GB2184186A - Improvements in or relating to pipe couplings - Google Patents

Improvements in or relating to pipe couplings Download PDF

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Publication number
GB2184186A
GB2184186A GB08628509A GB8628509A GB2184186A GB 2184186 A GB2184186 A GB 2184186A GB 08628509 A GB08628509 A GB 08628509A GB 8628509 A GB8628509 A GB 8628509A GB 2184186 A GB2184186 A GB 2184186A
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United Kingdom
Prior art keywords
pipe
member
encircling
coupling according
ofthe
Prior art date
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GB08628509A
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GB8628509D0 (en
Inventor
Anthony John Lawrence
John Edward George Woodman
Patrick George Tomkinson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TUNGUM HYDRAULICS Ltd
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TUNGUM HYDRAULICS Ltd
Priority date (The priority date 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 date listed.)
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Publication date
Priority to GB858529582A priority Critical patent/GB8529582D0/en
Priority to GB868607541A priority patent/GB8607541D0/en
Application filed by TUNGUM HYDRAULICS Ltd filed Critical TUNGUM HYDRAULICS Ltd
Publication of GB8628509D0 publication Critical patent/GB8628509D0/en
Publication of GB2184186A publication Critical patent/GB2184186A/en
Application status is Withdrawn legal-status Critical

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16LPIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L23/00Flanged joints
    • F16L23/02Flanged joints the flanges being connected by members tensioned axially
    • F16L23/032Flanged joints the flanges being connected by members tensioned axially characterised by the shape or composition of the flanges
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16LPIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L19/00Joints in which sealing surfaces are pressed together by means of a member, e.g. a swivel nut, screwed on or into one of the joint parts
    • F16L19/06Joints in which sealing surfaces are pressed together by means of a member, e.g. a swivel nut, screwed on or into one of the joint parts in which radial clamping is obtained by wedging action on non-deformed pipe ends
    • F16L19/061Joints in which sealing surfaces are pressed together by means of a member, e.g. a swivel nut, screwed on or into one of the joint parts in which radial clamping is obtained by wedging action on non-deformed pipe ends a pressure ring being arranged between the clamping ring and the threaded member or the connecting member

Abstract

A fire and/or corrosion resistant pipe coupling comprises first and second pipe-encircling members 10, 16 in screw-threaded engagement with one another, a pipe-gripping collar 28 within the second member 16 having an external frusto-conical surface so arranged that, as the first and second members are screwed together, the collar is contracted radially to grip the pipe 12, and a compressible annular sealing member 41 of fire and/or corrosion resistant material disposed within an annular recess in one of the two pipe-encircling members. A conventional O-ring 19, which may be omitted, is also located in the recess and a thrust washer is provided to compress the annular sealing member 41 between the recess and the pipe as a result of the screwing together of the two members 10, 16. The member 41 may provide a fire and/or corrosion resistant secondary back-up to the O-ring 19 or may itself provide the primary seal. <IMAGE>

Description

SPECIFICATION improvements in or relating to pipe couplings The invention relates to pipe couplings ofthe kind comprising a first pipe-encircling member, a second pipe-encircling member, means connecting the first and second members in such manner that relative axial movement may be effected between them, and a pipe-gripping collarwithin the second member having an external frusto-conical surface so arrangedthat, upon axial movementofthefirstand second memberstowards one another, the collaris contracted radially to grip the pipe.

The two pipe-encircling members are normally in screw-threaded engagement so that relative rotation between them effects the necessary axial move ment,butotherarrangementsareincludedwithin the scope ofthe invention, such as arrangements wherethemembersareconnectedtogetherbyclam- ping bolts or other axial clamping devices.

In couplings of this type a sealing ring formed from rubber, synthetic rubber or other elastomer is normally disposed within one of the members, usually the first member, to provide a seal between it and the pipe. While such sealing rings provide an extremely effective seal against leakage under high pressures, they are susceptible to failure under conditions of high temperature such as may occur, for example, in a fire on an oil drilling installation. Since the system in which the coupling is used may well be carrying flammable liquids it is desirable that the coupling should be able to withstand high temperaturesforat least a reasonable length of time.Standards offire resistance for pipe couplings when used in environmentswhich may be susceptible to high temperatures are such that couplings relying on elastomer sealing rings do not meet the required standard of fire resistance.

In order to provide fire resistance, all-metal compression couplings have been used, but such couplings are generally more prone to leakage than couplings using elastomer sealing rings. In one common form of all-metal coupling the separate sealing ring is omitted and the pipe-gripping collar is deformed upon compression of the coupling to provide the seal as well as biting into the pipe and securing the coupling to it. Any hydraulic or mechanical shocks received by the coupling therefore have a tendency to affectthe seal, leading to leakage. Also,thecoupl ing cannot readily be removed or replaced, due to the deformation ofthe pipe by the sealing member.

According to the invention there is provided a pipe coupling comprising a first pipe-encircling member, a second pipe-encircling member, means connect ing the first and second pipe-encircling members in such mannerthat relative axial movement may be effected between them, a pipe-gripping collarwithin the second member having an external frustoconical surface so arranged that, upon axial move ment ofthe first and second members towards one another, the collar is contracted radially to gripthe pipe, and an annularsealing memberoffire and/or corrosion resistant material disposed at least partly within one of said pipe-encircling members, means being provided to compress at least part of the annular sealing member between the said one pipeencircling memberandthe pipeasa resultofthe aforesaid axial movement.

Preferably a resilient sealing ring is also disposed within one of said pipe-encircling members to provide a seal between it and the pipe, the sealing member providing a fire and/or corrosion resistant back-u p to the aforesaid sealing ring.

