. However a ring with this kind of cross ssction profile does not provide the same high degree of recovery aft~r compression as the ring illustrated in the drawing, and it provides a smaller sealing contact pressure, therefore it cannot be used in very highly demanding applications, as can the ring illustrated in the drawings.
- : ,: : . :,~ - : -,, : , . ., :~. , :
: . : . ::.::, : : .,: , :: - :
~7'~2~ ~
.
The surfaces 25 should be given a high surface finish and close tolerances, for example by machining and lapping.
The present seals can be manufactured .Eor example by machining from solid; by a combination of machining and rolling; or by initially manufacturing two ring halves and then welding these together on a radial surface ; perpendicular to the seal ring axis.
In the case of a seal ring of welded construction, the individual ring halves can be made by machining from plate, by pressing, or in any other convenient way.
~elding can for example be by TIG or micro-plasma welding, but electron beam welding is preferred owing to -its lower heat input, making it poissible to weld without ~, ~- difficulty sections having a heel thickness up to 35mm.
Particularly in the case of a seal made by electron beam - welding, it may be desirable to heat treat the seal after welding, for example by re-solution heat treatment, before any subsequent age hardening treatment.
~7r~26~3 : 14 Seals embodying the invention can be made of any suitable metal. High nickel alloys are particularly suitable, for example Nimonic (registered trade mark~
and Inconel ~registerèd trade mark~. A suitable alloy for sub-sea sour well applications is Inconel 718.
The spring oharacteristics of the seal and therefore its recovery factor after compression can be greatly improved by age-hardening.
The seals may be coated before use with a protective a~d/or low friction coating for example lead, silver, gold, nickel, PTFE, or a combination of nickel or other metal and PTFE. The last mentioned combination is valuable for educing galling during sompression, when . an Inconel seal i6 compressed between Inconel flanges, or more generally, when nickel alloy seals are used in conj unotion with nickel-containing or ooated flanges.
.
,, . ~,. , - . . :, . . .. .
:
:
HOLLOW METAL SEALING RINGS
This invention relates to hollow metal sealing rings, and in particular to sealing rings of the so called low-ioad self-energizing s~atic kind, as used for example in valves, pumps, motors and other apparatus to form leakproof seals between opposed, usually plane, parallel surfaces.
One known form of sealing ring has a radial cross section of C shape, with the open side of the C facing the centre of the ring. Another known seal is that known as the "Ellipseal" ~Trade Mark), described in British patent specification 2187805, comprising a radial cross section of modified parabolic form with convergent margins. A further known seal is that of GB
2038961, in which the limbs of the seal cross section have out-turned lips, forming an n-shaped cross section.
The above-mentioned seals have been very suacessful in numerous stat1c sealing applications, but are not always entirely successful in meeting the demands o sealing equipment and pipelines used in natural gas fields, where pressures are commonly in the region of 10Q00 PSI~
;:
' .
': i' ' `': ' ~' ~ ~ ~ 2 ~ ~ 7 6~ .3 .
~ and may exceed 30000 PSI
`
A reason for the lack of success with these known seals when sealing extremely high pressures, is their lack of hoop strength. Because of this, the seal rings can expand under the applied internal fluid pressure until they can expand no further ~eeause of the restriction imposed by the recesses in which tha seals sit. During this change of diameter of the seal ring, the areas of the seal ring surfaee in contact with the mating faees to be sealed are subjected to a galling aetion whieh roughens the surfaees, and in many eases it beeomes impossible to establish a satisfactory seal. If the thiekne~s of the ~eal ring metal is increassd, to inerease the hoop strength,~ the flexibility of the seal is substantially reduced, as the seals are made of metal ., .
of eonstan~ thiekness. This then requires larger bolts and increased torque to compress the seal, and makes the seal less able to cope with rotation of the flanges to be sealed, i.e. loss of paralellism, whieh can occur under the action of the pressure of a contained fluid.
:~ , Our GB-A-2239496 (8928648.8) describes self-energizing metal seals eapable of overeoming the described shortcomings of the known seals, and in partieular ;` ' 2 ~ 3 ~
capable of providing reliable sealing against a fluid at very high pressure.
``'' - .
