WO2008001111A1

WO2008001111A1 - Water jet cutting apparatus

Info

Publication number: WO2008001111A1
Application number: PCT/GB2007/002443
Authority: WO
Inventors: Trevor Richard Fewell; Paul Anthony Fuller; Mathew John Brooks
Original assignee: Bhr Group Limited
Priority date: 2006-06-29
Filing date: 2007-06-29
Publication date: 2008-01-03
Also published as: ATE499182T1; ES2361504T3; EP2038088A1; DE602007012702D1; EP2038088B1; GB0612944D0; DK2038088T3; PT2038088E

Abstract

The present invention relates to water jet cutting apparatus and methods of using same, particularly to manually portable suspension water jet cutting, fire fighting, cleaning, decontamination, surface preparation and decommissioning equipment.

Description

Water Jet Cutting Apparatus

The invention relates to water jet cutting apparatus and methods of using same, particularly to manually portable suspension water jet cutting, fire fighting, cleaning, decontamination, surface preparation and decommissioning equipment.

BACKGROUND Abrasive water jet cutting is a known technology and falls into two main groups:

1. The entrainment system,

2. The suspension system.

The entrainment system, as the name suggests entrains an abrasive into a pre-formed high-pressure water jet, which once mixed and then re-focused is directed towards the work piece. This system's advantages include the ability to turn the abrasive on and off very quickly, effectively stopping the jet from cutting. This is a useful feature when cutting accurate profiles etc. Another feature is that only the pipe and initial jetting head from the high-pressure pump need be rated to the maximum working pressure, and does not include any significant pressure vessels. However, lower cutting efficiency relative to water pressure employed and problems with site-based pneumatic abrasive transfer are this system's main disadvantages.

Suspension systems cut far more efficiently relative to the water pressure employed and nozzle diameter. This is because there are less energy losses within such a system's single jet focusing nozzle. Due to this higher efficiency, the pumps, motors and hoses used for suspension systems can all be much smaller and lighter than those used on an entrainment system with comparable cutting power - making these systems easier to deploy and ideal for use in difficult terrain and/or confined area . However, there are several classical problems associated with these systems. The first is that instead of entraining abrasive at the jetting head immediately before a focusing device and nozzle assembly, the suspension system pressurises and transfers a "ready made" slurry of water and abrasive/additive into the main high-pressure water flow prior to delivery via a single hose (often many hundreds of metres long) to the final jet focusing nozzle assembly. Therefore a slurry vessel of sufficient volume and being designed to sustain the full jet water pressure has to be used with the result that the maximum slurry/additive supply per operation in this type of system is dictated by the volume of the slurry vessel. In general these slurry vessels have been made from steel and when in a several litre configuration weigh many tens of Kg.

The second major problem concerns the speed at which the abrasive flow can be terminated at the work piece. As the slurry is introduced into the high-pressure water upstream of the jet nozzle, if the supply of abrasive is stopped at the slurry vessel, there is still premixed slurry within the main pipe between the module and the nozzle head to be expelled before the cutting stops. Depending on the exact type and design of suspension system being used, the time between turning off the slurry at the vessel and the abrasive ceasing to flow through the nozzle can range from tens of seconds to many minutes.

It has been discovered that for fire fighting, water mists have the ability to control and contain fires and even reduce the intensity of established fires when deployed. However, established fires located within rooms, whether domestic or industrial/marine, become extremely hot and starve their environment of oxygen. This makes entering the hot room via a door or window extremely dangerous because when the fire and the hot material within the room receive a new oxygen supply, it will flare violently. It has been discovered that an in situ water mist system can contain and reduce the intensity of fires. However, if an in situ system is not in place, getting the mist to the fire necessitates a more aggressive approach. This has been accomplished by using suspension water jet cutting to pierce the wall, door or window and then spray a very high-pressure atomising water jet into the room to fight the fire. These systems already exist and are used to fight land-based domestic and industrial fires.

However, these existing systems are vehicle based and the operator simply holds the jetting gun connected via a high-pressure pipe to the pump and slurry module situated on a vehicle which is usually many metres distant. High-pressure slurry-conveying pipes have to_.be sized so the flow is slow enough to stop internal erosion of the pipe during slurry passage. Therefore, these pipes are of a larger diameter and thicker wall section than would be required to just carry clean water at equivalent flows and pressures. This makes the existing slurry pipes significantly heavier and stiffer and less deployable than their clean water equivalents.

Therefore, the operator of such systems is limited to a degree by the length of pipe they can manually deploy and the fact that they have to be within a vehicle support arena.

Again, as was discussed earlier, the rate of abrasive termination within these systems will be many seconds or even minutes and when considering the possibility of casualties being in the room the jet is piercing, minimising the potential exposure to an abrasively enhanced water jet is of obvious benefit.

It is an object of the invention to seek to mitigate these disadvantages.

According to one aspect of the invention, there is provided apparatus for fluid jet blasting of a workpiece, comprising a module for containing slurry and adapted to be handled manually by an operator.

Preferably, the pressurisable vessel contains an abrasive slurry.