Although primarily intended for use in circumstances where the coupling may be subjected to high temperature, the latter, preferred form ofthe invention may also provide a coupling which guards againstthefailureofthesealing ring for other reasons, for example dueto accident or misuse causing the ring to be subjected to corrosion attack by a fluid passing through the coupling.

Preferably the sealing member, and the resilient sealing ring where such is provided, are disposed within said first pipe-encircling member.

In one form of the invention the annular sealing member is substantially fixed ly located in relation to the second pipe-encircling member, so as to be axially movable therewith, and engageablewith an abutment surface which is substantially fixedly located in relation to the first pipe-encircling member, said abutment surface and the sealing member being so shaped that the sealing member is compressed on to the pipe by relative axial movement of said abutment surface and the second pipeencircling membertowards one another. The abutment surface is preferably provided on the first pipeencircling member itself, although it might also be provided on an element separately formed from the pipe-encircling member but movable therewith.The abutment surface may be engageable with a surface on the annular sealing member, one or both of said surfaces being inclined with respect to the axis of the ~ coupling in order to effect said compression ofthe sealing member upon said relative axial movement.

For example, either or each of said surfaces may be conically tapered. In this case the abutment surface may be an internal conical surfacewhich is inclined at a greaterangletothe axis ofthe coupling than an external conical surface on the annular sealing member. Alternatively, both conical surfaces may be equally inclined so that they come into mating engagement.

The extremity of the sealing member towards the first pipe-encircling member may comprise a conical tapered portion inclined atasmallerangletotheaxis ofthe coupling than the main conical surface ofthe sealing member. In this case the less sharply tapered extremity may become forced into the small clear ance between the pipe and the inner end ofthe conical abutment surface so as to close that clearance as the main surface ofthe sealing member is brought into abutting relation with the internal conical abut ment surface.

Alternatively, the circumferential extremity of the annularsealing mernbertowardsthefirst pipe en- circling member may be formed with a peripheral edge portion which engages said internal abutment surface. Said peripheral edge portion may be convexly curved as viewed in section. The inter engagement between the curved peripheral edge and the encircling internal conical surface may be arranged to deform the peripheral edge inwardly so that it not only grips the surface of the pipe but also bites into it.

In an alternative arrangement according to the in ventiontheannularsealing member comprises a ring of hollow cross-section located in an annular re cessinthefirstpipe-encircling member, so asto be axially movable therewith, means movable with the second pipe-encircling member being engageable with the sealing member to compress it upon relative axial movement ofthe pipe-encircling members towards one another, whereby the sealing member is deformed into sealing engagement with the pipe.

Thesealing membermay,forexample,begener- allyC-shaped in cross-section, the mouth oftheC- shape facing generally in an axial direction.

In any ofthe above-mentioned arrangements, the means to compress the annular sealing member may include a thrust-transmitting element which transmits axial thrusttothe sealing member as the pipe-encircling members are moved axially towards one another. The thrust transmitting element may abutthe pipe-gripping collar, so thatthrust is transmitted from the second pipe-encircling memberto the sealing membervia the collar and thethrusttransmitting element.

The th rust-transm itting element may comprise an annularthrustwasher. The annularthrustwasher may be integral with the annular sealing member. It may have a peripheral resilientflangeforengage- mentwithinthesecond memberto retain the collar, and the sealing member in the case where itis integral with the thrust washer, within the second pipeencircling member. Theflange may be of rubberor other resilient material bonded to a metal body ofthe thrust washer.

In anyofthe above arrangements resilient means are preferably provided to oppose axial movement ofthe pipe-gripping collartowards the first pipe- encircling member, the resilient means being so located that, as the aforesaid axial movement is effected, some compression of the resilient means occurs beforetheannularsealing member is compressed between the first pipe-encircling member and the pipe to form a seal. This ensures that some axial movement of the pipe-gripping collar can occur be fore such movement is opposed by the annular sealing member, and thus ensures that the collaradequ atelygripsthe pipe.

The resilient means may be disposed between a partmovablewiththeannularsealing memberanda part of the first pipe-encircling member, or a part movable therewith. For example, where a thrust- transmitting element is provided, as referred to above, the resilient means may be disposed between the thrust-transmitting element and the first pipeencircling member or part movable therewith.

In the case where the thrust-transmitting element is an annuiarthrustwasher having a peripheral resilientflange for engagement within the second pipe-encircling member, the resilient means may comprise a portion of said resilientflangewhich extends between one face of the thrust washer and an opposed face of the first pipe-encircling member or part movable therewith.

Alternatively,the resilient means maybedisposed between the pipe-gripping collar and the annular sealing memberora part, such astheaforesaid thrust-transmitting element, movable therewith.

The resilientmeans may comprise an annularelement of rubber or other resilient material. Alternatively, it may comprise a spring element such as an axially resilient metal or plastics washen In the case where a resilient ring is provided in addition to the annular sealing member, the sealing ring itself may be so located as to constitute said resilient means.

In any ofthe above arrangements a slip ring may be located within a bore of the second member againstan internal shouldthereofand having an internal frusto-conical surface which co-acts with the external frusto-conical surface of the pipe-gripping collar.

In any of the above arrangements also the pipegripping collar may be longitudinally split and may have a circumferential groove in the external frustoconical surface thereof.

The following is a more detailed description of embodiments ofthe invention, reference being made to the accompanying drawings in which: Figure 1 is a longitudinal section through one form of pipe-coupling according to the invention, Figure 2 is a section through an alternative form of componentforthecoupling of Figure 1, Figure3 is a longitudinal section through an alternative form of pipe-coupling according to the invention, Figure4is a section on an enlarged scale through partofafurtherform of coupling, FigureSis a similarviewto Figure4through a further alternative embodiment, Figure 6is a section through part of a still further form of coupling in accordance with the invention, and Figures 7to 15 are longitudinal sections through still further alternative embodiments.