According to G~-A-2239496 a metal sealing ring has a cross section which is hollow and open on its radially inner side and has convergent limb regions at this side, ~ .
and the radially outermost region is provided with reinforcement locally increasing its hoop strength.
Preferably the reinforcement of this outermost region is provided by a greater thickne~s of material than radially inner limb regions which in use engage the surfaces to be sealed.
. ~
The increased material thlckness in the radially outermost reglon and resulting increased hoop strength resist expansion of the seal in use, whereas the smaller thickness o~ inner regions, comprisi~g the flexible limbs which contact the surfaces to be sealed, provides ample flexibility. Relative movement of the seal and sealed surfaaes is therefore reduced or eliminated, so that the seal is not subjected to galling and roughening, but the load required to compress the seal is not substantially~increased and the seal remains sufficientIy flexible to accommodate misalignment and lack of parallelism of the surfaces to b~ sealed.
: ~7Pd~2~
;~ - 4 :; .
In this the present seal contrasts significan~ly with the conventional seals, which are made of metal of constant thickness.
.
` The hoop strength of the sealing ring can be further increased by broadening (in the axial direction) the outer rim or heel region of the seal ring that is of increased radial thickness.
The hoop strength and limb fle~ibility can be ~elected within wide ranges, independently of one another.
According to another aspect of GB-A-2239496, a hollow self-energizing metal seal ring and its seating are provided with complementary aross sectional shapes which - cooperate to limit rotation of the seal cross section when compressed.
The present invention concerns a further improved hollow metal sealing ring, applicable to situations in which there is exceptionally high pressure to seal, and/or a tendency to separation of the.flanges or o~her surface6 to be sealed owing to the extremely high pressures.
According to the present invention, in a metal sealing ,, :, ,, . . :,. :., . : , '': ,: -: , ~ . . ,; - . , 2 ~ ~
s .
ring of the kind generally set forth in GB-A-8928648.8, the said rein~orcement of the radially outermost region is provided by an increase of the thickness of the ring material in this region; this thicker region is shaped to provide an axially broad outer rim or heel surface generally parallel to the axis of the ring; the radially innermost free ends of the limb regions have axially outwardly projecting tips which provide the maximum axial dimension of the ring in its relaxed state; and the limb regions preferably have, radially external to the said projections, regions of reduced axial thickness providing points of preferential flexing of the inner ends of the limb regions during axial compression.
Preferably the maximum axial dimension is no greater than, preferably less than the radial dimension of the ring cross section between its radially innermost and outermost surfaces.
In one form of ring embodying the invention, the limb regions are convergent on their axially outer surfaces, for example along circular or other arcs blending into the regions of lea t thickness, whereas the internal profile of the ring cross section comprises axially inner limb surfaces which, in the relaxed condition, are substantially parallel to 8 ach other, being interconnected at their radially outer sides by a :: ' ':' ' '~ ,,'~':, : ,'., ! ': ' . , `~ :
~ ~ 7 '~ 2 ~ ~
.~ .
~ smoothly blended part-circular or other arc.
;,'` .
One form of seal ring embodying the present invention will be described, by way of example only, with reference to the accompanying drawing, which is a cross section on a radial and axial plane of one side of a sealing ring seated in a recess.
The drawing shows part of a lower flange 3 to be sealed ~ .:
against an upper flange (not shown), for example pipe end flan~es in a natural gas pipeline. The upper flange has a plane surface, the lower flange has a rectangular recess S at the end of the plpeline bore 1, and a hollow metal sealing ring 7 is seated i~ this rece~s. The overall axial dlmension A of the sealing ring in its relaxed condition is greater than the axial depth of the recess, so that one axial side of the ring stands proud of the flange surface and is compressed by the opposite flange in use. In the lllustrated case, the depth of the recass is 0. sa A.
With the exception of the radial extent B of the ring cross section, all of the dimensions of the ring cross section are related to the maximum axial dimension A, and a preferred set of relationships between the ring ., i ~ .....
~ ~ rl~ 7 2 ~ ;~
.
dimensions is illustrated in the drawing. B may be equal to A, or greater than A to give greater strength.
