GB2523066A

GB2523066A - Seal ring assembly

Info

Publication number: GB2523066A
Application number: GB1318820.6A
Authority: GB
Inventors: Nicholas Long; Philip Embury
Original assignee: Freudenberg Oil and Gas Technologies Ltd
Current assignee: Freudenberg Oil and Gas Technologies Ltd
Priority date: 2013-10-24
Filing date: 2013-10-24
Publication date: 2015-08-19
Also published as: GB201318820D0

Abstract

An axially compressible annular seal ring assembly comprises a first annular sealing surface 6 adapted to form a first annular seal with a first pipe end member (12, figure 4) and a second annular sealing surface 7 adapted to form a seal with a second pipe end member (18), wherein said assembly comprises a casing ring 3 and an elastomeric ring 2, wherein the elastomeric ring is located substantially within the casing ring and the casing ring surrounds the elastomeric ring at least at the outer peripheral edge thereof. A subsea pipeline repair comprises a tightenable pipe joint including the seal ring assembly of the invention. The elastomeric ring may be a seal ring that includes the annular sealing surfaces or the casing ring may be a metal seal ring including the annular sealing surfaces.

Description

SEAL RING ASSEMBLY

The present invention relates to a seal ring assembly including an elastomeric ring, a pipe joint incorporating said assembly and a pipeline repair utilising at least one said pipe joint.

In a pipe joint incorporating an elastomeric seal ring, it is necessary to compress the seal ring into sealing engagement with portions of the joint as the joint is assembled or tightened.

In the subsea art, at least in relation to blowout preventers used in oil and gas production, it is known to employ an elastomer seal having circumferentially spaced or otherwise radially disposed metal inserts or supports embedded or otherwise disposed therein, the purpose of which inserts or supports is to minimize or prevent extrusion of the elastomer from a joint when it is tightened and when in use under high pressure. Examples of such prior art are disclosed in United States Patents and applications US4229012A (Williams, III); US4332367A (Nelson); US4444404A (Parks, Jr.); US4550895A (Shaffer); US5O1 11 1OA (Le); US5064164A (Le); US6296225B1 (Wafts) and US6367804B 1 (Watts).

It is also known to employ an elastomeric seal ring axially disposed between metallic elements adapted to reduce extrusion of elastomeric material in an axial direction when the seal ring is compressed and energised. See United States Patent US5350017A, United States Patent applications US2013008672A1 and US2013087977A1 and in United Kingdom Patent GB 1379134.

The primary object of the present invention is to provide an annular seal ring assembly which employs an elastomeric ring to compression energise first and second annular seals into sealing engagement with first and second pipe end members between which a tightenable pipe joint is being formed, while said joint is being tightened, the assembly serving to substantially prevent extrusion of elastomeric material from that joint.

The present invention provides according to a first aspect an axially compressible annular seal ring assembly comprising a first annular sealing surface adapted to form a first annular seal with a first pipe end member and a second annular sealing surface adapted to form a seal with a second pipe end member, said seal ring assembly comprising a casing ring and an elastomeric ring, said elastomeric ring being located substantially within said casing ring, said casing ring surrounding said elastomeric ring at least at the outer peripheral edge thereof and forming in conjunction with said first and second pipe end members a substantially enclosed annular chamber substantially filled by the elastomeric material of said elastomeric ring.

In that the casing ring effectively encloses said elastomeric material in a chamber in use, it serves to substantially prevent extrusion of said elastomeric material from said joint.

A preferred arrangement according to said first aspect provides a tightenable pipe joint including a seal ring assembly according to said first aspect and a first pipe end member incorporating a first annular seal face, said first pipe end member being adapted to fit in overlapping fashion over a second pipe end member.

An even further preferred arrangement according to said first aspect provides a subsea pipeline repair utilising at least one tightenable pipe joint according to the preferred arrangement as set out in the paragraph above, said second pipe end member being a cut end of a subsea pipeline to which said first pipeline end member to be connected. The first pipeline member may be a replacement pipeline section or pipe end termination such as a flanged end.

The present invention provides according to a second aspect a pipe joint comprising first and second flanged pipe end members adapted to be bolted together in use, said pipe joint comprising an annular seal ring assembly which comprising an elastomeric ring located substantially within an axially compressible annular casing ring, said casing ring being a seal ring which includes a first annular sealing surface adapted to engage and form a fir St annular seal with a first seal surface on said first flanged pipe end member and a second annular sealing surface adapted to engage and form a second annular seal with a second seal surface on said second flanged pipe end member, said casing ring being adapted to form in conjunction with said first and second flanged pipe end members a substantially enclosed annular chamber substantially filled by elastomeric material of said elastomeric ring, said casing ring surrounding said elastomeric ring at least at the outer peripheral edge thereof and serving to substantially prevent extrusion of said elastomeric material from said joint.