Referring to Figurel,thecoupling includes a first pipe-encircling member 10 having a stepped through-bore 11 to receive the end of a pipe 12. The member 10 is formed with a central portion 13 of external hexagonal shape, on either side of which are provided externally threaded portions 14 and 15 which arealigned and co-axial withthethrough-bore 11.

The member 10 is provided with means, not shown, for mounting it on a fitting which requires to be connected to the pipe 12 or, alternatively, the member 10may be an integral part of a fitting which is to be connected to the pipe 12.

The shoulder 17 atthejunction betweenthetwo different diameter portions of the stepped bore 11 acts as a stop to limit the distance by which the pipe 12 can be inserted into the bore. The larger diameter portion of the through-bore 11 is formed with an an- nular recess 18 in which is received an O-ring 19 of rubber, synthetic rubber or other elastomer. Abutting the O-ring 19 within the annular recess 18 is a washer 20 of PTFE or other suitable material, the pur pose of the washer being, in known manner, to prevent the O-ring 19 from being extruded from the re cess 18 under the pressure offluid flowing through the pipe.

The inner end of the member 10 is formed with a counterbore 40 having an internal frusto-conical surface 41.

The coupling also comprises a second pipeencircling member in the form of a coupling nut 16 which is threadedly engageable with the threaded portion 15 of the member 10. An enlarged head portion 21 is provided at the outer end ofthe nut 16, and the internal bore of the nut 16 includes a plain unthreaded cylindrical portion 22 and an internally threaded portion 23 which is engageablewith the threaded portion 15 of the member 10.

Ashortunthreaded bore portion 24, the diameter of which is substantially equal to the trough diameter ofthe portion 23, is disposed between the portions 22and23.

The plain cylindrical bore portion 22 contains a freely rotatable slip ring 25 having an internal frustoconical surface 26. The external diameter of the slip ring 25 is such that it will pass with clearance through the threaded bore portion 23.

The internal frusto-conical surface 26 of the slip ring 25 engages a complementary external frustoconical surface 27 on an annular pipe-gripping collar 28 which surrounds the pipe 12. The collar 28 is longitudinally split throughout its length and has a flat end surface 29 which engages an annularthrust washer 30. The thrust washer is integrally formed with an axial extension 31 which has an external frusto-conical surface 32 and extends into the aforementioned counterbore 40 in the member 10. The extension 31 constitutes the aforementioned annular sealing member.

The inner and outer surfaces ofthe extension 31 are relieved, as indicated at3la and 31b respectively, so that only the extremities of these surfaces contact the surfaces ofthe pipe 12 and counterbore 41 respectively.

Bonded to the outer periphery of the thrust washer 30 is a resilient flange 33 ofrubberorotherelas- tomer. An annular portion 33a of the flange extends radiallyinwardlyovera peripheral portion ofthesurface of the washer 30 so as to lie between the washer and the opposed end face of the pipe-encircling member 10.

The dimensions of the components are such that when the resilient portion 33a just abuts the end surface of the member 10, there is a small clearance between the extremity of the extension 31 and the counterbore surface 41.

in assemblingthecomponentsofthecoupling,the slip ring 25 and the pipe-gripping collar 28 arefirst placed in the bore of the coupling nut 1 6 and the th rust washer 30 is then inserted in the bore, the flange 33 being deformed to allowthewasher30to pass along the threaded portion 23 ofthe bore until it reaches the intermediate bore portion 24. The peripheral flange 33 then prevents the th rust washer 30 from falling out of the nut 16 so that ittherefore acts as a holding memberto retain the collar 28 and slip ring 25 within the nut 16, which can then be used as a pre-assembled coupling membercapable of use, storage and transport as a one-piece assembly.

Toassemblethecoupling;thisone-piece assembly is passed overthe end ofthe pipe 12, and the end of the pipe is then inserted into the bore 11 of the member 10 until it engages the shoulder 17, the O-ring 19 and washer 20 having previously been inserted in the recess 18 in the member 10. The nut 16 is then threadedly engaged with the member 10 and tightened up.

As the nut 16 is tightened on to the member 10, the thrust washer 30 is urged axially towards the member 10 bythe collar 28, compressing the re silient portion 338 ofthe flange 33. This movement is permitted by the initial clearance between the end of the extension 31 and the counterbore surface 41.

During this slight movement, the collar 28 is slightly compressed radially and begins to grip the pipe 12.

When the extremity of the extension 31 has been brought into firm contact with the surface 41, further axial movement causes the extension to be compressed radially inwardly and deformed by the surface 41 so as to grip the external surface of the pipe 12.The extremity ofthe extension 31 thus becomes jammed between the surface 41 and the pipe 12 so as to form an effective seal between the pipe and the surface ofthe counterbore.

During the initial axial movementofthethrust washer 30 and compression of the flange portion 33a, there is comparatively little restraint to the axial movement of the collar 28 along the pipe 25, but the restraint is sufficient to cause the collar to be slightly contracted radially to begin to grip the pipe. As the end ofthe extension 31 becomes compressed, the restraint to axial movement of the collar 28 increases so that continued tightening ofthe nut 16 on the member 10 urges the slip ring 25to move towards the th rust washer 30 and relatively to the collar 28.

This movement of the slip ring compresses the collar 28 inwardly to grip the pipe 12. However, bythistime the extension 31 will have been sufficiently deformed and compressed to form an effective seal between the counterbore 40 and the pipe 12.