The present illustrated ring combines certain aspects of the rings shown in Figures 4 and 9 of GB-A-2239496 but is modified to cope with higher pressures and greater flange separations.
The seal ring is of metal with a hollow cross section, open on its radially inner side, that i8 to say, towards the pipeline bore so that the fluid being conveyed has access to the interior of the seal ring cross section and the pressure of this fluid therefore acts on the interior of the seal ring to force its limbs 9 into contact with the flange surfaces. The limbs 9 have arcuate convergent external margins 11, so that the external surface of the ring is convex whsre it meets the flange surfaces.
.
The internal surface of the seal ring cross section is ; U-shaped with parallel surfaces 21 joined by a semi circular surface 23. The external surface of the seal ring cross section is non-circular and is such that " " , ,,,, " ~,", ,., ~ "., ;,.,," ,~
'.. ' 7 ~
the thickness of the metal of the seal ring is increased progressively into the radially outermost heel or rim region 13.
: ' ' The thicker heel region 13 enhances the hoop strength of the seal ring, without reducing the flexibility of the l l mbs 9 . ' ~he relaticnship between the thickness of the heel and -;the limbs is selected according to the required hoop strength and flexlbility in relation to the intended use.
The thicker heel region has an effectively cy1indr1cal outermost surface 15, joined to the circular arcs 11 ~: :
deflning the 11mbs by frusto-conical surfaces 17 tangential to the limbs, and radiused transitions 19.
This profile substantiaIly increases the hoop strength of the heeI region. In the illustrated seal the heel surface lS has an axia1 extent of 0.6 A.
It is desirable that rotation of the seal ring cross section within its seat be prsvented. The cylindrical outermost surface 15 cooperates directly with the sylindrical radially outer surface o~ the recess or seat S to prevent rotation.
.
' `:
~ .
\` `
~7 ~ 9 The inner ends o the limbs have axially outwardly turned lips 31, so that the profile is approximately that of the greek letter Q.
These outwardly turned lip8 also prevent the seal from rotating in its 5 eat.
The outwardly turned lips 31 have axially ~acing flat surfaces 25, which converge with one another in the radially outward direation. ~hus, when these lip~ are put under compression between the flanges, it is the radially innermost edges or angles o~ the lips 31 which first come under compression, as these define the maximum axial dimension A of the sealing ring.
Because the internal surfaces ~1 of the ring cross section are plane radial surfaces whereas th~ outer surfaces 11 are convergent arcuate surfaces, regions 27 of minimum thickness of the limbs are defined, immediately radially outside the lips 31.
:;
When the illustrated sealing ring is compressed axially, the points E at the r~dially innermost extremities of ~-~ the lip surface6 25, are the first to contact the mating ;~
faces of the flanges. Vnder compression, initially the :: : , . :. : . : i;, - ' :
'' : ' ' " ,', ', .,,' - ::' ' ,, .. : :., :. :.:. :- . - .
: , .: . : . .: : .-, 2~7726~
lips 31 are compressed, flexing about the regions 27 of least thickness, until the flanges make contact with the next widest part of the ring cross section, at the positions C on the convex portion o:E the ring profile.
At this time, the surfaces 25, having rotated under the initial compression, lie substantia:Lly flat against the flange surfaces.
.
Accordingly, at this tima there is a primary seal at positions E (surfaaes 25) and a secondary seal at : ~ positions C. Because the limb thickness at points C is greater than in regions radially inwards from these points, and increases furthe.r, radially outwards of the points C, the contact pressure at the point~ C is much greater than that at the points E. During further comprAssion of the sealing ring, now effecting compression at the points C, the limbs flex at the radiused diameter of surface 23 of the internal groove 29 in the sealing ring.
To cope with extremes in flange separation or rotation, as may occur in the seallng of pressure vessels, the radial distance between points C and E can be increased ~' as necessary.
:
~:: ., ~ : :: .~ . . .
,~ ~ r~l ~7 2 $
ll It will be seen that the present ring provides a two-stage sealing action, in which sealing contact is initially made only at the relatively flexible lip8 31, forming a primary seal, and after initial compression a further, stronger, secondary seal is formed at the position C. This, together with the increased radial extent of the seal ring cross section and in particular of the flattsned heel region, enable the sealing ring to cope wi~h the most extreme sealing conditions.
