WO1992005376A1

WO1992005376A1 - Coupling device for sealingly interconnecting two pressure vessel portions axially

Info

Publication number: WO1992005376A1
Application number: PCT/SE1991/000632
Authority: WO
Inventors: Lars Göran TRUEDSSON; Sven Andersson; Bengt ANDRÉASON; Bertel Emmertz; Rolf HELLMÉN; Ulf Nilsson
Original assignee: Kockums AB
Current assignee: Saab Kockums AB
Priority date: 1990-09-24
Filing date: 1991-09-20
Publication date: 1992-04-02
Anticipated expiration: 1993-03-24
Also published as: AU8643391A; SE467064B; SE9003013L; SE9003013D0

Abstract

Coupling device for sealingly axially interconnecting two pressure vessel portions (1, 6) having a circular cross-section and annular coupling flanges (4, 5). On the surfaces facing away from each other the coupling flanges are provided with frusto-conical coupling surfaces for cooperation with corresponding coupling surfaces in two semicircular coupling ring halves (8, 9) gripping said coupling flanges (4, 5), said coupling ring halves by being tightened towards each other, via said coupling flanges sealingly locking both pressure vessel portions (1, 6) with respect to each other. The frusto-conical coupling surfaces (13) of said coupling flanges (4, 5) are directed obliquely upwards-outwards. Each coupling ring half (8, 9) is provided with an annular recessed groove (21), the limiting surfaces (22) facing each other having frusto-conical form with the same conicity as the coupling surfaces (13) of the coupling flanges (4, 5). One of the pressure vessel portions (6) is on the inside of adherent coupling flange (5) provided with a tubular, axially protruding coupling sleeve (15) sealing against the inner surface thereof. The protruding portion of the coupling sleeve (15) is provided externally with peripheral grooves (19) for a gasket (20) of the O-ring type. During interconnection of the pressure vessel portions the coupling sleeve (15) protrudes into the coupling flange (4) of the opposite pressure vessel portion and provides a seal against the inner surface thereof.

Description

TITLE OF INVENTION: COUPLING DEVICE FOR SEALINGLY

INTERCONNECTING TWO PRESSURE VESSEL PORTIONS AXIALLY

The present invention relates to a coupling de¬ vice for providing a sealing interconnection in the axial direction of two pressure vessel portions hav¬ ing a circular cross section, particularly for pres¬ sure vessels of great dimensions and intended for use at very high internal pressures above the atmospheric.

Pressure vessels of this kind are particularly used in marine industry for testing constructions and components for submarine use which must be keep- able of withstanding very high pressures. Pressure testing mini-vessels for submarine use, scale models of submarines, components for submarine plants etc may be mentioned as exemples.

Large pressure vessels for this purpose are previously known and usually consist of a cylindri¬ cal container with a spherical gable and at the op¬ posite end provided with a removably attached spherical gable, which by means of a coupling device may be attatched at the open end of the container for closing said end. At the open end the cylindri¬ cal container is provided with a strong annular coupling flange for cooperation with a corresponding coupling flange on the spherical gable intended for closing the pressure vessel. In previously known pressure vessels of this kind the interconnection has been effected by means of strong bolts spaced along the annular flanges. Sealing is effected by means of annular gaskets disposed between the flanges which by the bolts being pressed against each other. Since the internal pressure to which vessels of the kind mentioned may be subjected are very high, e.g. of the magnitude of 160 bar or more, and the dimensions of the pressure vessels may be very large, the dimensions of the coupling bolts needed for the interconnection may be very great. The result is that the working operations needed for opening and for closing the pressure vessel are com¬ plicated and time consuming. As an exemple it may be mentioned that the time required for closing re¬ spectively opening a large pressure vessel of the kind mentioned may amount to one or two days.