Preferably, all the components of the coupling, otherthan the non-metallic parts, are formed from the same metal so asto minimise oreliminatethe change in tolerances which would be caused by dif ferential expansion ofthe components. In this case the required hardness characteristics of the different components may be provided by the different forms of heat treatment to which they are subjected. Thus, the pipe-encircling members 10 and 16 and the pipegripping collar 28 require to be comparatively hard whereasthesealing member 31 requiresto becomparatively soft so that it readily becomes deformed and compressed when the coupling is tightened up.

Figure 2 shows an alternative shapeforthe resilientflange 33 and radial extension 33a.

It will be appreciated thatthe resilient means prov- ided by the extension 33a could take other forms, for example, the annular extension could be replaced by a spring element such as an axially resilient metal or plastics washer.

Also, the resilient means could be located elsewhere to achieve a similar effect. For example, it could act between the end face 29 of the pipe encircling collar 28 and the thrustwasher 30, or be- tween the extension 31 and the member 10. In each case the purpose of the resilient means is to permit initial axial movement of the collar28, against some resilient restraint, to ensure that it begins properly to gripthesurfaceofthe pipe 12.

Although the provision of such resilient means is preferred, it is not essential to the invention, and Fig ures 3 to 6 show alternative arrangements without such resilient means. In Figures 3 to 6, components corresponding to components of the Figure 1 arrangement bearthe same reference numerals.

In the arrangement of Figure 3, the extension 33a ofthe resilientflange 33 is omitted, and there is a clearance 34 between the thrust washer 30 and the opposed face of the member 10. The external frustoconical surface 32 ofthe extension 31 is unrelieved, but is inclined at a smallerangleto the central axis of the coupling than the internal frusto-conical surface 41 ofthe counterbore 40.

In this arrangement, asthe nut 16 is tightened on to the member 10, the extension 31 of the thrust washer is urged axially into the counterbore 41, such movement being permitted by the initial clearance 34 between the thrust washer 30 and the end face of the member 10. As the frusto-conical extension is forced in the counterbore it is compressed radially inwardly and deformed by the surface 41 so as to grip the external surface ofthe pipe 12. The leading peripheral edge of the extension 31 becomes jammed into anytolerance gap between the bore 11 and the pipe and fills such gaps, as well as at least the inner end ofthe frusto-conical counterbore 41,so as toform an effective seal between the pipe 12 andthe surface ofthe counterbore.

In the arrangement shown in Figure 3, the difference in angle of inclination ofthefrusto-conical surfaces 32 and 41 is preferably sufficiently small that the deformation of the extension 31 causes it to fill the entire space between the pipe 12 and the surface 41 before the gap 34 is closed. (The angle of inclination is shown exaggerated in Figure 3).The surface 32 may be inclined, for example, at approximately 10 totheaxisofthecoupling andwhilethesurface 41 may be inclined at upto 15"to the axis, preferably there is only a small difference in the angle, such as 1% In the alternative arrangement shown in Figure4, the outer conical surface 32 ofthe extension 31 is at substantially the same angle of inclination to the axis of the coupling as the inner surface 41 of the counterbore.In each case the angle of inclination maybe substantially 300. In this arrangement, however, the extremity ofthe extension 31 is formed with an end portion 35 the outer surface of which is inclined at a smaller angle, such as 150, to the central axis ofthe coupling.

In useofthisembodiment,theshallowerangled extremity35 jams into any gap between the bore 11 and the pipe 12, as the extension 31 is compressed into the counterbore 40, so as more effectively to formacompleteseal. The main partoftheextension 31 continues to be pressed into the counterbore 40 until the two matching frusto-conical surfaces 32 and 41 engage firmly.

In the arrangements described above the compression and deformation of the sealing member constituted by the extension 31 results in the inner periphery of the extension gripping the surface ofthe pipe 1 2to form a seal between it and the member 10.

However, by suitably shaping the inter-engaging surfaces on the extension 31 and the counterbore40, the extension may also bearrangedto biteintothe surface of the pipe 12 as well as gripping it. This may be advantageous if the surface ofthe pipe is likely to beuneven,forexampleduetothepresenceofdraw lines caused by extrusion. Figure 5 shows such an arrangement.

In the arrangement of Fig u re 5 the extension 31 is inclined ata shallowerangleto the axis ofthecoupl ingthan the surface 41 on the member 10, but in this case the extremity of the extension 31 is rounded, as viewed in cross-section, as indicated at 36. The engagementofthe rounded edge 36 by the surface 41 causes the extremity ofthe extension 31 to be deformed radially inwardly to bite into the surface ofthe pipe 12. In this arrangement the material ofthe extension 31 is harderthanthe material ofthe pipe so that it will bite into the pipe and provide a seal in spite of any irregularities in the surface of the pipe. It will be appreciated that other configurations ofthe extension 31 and the surface on the member 10 which it engages may be employed to achieve this effect.

In the arrangement of Figure 5, it may not be pos sible readilytoreplacethecoupling orthesealing element in view ofthefactthatthe extension 31 bites into the pipe. The previously described arrangements of Figures 1 to 4 havethe advantagethat, since the sealing extension is softer than the material ofthe pipe, the extension is merely compressed firmly against the pipe and does not bite into it. This meansthatthecoupling maybe readily removed or replaced.

In any ofthe arrangements the precise shape and characteristics of the sealing extension may be readily chosen to cope with the tolerances which are likely to be encountered in the other components of the coupling, no matter how largethosetolerances may be.

Figure 6 shows a further modification in which the extension 31 has a cylindrical portion3lcandacon- ical tapered portion 31 dwhich co-operate with sim ilarlyshaped surfacesonthe member 10.

In all of the above arrangements the conventional O-ring 19 of rubber or other elastomer provides the primary sealing meansforthe coupling during normal operation, and the back-up seal provided by the sealing extension 31 will not normally be subjected to fluid pressure due to the efficiency ofthe Oring 19 in providing a seal. However, should the 0ring 19 fail, due for example to prolonged subjection to high temperature, the back-up seal will prevent or at least minimise leakage offluid from the coupling.

