GB2411891A

GB2411891A - Emptying an overturned tanker

Info

Publication number: GB2411891A
Application number: GB0405132A
Authority: GB
Inventors: Tom Owen Morgan; Melville Raymond Wilby
Original assignee: ACTION SEALTITE Ltd
Current assignee: ACTION SEALTITE Ltd
Priority date: 2004-03-08
Filing date: 2004-03-08
Publication date: 2005-09-14
Also published as: GB0405132D0

Abstract

A vessel 1 for containing fluid 8 comprises a port 2 in the vessel, wherein one end of a conduit 5,6 is engaged to the port, the other end being within the interior of the vessel, being flexible 16 along at least a part of its length. Thus, contact with the fluid 8 can be maintained despite the tanker 1 becoming upset from its normal state. Emergency offload of the content is made easier.

Description

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IMPROVEMENTS IN OR RELATING TO FLUID TRANSPORT TANKERS

TECHNICAL FIELD OF THE INVENTION

This invention relates to improvements in or relating to fluid transport tankers. It addresses various problems thereof, in particular the provision of a suitable electrostatic discharge device suitable for use on vessels containing petroleum or chemical products where static is liable to occur, whilst still permitting the offload of the product should the vessel become upset, for example in an accident.

BACKGROUND ART

Electrostatic discharge has long been known as a hazard associated with the handling of petroleum products. Static electricity is generated when liquids move in contact with other materials. This is a common occurrence when liquid is being moved through pipes, mixed, poured, pumped, filtered or otherwise agitated. Other causative processes include the settling of solids or immiscible liquid through a liquid, the ejection of particles or droplets through a nozzle and the splashing of a liquid against a solid surface, i.e. the sides of the vessel containing the liquid.

Furthermore, in certain conditions, static may also accumulate in the liquid, particularly with liquid hydrocarbons, with the danger of subsequent sparking in a flammable vapour-air mixture. .

. . . c: :. . Various methods of reducing the problems of static are well known, although none of the methods can prevent absolutely the generation of the static because its intrinsic origins are present at every interface. The methods of reducing the problem include careful stripping and gas freeing to control the atmosphere in the tankers and assuring an over-rich mixture in the tankers.

These methods are suitable when tankers are loaded or unloaded in suitably controlled atmospheres and sites, for example at the filling depot and petrol stations where the tankers are emptied.

The problems of electrostatic charge become more severe when the tanker needs to be emptied at a site that is not controlled.

In addition to the above problems faced by operators of fluid transport vehicles, it is sadly the case that, from time to time, the tankers used to transport liquids become involved in accidents and are as a result upset from their normal configuration and left lying on one side. Roadgoing tankers can be involved in single or multiple vehicle accidents and their high-sided nature and high centre of gravity mean they will often settle on one side. Other tankers such as those incorporated in rail rolling stock are generally less prone to accident but are still vulnerable. A problem then arises in that recovery of the tanker in its fully filled condition is extremely difficult. Unloading the tanker is also difficult in that the normal on-board apparatus may be damaged and is in any case often inoperative in the absence of power and/or compressed air from the truck, or as a result of the unusual disposition of the vehicle.

The problem therefore exists of how to unload the vehicle contents in such an emergency state. Where the vehicle contents are hazardous or flammable such as hydrocarbons (or other fuels) or harmful or hazardous chemicals, this may not be a straightforward task. In the specific case of hydrocarbons, strict rules exist regarding the release of both product and vapour during the normal course of operations, and these rules reflect the genuine dangers inherent in such spillages. It would therefore be desirable to minimise such loses during the emergency rescue of such a tanker. Similar considerations exist in respect of other contents such as dangerous chemicals. e

The present invention seeks to provide a device that can be used to offload the contents of the tanker in a legal and safe manner whilst maintaining the necessary protection against electrostatic build-up.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a vessel for containing fluid comprising a port in the vessel, wherein one end of a conduit is engaged to the port, the other end being within the interior of the vessel, being flexible along at least a part of its length.