In order to avoid in connection with pressure vessels of the kind mentioned the disadvantages in¬ herent in axial interconnections based on bolt con¬ nections a coupling arrangement has also been devel¬ oped in which the coupling flanges are pressed against each other by means of semicircular coupling rings gripping both coupling flanges, said coupling rings during radial clamping towards each other exert a pressure force on both coupling flanges in a direction towards each other. Both coupling flanges have a radially outwardly tapering wedgelike cross section for cooperation with a corresponding groove in both of the semicircular coupling rings. When the coupling ring halves are pressed towards each other, the coupling flanges are pressed against each other through wedge action. Even if the last mentioned coupling arrangement involves considerable time sav¬ ings compared to axial interconnection by means of bolt connections, it also suffers from certain dis¬ advantages. Since the axial forces generated by the internal pressure act upon the spherical gable in a direction away from the rest of the pressure vessel, the coupling flanges are subjected to axial forces tending to separate the flanges from each other and thus to exert less pressure force upon the annular gaskets disposed between the coupling surfaces of the flanges. This imposes great demands on the seal¬ ing capacity of the gaskets. Due to the radially and outwardly tapering wedgelike sections of the flanges the axial forces acting at the coupling surfaces be¬ tween the coupling flanges and said semicircular coupling ring halves give rise to force components directed outwardly in the radial direction and tend¬ ing to separate the coupling ring halves. For the reasons mentioned said circumstances have been found to involve difficulties in obtaining a satisfactory sealing effect, and said difficulties are accentuat¬ ed the higher the internal pressure is to which the pressure vessel is exposed.

The object of the present invention is to pro¬ vide a coupling device of the kind mentioned in¬ itially, in which the disadvantages mentioned above and inherent in the known coupling devices are avoided or decreased to a great extent. A further object of the invention is to provide a coupling de¬ vice of the kind mentioned in which the forces caus¬ ed by the overpressure cooperate for securing an in¬ creased sealing effect of the gaskets when the internal pressure increases. A further object of the invention is to provide a coupling device in which the advantages mentioned above are obtained without rendering the coupling operation more difficult.

The objects mentioned above are obtained by a design i accordance with the appended claims.

The invention will be described below in con- nection with an embodiment and with reference to the appended drawings, on which fig 1 is a schematical perspective view of a pressure vessel provided with a coupling device in accordance with the invention, and with the pressure vessel in open position for inserting or removing a test object, fig 2 is a side view of a pressure vessel in which the coupling device according to the invention is used, the spherical end portion of the pressure vessel illustrated in uncoupled position, fig 3 is an end view taken as indicated by ar¬ rows A-A in fig 2, with the coupling ring halves spaced apart, fig 4 is a side view of the pressure vessel of fig 1, both portions of the pressure vessel being coupled to each other,

- fig 5 in an end view of the container according to fig 4, taken as indicated by arrows B-B of fig 4,

- fig 6 is a cross section through the coupling device according to the invention, both portions of the pressure vessel being coupled to each other, figures 7-11 illustrate some coupling sequences during interconnection of the pressure vessel por¬ tions respectively during disconnection of said por¬ tions.

Figures 1 to 5 disclose a cylindrical pressure vessel 1 which is supported on a bedding by means of a strong mounting 2. At one end the cylindrical con¬ tainer 1 is rigidly connected by welding with a spherical end portion 3. At the opposite end the cylindrical pressure vessel 1 is provided with an annular coupling flange 4 for connection with a cor¬ responding coupling flange 5 on a spherical end por¬ tion 6 which is connectable to the pressure vessel 1. The spherical end portion 6 is supported by means of an arrangement, not shown in detail, so that it may be swung sideways as shown in fig 1 and thereby leaving the area in front of the opening of the pressure vessel completely exposed. Figures 2 to 4 show the spherical end portion 6 swung into a posi¬ tion in which the end surface of the end portion 6 is parallel with the end surface of the cylindrical pressure vessel 1. The spherical end portion 6 is then supported on a supporting frame disposed in front of the pressure vessel opening, said support¬ ing frame comprising an axially extending guideway, not shown in detail, for axial displacement of the end portion 6 in the axial direction towards or away from the opening of the cylindrical pressure vessel 1.

Disposed in the coupling area for connecting the end portion 6 with the end of the cylindrical pressure vessel 1 is a vertical frame 7 surrounding said coupling area, supporting an upper semicircular coupling ring 8 and a lower semicircular coupling ring 9 which are movable towards and away from each other by means of power devices 10. Figures 1 and 3 show the coupling ring halves 8, 9 separated from each other and fig 5 shows said coupling ring halves moved into engagement with each other at the same time gripping the coupling flanges 4 and 5.

