Guide plate

A guide plate for a lug type closure arrangement is provided with a stepped profile to aid a user move the head of the closure arrangement relative to the hub from a locked to an unlocked position. A marker pin is provided to align with the guide plate at various stages in the unlocking sequence. The relative positions of the marker pin and the guide plate indicate to the user the relative positions of the lugs on the head and the lugs on the hub.

FIELD OF THE INVENTION

The present invention relates to a guide plate for a closure arrangement. More particularly the present invention relates to a guide plate for a lug type closure arrangement and a method of aiding a user open and close such a closure arrangement.

BACKGROUND OF THE INVENTION

Pipelines and pressure vessels that generally operate under high pressure are very common in industry. Such pipelines and pressure vessels are used to transport or store a large variety of pressurised gasses and fluids. Closure arrangements are commonly used to provide quick access to the interior of such fluid or gas handling systems. Before accessing these systems via a closure arrangement, it is generally known to depressurize the system by means of a main bleed valve.

Closure arrangements often comprise a flange formed around an opening at the end of a hub-shaped extension that extends from some part, such as a pipe, of the fluid or gas handling system. A covering or closing element, which forms a cap, referred for the purposes of this document at as a “head”, is securely attached over the flanged opening to provide a fluid-tight and pressure-tight seal when the closure arrangement is closed. The head is removable to provide access to the interior of the pressurized system via the opening in the flange of the hub.

The head can be secured onto the flanged opening of the hub by a variety of different ways. One way is simply to provide a series of corresponding bolt holes through the head and around the circumference of the flange so that individual bolts may be inserted through the corresponding holes and tightened. A gasket is provided between the head and the flange, and tightening of the bolts causes the circumference of the head to be pressed against the flange. Fully tightening all the bolts provides sufficient closing pressure to provide a seal at the gasket that is sufficient to prevent the escape of the pressurized fluid or gas. However, a disadvantage of such bolt type closures is the installation and removal of the individual bolts can be time consuming. This is particularly the case when there are a large number of bolts to install or remove.

Another common type of closure is often referred to as a screw type closure. In such closure arrangements the flange is provided with a threaded outer surface, and the head is provided with a corresponding threaded inner surface. To seal the closure arrangement, the head is screwed onto the flange. However, a disadvantage of screw type closures is that the head may be required to be rotated around several rotations in order to be screwed onto the flange. For large closure arrangements, the head can be very heavy, and therefore it can be very difficult for a user to screw the head onto or off the flange.

Another type of closure is a lug type closure. An example of a lug type closure arrangement10is shown in FIG.1. This prior art closure is an early closure from GD Engineering.

The closure arrangement10comprises a hub12that is adapted to fit over a part, such as a pipe, of a fluid handling system. At the outer end of the hub12is a radially outwardly extending flange14. The flange14is provided with four lugs16that project outwardly from the flange14. The closure arrangement10also comprises a head20that is adapted to fit over the flange14of the hub12. The head comprises four inwardly projecting lugs22that correspond in size to the lugs16on the flange14.

In addition the closure arrangement10comprises a pressure release device40. The pressure release device40comprises a pressure release screw42that is rotatably connected to a deflector plate44. Attached to the deflector plate44is a locking pin46projecting from the deflector plate44in a direction parallel to the pressure release screw42.

The pressure release screw42is adapted to be received in a vent bore25extending from the outside of the head20inside the closure arrangement10. The locking pin46is adapted to be received in a locking bore29on the head20and a corresponding locking bore19on one of the lugs16on the flange14. The locking bore29extends through the head20and is aligned with the locking bore on one of the lugs16on the flange14when the closure arrangement10is in a closed position. The locking bore19on the flange14extends partially into the lug16.

To close the closure arrangement10the head20is oriented such that the lugs22on the head are at different angular positions to the lugs16on the flange. The head20is then pushed axially onto the flange14without the lugs22on the head20interfering with the lugs16on the flange14. Once the lugs22of the head20have been pushed past the lugs16of the flange14in the inner axial direction, the head20is rotated around a predetermined angle such that the lugs22are located behind the lugs16of the flange14. The lugs16of the flange14will then prevent axial moment of the head20in the outer direction, and the head20is thus held pressure-tight against the flange14.