Other preferred and optional features of the invention are described below and in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a view from the rear of a petroleum tanker fitted with a first embodiment of the present invention, in an upright position; Figure 2 shows a view from the rear of the petroleum tanker of figure 1 in a partially upset state; Figure 3 shows a view from the rear of the petroleum tanker of figure 1 in a fully upset state, i.e. lying on one side; Figure 4 shows a view from the rear of a petroleum tanker fitted with second embodiment of the present invention, in an upright position; Figure 5 shows a view from the rear of the petroleum tanker of figure a fully upset state; Figure 6 shows the cap of the second embodiment in vertical section cc: .:. be: : : :: e Figures 7 and 8 show vertical sections of the retaining latch of the second embodiment, being a section in the transverse and longitudinal planes relative to the tanker, respectively; and Figure 9 shows a view corresponding to that of figure 7, after the tanker has been upset to the state illustrated in figure 5.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Figure 1 shows a tanker 1 in the upright position, with an openable circular portion or outlet 2 on the manlid 3. Each compartment of a tanker is usually provided with such a manlid with various outlets. One of the outlets on the manlid is for the purposes of inserting a dipstick to ascertain the level of the liquid 8 inside the compartment of the tanker, and thus the volume. In Europe, however, other methods of ascertaining the volume of liquid 8 inside a tanker are now used, as it is inadvisable to allow vapours to escape into the atmosphere. Elsewhere, dipsticks may still be used to calculate the volume of the liquid.

A combined offload device and electrostatic discharge 4 may be attached to the former dipstick outlet. In this embodiment, this comprises two main parts. One part comprises a conduit having a rigid portion 5 depending from the upper internal wall of the compartment and a further flexible portion 6 depending therefrom. The flexible portion 6 may comprise a tube of (for example) a suitable rubber grade, a fabric or a composite fabric, a sectional metal tube, or a laminated composite of such materials. Composite fabric tubing comprises a plastic or other suitable tubing material wound together with metal wiring. The flexible portion of the discharge device may also comprise a metal woven or chain- like structure that is capable of bending or flexing to provide discharge of the static when the tanker is no longer in an upright position. In other embodiments the rigid portion 5 may comprise a laminate with the flexible portion surrounded by a metal cage thereby to hold the upper portion of an otherwise flexible discharge device in a rigid fashion. Such a metal cage may be fixedly attached to or integrated with the flexible portion or it may simply enclose the flexible portion. 8 8

8 # 8 . .. 8..

Figure 1 also shows a conductive member 7 providing the electrostatic discharge function of the embodiment. This is attached at its upper end to the inside of the top of the tanker, adjacent to the manlid, and located at its bottom end to a restrainer on the inside of the tanker. The member extends from top to bottom of the compartment of the tanker in a parallel direction to the discharge device. This serves to provide a main or additional earth, to discharge electrostatic charge, particularly when the tanker is in an upright and normal situation. This member may of course be rendered redundant by the conduit 5 & 6 in some cases. Conductivity may be imparted to the conduit 5 & 6 in a variety of manners, such as forming the conduit of a conductive material or as a composite including a conductive material, or by a surface coating of a conductive material.

The conductive member 7 (when present) may be formed in a variety of constructions and materials. A simple rigid rod or chain of a metallic material such as steel, aluminium, brass or copper will suffice. If formed of a suitable length of conductive pipe, the member can then be used as an occasional dip facility in addition to its other functions.

Figure 2 shows the tanker 1 being upset. As the tanker moves away from the upright or vertical position, the flexible portion 6 of the discharge device flexes under the influence of gravity, to assume a position closer to the vertical.

It is thereby able to maintain its contact with the liquid 8 inside the compartment of the tanker. If conductive, it will continue to provide discharge of potentially hazardous static charges.

Figure 3 shows the tanker on its side. The discharge device continues to maintain its contact with the liquid 8 inside the vessel. As a result, in order to discharge the fluid 8, rescuers can attach suitable conduits to the outlet 2 and remove the fluid via the tube 6.

Figures 4 and 5 show a tanker 1 fitted with a second embodiment of the present invention. The outlet 2 and the manlid 3 are the same as those of the first embodiment, but the offload device 14 is revised and includes a flexible portion 16 adjacent the outlet 2 and a rigid portion 15 depending therefrom. l

r Thus, as shown in figure 5, when the tanker is upset the flexible portion 16 bends to allow the rigid portion 15 to descend into the liquid 8. Contact is thus maintained for electrostatic discharge and for offload. In addition, the weight of the rigid portion 15 may assist in urging the conduit into the appropriate position.

In this second embodiment, the conductive member 17 is again shown.

This corresponds to the conductive member 7 of the first embodiment and similar comments apply. As illustrated, the conductive member 7 is adjacent and parallel to the conduit 15, 16 when the latter is in its normal state with the tanker 1 upright. In this embodiment, as the lower portion of the conduit comprises the rigid portion 15, the lower end is latched to the conductive member 17 in the manner to be described below. This latch releases when the tanker is upset and thus allows its correct mode of operation. However, it prevents motion of the conduit 15 during normal upright operation as a result of lateral forces, for example during cornering or bottom loading.

It will be appreciated that the length of the rigid portions 5, 15 may be varied, for example to suit the design of the tanker 1. Indeed, the rigid portions 5, 15 may be omitted entirely.