In practice, when subjected to heat the O-ring 19 is Iikelytocarboniseandthefluid pressurewilltendto force the carbon particles into the tolerance gaps between the bore 11 and the pipe 12, thus enhancing the seal.

Referring again to the arrangement of Figure 3, if the O-ring 19 and/orthe washer 20 require to be inserted or replaced underfield conditions there is a risk of one or other of these components becoming damaged if thins is not done sufficiently carefully, due to the difficulty of introducing the components into the annular recess 18. To facilitate introduction of the components into the recess, the counterbore 40, instead of being directly formed in the member 10, is formed in a conical ferrule 42 (indicated in dotted lines in Figure 1) which is engaged within a larger conical bore in the member 10. The inner annular end face of the ferrule 42 forms the sidewall ofthe annular recess 18. Accordingly, the O-ring washer 20 may be readily inserted or removed by first remov ingtheferrule 42.The outer conical surface of the ferrule 42 is inclined at the same angle as the inner conical surface in the member 10 so asto mate firmly therewith.

In order to provide the necessary fire resistance, the back-up sealing component in the abovedescribed arrangements will normally be formed of metal. However, in some applications sufficient fire resistance may be provided by some other material.

For example, certain known synthetic materials may be of sufficient fire resistance to be useful, and the use of such materials falls within the scope of the invention. In any arrangement according to the invention, however, the fire resistance ofthe back-up sealing element must always be greaterthan that of the primary sealing ring.

The arrangements of Figures 1 to 6 may also, in some circumstances, be modified by omission ofthe resilient O-ring 19 so thatthe metallic compression sealing means provides the primary sealing means.

Such omission ofthe conventional O-ring is part icularly suitable in arrangements, such as that des- cribed in relation to Figure 5, where the metallic seal- ing member, such as the extension 31, bites into the material of the pipe since this improves the seal provided bythe metallic members which may then be adequate for use as the primaryseal.

Figures 7 to 12 show arrangements in which the annular,fireand/orcorrosion resistantsealing member is in the form of a metallic ring which is Cshaped in cross-section so asto be both axially and radially resiliently compressible. Components ofthe coupling which correspond to components ofthe couplings of Figures 1 to 6 are given the same reference numerals.

In the arrangement of Figure 7 thefirst pipeencircling member 10 is forrned atthe end facing the pipe-encircling member 1 6 with an annular recess 40 within which are located both the metallic C-section ring 41 and a conventional resilient elastomer O-ring 19. The metallic ring 41 abuts the end surface 42 of the recess 40 and the O-ring 19 is disposed between the metallic ring 41 and a radial surface 43 on the thrust washer 30.

In this case the O-ring 19 serves both to provide a seal between the member 10 and the pipe 12 and also to provide the resilient restraint to movement of the pipe-encircling collar 28 along the pipe 12. As the nut 16 is tightened onto the member 10,thethrust washer 30 is urged axially towards the member 10 by the collar28, compressing the O-ring 19 axially. This movement is permitted by the initial clearance between the thrust washer 30 and end of the member 10. During this slight movement the collar28 is slightly compressed radially and begins to gripthe pipe 12.The O-ring 19 also transmits axial thrustto the C-sectioned metallic ring 41 so that it is also compressed axially and deformed radially so as to press against the surface of the pipe 1 2, forming a seal.

The embodiment of Figure 8 is similarto that of Figure 7 but in addition a back-up washer44 of PTFE or other suitable material is disposed between the thrust washer 30 and the O-ring 19 to prevent extrusion of the O-ring 19 out of the recess 40.

In the modified arrangement of Figure 9, the conventional O-ring 19 is replaced by a rectangular section resilient washer45 which is disposed between the metallic C-section ring 41 and the ehd su rface 42 of the recess.

Figure 10 shows a furthervariation wherethe re- silientO-ring 19 is disposed adjacentthe end wall 42 of the recess in the member 10, the metallic C-section ring 41 is disposed adjacentthe th rust washer 30, and a further thrust washer 46 and back-up washer 47, for example of PTFE, are disposed between the metallic ring 41 and O-ring 19. In this case a resilient ring 48 is disposed between the thrust washer 30 and end surface of the member 10 to provide the initial resilient restraint to axial movement ofthe tight gripping collar 28.

In all ofthe arrangements described above, the metallicfire and/or corrosion resistant metallic sealing member is provided in series with a conventional resilient O-ring or other resilient sealing member and, as previously described, serves to provide a back-upforthe resilient membershouldthis become ineffective due to hightemperatureand/orcorro- sion. In some circumstances, however, the resilient seal provided bythemetallicsealing member may itselfbesufficientto provide sealing during normal use ofthe coupling. Inthiscasethemetallicsealing member does not merely provide a back-up to a con ventionalsealing ring,butprovidestheprimarvseal- ing meansforthe coupling. Figure 11 shows such an arrangement.

In this arrangementthe C-section metallic sealing ring 41 is provided alonewithintherecess40andis compressed axially by the thrust washer 30 as the coupling is tightened up, the axial compression of the ring 41 also serving to provide a radial seal between the ring and the pipe 12 and the surrounding surface ofthe recess 40. A resilient member48 is provided between the end surface of the member 10 and the thrust washer 30 to provide initial resilient restraintto movement ofthe pipe gripping collar 28 along the pipe 12. In known manner, the metallic Csection ring 41 may have an outer softer coating which, when the sealing ring is compressed, ac commodates irregularities in the surface texture of the pipe 12 so as to provide a better seal.