When a pressure test shall be carried out, the spherical end portion 6 is swung sideways into the position shown in fig 1. The object to be pressure tested, e.g. a minivessel for submarine use, is then introduced into the cylindrical pressure vessel. The spherical end portion 6 is then brought into the po¬ sition illustrated in fig 2, after which the end portion 6 by means of power means, not shown, is displaced axially into abutment with the end of the open pressure vessel 1. The coupling ring halves 8, 9 are then moved towards each other into locking en¬ gagement between the abutting coupling flanges 4 and 5. The pressure vessel 1 is then filled up with liquid, preferably water, to which the desired pres¬ sure, which may be very high, e.g. 160 bar or more, has been imparted by means of a pressure unit, not shown. After termination of the pressure test the liquid pressure is released, and the liquid is drained off from the container. The spherical end portion 6 is then disconnected from the cylindrical pressure vessel 1 and is caused to take the position shown in fig 1, after which the test object may be- removed from the pressure vessel 1.

The coupling device according to the invention together with the components thereof are described in more detail with reference to figures 6-11.

At the open end the pressure vessel portion 1 is provided with an annular coupling flange 4 having a substantially rectangular cross section. The annular coupling flange 4 has the same internal dia¬ meter as the internal diameter of the pressure ves¬ sel 1, but the thickness of the coupling flange is consedeably larger than the shell thickness of the pressure vessel 1. The coupling flange 4 has a plane, vertical end surface 11. A recess 12 is form¬ ed into the outer surface of the coupling flange 4. The limiting surface 13 of the recess 12 which is disposed closest to the vertical coupling surface 11 of the coupling flange 4 has frusto-conical ring form, whereas the opposite limiting surface 14 ex¬ tends in a vertical plane in parallel with the coupling plane 11. The limiting surface 13 of the recess 12 extends in a direction obliquely upwards- outwards with respect to the vertical coupling plane 11.

The other portion of the pressure vessel 1, i.e. the spherical end portion 6, is at the free end thereof in a corresponding manner provided with a coupling flange 5, the shape of which being analog¬ ous with the described shape of the coupling flange 4, but in a reversed design. The coupling flange 5 thus has a plane, vertical end surface 11, a recess 12 formed in the upper surface of the coupling flange with a ring shaped, frusto-conical limiting surface 13 disposed closest to the end surface 11, and a limiting surface 14 opposite said frusto- conical limiting surface. The limiting surface 13 thus extends in a an inclination obliquely upwards- outwards with respect to the vertical coupling plane 11, whereas the limiting surface 14 extends in a vertical plane in parallel with the coupling plane 11.

At the inside of one of the portions of the pressure vessel - in the embodiment shown the spherical end portion 6 - is a tubular coupling sleeve 15 which extends into the coupling flange 5. The outside diameter of the coupling sleeve 15 co¬ incides with the inner diameter of the coupling flange 5. The coupling sleeve 15 further protrudes outside the end surface 11 of the coupling flange 5, so that when the coupling flange 5 abuts the coup¬ ling flange 4, the coupling sleeve 15 extends into the coupling flange 4 in abutment with the inner surface thereof. The end of the coupling sleeve 15 which extends into the coupling flange 5 is formed with a smaller diameter than the inner diameter of the coupling flange 5 in order to form a shoulder 16 intended to bear against an annular bead 17 formed on the inner surface of the coupling flange 5, said bead limiting the insert length into the coupling flange 5 of the coupling sleeve 15. The part of the coupling sleeve 15 which extends into the coupling flange 5 beyond said bead 17 is provided with stop screws 18, which together with the bead 17 and the shoulder surface 16 locks the coupling sleeve 15 axially or limits the possibility of axial movement to a minimum. Disposed on the portion of the coup¬ ling sleeve 15 which extends into the coupling flange 5 is one, but preferably two annular grooves 19, as shown in the figure, for gaskets of the O-ring type 20 located in said grooves, said gaskets securing the sealing effect between the coupling sleeve 15 and the coupling flange 5. The portion of the coupling sleeve 15 which protrudes out of the coupling flange 5 is in a corresponding way on its outer surface provided with one, but preferably as shown, with two annular grooves 19 for gaskets of the O-ring type 20 for sealing against the inner surface of the coupling flange 4 when the coupling flanges 4 and 5 have been brought into contact with each other.