Once the head20is in the closed position the pressure release40device is used to lock the closure arrangement10. To lock the closure arrangement10the user installs the pressure release device40onto the closure arrangement10. The user aligns the pressure release screw42with the vent bore25and the locking pin with the locking bore29on the head20. The user then tightens the pressure release screw42, which will urge the entire pressure release40device towards the head20. The pressure release screw42will seal the vent bore25, and provide a pressure tight seal. Furthermore the pin46will extend through the bore29on the head and into the bore19on the flange. The pin46will thus prevent rotation of the head20and opening of closure arrangement10until the pressure warning release screw42is released. Thus, the closure arrangement10will be in a locked state and the closure arrangement10cannot be opened until the pressure release screw42is unscrewed.

Lug type closure arrangements10of this type are preferable to screw type closure arrangements as the head can be moved from an open position to a closed position by rotating the head through a partial turn, e.g. 45°. For large closure arrangements, this can greatly increase the ease of opening and closing of the closure arrangement.

When in a closed position, the lugs provided on the head20and the flange14are disposed opposite each other and internal the closure arrangement10. They are therefore are obscured from the view of the user by the head20and the flange14, and it may be difficult for the user to appreciate how far the head20needs to be rotated before is can be moved axially off the flange14.

In order to open the head20, it is first necessary to unlock the closure arrangement10. Unscrewing the pressure release screw42so that the pin46clears at least the bore19on the flange, release the seal between the pressure release screw42and the vent bore25. If there is considerable internal pressure the user will be warned in the form of noticeable escaping gas or fluid. Opening the vent bore25will vent any fluids or gas that are under residual pressure inside the system near the closure arrangement10. The user can then remove the pressure release device40from the head20, permitting the rotation of the head20relative to the hub12. The vent bore25is not used for venting the pressure in the system, but merely as a safety device to warn of the presence of pressure in the system. It can also vent any small residual pressure to ensure pressure equalization across the closure before opening.

On opening the closure arrangement10, and once the pressure release device40has been removed, the head20is rotated relative to the hub12to a position at which the lugs22provided on the head20are not aligned with the lugs16provided on the flange14. As both sets of lugs are not visible to the user, it can be difficult to align the lugs in such a way, and the user can therefore struggle to align the lugs and remove the head20from the flange14.

FIG. 2shows another example of a lug type closure arrangement50by GD Engineering. The closure arrangement60is substantially similar to the closure arrangement10shown inFIG. 1except that it is provided with a stepped lug24adjacent each lug22of the head20, and also that a stop pin18provided on the flange14.

The closure arrangement60shown inFIG. 2is closed in the same way as the closure arrangement10of FIG.1. The head20is first pushed axially onto the flange14, and then rotated relative to the flange14such that the lugs22on the head20are located behind the lugs16on the flange14. The pressure release device40is then installed to lock the closure arrangement60.

However, the closure arrangement60is opened in a different way to the closure arrangement10shown in FIG.1. To open the closure arrangement60the pressure release device40is first removed, and then the head20is rotated relative to the flange14until one of the lugs22contacts the stop pin18. The stop pin18is located such that when the lugs22are rotated to contact it, the lugs22are no longer located behind a corresponding lug16, but each of the stepped lugs24is still located behind a corresponding lug16.

If there is sufficient residual pressure in the fluid handling system the head20will then be urged axially in an outward direction until the stepped lugs24contact the lugs16. The head20will therefore have been partially pushed off the flange14by the pressure of the system. The residual pressure can then therefore be safely vented without the pressure causing the head20to fly off the flange14. If the pressure inside the system is not sufficient to urge the head20outwards such that the stepped lugs24contact the lugs16on the flange14, the head20can be moved manually sufficiently outwards.

The user then rotates the head20until the lugs24are no longer located behind the lugs16. At this point the head20can be moved off the flange14without any of the lugs interfering with each other.

FIGS. 1 and 2show closure arrangements that only comprise a head20and a hub12. However, as discussed closure arrangements for fluid handling systems can be very large, and therefore the heads20of such closure arrangements can be extremely heavy. For large closure arrangements, mechanical actuating means may be required both to rotate the head20relative to the flange14and remove it from the hub12. The lugs on both the head20and the hub12, as well as the stop pin18are not visible to the user from the outside of the closure arrangement10when it is in a closed position. Therefore, it is possible the user will forcibly rotate the head20too far relative to the hub12, causing a lug22to forcibly impinge on the stop pin18, potentially damaging both the stop pin18and the lug22.

Similarly, if the lugs22,24on the head20are not properly aligned relative to the lugs16on the flange14before axial force is applied to the head20to urge it from the flange14, the lugs22,24will be forced against the lugs16on the flange14. Applying a large amount of force to both sets of the lugs in this way, particularly if powerful mechanical actuating means are used, could lead to deformation and damage of the lugs.

Lug type closure arrangements can also comprise support means such as davit arms to support the head20when it is removed from the hub12. Other configurations of lug type arrangements are possible, but lug type closures all relying on a sequence of rotational and translation movements of the head20relative to the hub12, and are all associated with the problems of the sort encountered with the arrangements ofFIGS. 1 and 2.

It is an object of the invention to mitigate the above problems associated with lug type closure arrangements.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a lug type closure arrangement comprising a hub, a head adapted to be disengageable from said hub in a locked position to an unlocked position by a sequence of relative rotational and translational movements, and a guide device to aid a user perform said sequence of relative rotational and translation movements.

In a one embodiment said guide device comprises a guide plate attached to said hub or said head. The guide plate can comprise a stepped profile.

In an embodiment said guide plate is attached to said hub and associated with a marker on said head, wherein said marker is adapted to align with predetermined positions of said guide plate at predetermined stages in said sequence of relative rotational and translational movements. The marker can comprise a radially outwardly projecting pin.

In an embodiment said guide plate is attached to said head and is associated with a marker on said hub, wherein said marker is adapted to align with predetermined positions of said guide plate at predetermined stages in said sequence of relative rotational and translational movements. The marker can comprise a radially outwardly projecting pin.

According to a second aspect of the invention there is provided a method of opening a closure arrangement, the closure arrangement comprising a hub and a head adapted to be rotatable relative to the hub, the method comprising providing a guide device to guide a user to perform a sequence of relative rotational and translation movements in order move the head from a locked to an unlocked position.

In one embodiment said guide device is provided as a guide plate attached to said hub or sad head. The method can further comprise providing said guide plate with a stepped profile.

In one embodiment said guide plate is provided on said hub, the method further comprising providing a marker on said head, and aligning said marker with predetermined positions of said guide plate at predetermined stages in said sequence of relative rotational and translational movements. The method can comprise using a radially outwardly projecting pin as said marker.

In an embodiment said guide plate is provided on said head, the method further comprising providing a marker on said hub, and aligning said marker with predetermined positions of said guide plate at predetermined stages in said sequence of relative rotational and translational movements. The method can comprise using a radially outwardly projecting pin as said marker.

According to a third aspect of the invention there is provided a closure arrangement comprising: a hub comprising at least one first type of lug projecting from the hub; a head adapted to be rotatable relative to said hub, the said head comprising at least one stepped second type of lug and at least one third type of lug projecting from said head, wherein the or each stepped second type of lug is situated adjacent a single third type of lug, wherein the or each stepped second type of lug is arranged to provide a stepped profile relative to the adjacent third type of lug, wherein said head is arranged to be in a first position when the or each stepped second type of lug and the or each third type of lug are arranged so as to not interfere with a corresponding first type of lug, wherein said head is arranged to be in a second position when the or each stepped second type of lug at least partially overlaps in an axially direction with a corresponding first type of lug, wherein said head is arranged to be in a third position when the or each stepped second type of lug contacts a corresponding first type of lug, and wherein said head is arranged to be in a fourth position when the or each stepped second type of lug and the or each third type of lug are arranged so as to at least partially overlap in an axial direction with a corresponding first type of lug; a marker; and a guide plate having a stepped profile, wherein said marker and said guide plate are adapted to aid a user perform a sequence of relative rotational and translation movements that is required to move said head from the fourth position to the first position via the third and second positions.

In a preferred embodiment said guide plate comprises a first portion, a stepped second portion, and a third portion. Preferably said marker is adapted to contact said first portion of said guide plate when the closure arrangement is in the third position, wherein said marker is adapted to be located just above said stepped second portion of said guide plate when the closure arrangement is in the second position, and wherein said marker is adapted to contact said second portion of said guide plate when the closure arrangement is in the first position

In a preferred embodiment said guide plate is attached to said hub. Preferably said marker comprises a radially outwardly projecting pin attached to said head.

In a preferred embodiment said guide plate is attached to said head. Preferably said marker comprises a radially outwardly projecting pin attached to said hub.

According to a fourth aspect of the invention there is provided a method of opening a closure arrangement according to the third aspect of the invention, comprising; rotating said head relative to said hub until there is contact between said marker and a first portion of said guide plate; moving said head in an outer axial direction relative to said hub until said marker is located just away from a second stepped portion of said guide plate; rotating said head relative to said hub until there is contact between said marker and a third portion of said guide plate; and moving said head in the outer axial direction relative to said hub until said head is separated from said hub.

According to a fifth aspect of the invention there is provided a lug type closure arrangement comprising a hub, a head adapted to be disengageable from said hub in a locked position to an unlocked position by a sequence of relative rotational and translational movements, and a guide means for aiding a user perform said sequence of relative rotational and translation movements.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 3shows a closure arrangement100of a first embodiment of the invention comprising a head20, a hub12, a pressure release device40, an actuating means for lifting the head20vertically, and a means for supporting the head20when it is not on the hub12. The closure arrangement100further comprises a marker pin30and a guide plate50.

The head20and hub12are generally similar to those illustrated in FIG.2. The head20comprises a set of four lugs22and a set of four stepped lugs24, and the hub12comprises a flange14with a set of four lugs16. The head also comprises two diametrically opposite handles27, which aid the user rotate the head20relative to the hub12. The pressure release device40comprises a pressure release screw42that is rotatably connected to a deflector plate44. Attached to the deflector plate44is a locking pin46projecting from the deflector plate44in a direction parallel to the pressure release screw42.

The support means comprises a hinged davit arm140that is rotatably connected at its bottom end to a hinged bore106. The hinged bore106is attached to a connecting portion28of the hub12. The davit arm140extends in an upward direction from the bore106and is connected at its upper end to a screw thread102. The screw thread102is connected to the head20and to a rotatable handle104. Rotating the handle104lifts or lowers the head20on the screw thread102in a vertical direction, and thus the user is not required to lift the head20manually. When the head20is free from the flange14, the head20can be moved to one side of the hub12by rotating the davit arm140about the hinge bore106. This allows the user to access to the inside of the fluid handling system to which the hub12is attached.

The marker pin30is attached to the head20, and comprises a radially outwardly projecting pin. The guide plate50comprises a base portion51having two screw holes52, and is attached to the connecting portion28of the hub12by two screws26threaded through the screw holes52. Extending from the base portion51of the guide plate50is a first pin contact portion53. The guide plate50further comprises a stepped portion54and a second pin contact portion55. The portions53,54and55are arranged to provide the guide plate50with a stepped profile.

As discussed, the head20and hub12of the closure arrangement100shown inFIG. 3have substantially the same internal configuration of lugs as the closure arrangement60shown in FIG.2. Therefore, after venting the pressure by removing the pressure release device40, the same series of relative rotational and translational movements of the head20will be needed in order to open the closure arrangement100as that described above in relation to the closure arrangement60shown in FIG.2. The rotational movements of the head20relative to the hub12are facilitated the handles27comprised on the head20, and the translational movements of the head20are facilitated by the handle140.

The marker pin30and guide plate50are positioned in order to act as a visual guide to help the user remove the head20from flange14without damaging either the lugs or the stop pin18.FIG. 4schematically illustrates the positions of the marker pin30relative to the guide plate50at various stages as the closure arrangement100is opened.

At stage S1the closure arrangement100is in the closed position, and the marker pin30is located away from the guide plate50. In the closed position, the lugs22,24on the head20are aligned to interfere with a corresponding lug16on the hub12.

To open the closure arrangement100, the user first removes the pressure release device40from the head to unlock the closure arrangement100. Then the user grips the handles27and rotates the head20in the direction that brings the marker pin30closer to the guide plate50.

At stage S2, the marker pin30contacts the first pin contact portion53of the guide plate50. At this point the lugs22on the head20have been are rotated so that they are no longer aligned to interfere with a corresponding lug16on the hub12, but each of the stepped lugs24is still located behind a corresponding lug16. At this stage a lug22will have contacted the stop pin18on the flange14.

In this embodiment, the handle104is then rotated to lift the head20vertically until the marker pin30is located just above the stepped portion54of the guide plate50(stage S3). At this stage, the lugs24will contact the lugs16, preventing further axial movement of the head20in an outer (vertical) direction. Any residual internal pressure of the fluid handling system can then therefore be safely vented at this stage.

The user then rotates the head20until the marker pin30reaches the second pin contact portion55of the guide plate (stage S4). At this point, the stepped lugs24of the head are no longer located behind the lugs16of the hub12. The user can then rotate the handle104in order to raise the head20off the flange14(stage S5). The head20will then be completely free of the flange14and can be rotated to one side of the hub12about the hinge bore106.

The guide plate50helps prevent the user from rotating the head20too far such that a lug22damages the stop pin18, as the position of the marker pin30relative to the guide plate50at stage S2indicate to the user that a sufficient rotation of the head20has taken place.

The guide plate50also helps prevent the user from rotating the handle104, and thus urging the head20vertically away from the flange14, when the lugs22,24on the head20are not properly aligned with the lugs16on the flange14. The guide plate50therefore helps prevents the user from damaging the lugs by forcibly urging them against each other by the action of the actuating means.

The vertical position of the guide plate50is adjusted by the use of the screw holes52, which allow the guide plate50to be fitted at a range of vertical positions on the connecting portion28. The relative positions of the marker pin30and guide plate50are adjusted to suit the dimensions of the head20and the hub12, as well as the number and configuration of the lugs on both the head20and the flange14

FIG. 5is a view of a horizontally orientated closure arrangement200of a second embodiment of the invention. The closure arrangement200comprises a head20, a hub12, a pressure release device40, and support means for supporting the head20when it is not on the hub12. The closure arrangement further comprises a marker pin30and a guide plate50.

The head20and hub12are generally similar to those illustrated in FIG.2. The head20comprises a set of four lugs22and a set of four stepped lugs24, and the hub12comprises a flange14with a set of four lugs16. The pressure release device40comprises a pressure release screw42that is rotatably connected to a deflector plate44. Attached to the deflector plate44is a locking pin46projecting from the deflector plate44in a direction parallel to the pressure release screw42.

The support means comprises a hinged davit arm240that is connected to at one end to a fitting212that is journaled to a shaft206. The shaft206is connected to the head20, and the fitting212is kept in place on the shaft206by a stop208. Thus the head20can rotate around the shaft206relative to the davit arm240.

The hinged davit arm240is mounted in a housing216. The housing216is connected to a connecting portion28by a connecting shaft205. The housing216comprises rollers202and204that allow the davit arm240to move relative to the housing216in an axial direction and to rotate about its longitudinal axis relative to the housing216. Thus the head20, supported by the davit arm240, can move axially towards and away from the hub12and can be rotated about the longitudinal axis of the davit arm240away to one side of the hub12.

A stop214is provided at the free end of the davit aim240to limit the longitudinal movement of the davit arm240and to prevent it from leaving the housing216.

The marker pin30and guide plate50have substantially the same shape those of the closure arrangement100shown in FIG.3. In order to open the closure arrangement200, the same series of rotational and translational movements of the head20relative to the hub12will be needed as that described above in relation to FIG.4.

In all previously described embodiments, the guide plate50is connected to the hub12and the marker pin30is connected to the head20.FIG. 6is a view of a horizontally orientated closure arrangement210employing an embodiment of the invention, in which the guide plate50and marker pin30are configured differently. The head20, hub12and supporting means of the closure arrangement210are substantially similar to those of the closure arrangement shown in FIG.5.

In this embodiment, the marker pin30comprises a pin projecting radially outwardly from the connecting portion28attached to the hub12. The guide plate50comprises a base portion51having a screw hole52, and is attached to the head20by a screw26threaded through the screw holes52. Extending from the base portion51of the guide plate50is a first pin contact portion53. The guide plate50further comprises a stepped portion54and a second pin contact portion55. The portions53,54and55are arranged to provide the guide plate50with a stepped profile. In this embodiment, instead of the marker pin30moving relative to a stationary guide plate50as described in relation to previous embodiments, the guide plate50moves relative to the marker pin30.

FIG. 7schematically illustrates the positions of the marker pin30relative to the guide plate50at various stages as the horizontal closure arrangement210is opened.

At stage S11the closure arrangement210is in the closed position, and the guide plate50is located away from the marker pin30. In the closed position, the lugs22,24on the head20are aligned to interfere with a corresponding lug16on the hub12.

To open the closure arrangement210, the user first removes the pressure release device40from the head to unlock the closure arrangement210. Then the user grips the handles27and rotates the head20in the direction that brings the guide plate50closer to the marker pin30.

At stage S12, the first pin contact portion53of the guide plate50contacts the marker pin30. At this point the lugs22on the head20have been are rotated so that they are no longer aligned to interfere with a corresponding lug16on the hub12, but each of the stepped lugs24is still located behind a corresponding lug16. At this stage a lug22will have contacted the stop pin18on the flange14.

The head20, supported by the davit arm240, is then moved off the hub12in an axially direction until the marker pin30is located just above the stepped portion54of the guide plate50(stage S13). At this stage, the lugs24will contact the lugs16, preventing further axial movement of the head20in an outer (horizontal) direction. The internal pressure of the fluid handling system can then therefore be safely vented at this stage.

The user then rotates the head20until the second pin contact portion55of the guide plate reaches the marker pin30(stage S14). At this point, the stepped lugs24of the head are no longer located behind the lugs16of the hub. The user can then move the head20off the flange14(stage S15). The head20will then be completely free of the flange14and can be rotated away from the hub12about the longitudinal axis of the davit arm240.

The horizontal position of the guide plate50is adjusted by the use of the screw hole52, Which allows the guide plate50to be fitted at a range of horizontal positions on the head20. The relative positions of the marker pin30and guide plate50are adjusted to suit the dimensions of the head20and the number and configuration of the lugs on both the head20and the flange14.

The combination of the guide plate50and the marker pin30in all the described embodiments act as a visual aid to the user and indicate the positions of the lugs22,24on the head20relative to the lugs16on the flange14. In the absence of the guide plate50, the user is unaware of the relative positions of the lugs.

The described embodiments show one stepped shape of the guide plate50. However, any type or shape of guide device can be used to act as a guide. For example, many other shapes of the guide plate50are possible, and different internal lug configurations of the head20and flange14would require the guide plate50to be shaped differently.

For example, a guide plate suitable for the closure arrangement10illustrated inFIG. 1could simply consist of a rectangular plate. This is because the closure arrangement illustrated inFIG. 1does not comprise stepped lugs on the head20, and is thus opened it a two, rather than four, stage process. In such an arrangement the head20would be simply rotated until it reached a marker pin or similar feature reached the guide plate, and then lifted off the flange14.

The guide device need not be a plate or planar, and could be a curved arm or rod to act as a guide with a corresponding curved marker. The guide device can comprise a single element or any number of elements to perform the guide function. The guide device can be arranged on the head, the flange, or partially on both.

In all the described embodiments, a dedicated marker pin30is not required, and another feature of the head20could be used to align with the guide plate50.

Many further variations and modifications will suggest themselves to those versed in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only, and which are not intended to limit the scope of the invention, that being determined by the appended claims.