WO1994008841A1

WO1994008841A1 - An access device

Info

Publication number: WO1994008841A1
Application number: PCT/GB1993/002126
Authority: WO
Inventors: John Arthur Mair; Stewart Risk
Original assignee: Sub Sea Offshore Ltd
Current assignee: Sub Sea Offshore Ltd
Priority date: 1992-10-16
Filing date: 1993-10-14
Publication date: 1994-04-28
Anticipated expiration: 1995-04-16
Also published as: GB9412100D0; GB2278317A; AU5283293A; GB9221740D0

Abstract

An access device for a fluid container (2) includes a body member (1), a rupturable member (3) and a removable closure device (4). The body member (1) is installed in a fluid container (2) and defines an access opening. The rupturable member (3) is mounted across the access opening and the removable closure device (4) provides a barrier between the outside of the container (2) and the rupturable member (3).

Description

1 "An Access Device" z -.>

3 The invention relates to an access device, and in

4 particular, an access device for installing in a wall

5 of a fluid container, for example a tanker or gas

6 container. 7

8 One of the problems with tankers, such as floating

9 tankers, road tankers or rail tankers, is that of 0 safely gaining access to the fluid in the tanker in 1 order to recover the fluid and/or render the fluid 2 harmless in an emergency situation or where the tanker 3 has been damaged. 4 5 This is a particular problem with floating tankers 6 where, for example if a tanker vessel hits a rock or 7 runs aground, the resulting damage to the tanker can 8 often result in the tanker vessel becoming crippled. A 9 change in buoyancy as a result of an impact may cause 0 the vessel to depart from its normal flotation 1 characteristics which (for example if the vessel is on 2 its side or inverted) may mean that access to the 3 normal tanker ports in order to empty the tanker of its 4 contents is either difficult or impossible.

SUBSTITUTE SHEET To date, solutions have been proposed for attempting to contain spillages from floating tankers, such as oil tankers , but there have been no practical proposals to facilitate easier recovery of fluid from within the tanker, or how to access the fluid within the tanker in order to render it safe to the surrounding environment before the fluid escapes from a tanker if the tanker is damaged.

A similar problem exists with tankers other than floating tankers and the problem relates in general to all transportable or mobile tankers which carry fluid, whether they be land or water based.

In accordance with one aspect of the present invention, an access device for installing in the wall of a fluid container, comprises a body member which defines an access opening which extends through an outside wall of the fluid container to the interior of the fluid container; a rupturable member mounted across the opening in the body member; and a removable closure device which engages with the body member to provide a barrier between the rupturable member and the outside of the container.

In accordance with a second aspect of the invention, a method of installing an access device in a wall of a fluid container comprises inserting a body member which defines an access opening into a wall of the fluid container, the access opening extending through an outside wall of the fluid to the interior of the fluid container; mounting a rupturable member across the opening in the body member; and engaging a removable closure device with the body member to provide a barrier between the rupturable member and the outside

SUBSTITUTE SHEET of the container.

In accordance with a third aspect of the present invention, a method of accessing a fluid container having an access device in accordance with the first aspect of the invention installed in a wall of the fluid container, comprises removing the removable closure device from the body member, coupling a fluid transfer means to the body member, applying a fluid pressure through the fluid transfer means to the outside of the rupturable member, increasing the pressure applied to the outside of the rupturable member to create a sufficiently high pressure differential across the rupturable member to cause the rupturable member to rupture and open the access device; and passing fluid through the access device.

Preferably, the removable closure device may include sealing means to permit the removable closure device to seal with the body member. Typically, the removable closure device also includes pressure testing means which permits the integrity of the rupturable member to be pressure tested after installation of the removable closure device. Preferably, the pressure testing means may comprise closable through bores in the removable closure device which permit a fluid to be introduced between the rupturable member and the removable closure device in order to pressure test the rupturable member. Preferably, the pressure testing means also permits a corrosion inhibitor to be introduced between the rupturable member and the removable closure device.

Typically, the removable closure device may include locking means to retain the removable closure device on the body member. Typically, the locking means

SUBSTITUTE SHEET comprises movable members which may be biased by biasing means into engagement with the body member to secure the removable closure device to the body member. Typically, the biasing means may comprise a spring. Preferably, the movable members may comprise profiled segments or balls which engage a recess in the body member.

Typically, the rupturable member may be in the form of a burst disc and could be of a type supplied by BS & B Safety Systems. Typically, the rupturable member may comprise a thin sheet of material and preferably, may be calibrated to rupture when a predetermined pressure differential is applied across the rupturable member.

Typically, the access device is particularly suitable for fluid containers which are transportable or mobile,^' such as road tankers, floating tankers or rail tankers.

Preferably, a number of access devices are provided in different locations on the fluid container and typically, at least one access device is provided on each side wall of the fluid container.