The cross section of each one of the semi¬ circular coupling rings 8, 9 is substantially rec- tangular. The inner surface of the coupling rings 8, 9 is provided with a recessed groove 21. Both limit¬ ing surfaces 22 of the groove which are facing each other are frusto-conical in shape and extend in an inclination towards each other so that the width of the groove 21 at the opening thereof is less than its width at the base of the groove. The frusto- conical limiting surfaces 22 have a shape with the same conicity as corresponding frusto-conical sur¬ faces 13 on said coupling flanges 4 and 5 respect¬ ively. The end surfaces of the section of the coup- ling ring halves are plane-parallel and vertical. The distance a between the limiting edges of the groove 21 on the inside of the semicircular ring half 8, 9 corresponds to the distance between the outer limiting edges of the frusto-conical coupling surfaces of two coupling flanges 4 and 5 disposed in axial contact with each other, with the addition .of a small gap for rendering possible the lowering in¬ to, respectively the lifting up from the grooves 12 in said coupling flanges 4 and 5. The width of the respective coupling ring halves 8, 9 substantially corresponds to the distance between the vertical limiting surfaces 14 of the recesses 12 in the coup¬ ling flanges 4, 5, when the coupling flanges 4, 5 are in axial contact against each other, with the deduction for a small gap for rendering possible in¬ troduction into, respectively the removal from the recess of said coupling flanges.

Some sequences during interconnection and dis¬ connection, respectively, of the pressure vessel portions from each other will be described below with reference to figures 7-11.

Fig 7 illustrates a position in which the spherical end portion 6 has been brought into tight contact between the coupling surfaces 11 of the coupling flanges. During this operation the semi¬ circular coupling ring halves 8 and 9 are in the po¬ sition illustrated in figures 1 and 3. The coupling ring halves are then displaced in a direction towards each other and may then freely grasp the coupling flanges 4 and 5 as shown in figures 6 and 7. In that connection there is a certain gap between the limiting surfaces 22 and 13.

The spherical end portion 6 is then caused to displace in a direction from the pressure vessel portion 1 and simultaneously, after established con¬ tact between the limiting surfaces 22 and 13 of the flange coupling 5 respective of the coupling rings 8 and 9, forcing said coupling rings to move together with said spherical end portion until contact be¬ tween the coupling surfaces 13 and 22 of the coup¬ ling flange 4 and the coupling rings 8, 9 respect¬ ively has been established. The position shown in fig 9 has then been obtained.

Fig 9 thus illustrates the position in which the interconnection has been effected. The pressure vessel 1 may then be filled up with water and may be set under an inner overpressure for carrying out the intended pressure test. The required sealing was then secured by means of the 0-ring sealings 20 be¬ tween the coupling sleeve 15 and the inner surface of the coupling flanges 4 and 5 respectively. When the pressure increases the coupling sleeve 15 is pressed by an increasing force against the inner surfaces of the coupling flanges 4, 5, resulting in increased sealing capacity. The force components oc- curing in the limiting surfaces 13 and 22 also tend to press the sealing surfaces of the coupling device towards each other.

When the pressure test has been completed, the pressure in the pressure vessel is relieved and water is drained off from the pressure vessel. The spherical end portion 6 is then caused to move in a direction towards the pressure vessel portion 1. After overcoming the gap between the limiting sur¬ faces 14 of the coupling flange 5 and the end sur¬ face of the coupling ring 8, 9, the coupling rings 8, 9 are caused to move axially until the position illustrated in fig 11 has been obtained. This allows for vertical displacement of the semicircular coup- ling ring halves 8, 9 in a direction from each other out of engagement with the coupling flanges 4 and 5 respectively. The spherical end portion 6 may then be displaced axially from the pressure vessel por¬ tion 1 and may be swung sideways into the position illustrated in fig 1.

