GB2558001A

GB2558001A - Seal ring and joint

Info

Publication number: GB2558001A
Application number: GB1621915.6A
Authority: GB
Inventors: Long Nicholas
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-12-21
Filing date: 2016-12-21
Publication date: 2018-07-04
Anticipated expiration: 2036-12-21
Also published as: GB201621915D0; GB2558001B

Abstract

A seal ring 1 comprises an inner sealing portion 2 connected by a radially extending annular web 3 to an outer sealing portion 4. Both inner and outer annular sealing portions have a pair radially outwardly facing annular sealing lips 5, 6, 7, 8. In use, the sealing portions 2, 4 contact corresponding inwardly facing annular contact surfaces on adjacent conduit joint components 9, 10, providing inner and outer seals against internal bore pressure. The seal ring 1 is provided with an annular slot 11 extending through the outer sealing portion 4 and into said annular web 3. When external pressure is greater than internal pressure, the annular groove 11 is forced open and the outer sealing lips 7, 8 are forced apart, strengthening the seal against external pressure, e.g. hyperbaric pressure at a subsea location. A bore, somewhere on the periphery of the annular slit 11, provides easier ingress for external pressure fluid.

Description

(54) Title of the Invention: Seal ring and joint

Abstract Title: Sealing ring for pipe joint contains both internal and external pressure (57) A seal ring 1 comprises an inner sealing portion 2 connected by a radially extending annular web 3 to an outer sealing portion 4. Both inner and outer annular sealing portions have a pair radially outwardly facing annular sealing lips 5, 6, 7, 8. In use, the sealing portions 2, 4 contact corresponding inwardly facing annular contact surfaces on adjacent conduit joint components 9, 10, providing inner and outer seals against internal bore pressure. The seal ring 1 is provided with an annular slot 11 extending through the outer sealing portion 4 and into said annular web 3. When external pressure is greater than internal pressure, the annular groove 11 is forced open and the outer sealing lips 7, 8 are forced apart, strengthening the seal against external pressure, e.g. hyperbaric pressure at a subsea location. A bore, somewhere on the periphery of the annular slit 11, provides easier ingress for external pressure fluid.

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Figure 6

Intellectual

Property

Office

Application No. GB1621915.6

RTM

Date :2 March 2017

The following terms are registered trade marks and should be read as such wherever they occur in this document:

Inconel

Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo

Seal Ring and Joint [0001] The present invention relates to a seal ring and to a conduit joint incorporating the same.

[0002] According to a first aspect, the present invention relates to a seal ring of known type comprising an inner annular sealing portion connected by a radially extending annular web portion to an outer sealing portion, said inner annular sealing portion having a first annular sealing lip/surface facing outwardly and in a first axial direction and a second annular sealing lip/surface facing outwardly and in a second axial direction opposite to said first axial direction, said outer sealing portion having a third annular sealing lip/surface facing outwardly and in said first axial direction and a fourth annular sealing lip/surface facing outwardly and in said second axial direction. Such a seal ring will be subsequently referred to as a seal ring of the type described.

[0003] The present invention further relates to a conduit joint incorporating a seal ring according to said first aspect, said conduit joint including first and second adjacent conduit joint components, said first and second adjacent conduit joint components each having a corresponding first or second inwardly facing annular contact surface thereon, said inwardly facing contact surfaces facing radially inwardly and in opposite axial directions.

[0004] In a seal ring of the type described in paragraph [0002] above; said inner sealing portion has two outwardly facing annular sealing lips which in use contact and form an inner seal with corresponding inclined and inwardly facing inner annular sealing surfaces one on each of two adjacent conduit joint components, so that a first inner seal seals against an internal pressure in said conduit joint is made, and said outer sealing portion also has two outwardly facing annular sealing lips which in use contact and form an outer seal with corresponding inclined and inwardly facing outer annular sealing surfaces one on each of said two adjacent conduit joint components so that a second outer seal against internal pressure is also made. A seal ring of the type described thus has the substantial advantage of being capable of providing (when in use in an appropriate conduit joint) a double seal against an internal pressure in said conduit joint. This is particularly advantageous when said seal ring is used in a subsea environment (for example in an oil and/or gas riser or pipeline) where leakage of fluid under pressure from said conduit joint could result in catastrophic pollution of that environment.