Figure 12 shows a further alternative arrangement where the thrust washer is in the form of a metallic annular insert 49 embedded in an annular body 50 of rubber, synthetic rubber or other elastomer. In this case the resilience of the material of the thrust washer itself provides the resilient restraint to initial axial movementofthe pipe gripping collar 28.

In the alternative arrangement shown in Figures 13 and 14, the resilient O-ring 19 is located against the bottom of the recess 40 and abutting the O-ring 19, also within the recess 40, is a rectangular-section ring 60 of PTFE orsimilar material.

The outer end of the recess 40 is formed with an enlarged diameter portion 61 within which is located a metal sealing washer 62 which is generally conical in configuration. The inner and outer peripheries of the washer 62 engage the pipe 12 and innerwall of the recess 61 respectively and may be chamfered to provide a sharp cutting edge. The surface ofthe thrustwasher 30 which faces the sealing elements is formed with a shallow annular recess as indicated at 63.

Figure 13 shows the configuration ofthe parts of the coupling after initial assembly. As the nut 16 is tightened on to the member 10,the th rust washer 30 is urged axiallytowardsthe memberlObythe collar 28. This movement is resiliently restrained by re- silienceofthe0-ring 1 9 and of the sealing washer62.

As axial compression is applied to the sealing washer 62 by the th rust washer 30, the sealing washer tends to flatten out so that its inner peripheral edge bites into the surface ofthe pipe 12, and its outer peripheral edge bites into the wall of the re cress as shown in Figure 14. The restraintto axial movementofthecollar28thusincreasessothatcon- tinuedtightening ofthe nut 16 urges the slip ring 25 to move towards the thrust washer 30 and relatively tothecollar28 sothatthe collar is compressed in wardlyto grip the pipe 12.However, by this timethe resilient O-ring 19 will have been compressed bythe back-up ring 60so asto providethe primarysealfor the coupling, and the peripheral edges of the sealing washer 62 will have bitten into the surfaces ofthe pipe 12 and recess 61 sufficiently to provide a fire and corrosion resistant secondary seal to back up the primary seal.

In all ofthe arrangements described above, the pipe-encircling members 10 and 16 are in screwthreaded engagement and are urged axiallytowards one another by rotation of the member 16 relatively to the member 10. However, the as previously mentioned, other means may be provided for urging the two pipe-encircling members towards one another.

Figure 13 shows such an arrangementwhere the two pipe-encircling members 51 and 52 are formed with radial flanges formed with registering holes through which pass threaded studs 53, nuts 54 engaging the ends of the threaded studs so that by tightening up the nuts 54the members 51 and 52 may be urged towards one another.

twill be seen thatthecoupling of Figure 13 isa double coupling forconnecting two pipes 12 and 12a. In this case each pipe-encircling memberforces a pipe-gripping collar28or28aintoengagement with the corresponding pipe and the ends ofthetwo pipes are encircled and received in sockets in a dou ble-ended pipe-encircling member 55. The sealing arrangement between the pipe-encircling member 55 and each ofthe pipes 12 and 1 2a may be of any of the types previously described and will not therefore be described in detail.

Claims (29)