Figure 6 shows the outlet 2 in more detail. A collar 40 is attached to the tanker 1 by a suitably secure means such as bolts or the like. This has a central aperture 42, located over a corresponding aperture 44 in the tanker 1. The collar 40 has an upstanding cylindrical ring 46 forming a short length of conduit.

At the base of the ring 46, the outside thereof is formed with shoulders 48 behind which the cap can engage. An O-ring 50 is provided on the outer surface of the ring 46 to seal against the cap once fitted.

The cap 52 for the outlet 2 has a generally cylindrical conduit section 54, at the base of which is an annular recess 56 sized to receive the upstanding ring 46. Engagement lugs (not shown) engage behind the shoulders 48 after rotation into position in a generally known manner. The opening of the conduit section 54 is temporarily covered with a plastics plug 58 (shown dotted) to prevent ingress of dirt, foreign objects etc. The plug 58 is removable for use by 4 4 ec 4 4 4e e e 4 4 e e e. 4. e e ee4 e ë e e ee ee-e e e removing a pin seal 60. Removal of the plug 58 reveals an internally threaded portion 62 of the conduit section 54.

A rupture disc 64 is fitted in the conduit section 54 to prevent egress of liquid 8 from the tanker 1 during normal use. This rupture disc 64 is held within a locally wider internal region 66 of the conduit section 54. An O-ring 67 is sandwiched between the rupture disc 64 and the sides of the wider region 66 to provide a complete seal. To withdraw fluid 8 in an emergency, an adaptor is screwed into the threaded portion 62. That adaptor should have a narrower extending part ahead of its threaded portion, which can impact the rupture disc 64 and displace it from its correct location. It will then fall into the cylindrical ring 46 and fluid can flow past.

To check the level of fluid 8 within the tanker, the cap 52 can be removed from the collar 40 to allow access via the apertures 42 and 44.

Figures 7 to 9 show the manner in which the rigid part 15 of the offload conduit is attached to the conductive member 7 at its lower end. A pin 20 extends laterally from the rigid tube 15 towards the rod 17 and is held within a latch arrangement 22. The latch comprises a pendulum 24 secured to the rod 17 by a pivot 26 at its upper end and with a bob weight 28 at its lower end.

Thus, when the tanker is upset, the pendulum 24 will swing about the pivot 26.

The pendulum 26 also has an inverted U-profile catch 30 facing away from the rod 17 opposite the pivot 26, and in normal use the pin 20 extends into the catch 30. Thus, when the tanker 1 is upright, the pendulum 24 is vertical and the sides of the U-profile catch 30 prevent the pin 20 from swinging to either side. The conduit 15 is thus maintained in the vertical position.

As shown in figure 8, the catch is aligned such that the pin 20 is at the same height as the pivot 26. Thus, if the conduit 15 tries to swing, for example under cornering forces, it will exert little or no moment on the pendulum 24 and will not force the catch 30 open. The pendulum 24 will also be affected by cornering forces, but its shorter length means that the amplitude will be less.

t I r e C t The pendulum may also be damped by fluid 8 in the tanker i. Additional damping could be provided if desired.

When the tanker 1 is fully upset, the pendulum will swing by 90 to one side and the catch 30 will likewise rotate to the position shown in figure 9. In this position, the conduit 15 is free to move under the influence of gravity to the position shown in figure 5.

It will be appreciated that many variations may be made to the abovedescribed embodiments without departing from the scope of the present invention.

Claims

. . . . CLAIMS

1. A vessel for containing fluid comprising a port in the vessel wherein one end of a conduit is engaged to the port, the other end being within the interior of the vessel, being flexible along at least a part of its length.

2. A vessel according to claim 1 wherein the port comprises a valve which in normal use closes off the conduit.

3. A vessel according to claim 2 in which the port is on a upper face of the vessel.

4. A vessel according to any one of claims 1 to 3 wherein the engagement means between the port and the conduit allow communication between the conduit and the exterior of the vessel.

5. A vessel according to any of claims 1 to 4 wherein the conduit includes conductive material.

6. A vessel according to any of claims 1 to 5 wherein the conduit includes a composite of conductive and flexible material.

7. A vessel according to any one of claims 1 to 6 in which the at least part of the length of the conduit includes a section adjacent the one end thereof.

8. A vessel according to any one of claims 1 to 6 wherein the at least part of the length of the conduit includes a section remote from the one end thereof.

9. A vessel according to any one of claims 1 to 8 wherein the at least part of the length of the conduit includes a section at the middle thereof.

10. A vessel substantially as hereinbefore described, with reference to the accompanying drawings.

11. A vehicle provided with a vessel according to any one of the preceding claims. c c

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12. An oil tanker provided with a vessel according to any of claims 1 to 10.