[0005] Said conduit joint could for example be flanged joint in which adjacent components are provided with flanges which are bolted or clamped together as is well known in the art of flanged joints. Alternatively said adjacent components (which could be adjacently components of a very high pressure valve housing) could be bolted directly together in wellknown manner, or could be provided with flanges clamped together in well-known manner by a clamp connector.

[0006] A seal ring of the type described thus has the substantial advantage in that when installed in a conduit joint between two adjacent conduit joint components and after initial energisation by bolting or clamping said joint components together, said inner sealing portion can function as a first inner annular seal between said two adjacent joint components, which first annular seal is effective against an internal pressure in said conduit joint, while said outer sealing portion can functions as a second annular seal between said same two adjacent conduit joint components which seal is independently effective against said internal pressure in the conduit joint.

[0007] While a seal ring of the type described thus has the substantial advantage of being able in many normal circumstances of use between two adjacent joint components of a known conduit joint to provide two separate (inner and outer) annular seals each independently effective against said an internal pressure in the conduit joint, it has however the major disadvantage that either or both of inner and outer seals can fail in use if the ambient or external/hyperbaric pressure in the environment in which it is used exceeds said internal pressure within said joint. This is most likely to happen in a subsea environment where the external/hyperbaric pressure could be more than 100 atmospheres due to ocean depth and/or conditions such as underwater earth quakes.

[0008] The primary object of the present invention is to provide a seal ring of the type described and thus having said substantial advantage but which also substantially eliminates this major disadvantage.

[0009] According to a first aspect the present invention, a seal ring comprising an inner annular sealing portion connected by a radially extending annular web portion to an outer sealing portion, said inner annular sealing portion having a first annular sealing lip/surface facing outwardly and in a first axial direction, and a second annular sealing lip/surface facing outwardly and in a second axial direction opposite to said first axial direction, said outer sealing portion having a third annular sealing lip/surface facing outwardly and in said first axial direction and a fourth annular sealing lip/surface facing outwardly and in said second axial direction, said seal ring being characterised in that it includes an annular slot which extends through the outer sealing portion and into said annular web around substantially the entire outer periphery of said seal ring.

[0010] According to a second aspect, the present invention provides a conduit joint including a seal ring according to said first aspect, each of said adjacent conduit joint components having an inwardly facing annular contact surfaces thereon, said conduit joint comprising two adjacent conduit joint components, each of said inwardly facing annular contact surfaces being substantially of partly spherical and partly conical form.

[0011] Seal rings of the type described and conduit joints incorporating the same, and will now be described solely by way of example and with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of a seal ring according to the present invention, Figure 2 shows a plan view of the seal ring shown in Figure 1,

Figure 3 shows a front view of the seal ring shown in Figure 1,

Figure 4 shows in magnified form a cross section through a right-hand portion of the seal ring shown in Figure 3,

Figure 5 shows in magnified form a cross section through a right-hand portion of the seal ring shown in Figure 1 in a conduit joint according to the second aspect of the present invention, and

Figure 6 shows in magnified form a cross section through a right-hand portion of a prior art seal ring in a prior art joint known to the present applicant.

[0012] As shown in Figure 6 a known seal ring 1 comprises an inner annular sealing portion 2 connected by a radially extending annular web portion 3 to an outer sealing portion 4, said inner annular sealing portion having a first annular sealing lip/surface 5 facing outwardly and in a first axial direction 20 and a second annular sealing lip/surface 6 facing outwardly and in a second axial direction 21 opposite to said first axial direction, said outer sealing portion 4 having a third annular sealing lip/surface 7 facing outwardly and in said first axial direction and a fourth annular sealing lip/surface 8 facing outwardly and in said second axial direction.