1. A pipe coupling comprising afirstpipeencircling member, a second pipe-encircling member, means connecting the first and second pipe-encircling members in such mannerthat relative axial movement may be effected between them, a pipe-gripping collarwithin the second memberhaving an external frusto-conical surface so arranged that, upon axial movement ofthe first and second members towards one another, the collar is contracted radially to grip the pipe, and an annularsealing member offire and/or corrosion resistant material disposed at least partly within one of said pipeencircling members, means being provided to compress at least part ofthe annular sealing member between the said one pipe-encircling member and the pipe as a result ofthe aforesaid axial movement.
2. A pipe coupling according to Claim 1,wherein a resilient sealing ring is also disposed within one of said pipe-encircling members to provide a seal between it and the pipe, the sealing member providing a fire and/or corrosion resistant back-uptothe aforesaid sealing ring.
3. A pipe coupling according to Claim 1 or Claim 2, wherein the sealing member, and the resilient sealing ring where such is provided, are disposed within said first pipe-encircling member.
4. A pipe coupling according to any of Claims 1 to 3, wherein the annular sealing member is substantiallyfixedly located in relation to the second pipeencircling member, so as to be axially movable therewith, and engageable with an abutment surface which is substantiallyfixedly located in relation to the first pipe-encircling member, said abutment surface and the sealing member being so shaped that the sealing member is compressed on to the pipe by relative axial movement of said abutment surface and the second pipe-encircling membertowards one another.
5. A pipe coupling according to Claim wherein the abutment surface is provided on the first pipeencircling member itself.
6. A pipe coupling according to Claim 4, wherein the abutment surface is provided on an element separately formed from the pipe-encircling member but movable therewith.
7. Apipecoupling according to any of Claims 4 to 6, wherein the abutment surface is engageable with asurfaceontheannularsealing member, one or both of said surfaces being inclined with respect to the axis of the coupling in order to effect said compression ofthe sealing member upon said relative axial movement.
8. A pipe coupling according to Claim 7, wherein either or each ofsaidsurfacesisconicallytapered.
9. Apipecoupling according to Claim 8,wherein the abutment surface is an internal conical surface which is inclined at a greater angle to the axis ofthe coupling than an external conical surface on the an nularsealing member.
10. A pipe coupling according to Claim 8, wherein both conical surfaces are equally inclined so that they come into mating engagement.
11. A pipe coupling according to any of Claims 8 to 10, whereinthe extremity ofthe sealing member towardsthefirstpipe-encircling member comprises a conical tapered portion inclined at a smaller angle to the axis of the coupling than the main conical surface of the sealing member.
12. A pipe coupling according to any of Claims 8 to 10, wherein the circumferential extremity of the annular sealing membertowardsthefirst pipe en circling memberisformedwithaperipheraledge portion which engages said internal abutment surface.
13. A pipe coupling according to Claim 12, wherein said peripheral edge portion is convexly curved as viewed in section.
14. Apipecoupling according to Claim 13, wherein the inter-engagement between the curved peripheral edge and the encircling internal conical surface is arranged to deform the peripheral edge inwardly so that it not only grips the surface ofthe pipe but also bites into it.
15. A pipe coupling according to any of Claims 1 to6,whereintheannularsealing membercomprises a ring of hollow cross-section located in an annular recess in the first pipe-encircling member, so as to be axially movable therewith, means movable with the second pipe-encircling member being engageable with the sealing member to compress it upon relative axial movement ofthe pipe-encircling members towards one another, whereby the sealing member is deformed into sealing engagement with the pipe.
16. A pipe coupling according to Claim 15, wherein the sealing member is generallyC-shaped in cross-section, the mouth of the C-shape facing generally in an axial direction.
17. A pipe coupling according to any ofthe preceding claims wherein the means to compress the annular sealing member include a thrusttransmitting element which transmits axial thrustto the sealing member as the pipe-encircling members are moved axially towards one another.
18. A pipe coupling according to Claim 17, wherein the th rust transmitting element abuts the pipe-gripping collar, so that thrust is transmitted from the second pipe-encircling memberto the sealing memberviathe collar and the thrust-transmitting element.
19. A pipe coupling according to Claim 17 or Claim 18, wherein the thrust-transmitting element comprises an annularthrustwasher.
20. Apipe coupling according to Claim 19, wherein the annularthrustwasher is integral with theannularsealing member.
21. A pipe coupling according to Claim 19 or Claim 20, wherein the annularthrustwasher has a peripheral resilient flange for engagement within the second pipe-encircling memberto retain the collar, and the sealing member in the casewhere it is integral with the thrust washer, within the second pipeencircling member.
22. A pipe coupling according to any of the pre- ceding claims, wherein resilient means are provided to oppose axial movement of the pipe-gripping collartowardsthefirst pipe-encircling member,the resilient means being so located that, as the aforesaid axial movement is effected, some compression ofthe resilient means occurs before the annular sealing member is compressed between the first pipeencircling member and the pipe to form a seal.
22. A pipe coupling according to Claim 21, wherein the resilient means are disposed between a partmovablewiththeannularsealing member and a partofthefirstpipe-encircling member,orapart movable therewith.
23. A pipe coupling according to Claim 22, and in which a thrust-transmitting element is provided, wherein the resilient means are disposed between the thrust-transmitting element and the first pipeencircling member or part movable therewith.
24. A pipe coupling according to Claim 23, and in which the thrust-transmitting element is an annular thrust washer having a peripheral resilient flange for engagement within the second pipe-encircling member, wherein the resilient means comprise a portion of said resilient flange which extends between one face of thethrustwasher and an opposed face of the first pipe-encircling member or part movable therewith.
25. A pipe coupling according to Claim 22, wherein the resilient means are disposed between the pipe-gripping collar and the annular sealing member or a part movable therewith.
26. A pipe coupling according to any of Claims 22 to 25, wherein the resilient means comprise an annular element of rubber or other resilient material.
27. A pipe coupling according to Claim 26, and in which a resilient ring is provided in addition to the annularsealing member, the sealing ring itself may be so located asto constitute said resilient means.
28. A pipe coupling according to any ofthe preceding claims, wherein a slip ring is located within a bore ofthe second member against an internal should thereof and having an internal frusto-conical surface which co-acts with the external frustoconical surface of the pipe-gripping collar.
29. A pipe coupling according to anyofthe pre- ceding claims, wherein the pipe-gripping collar is longitudinally split and has a circumferential groove in the external frusto-conical surface thereof.
GB08628509A 1985-11-30 1986-11-28 Improvements in or relating to pipe couplings Withdrawn GB2184186A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB858529582A GB8529582D0 (en) 1985-11-30 1985-11-30 Pipe couplings
GB868607541A GB8607541D0 (en) 1986-03-26 1986-03-26 Pipe couplings

Publications (2)

Publication Number Publication Date
GB8628509D0 GB8628509D0 (en) 1987-01-07
GB2184186A true GB2184186A (en) 1987-06-17

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB08628509A Withdrawn GB2184186A (en) 1985-11-30 1986-11-28 Improvements in or relating to pipe couplings

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Country Link
GB (1) GB2184186A (en)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2197410A (en) * 1986-10-11 1988-05-18 Samuel Booth & Company Limited Pipe coupling
GB2205912A (en) * 1985-11-25 1988-12-21 Nat Coupling Co Inc Sealing ring
GB2209373A (en) * 1987-09-02 1989-05-10 Waelzlager Normteile Veb Pipe coupling
GB2210123A (en) * 1987-09-24 1989-06-01 Philmac Pty Ltd Pipe fitting assembly
US4854615A (en) * 1985-11-25 1989-08-08 National Coupling Company, Inc. Metal sealed joint for large diameter rocket motor casings
GB2264543A (en) * 1992-02-19 1993-09-01 Sergio Marius Julius Meli Compression fitting for soft pipes with split frustoconical gripper ring
DE4212771A1 (en) * 1992-04-16 1993-10-21 Viegener Ii Fa Franz Tube Fitting
GB2289735A (en) * 1994-05-26 1995-11-29 Polypipe Plc A set of parts for connecting a pipe to a fitting
DE19607784A1 (en) * 1995-03-29 1996-10-10 Manfred Dipl Ing Wilfer Screw clamp for joining sanitary or heater pipes, e.g. water pipes
WO2002086371A1 (en) * 2001-04-19 2002-10-31 Philmac Pty Ltd Pipe coupling
GB2385896A (en) * 2002-02-27 2003-09-03 Hydro Int Plc A coupling for a vortex valve
EP1939410A1 (en) * 2006-12-27 2008-07-02 Techspace aero Connection system
US7661729B2 (en) * 2006-06-30 2010-02-16 Anna Kui Gey Apparatus for connecting plastic-lined metallic pipes
US20120211209A1 (en) * 2011-02-21 2012-08-23 Samsung Electronics Co., Ltd. Structure for connecting refrigerant pipe and air conditioner having the same
EP2952797A1 (en) 2014-06-03 2015-12-09 Officine Meccaniche Industriali S.R.L. Connection joint for pipes to convey gas, compressed air and other fluids
US10330228B2 (en) 2015-08-31 2019-06-25 Ingersoll-Rand Company Pipe connection fitting