The term "bolted flange joint" as used herein is intended to include any pipe joint in which flanged pipe ends are held together by bolts or studs and nuts. It a should be clear to one skilled in the art that the term "bolted together" is intended to include secured together by studs and nuts and the term "bolts" is intended to include "nuts".

In use of any embodiment described below a tightenable pipe joint is assembled and subsequently tightened. When the joint is tightened the seal ring assembly is axially compressed causing the pressure within said elastomeric material (which material functions like an incompressible fluid) to increase resulting is said first and second annular sealing surfaces to be forced into energised sealing engagement with said first and second pipe end members thus energising those sealing surfaces. This enables easy assembly of the joint. The clamping or bolting forces necessary to hold said first and second pipe end members together so as to form the joint are harnessed to pressure energise said first and second annular sealing surfaces into energised into sealing engagement with said first and second pipe end members with appropriate initial contact pressures. If the pressure within a fluid flowing through a pipeline joint including such a seal ring assembly increases the pressure within said elastomeric material increases said contact pressures. The resulting increased efficiency enables lower clamping or bolting forces to be employed. This is particularly of economic significance where a ROV is employed to tighten a clamp or bolts.

In the embodiment described below with reference to Figures 1 and 2, said elastomeric ring is a seal ring which includes said first and second annular sealing surfaces which are biased to protrude or protrude further through a single annular opening in said casing ring so as to be energised into respective sealing engagement with first and second seal surfaces respectively on said first and second pipe end members when said seal ring assembly is compressed as a result of said first pipe end portion being fitted in overlapping fashion within said second pipe end portion and a joint therebetween being tightened.

In a second embodiment, described below with reference to Figures 9 and 10 (which embodiment is particularly suitable for use in a bolted flange joint) said casing ring is preferably a metal seal ring including said first and second annular sealing surfaces which are energised into respective sealing engagement with first and second seal surfaces respectively on said first and second pipe end members so as to form a metal to metal seals with said pipe end members when said seal ring assembly is compressed as a result of said first pipe end portion being fitted in overlapping fashion within said second pipe end portion and a joint therebetween is tightened.

As a further alternative said elastonieric ring and said casing ring could both be seal rings as set out respectively in the two preceding paragraphs above.

In all embodiments said elastomeric ring is preferably bonded to said casing ring.

While said casing ring could be formed from a hard plastics material it is preferably metallic.

The present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is an axial view of a seal ring assembly according to a first embodiment; Figure 2 is a first radial cross-sectional side view through a section of the seal ring assembly as used in that embodiment; Figure 3 shows a cross-sectional view of a seal ring assembly having a minorly modified cross section as shown in Figure 6; Figure 4 shows a radial cross sectional view of a pipe joint prior to energisation of a seal ring assembly therein; Figure 5 shows a radial cross sectional view of the pipe joint after energisation of a seal ring assembly therein; Figure 6 shows a cross-sectional view of a seal ring assembly having a minorly modified cross section; Figure 7 shows a radial cross sectional view of the pipe joint prior to energisation of a seal ring assembly therein having a minorly modified cross section as shown in figure 6; Figure 8 shows a radial cross-sectional view of the pipe joint as shown in Figure 7 after energisation of the seal ring assembly therein; Figure 9 is an axial view of a second embodiment; and Figure 10 is a cross sectional view through the second embodiment taken along the line A-A shown in Figure 9.

A first embodiment will now be described with reference to Figures 1 to 8.

As shown in Figures 1 and 2, a seal ring assembly I comprises an elastomeric seal ring 2 located substantially within and bonded to a casing ring 3 which surrounds at least the outer peripheral edge of the elastomeric seal ring 2. The casing ring 3 is made of corrosion resistant alloy and serves as an anti-extrusion ring which substantially prevents or minimises extrusion of elastomer material of which the seal ring is made from a pipe joint in which the seal ring is to be located.

As best shown in Figure 2 the seal ring assembly 1 is asymmetric in cross section. The casing ring 3 extends radially inwardly on one side thereof terminating in a peripheral edge 4 which includes a plurality of narrow radially extending slots 5 shown in Figure 1 which slots divide said peripheral edge to form a number of discreet segments or fmgers'. The purpose of the slots is to render the casing ring and thus the seal ring assembly 1 more axially compressible.