[0013] Said seal ring is integrally formed by machining a forged resilient metal ingot of an alloy such as an Inconel. The resulting seal ring is thus elastically flexible.

[0014] Referring initially to Figure 6, operation in use of this prior art arrangement, which arrangement is believed by the present applicant to be the nearest prior art to the present invention, will now be described. Other examples of a seal rings of the type described and known conduit joints in which they can be used are shown and described in International Patent Publication Number WO 2015/101835 (ONESUBSEA IP UK LIMITED).

[0015] It is thus clear from paragraph [0002] above that this prior art seal ring is of the type described. It however has the major disadvantage set out in paragraph [0005] above i.e. that either or both of inner and outer seals can fail in use if the ambient or external/hyperbaric pressure outside said conduit joint at a location of use rises above the internal pressure to which said outer seal is currently energised. This is most likely to happen in a subsea environment where the external/hyperbaric pressure could be more than 100 atmospheres due to ocean depth and/or conditions such as underwater earth quakes.

[0016] More specifically with the conventional technology / prior art, if the external hyperbaric pressure increases to a sufficient level, the resultant load pushing against the seal ring lips can overcome the initial energisation of the seal against the seal faces (in the flange, Clamp Connector hubs, valve casings), which will cause the seal ring to leak. This phenomenon exists on all high pressure, pressure energised seal rings, which seal in one direction, where pressure in the reverse direction is experienced. This is common on subsea seal rings where they are designed to seal in one direction (e.g.:- for bore pressure), however the ambient external pressure resulting from deep water depths, can cause pressure effects in the wrong direction for the seal design.

[0017] As shown in Figures 1 to 5, a seal ring in accordance with the present invention includes an inner sealing portion 2 connected by an annular web 3 to an outer sealing portion 4, both sealing portions having two radially outwardly facing annular sealing lips 5 & 6 and 7 & 8 respectively, (so that both sealing portions can be in contact with corresponding inwardly facing annular contact surfaces on adjacent conduit joint components 9 and 10) thus providing inner and outer seals against internal bore pressure, said seal ring being characterised in that includes an annular slot 11 extending through the outer sealing portion and into said annular web around substantially the entire outer periphery of said seal ring.

[0018] As shown in Figure 4 the annular slot 11 includes at least one radially extending bore 12, which extends inwardly and into said annular web portion 3. This ensures that hyperbaric pressure can get into the annular slot even if the slot has been closed by the initial energisation of the seal ring.

[0019] Operation of the preferred embodiment shown in Figure 5 will now be described.

With the conventional technology / prior art, if the external hyperbaric pressure increases to a sufficient level, the resultant load pushing against the seal ring lips can overcome the initial energisation of the seal against the seal faces (in the flange, Clamp Connector hubs, valve casings), which will cause the seal ring to leak. This phenomenon exists on all high pressure, pressure energised seal rings, which seal in one direction, where pressure in the reverse direction is experienced. This is common on subsea seal rings where they are designed to seal in one direction (e.g.:- for bore pressure), however the ambient external pressure resulting from deep water depths, can cause pressure effects in the wrong direction for the seal design.

[0020] As shown the seal ring and joint components shown are particularly suitable for use in subsea applications where very high extemal/hyperbaric pressures above said bore pressure can be experienced due to for example to the ocean depth or major local pressure increases caused by underwater earth quakes etc. As shown the joint components 9 and 10 are adjacent components in flanged joints, valve casings etc. clamp connectors. It provides a double metal to metal seal.

[0021] Each inwardly facing annular contact surfaces comprises a partly spherical portion 14 and partly conical portion 15. In operation, as the hyperbaric pressure rises, the hyperbaric pressure enters the annular slot 11 and the radially extending bore or bores 12, causing the annular seal lips 7 & 8 to move axially apart.