Preferably, the surfaces 25 are tangential to the convex arcuate secondary seal regions, in the relaxed state;
this is indicated by broken lines in the drawing. As already stated, surfaces 25 will be tangential to regions C after compression when they lie againt the sealed surfaces.
The surfaces 25 should be given a high surface finish and close tolerances, for example by machining and lapping.
~ .
The present seals can he manufactured for example by machining firom solid; by a combination of machining and rolling; or by initially manufacturing two ring halves and then welding these together on a radial surface perpendicular to the seal ring axis.
In the case of a seal ring of welded construction, the individual ring halves can be made by machining from plate, by pressing, or in any other convenient way.
Welding can for example be by TIG or micro-plasma welding, but electron beam wslding is preferred owing to :
'~
:
.. . ...
. . .: . . . , , ~:
:, ~, .. , - ::-. . .: :
, :.:,., .: .:: . i: ,. .: :.: . ::::
2~7~2~
its lower heat input, maXing it posstble to weld without difficulty sèctions having a heel thickness up to 35mm.
Particularly in the case of a seal made by electron beam welding, it may be desirable to heat treat the seal after welding, for example by re-solution heat treatment, before any subsequent age hardening treatment Sea1s embodying the invention can be made of any suitable metal. High nickel alloys are particuIarly suitable, for example Nimonic (registered trade mark) and Inconel (registered trade ntark). A suitable alloy for sub-sea sour well applications is Inconel 718.
The spring ¢haracteristics of the seal and therefore its recovery factor after compression can be greatly improved by age-hardening.
:`~
, ~
The seals may be coated before use with a protective and/or low friction coating for example lead, silver, ~, gold, nickel, PTFE, or a combination of nickel or other metal and PTFE. The last mentioned combination is ,:~
valuable for reducing gall1ng during compression, when an Inconel seal i6 compressed between Inconel flanges, : ~ ~
or more generally, when nickel alloy seals are used in conjunction with nickel-containing or coated flanges.
' '~: :
'~
.,., ~, , . :: : :. :; : : :~: :, , :::, :.. , :
~ ~ r~ P~
It will be seen that the present ring provides a two-stage sealing action, in which sealing contact is initially made only at the relatively i`lexible lips 31, forming a primary seal, and after initial compression a further, stronger, secondary seal is formed at the position C. This, together with the increased radial axtent of the seal ring cross section and in particular of the flattened heel region, enable the sealing ring to cope with the most extrsme sealing conditions.
Preferably, the surfaces 25 are tengential to the convex arcuate secondary seal regions, in the relaxed state;
this i8 indicated by broken lines in the drawing. As already stated, surfaces 25 will be tangential to regions C after compression when they lie agaisnt the sealed surface.
By providing that the primary seal surfaces 25 are tangsntial to the secondary seal surfaces, we ensure the optimum progression of sealing action from initial contact at the corners of the surfaces 25, to the condition in which the surfaces 25 lie flat against the sealed surfaces and the secondary sealed regions are in contact with the sealed surfaces. This also ensures particularly good sealing in the final compressed condition.
::
' :::
, . , ~ ~ . , ~ .. , ,. . ", .
~ ~7~
In the illustrated embodiment, the limbs of the seal ring cross section have minumum thickness at the positions 27, immediately adjasent the outwardly turned lips. This has the important advantage that the lip regions flex ahout the regions of minimum thickness, relative to the portions of the limbs which are of greater radius from the centre of the ring.
this design in which the tip regions of the limbs flex preferentially at the adjacent regions 27, provides particularly high elestic recovery after compression, typically a recovery of 43% is achieved with the illustrated ring profile, which enables the sealing ring to be re-used.
However, it is also possible to use a seal ring in . .
~. accordance with the present invention, having a constant ; limb thickness, in the region between the outwardly A' turned lips 31, and the secondary seal regions. In this case the internal surfaces 21 are not paralle to each other, but instead, each is parallel to the respective outer surface 11 of the same limb. However a ring with this kind of cross ssction profile does not provide the same high degree of recovery aft~r compression as the ring illustrated in the drawing, and it provides a smaller sealing contact pressure, therefore it cannot be used in very highly demanding applications, as can the ring illustrated in the drawings.