After the access device has been opened, fluid may be passed through the access device into the fluid container, for example, in order to render the contents of the container inert or safe or to reduce the risk of fire or explosion and/or the fluid within the fluid container may be extracted from the container through the access device.

Preferably, at least two access devices are provided in the walls of the fluid container and preferably, at least two of the access devices are opened to permit

SUBSTITUTE SHEET fluid from an external fluid source to be pumped into the container through one of the access devices and fluid from within the container to be extracted via the other access device.

According to the invention there is provided a fluid container having an aperture in the container wall, the aperture constituting an access socket body through which fluid is dischargeable from or through which fluid is admissible into the container, the aperture being closable to the outside environment by a removable cap and the aperture being sealable by a bursting disc within the container and facing the inside of the cap, the bursting disc being arranged to resist substantially more than the internal working pressure of the container and rupturable inwards on connection thereto to an external pressure source, whereby when required discharge of fluid from or admission of fluid into the container is obtainable by remote control or by manual means by removing the cap from the socket body, connecting a spigot adaptor to fit the socket body and connecting thereto the required hose and pumping means to effect the necessary transfer of fluid.

The fluid container may be an oil tanker.

Typically, the fluid container may be double walled and connection to an inner wall of the container may be provided by an internal pipe fixed to the body member.

Preferably, the cap when closing the aperture is retained against the socket body by locking means, for example, locking balls or locking segments, which locate by spring loaded means into an annular groove in

SUBSTITUTE SHEET the socket body. A said fluid container may have a plurality of said access socket bodies and caps therefor.

Examples of an access device in accordance with the invention will now be described with reference to the accompanying drawings, in which:-

Fig. 1 is a cross-sectional view through an access device, with a first example of a removable cap, installed in a fluid container; Fig. 2 is a part cross-sectional elevation of an access device, with a second example of a removable cap, installed in a fluid container; Fig. 3 is a cross-sectional view showing installation of the removable cap shown in Fig. 1 with a cap installation tool; and, Fig. 4 is a cross-sectional view showing the removable cap of Fig. 1 being extracted by a cap extraction tool.

Referring to Fig. 1, the device illustrated comprises an access socket body 1 and a cap 4 therefor. In practice the socket body 1 is fitted into a fluid container or tank wall 2 during construction of the tank or later. The inside surface of the tank wall 2 is denoted by 26 and the outside surface of the tank wall 2 by 27. The socket body 1 is welded (or if desired bolted) to the tank wall 2. The body socket l is provided with a bursting disc 3.

For double walled tanks connection to an inner wall (not shown) is provided by a pipe 5 fixed to the socket body 1 by bolts 7. In an alternative embodiment illustrated by Fig. 2, pipe 5 is fixed to the socket body 1 by weld 6.

The socket body 1 is sealed by the bursting disc 3. The bursting disc is adapted to resist substantially more than the maximum internal working pressure of the tank and is rupturable inwards upon application to the disc 3 of an external pressure source. The disc 3 is protected mechanically by the cap 4. The cap 4 also protects sealing surfaces 8 of the socket body 1 and a connection flange 9 of the socket body 1 against mechanical damage and corrosion.

The cap 4 is retained against the socket body 1 by a series of locking balls 10 which locate into a groove 14 in the socket body 1.

In an alternative embodiment illustrated by Fig. 2, the cap 4 is retained against the socket body 1 by locking segments 11 which locate into groove 14.

The locking elements 10 or 11 are controlled by spring means 23 arranged to provide a retaining force which is sufficiently high enough to withstand the maximum working pressure of the tank. Hence, in the event of failure of the burst disc 3, the cap 4 will retain the contents of the tank.

Referring to Fig. 3, the cap 4 may be fitted to the socket body 1 using a tool 22 which presses the cap 4 into the socket body 1. The locking elements 10 or 11 are initially compressed by an inwardly tapered portion 13 of the socket body as the cap 4 moves towards the socket body 1 and will then spring out into the groove 14 when they reach the groove 14. The cap fitting tool 22 comprises hollow studs 24 through which bolts 25 pass. The bolts 25 pass through a robust backing plate 110 and into tapped holes 19 in the socket body 1. 108 denotes a pressure screw and arrow 109 indicates clockwise rotation of screw 108 to draw the cap 4 towards the socket body 1. Alternatively, the pressure screw 108 may take the form of a nydraulic cylinder (not shown) .

After fitting the cap 4, the presence of the seal 12 permits the burst disc 3 to be pressure tested via cap ports 15 and 16. The cap ports 15 and 16 are then used to inject grease or other corrosion inhibitor into the space between the cap 4 and the socket body 1. To ensure that the sealing surfaces 8 of the socket body 1 do become coated, a corrosion inhibitor is injected at cap port 15 and air bled off at cap port 16 until the corrosion inhibitor is shown to be present there. Ports 15 and 16 are then plugged with screwed caps.