[0022] With the conventional technology / prior art, when in use, if the external hyperbaric pressure increases to a sufficient level, the resultant load pushing against the seal ring lips can overcome the initial energisation of the seal against the seal faces (in the flange, Clamp Connector hubs, valve casings), which will cause the seal ring to leak. This phenomenon exists on all high pressure, pressure energised seal rings, which seal in one direction, where pressure in the reverse direction is experienced. This is common on subsea seal rings where they are designed to seal in one direction (e.g.:- for bore pressure), however the ambient external pressure resulting from deep water depths, can cause pressure effects in the wrong direction for the seal design.

[0023] With the present invention, when in use, the inner seal is the primary bore fluid seal and is initially energised by the seal seats (in the flange, clamp hubs, valve body/components etc.) being brought into the desired relative positions, thus radially compressing the inner seal lips inwards towards the bore. The inner seal is then further energised by the bore pressure. The annular outer seal is primarily used to prevent the ambient external pressure pushing fluid into the seal ring annulus (space between the inner seal and the outer seal) or bore. The outer seal operates similarly to the inner seal and is initially energised in the same way by the seats being brought in to the desired relative positions, radially compressing the outer seal lips inwards towards the inner seal. The outer seal is also further energised by the bore pressure, should it leak past the inner seal. This provides a true pressure energised secondary bore seal. In this invention, there is also a groove in the outside diameter of the seal ring, between the outer seal lips, which protrudes into the seal ring central rib. This groove utilises the ambient external pressure to move the annular web portions 3, divided by the annular slot 11 of seal ring annular web portions on either side of the annular slot apart and thus also each annular seal lips axially apart along the seal ring centre line axis. Although the ambient external pressure tries to de-energise the annular seal lips by radially pushing inwards, the fact that the annular seal lips move axially apart, this compensates for the radial de-energisation in the annular seal lips and can cause a net increase in the annular seal energisation of the annular seal lips. This can be assisted by appropriate seat design as typically shown in the drawings. Therefore, the annular seal lips become both pressure energised by the bore pressure and by the ambient external pressure. Radial load from the bore pressure will try to expand the whole seal ring radially outwards. If the bore pressure leaks past the inner seal, the bore pressure load would then be on the larger diameter outer seal. This could increase the nett pressure load on the seal ring. It is therefore preferable to have the outer seal shorter than the inner seal to minimise / eliminate / reduce any load increase.

[0024] In the present invention as in the prior art seal ring shown in Figure 5, said seal ring is integrally formed by machining a forged resilient metal ingot of an alloy such as an Inconel.

The resulting seal ring is thus elastically flexible. Alternatively, the seal ring could be made of ceramic material, elastomeric material, thermoplastic material, or any combination of the above.

Claims

1. A seal ring comprising an inner annular sealing portion connected by a radially extending annular web portion to an outer sealing portion, said inner annular sealing portion having a first annular sealing lip/surface facing outwardly and in a first axial direction, and a second annular sealing lip/surface facing outwardly and in a second axial direction opposite to said first axial direction, said outer sealing portion having a third annular sealing lip/surface facing outwardly and in said first axial direction and a fourth annular sealing lip/surface facing outwardly and in said second axial direction, said seal ring being characterised in that it includes an annular slot extending through the outer sealing portion and into said annular web around substantially the entire outer periphery of said seal ring.

2. A seal ring according to claim 1, said seal ring to be integrally formed by machining a forged resilient metal ingot of an alloy.

3. A seal ring according to claim 1, said seal ring being made at least partially of ceramic material.

4. A seal ring according to claim 1, said seal ring being made at least partially of elastomeric material.

5. A seal ring according to claim 1, said seal ring being made at least partially of thermoplastic material.

6. A conduit joint including a seal ring according to said first aspect, each of said adjacent conduit joint components having an inwardly facing annular contact surfaces thereon, said conduit joint comprising two adjacent conduit joint components, each of said inwardly facing annular contact surfaces being substantially of partly spherical and partly conical form.

Intellectual

Property

Office

Application No: GB1621915.6