The elastomeric ring 2 includes a first radially inwardly facing annular sealing surface 6 adapted to form a first annular seal with an annular seal surface on a first pipe end member and a second radially extending annular sealing surface 7 adapted to form a seal with a second pipe end member in a manner that will become clear from the description below with reference to Figures 4 and 5 of a pipe joint.

The radially extending annular sealing surface 7 may be smooth as shown in Figure 2 or may comprise a plurality of circumferentially extending sealing lips 8 as shown in Figure 6. Figure 3 shows an axial cross-sectional view of a seal ring assembly so modified.

Installation of a seal ring assembly in a pipe joint will now be described.

Figures 4 shows a detail of a pipe joint in which a first pipe end member 12 is fitted in overlapping fashion over a second pipe end member 14 and before a joint formed therebetween is tightened.

Figures 5 shows a detail of the same pipe joint after the joint has been tightened.

Figures 7 and 8 show details substantially identical to those of Figures 4 and 5 respectively except that the inwardly facing annular sealing surface 6 of the elastomer ring is slightly modified as described with reference to Figure 6 above.

The second pipe end member may be a cut end of a subsea pipeline over which the first pipeline end member is to be fitted. The first pipeline member may be a replacement pipeline section or pipeline end termination such as a flanged end.

A clamp not shown is employed which engages said first and second pipe end members and when tightened forces said first and second pipe end members into further overlapping relationship. One skilled in the art would have no difficulty in devising a clamp suitable for that purpose. One such clamp is disclosed in United Kingdom Patent Application Number (3Bl3 14260.9 (Vector International Ltd) the subject matter thereof is incorporated herein by reference and to which attention to the claims therein is directed.

As shown in Figures 4 and 7 the first pipe end member 12 is provided adjacent one end thereof with an annular recess 17 having an annular seal face 15 on a radially extending inner face 16 of said recess. A seal ring assembly 1 as described with reference to Figures 1 and 2 fits into the annular recess 17. The elastomeric ring 2 includes a radially inwardly facing annular sealing surface 6 adapted to form a first annular seal with the annular seal surface 15 on said first pipe end member 12 and a radially extending annular sealing surface 7 adapted to form a seal with a second pipe end member 18. The first pipe end member 12 may be a replacement pipeline section or pipeline end termination such as a flanged end and the second pipe end member 18 may be a cut end of a subsea pipeline to be repaired.

The casing ring 3 may form a metal to metal seal with the first pipe end member.

The casing ring 3 may be shaped as shown at 20 in Figure 4 to make the casing ring more flexible. An 0-ring may be located in an annular groove 21 so formed therein. A small void such as that shown at 22 may be provided in the elastomer ring 2. When the clamp is tightened axially compressing said seal ring assembly the void reduces in size as shown in Figure 5.

The clamp employed to force said first and second pipe end members into further overlapping relationship may directly engage and axially compress the seal ring assembly or an actuation ring 23 which moves axially when engaged by a radial movable portion 24 of a clamp described in GBI3 14260.9 may be employed.

A bolted flange joint embodiment is now described with reference to Figures 9 and 10. The term "bolted flange joint" is intended to include any pipe joint in which flanged pipe ends are held together by bolts or studs and nuts. It should be clear to one skilled in the art that the term "bolted together" is intended to include secured together by studs and nuts and. the term "bolts" is intended to include "nuts".

Figure 9 shows an end view of a bolted flange and Figure 10 shows an axial cross-sectional view through said bolted flange.

As best seen in Figure 10 flanges 31 and 32 are bolted together by studs 33 and nuts 34 to form a bolted flange joint. As shown flanges 31 and 32 are provided with API BX grooves to accommodate a seal ring assembly, but any grooves which together can accommodate an annular seal ring assembly may be employed as long as they are shaped to compress axially a seal ring assembly therein.

The seal ring assembly is symmetrical and comprises a toroidal elastomer ring 2 substantially located within a metal casing ring 3. The casing ring may have a smaller axial width than the elastomer ring to make the seal ring assembly more axially compressible. The casing ring forms metal to metal seals with annular seal faces on the flanges and serves to prevent extrusion of elastomer from the joint. The elastomer ring is axially compressed as the joint is tightened, provides a second annular seal between the flanges and increases the contact pressures of the metal to metal seals.