The annular space outside the connection flange 9 is also filled with corrosion inhibitor via two ports 17 and 18. The ports 17 and 18 serve to access the tapped holes 19 which provide reaction points for the cap fitting tool 22, and are again capped with screwed plugs when the cap 4 has been filled with corrosion inhibitor. The corrosion inhibitor is retained in the annular space by seals 20 and 21.

Referring to Fig. 4, the cap 4 may be extracted from the socket body 1 by a mechanical pull using an extracting tool. The extraction tool may be deployed by remote or manual means and consists of two hydraulic functions, namely cap latching and cap extracting.

Latching the cap 4 is accomplished by engaging a number of hinged dogs 101 under the flange 102 in the centre hole 103 of the cap 4. The dogs 101 are extendible by hydraulic cylinder 104 against a spring 105. If hydraulic power is lost, the dogs 101 are automatically released from the cap 4. Once the dogs 101 are engaged in the cap 4 , the extraction tool is retracted by a second hydraulic cylinder 106. The extraction tool extracts the cap 4 by pushing against the socket body 1 via its housing 107.

In practice fluid discharge and supply may be carried out using the apparatus described above and illustrated by Figs. 1 to 4 of the accompanying drawings using a suitable spigot adaptor (not shown) to fit the access socket body 1, and ancillary hose and pumping equipment of a conventional kind but not shown.

The access socket body 1 is intended to allow emergency connection to pressure vessels, storage tanks, ships hulls, etc. in order to access their contents. The access socket body may be used to remove the contents of a tank (as for example, in the case of a disabled chemical carrier) or for the introduction of other fluids such as water, compressed air or foam, to displace the tank contents or render it safe.

The access socket body may be fitted in normally accessible locations as well as locations normally difficult to reach. For example, a tanker vessel may have an aόcess socket body fitted in the deck above the tank, and also in the side below the water line. In the event of the vessel sinking and settling on her side, access to the side access socket body might well be easier than access to the desk. If the cargo is lighter than water then the highest access socket body would be connected for removal of the cargo and the lowest available access socket body would be used to introduce seawater to displace. Clearly, if access socket bodies are placed so that one will be close to the top of the tank regardless of attitude then the maximum amount of cargo can be recovered.

Modifications and improvements may be incorporated without departing from the scope of the invention.

Claims

1. An access device for installing in the wall of a fluid container, the access device comprising a body member which defines an access opening which extends through an outside wall of the fluid container to the interior of the fluid container; a rupturable member mounted across the opening in the body member; and a removable closure device which engages with the body member to provide a barrier between the rupturable member and the outside of the container.

2. An access device according to Claim 1, wherein the removable closure device includes sealing means to seal the removable closure device to the body member.

3. An access device according to Claim 2, wherein the removable closure device includes pressure testing means to permit pressure testing of the rupturable membrane.

4. An access device according to Claim 3, wherein the pressure testing means comprises at least one through bore in the removable closure device.

5. An access device according to any of the preceding Claims, wherein the rupturable member comprises a burst disc.

6. An access device according to any of the preceding Claims, wherein the removable closure device includes locking means to secure the removable device to the body member.

7. A method of accessing a fluid container provided with an access device in the wall of the container; the access device comprising a body member which defines an access opening which extends through an outside wall of the fluid container to the interior of the fluid container, a rupturable member mounted across the opening in the body member, and a removable closure device which engages with the body member to provide a barrier between the rupturable member and the outside of the container; the method comprising removing the removable closure device from the body member, coupling a fluid transfer means to the body member, applying a fluid pressure through the fluid transfer means to the outside of the rupturable member, increasing the pressure applied to the outside of the rupturable member to create a sufficiently high pressure differential across the rupturable member to cause the rupturable member to rupture and open the access device; and passing fluid through the access device.

8. A method according to Claim 7, the fluid container being provided with at least two access devices, the method further comprising removing the removable closure device from at least two access devices, rupturing the rupturable member of each closure device which has had the removable closure device removed, and passing a fluid into the fluid container through at least one of the opened access devices and removing fluid from the fluid container through at least one of the other opened access devices.

9. A method of installing an access device in a wall of a fluid container comprises inserting a body member which defines an access opening into a wall of the fluid container, the access opening extending through an outside wall of the fluid to the interior of the fluid container; mounting a rupturable member across the opening in the body member; engaging a removable closure device with the body member to provide a barrier between the rupturable member and the outside of the container.

11. A method according to Claim 10, and further including the step of providing a through bore in the removable closure member; pressure testing the integrity of the rupturable member after the removable closure device has been engaged with the body member by passing a pressurising fluid through the through bore in the removable closure device; and subsequently closing the through bore.

12. A method according to Claim 11, and further including the step of inserting a corrosion inhibiting substance through the through bore to occupy a space between the removable closure device and the rupturable membrane, and subsequently closing the through bore.