- : ,: : . :,~ - : -,, : , . ., :~. , :
: . : . ::.::, : : .,: , :: - :
~7'~2~ ~
.
The surfaces 25 should be given a high surface finish and close tolerances, for example by machining and lapping.
The present seals can be manufactured .Eor example by machining from solid; by a combination of machining and rolling; or by initially manufacturing two ring halves and then welding these together on a radial surface ; perpendicular to the seal ring axis.
In the case of a seal ring of welded construction, the individual ring halves can be made by machining from plate, by pressing, or in any other convenient way.
~elding can for example be by TIG or micro-plasma welding, but electron beam welding is preferred owing to -its lower heat input, making it poissible to weld without ~, ~- difficulty sections having a heel thickness up to 35mm.
Particularly in the case of a seal made by electron beam - welding, it may be desirable to heat treat the seal after welding, for example by re-solution heat treatment, before any subsequent age hardening treatment.
~7r~26~3 : 14 Seals embodying the invention can be made of any suitable metal. High nickel alloys are particularly suitable, for example Nimonic (registered trade mark~
and Inconel ~registerèd trade mark~. A suitable alloy for sub-sea sour well applications is Inconel 718.
The spring oharacteristics of the seal and therefore its recovery factor after compression can be greatly improved by age-hardening.
The seals may be coated before use with a protective a~d/or low friction coating for example lead, silver, gold, nickel, PTFE, or a combination of nickel or other metal and PTFE. The last mentioned combination is valuable for educing galling during sompression, when . an Inconel seal i6 compressed between Inconel flanges, or more generally, when nickel alloy seals are used in conj unotion with nickel-containing or ooated flanges.
.
,, . ~,. , - . . :, . . .. .
Claims (7)
1. A self-energizing sealing ring, in which the axial cross section of the ring is generally C-shaped and open on its radially inner side, the radially outermost region is of increased thickness and is shaped to provide an outer rim or heel surface generally parallel to the axis of the ring, and the radially inner free ends of the limb regions of the cross section have axially outwardly turned tips, which in the relaxed state of the ring define the maximum axial dimension of the ring.
2. A self-energizing metal sealing ring having a cross section which is hollow and open on its radially inner side and has at this side limb regions which are convergent at least on their axially outer surfaces; and in which the radially outermost region of the cross section is of increased thickness and is shaped to provide an axially broad outer surface generally parallel to the axis of the ring; the radially innermost free ends of the limb regions have axially outwardly projecting tips which provide the maximum axial dimension of the ring in its relaxed state; and the limb regions have, radially external to and adjacent the said projections, regions of reduced axial thickness providing points of preferential flexing of the inner ends of the limb regions during axial compression of the ring.
3. A seal ring as claimed in claim 1 or 2 in which the said maximum axial dimension of the ring cross section is not greater than the maximum radial dimension of the ring cross section.
4. A sealing ring as claimed in claim 1, 2 or 3 in which the internal profile of the ring cross section comprises axially inner limb surfaces which, in the relaxed condition, are substantially parallel to each other, being interconnected at their radially outer sides by a smoothly blended arc.
5. A seal ring as claimed in any of claims 1 to 4 in which the outwardly projecting tips of the limb regions have axially outermost surfaces which, in the relaxed condition of the ring, extend obliquely relative to the radial direction and converge with one another in the radially outward direction.
6. A seal ring as claimed in claim 5 in which, in the relaxed condition, the said axially outermost surfaces are substantially tangential to outer convex surfaces of the ring.