In use of either embodiment described above the casing ring 3 serves to substantially prevent extrusion of the elastomeric material of the elastomer ring 2 from said joint. The casing ring forms in conjunction with said first and second pipe end members a substantially enclosed annular chamber substantially filled by the elastomeric material of said elastomeric ring. The casing ring thus effectively encloses said elastomeric material in a chamber.

When the joint is tightened the seal ring assembly I is axially compressed causing the pressure within the elastomeric material (which material functions like an incompressible fluid) to increase resulting is said first and second annular sealing surfaces 6 and 7 being forced into energiseci sealing engagement with said first, and second pipe end members thus energising those sealing surfaces. This enables easy assembly of the joint prior to tightening. Preferably the elastomeric seal ring exhibits zero contact pressure during initial assembly of a joint (and may have a slight clearance on the outside diameter of a pipe to be sealed). This enables an easy initial assembly of the components of a joint into position before energising said elastomeric seal ring by tightening said joint. The seal ring may be energised after initial assembly by applying axial compression by tilting' the seal into contact and/or constricting the seal inner diameter through the reduction of inner diameter of the metal casing ring.

Looked at another way, the clamping or bolting forces necessary to hold said first and second pipe end members together so as to form the joint are harnessed during tightening of the joint to pressure energise with appropriate initial contact pressures said first and second annular sealing surfaces into energised into sealing engagement with said first and second pipe end members. If the pressure within a fluid flowing through a pipeline joint including such a seal ring assembly increases the pressure within said elastomeric material increases said contact pressures. The resulting increased efficiency enables lower clamping or bolting forces to be employed. This is particularly of economic significance where a ROV is employed to tighten a clamp or bolts.

The elastomeric rings may be formed of a fluoropolymer, such as PTFE, or an elastomer, which may include fluoroelastomers. Examples of elastomers for use herein include nitrile butacliene rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), fluoroelastomers 5 (FKM as defined by ASTM Dl 418-I Oa, including vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, perfluoromethylvinylether, and combinations thereof as well as combinations including propylene or ethylene, such as TFE-P), perfluoro-elastomers (FFKM), tetrafluoro ethylene/propylene rubbers (FEPM), etc.

Claims

Claims An axially compressible annular seal ring assembly comprising a. first annular sealing surface adapted to form a first annular seal with a first pipe end member and a second annular sealing surface adapted to form a seal with a second pipe end member, said seal ring assembly comprising a casing ring and an elastomeric ring, said elastomeric ring being located substantially within said casing ring, said casing ring surrounding said elastomeric ring at least at the outer peripheral edge thereof and forming in conjunction with said first and second pipe end members a substantially enclosed annular chamber substantially filled by the elastomeric material of said elastomeric ring.
2 A tightenable pipe joint including an axially compressible annular seal ring assembly according to claim 1 and a first pipe end member incorporating a first annular seal face, said first pipe end member being adapted to fit in overlapping fashion over a second pipe end member.
3 A subsea pipeline repair incorporating at least one tightenable pipe joint according to claim 2, said second pipe end member being a cut end of a subsea pipeline to which said first pipe end member to be connected.
4 A subsea pipeline repair as claimed in claim 3 and in which said first pipe end member is a replacement pipeline section.
A subsea pipeline repair as claimed in claim 3 and in which said first pipe end member is a pipe end termination.
6 A subsea pipeline repair as claimed in claim 3 and in which said first pipe end member is a flanged end.
7 An axially compressible annular seal ring assembly as claimed in claim I and in which said elastomeric ring is a seal ring which includes said first and second annular sealing surfaces which are biased to protrude or protrude further through a single annular opening in said casing ring so as to be energised into respective sealing engagement with first and second seal surfaces respectively on said first and second pipe end members when said seal ring assembly is compressed as a result of said first pipe end portion being fitted in overlapping fashion within said second pipe end portion and a joint therebetween being tightened.
8 An axially compressible annular seal ring assembly as claimed in claim I or claim 7 and in which said casing ring is a metal seal ring including said fir st and second annular sealing surfaces which are energised into respective sealing engagement with first and second seal surfaces respectively on said first and second pipe end members so as to form a metal to metal seals with said pipe end members when said seal ring assembly is compressed as a result of said first pipe end portion being fitted in overlapping fashion within said second pipe end portion and a joint therebetween is tightened.
9 An axially compressible annular seal ring assembly as claimed in claim 1 or claim 7 and in which said casing ring is a metal seal ring and said elastomeric ring is bonded to said casing ring.