Claims

1. Coupling device for sealingly axially intercon¬ necting two pressure vessel portions (1, 6) having a circular cross section, each pressure vessel portion

(I) being provided at its coupling end with an an¬ nular coupling flange (4) for connection with a cor¬ responding coupling flange (5) on the other pressure vessel portion (6) , said coupling flanges being pro¬ vided on the sides thereof facing away from each other with annular, frusto-conical coupling surfaces for cooperation with corresponding frusto-conical coupling surfaces formed internally in two semi¬ circular coupling ring halves (8, 9) grasping said coupling flanges, said coupling ring halves inter-

- locking both pressure vessel portions (1, 6) in sealing cooperation with each other by exerting a radially tightening action on said pressure vessel halves towards each other via said coupling flanges (4, 5), c h a r a c t e r i z e d in that the frusto-conical coupling surfaces (13) of said coup¬ ling flanges (4, 5) are directed obliquely upwards- outwards with respect to the vertical coupling plane

(II) between the pressure vessel portions (1, 6) , the inner surface of each one of said semicircular coupling ring halves (8, 9) being provided with an annular recessed groove (21) , of which the limiting surfaces (22) facing each other have frusto-conical form with the same conicity as the conicity of cor- responding coupling surfaces (13) on said coupling flanges (4, 5) , for cooperation with said coupling flanges when interconnecting said pressure vessel portions, and that one of said pressure vessel por¬ tions (6) on the inside of the adherent coupling flange (5) is provided with a tubular coupling sleeve (15) attached to the coupling flange (5) and sealing against the inner surface thereof, said coupling sleeve protruding axially outside the coup¬ ling flange, sealing means (20) being arranged be¬ tween the coupling sleeve (15) .and the coupling flanges (4, 5) .

2. Coupling device as claimed in claim 1, c h a r a c t e r i z e d in that each one of said coupling flanges consists of a ring (4, 5) attached to the end of the pressure vessel portion (1, 6) and having the same inner diameter as the inner diameter of the pressure vessel, a recess (12) being provided in the outer surface of said ring (4, 5) , the limit¬ ing surface (13) of said recess being closest to the vertical coupling surface (11) of the coupling flange has frusto-conical form, the width of said recess (12) at the top thereof being greater than its width at the base of said recess (12) .

3. Coupling device as claimed in any of claims 1 or 2, c h a r a c t e r i z e d in that each one of said coupling ring halves (8, 9) consists of a semicircular ring having a substantially rectangular section, the inner surface of which being provided with a recessed groove (21) of which both limiting surfaces (22) facing each other have frusto-conical form and are inclined in a direction towards each other so that the width of said groove (21) at its opening is less than its width at the base thereof, said frusto-conical surfaces (22) having the same conicity as corresponding frusto-conical surfaces (13) on said coupling flanges (4, 5) .

4. Coupling device as claimed in claim 3, c h a r a c t e r i z e d in that the distance (a) between the limiting edges of the groove (21) on the inside of the semicircular ring half (8, 9) cor- responds to the distance (b) between the outer limiting edges of the frustorconical coupling sur¬ faces (13) on two coupling flanges (4, 5) axially abutting each other, with the addition of a small gas for rendering possible the introduction, re¬ spectively the withdrawal of said ring half from the recesses (12) in said coupling flanges (4, 5) .

5. Coupling device as claimed in claim 4, c h a r a c t e r i z e d in that the width of each one of said coupling ring halves (8, 9) substantial¬ ly corresponds to the distance between the vertical limiting surfaces (14) of the recesses (12) in the coupling flanges when said coupling flanges (4, 5) are in axial abutment against each other, with de¬ duction of a small gap for rendering possible the introduction into, respectively the removal of said ring half from the recesses (12) in said coupling flanges (4, 5) .

6. Coupling device as claimed in any of the pre- ceeding claims, c h a r a c t e r i z e d in that said tubular coupling sleeve (15) extends into the coupling flange (5) of one of the pressure vessel portions (6) and at the surface thereof engaging the inner surface of the coupling flange (5) is provided with at least one annular groove (19) for a sealing

(20) of the O-ring type, the coupling sleeve (15) being blocked against axial movement in the coupling flange (5) by means of one or several locking screws (17).