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB978343A (en) * 1962-04-17 1964-12-23 Hoke Mfg Company Inc Improvements in pipe couplings
GB1267007A (en) * 1970-07-10 1972-03-15
GB1383582A (en) * 1971-04-15 1974-02-12 Crawford Fitting Co Tube fittings
GB2054078A (en) * 1979-07-06 1981-02-11 Legris France Sa Pipe fittings in particular for high pressure fluid pipes
GB1602356A (en) * 1978-05-19 1981-11-11 Lucas Industries Ltd Pipe coupling
GB2102903A (en) * 1981-07-23 1983-02-09 Tungum Hydraulics Ltd Pipe coupling with tapered gripping collar

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB978343A (en) * 1962-04-17 1964-12-23 Hoke Mfg Company Inc Improvements in pipe couplings
GB1267007A (en) * 1970-07-10 1972-03-15
GB1383582A (en) * 1971-04-15 1974-02-12 Crawford Fitting Co Tube fittings
GB1602356A (en) * 1978-05-19 1981-11-11 Lucas Industries Ltd Pipe coupling
GB2054078A (en) * 1979-07-06 1981-02-11 Legris France Sa Pipe fittings in particular for high pressure fluid pipes
GB2102903A (en) * 1981-07-23 1983-02-09 Tungum Hydraulics Ltd Pipe coupling with tapered gripping collar

Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2205912B (en) * 1985-11-25 1990-02-07 Nat Coupling Co Inc Metal seal for an undersea hydraulic coupling
GB2205912A (en) * 1985-11-25 1988-12-21 Nat Coupling Co Inc Sealing ring
GB2190449B (en) * 1985-11-25 1989-08-02 Nat Coupling Co Inc An undersea hydraulic coupling and metal seal
US4854615A (en) * 1985-11-25 1989-08-08 National Coupling Company, Inc. Metal sealed joint for large diameter rocket motor casings
GB2197410A (en) * 1986-10-11 1988-05-18 Samuel Booth & Company Limited Pipe coupling
GB2209373A (en) * 1987-09-02 1989-05-10 Waelzlager Normteile Veb Pipe coupling
GB2210123A (en) * 1987-09-24 1989-06-01 Philmac Pty Ltd Pipe fitting assembly
GB2210123B (en) * 1987-09-24 1991-09-04 Philmac Pty Ltd Pipe fitting assembly
GB2264543A (en) * 1992-02-19 1993-09-01 Sergio Marius Julius Meli Compression fitting for soft pipes with split frustoconical gripper ring
GB2264543B (en) * 1992-02-19 1994-11-16 Sergio Marius Julius Meli Pipe fittings
DE4212771A1 (en) * 1992-04-16 1993-10-21 Viegener Ii Fa Franz Tube Fitting
GB2289735A (en) * 1994-05-26 1995-11-29 Polypipe Plc A set of parts for connecting a pipe to a fitting
GB2289735B (en) * 1994-05-26 1998-05-13 Polypipe Plc A set of parts for connecting a pipe to a fitting
DE19607784A1 (en) * 1995-03-29 1996-10-10 Manfred Dipl Ing Wilfer Screw clamp for joining sanitary or heater pipes, e.g. water pipes
DE19607784B4 (en) * 1995-03-29 2006-08-24 Simplex Wilfer Gmbh & Co. Compression fittings
WO2002086371A1 (en) * 2001-04-19 2002-10-31 Philmac Pty Ltd Pipe coupling
US6974162B2 (en) 2001-04-19 2005-12-13 David Chelchowski Pipe coupling
GB2385896A (en) * 2002-02-27 2003-09-03 Hydro Int Plc A coupling for a vortex valve
GB2385896B (en) * 2002-02-27 2005-06-08 Hydro Int Plc A coupling arrangement including an expandable ring
US7661729B2 (en) * 2006-06-30 2010-02-16 Anna Kui Gey Apparatus for connecting plastic-lined metallic pipes
EP1939410A1 (en) * 2006-12-27 2008-07-02 Techspace aero Connection system
US8157519B2 (en) 2006-12-27 2012-04-17 Techspace Aero Connecting system
US20120211209A1 (en) * 2011-02-21 2012-08-23 Samsung Electronics Co., Ltd. Structure for connecting refrigerant pipe and air conditioner having the same
US8925176B2 (en) * 2011-02-21 2015-01-06 Samsung Electronics Co., Ltd. Structure for connecting refrigerant pipe and air conditioner having the same
EP2952797A1 (en) 2014-06-03 2015-12-09 Officine Meccaniche Industriali S.R.L. Connection joint for pipes to convey gas, compressed air and other fluids
US9964242B2 (en) 2014-06-03 2018-05-08 Ingersoll-Rand Company Connection joint for pipes to convey gas, compressed air and other fluids
US10330228B2 (en) 2015-08-31 2019-06-25 Ingersoll-Rand Company Pipe connection fitting

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