7. A seal ring substantially as herein described with reference to the accompanying drawing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB919118823A GB9118823D0 (en) | 1991-09-02 | 1991-09-02 | Hollow metal sealing rings |
| GB9118823.5 | 1991-09-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2077266A1 true CA2077266A1 (en) | 1993-03-03 |
Family
ID=10700839
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2077266 Abandoned CA2077266A1 (en) | 1991-09-02 | 1992-09-01 | Hollow metal sealing rings |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA2077266A1 (en) |
| DE (1) | DE9211661U1 (en) |
| GB (2) | GB9118823D0 (en) |
| NL (1) | NL9201529A (en) |
| NO (1) | NO180395C (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9414113D0 (en) * | 1994-07-13 | 1994-08-31 | Specialist Sealing Ltd | Improvements relating to metallic seal rings |
| FR2726879B1 (en) * | 1994-11-10 | 1997-01-31 | Europ Propulsion | STATIC METAL V-SEAL AND SEALED ASSEMBLY |
| DE29612339U1 (en) * | 1996-07-16 | 1996-12-19 | Siemens AG, 80333 München | poetry |
| DE19704544C2 (en) * | 1997-02-06 | 2000-05-18 | Pauls Werner | Portable auto switch |
| WO2000011379A1 (en) * | 1998-08-21 | 2000-03-02 | The Advanced Products Company | Spring compression seal |
| EP1420161A1 (en) * | 2002-11-18 | 2004-05-19 | Wärtsilä Schweiz AG | Metallic sealing ring, as well as a pressure accumulator for a common-rail system with such a sealing ring |
| FR2981424B1 (en) * | 2011-10-14 | 2014-09-12 | Snecma | STATIC SEAL SEAL WITH V-LAYER SECTION |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3713660A (en) * | 1970-11-10 | 1973-01-30 | Fisher Controls Co | Metal seal for a control valve or the like |
| GB2038961B (en) * | 1979-01-03 | 1983-05-11 | Nicholson T P | Ring seal |
| GB2239496B (en) * | 1989-12-19 | 1993-09-15 | Specialist Sealing Ltd | Hollow metal sealing rings |
-
1991
- 1991-09-02 GB GB919118823A patent/GB9118823D0/en active Pending
-
1992
- 1992-08-29 DE DE9211661U patent/DE9211661U1/en not_active Expired - Lifetime
- 1992-08-31 NO NO923401A patent/NO180395C/en unknown
- 1992-09-01 CA CA 2077266 patent/CA2077266A1/en not_active Abandoned
- 1992-09-02 GB GB9218660A patent/GB2259121B/en not_active Expired - Fee Related
- 1992-09-02 NL NL9201529A patent/NL9201529A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| GB9218660D0 (en) | 1992-10-21 |
| GB2259121A (en) | 1993-03-03 |
| NL9201529A (en) | 1993-04-01 |
| NO923401L (en) | 1993-03-03 |
| GB9118823D0 (en) | 1991-10-16 |
| DE9211661U1 (en) | 1993-02-25 |
| NO923401D0 (en) | 1992-08-31 |
| NO180395C (en) | 1997-04-09 |
| NO180395B (en) | 1996-12-30 |
| GB2259121B (en) | 1995-04-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5354072A (en) | Hollow metal sealing rings | |
| US5669612A (en) | Metallic seal rings | |
| US5240263A (en) | Metallic sealing rings and their manufacture | |
| EP1104517B1 (en) | Spring compression seal | |
| US4915397A (en) | Hollow metallic sealing rings | |
| US7810816B1 (en) | Seal | |
| US6131915A (en) | Seal | |
| US9127775B2 (en) | Flexible seals for process control valves | |
| US6322087B1 (en) | Metallic seal for low load conditions | |
| EP0118170B1 (en) | Improved valve seat assembly and valve | |
| GB2190470A (en) | Valve | |
| JP4231789B2 (en) | Elements, systems and methods for forming gasketless seals between elements in an ultra high pressure system | |
| CA2077266A1 (en) | Hollow metal sealing rings | |
| WO1998009101A1 (en) | Gaskets | |
| US5467966A (en) | Seals | |
| GB2221000A (en) | Improvements relating to metallic sealing rings and their manufacture | |
| GB2239496A (en) | Hollow metal sealing rings | |
| JPH0446151Y2 (en) | ||
| US8651136B2 (en) | Valve with a metal gasket | |
| WO1998009102A1 (en) | Gaskets | |
| JPS6069367A (en) | Valve sealing mechanism | |
| GB2263739A (en) | Sealing ring | |
| CN115176107A (en) | Ball valve pad | |
| GB2307014A (en) | Seal |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |