GB2342137A

GB2342137A - Closure

Info

Publication number: GB2342137A
Application number: GB9821408A
Authority: GB
Inventors: Brian Smith
Original assignee: Plenty Ltd
Current assignee: Plenty Ltd
Priority date: 1998-10-01
Filing date: 1998-10-01
Publication date: 2000-04-05
Also published as: GB9821408D0; GB2342139A; GB2342139B; GB9922728D0

Abstract

The closure for a pipe (1) or pressure vessel comprises a door (3) and locking members (23), the door surrounding neck (5) of the pipe or pressure vessel and comprising a base (10) and a peripheral skirt (11), the door and the outer wall of the neck having respective facing recesses (6,12). The locking members (23) comprise blocks movable by cylinders (20) between a first position in the recesses (12) of the inner wall of the skirt (11) and a second position partly in that recess (12) and partly in the recess (6) of the neck (5).

Description

2342137 CLOSURE This invention relates to closures, especially for pipes

and pressure vessels.

In U.K. Patent Specification No. 1,508,998 there is disclosed a closure member for a pipe or pressure vessel comprising a door adapted to fit an aperture in the body of the pipe or the pressure vessel, a plurality of blocks slidably mounted adjacent the periphery of the door and movable from a position at least substantially wholly within the said periphery to a position in which a part of each block protrudes beyond the periphery for engagement with the said body, the said parts of the blocks together forming a protrusion extending substantially entirely around the periphery of the door, and means for moving the blocks from the withdrawn to the protruding position.

The closure member of that Specification was particularly designed for relatively large apertures in pipes and pressure vessels which are subject to high pressures. The complexity of the construction of the closure member, however, prevents a similar design firom being readily used in closures for small apertures. A closure for small apertures is described in U.K. Patent Specification 1,594,935, wherein the closure comprises a door adapted to fit into an aperture in the pipe or pressure vessel, an arcuate locking member disposed around the periphery of the door for locking the door to the pipe or pressure vessel, the ends of the locking member being movable towards and away from each other to cause radial contraction and expansion of the locking engagement with the pipe or pressure vessel, and a hinge assembly by means of which the door may be mounted on the pipe or pressure vessel, said hinge assembly comprising a main bracket adapted to be secured to the pipe or pressure vessel, a secondary bracket pivotally mounted on the main bracket and a support for the door mounted on the secondary bracket for movement about an axis parallel to the pivot axis of the secondary bracket.

In DE-C-1 023 742 there is described a closure which comprises a door adapted to fit into an aperture in a member to be closed, and an arcuate locking member disposed around the periphery of the door for locking the door to the said member, the ends of the locking member being movable towards and away from each other to cause 2 radial contraction and expansion of the locking member, whereby the locking member may be brought out of and into locking engagement with the said member, and wherein the arcuate locking member, when in locking engagement with the said member, is locked between surfaces of the said member and the door.

In accordance with EP-B-0 129 349, in a closure member of the above type the surfaces of the member and the door between which the locking member is located are at an acute angle relative to the plane of the door, and there is provided a segmental block which fits between the ends of the locking member when the locking member is expanded, the block being attached to a plate adapted, when the block is in position between the ends of the locking member, to overlie a bleed port in the door.

Nowadays a very large amount of fluid transportation is achieved by means of underwater pipelines, and it is clearly vital that such pipelines should be adequately closed and sealed. It is also of advantage for the closure to act as a protective cover when installed, and for it to be capable of quick release when required, and it is the object of the present invention to provide a closure which fulfils these requirements.

According to the invention a closure comprises (i) a door adapted to surround the neck of a member to be closed, the door comprising a base and a peripheral skirt, the inner wall of the skirt having at least one recess; (ii) the outer wall of the neck of the said member having at least one recess adapted, when the door is placed over the said neck, to face a corresponding recess in the inner wall of the skirt of the door; (iii) a locking member comprising a block positioned in the or each recess of the inner wall of the skirt of the door and movable between that (first) position and a second position in which it is partly in said recess and partly in said recess of the neck of the said member; and 3 (iv) means for moving the or each block from said first to said second position.

Pipelines, for conveying both gas and liquids, overland, underground and underwater, are generally cylindrical in form, and so in a preferred embodiment of the invention both the door and the neck of the pipeline are circular in section, each block is in the form of an arcuate segment and when the blocks are in the second position - i.e.

when the door is locked on to the neck of the pipe or other vessel - they together form an annular locking member.

The skirt of the door and the outer wall of the neck of the pipe or vessel being closed may have any number of facing recesses, each of which accomodates a locking block, but in a preferred embodiment each has a single recess, which extends circumferentially of the skirt and neck, respectively. The recesses may extend radially, but preferably they lie at an angle of between 15 and 25, suitably about 20, to the axis of the door and neck. In this way, when pressure is applied to the door from within the pipe or pressure vessel the inclined bearing surfaces transmit part of the axial forces to the radial direction, thus improving the engagement between the locking member and the pipe or pressure vessel being closed.

Movement of the locking blocks between the first portion, when they are accommodated in the recess or recesses in the skirt of the door, to the second position, when they are moved partially into the recess or recesses on the neck of the member being closed, is preferably achieved by means of one or more actuators mounted on the door. The actuators are preferably linked in order that they should operate in unison and suitably each actuator is a hydraulic or other fluid cylinder mounted on the door, the piston rod of which extends through the door and is attached at its distal end to a locking block. Alternatively the actuators may be manually- or electrically- operated.

The components of the closure of the invention, i.e. the door, neck and locking block or blocks, are suitably made of steel, although for special applications they may be of phosphor-bronze, stainless steel or cupro-nickel. They are thus heavy, and 4 suitably therefore the door is offered up to, and removed from, the pipeline neck by means of a lifting davit or the like. Alternatively the door is hingedly mounted on the pipe or pressure vessel, and in one form of hinged mounting a bracket is secured to the pipe or pressure vessel, a secondary bracket is pivotally mounted on the main bracket and a support for the door is pivotally mounted on the second bracket for movement about an axis parallel to the pivot axis of the secondary bracket. The pivotal axis of the door support is suitably spaced from the pivot axis of the secondary bracket by a distance equal to between 1/3 and 2/3 of the radius of the door, and most suitably by aproximately 1/2 of the radius of the door. Such a construction allows the closure to be withdrawn generally axially from the vessel neck before being pivoted to one side of the neck.

The invention is illustrated in the accompanying drawings, in which Figure 1 is a perspective view of a closure of the invention applied to one end of an oil or gas pipeline; Figure 2 is a sectional view of part of the closure, in the unlocked position; Figure 3 is a diagram showing the configuration of the locking member in the unlocked state; Figure 4 is a sectional view, similar to that of Figure 2 but of a slightly modified construction, showing the locking member in the locked position; and 25 Figure 5 is a diagram showing the configuration of the locking member in its locked position. Referring to the drawings, reference numeral 1 indicates a pipeline of 30 indeterminate length, closed at one end by a closure 2 comprising a door 3 and pipeline neck 4.

The neck 4 consists of a hub or collar 5 (see Figure 2) welded to the end of the pipe 1. The outer wall of the hub 5 is formed with an annular recess 6 comprising an abutment face 7, a semi-circular groove 8 and a flusto-conical seat 9.

Mounted on the hub 5 is a door 3 comprising a disc-like base 10 and a cylindrical depending skirt 11 about the periphery of the disc 10. The inner wall of the skirt 11 is formed with a circumferential recess 12 having a frusto- conical reaction face 13. The recesses 6 and 12 are formed at an angle (V) of about 20' to the axis of the pipe.

At spaced positions around the outside of the door 3 are mounted hydraulic cylinders 20, the rods 21 of which extend through apertures 22 in skirt 11 and are attached at their distal ends to arcuate locking segments 23. Six such segments are located in the recess 13, with gaps 24 therebetween. Sealing strips 25 are located in annular grooves 26 formed in the door 3. The Figure 2 embodiment shows the presence of a primary metal seal 27 located between the hub 5 and door 3, the embodiment of Figure 4 showing an elastomeric seal 28 set in an annular groove 29 in the underside of the top wall of the door 3. The seals 27 and 28 are primary seals; the seals 25 are secondary seals. Suitable elastomeric materials for the seals 25 and 28 are fluoroelastomers such as Viton and extruded PVC nitriles, e.g. those having a Shore hardness of 75'. Since the secondary seals 25 must seal against pressure in both directions, i.e. both from within the pipe and from outside, they are preferably of the double-lip type.

In operation, the door 3 is positioned to surround the hub 5, and the hydraulic cylinders 20 are then actuated to move the segments 23 from the position shown in Figure 2 to the position shown in Figure 4. In this position the segments 23 are partially within the recess 6 formed on the hub, and partially within the recess 12 formed on the skirt 11 of the door, with the inner face of each segment 23 in contact with the face 7 of the recess 6 and the sides of the segments locked between the faces 9 and 13.

In the position shown in Figure 4 the segments form a continuous annular locking member as shown in Figure 5. In the position of the segments 23 shown in Figure 4, the door 3 is securely locked to the hub 5, and thus securely and sealingly 6 closes the pipe 1. The door 3 may be quickly released from the pipe 1 by reversing the cylinders 20, and retracting the locking segments 23 into their Figure 2 position.

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Claims

1. A closure comprising (i) a door adapted to surround the neck of a member to be closed, the door comprising a base and a peripheral skirt, the inner wall of the skirt having at least one recess; (ii) the outer wall of the neck of the said member having at least one recess adapted, when the door is placed over the said neck, to face a corresponding recess in the inner wall of the skirt of the door; (iii) a locking member comprising a block positioned in the or each recess of the inner wall of the skirt of the door and movable between that (first) position and a second position in which it is partly in said recess and partly in said recess of the neck of the said member; and (iv) means for moving the or each block from said first to said second position.

2. A closure according to claim 1 wherein the door and neck are circular in section, each block is in the form of a segment, and when said blocks are in said second position they together form an annular locking member.

3. A closure according to claim 1 or claim 2 wherein each of said door and said neck has a single annular recess..

4. A closure according to any of claims 1 to 3 in which the or each recess is a radial recess.

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5. A closure according to any of claims 1 to 3 wherein each recess is formed at an angle of 15 to 25' to the axis of the door and neck.

6. A closure according to claim 5 wherein each recess is formed at an angle of 20' 5 to the axis of the door and neck.

7. A closure according to any of claims 1 to 6 wherein each block is associated with an actuator mounted on said door.

8. A closure according to claim 7, wherein said actuators are adapted to move in unison.

9. A closure according to claim 7 or claim 8 wherein each actuator is a hydraulic cylinder whose rod extends through the door and is attached to a said block. 15

10. A closure according to any of claims 1 to 9 wherein a seal is positioned between said door and said neck.