Preferably, the pressurisable vessel additionally contains chemical agents. For example, chemicals such as viscosity enhancers can be used to assist abrasive particulate slurry matter to remain in suspension. Alternatively, foaming agents and/or fire retardant chemicals can be contained in the pressurisable vessel.

Preferably, the apparatus is configured such that in-use the pressurisable vessel is at a pressure of at least 200 bar, more preferably at least 250, 300, 250, 400, 450 or 500 bar. Preferably, the other components of the apparatus are in-use at a fluid pressure of at least 200 bar, more preferably at least 250, 200, 250, 400, 450 or 500 bar. The apparatus may be adapted for portability for example by being carried by an operator, for example on an operator's back.

Preferably, the pressurisable vessel is readily removable and connectable with the apparatus in order to allow for the convenient interchange of vessels when for example a first one is exhausted. Preferably, the in-use interchange of first and second pressurisable vessels can be done in less than 60 seconds, more preferably less than 30, 15, 10 or 5 seconds. Preferably, the pressurisable vessel comprises a pressurisable vessel and a vessel cap.

Preferably, apparatus according to the present invention are also supplied in kit form with an at least one additional pressurisable vessel, for example containing abrasive slurry. This provides the distinct advantage that upon exhaustion of the contents of a first pressurisable vessel, it can be quickly and conveniently removed and replaced with another pressurisable vessel.

Alternatively, the apparatus can be put to an alternate use by the replacement of a first pressurisable vessel with a second pressurisable vessel containing different material, e.g. for nuclear decontamination, biological decontamination, chemical decontamination; or alternatively for surface cleaning or preparation, or paint cleaning preparation.

Preferably, the pressurisable vessels of the present invention are pre-filled and sealed in order to reduce or prevent tampering.

Preferably, the connection means is a quick connection means, thus allowing the quick and convenient connection and disconnection of the apparatus from a static water main.

In certain embodiments, the apparatus is mounted upon carrying apparatus, such as a backpack frame.

In certain embodiments, the apparatus also comprises breathing equipment. For example, apparatus for use by fire fighters can comprise an additional oxygen/air bottle, together with breathing apparatus. Thus, the apparatus can perform a dual function of enabling effective and convenient blasting, whilst at the same time allowing a user to work in a hostile environment such as a smoke-filled environment independent from an outside air supply.

According to a second aspect of the invention, there is provided a system for fluid jet blasting of a workpiece, comprising:

(i) a main for water under pressure; (ii) at least one connection point spaced therealong; and (iii) apparatus for fluid jet blasting of a workpiece, said apparatus comprising a module for containing slurry and adapted to be handled manually by an operator, and adapted for connection with said at least one connection point.

In the various aspects of the present invention, the main is preferably a static main.

Preferably, the fluid jet blasting apparatus being configured to be switchable between:

(a) a first state in which said slurry from said module and said water from said main are mixed to generate said fluid blasting jet; and (b) a second state in which a water jet is generated from said water from said main.

Preferably, the fluid jet blasting apparatus being fluid jet cutting apparatus and being configured to be switchable between: (a) a first state in which said slurry from said module and said water from said main are mixed to generate a suspension cutting jet; and

(b) a second state in which a water jet is generated from said water from said main, said method comprising the steps of: (i) with said fluid jet cutting apparatus set to said first state, fluid jet cutting said workpiece with said suspension cutting jet; and

(ii) with said fluid jet cutting apparatus set to said second state, fighting said fire with said water jet. According to a further aspect of the invention, there is provided a ship including a system as hereinbefore defined.

Thus, using the invention the best method for reducing the time of abrasive termination is to bring the pressurisable vessel for containing a solid-fluid mixture or fluid-fluid mixture to a position as close as possible to the jetting nozzle. To do this, the pressurisable vessel is located adjacent to the nozzle, so that when the slurry/additive flow is terminated, the active remaining length of pipe containing the slurry/additive is minimised, for example is reduced to as little as 1 metre or less.

Preferably, a lightweight high-pressure pressurisable vessel is used, for example fabricated in the manner of a diving/breathing air bottle, for example steel-, aluminium- or titanium-lined bottle with a spun carbon fibre outer. Typically, such bottles can weigh a factor of two or more time less than their steel equivalents. This makes the backpack weight when fully charge less than 25 Kg, which is within the manual handling limits. Indeed, apparatus according to the present invention have been constructed having a total mass (including slurry) of less than 15 Kg.

Other development work has demonstrated that the highly efficient slurry suspension system can cut steelwork up to 1/2" (12.7mm) thick at reasonable rates and for sufficient time to pierce with a 300 bar (30000 kPa) 2.5 litre pressurisable vessel. This makes the pressure threshold a more realistic target for a composite pressurisable vessel to sustain.

One use of this invention is for the Marine and/or Naval environment where a ship-wide high-pressure water main is present. Apparatus according to the present invention can be located around the ship in a similar fashion to conventional fire extinguishers. When a fire is detected, an operator can transfer apparatus to the fire's location, plug the unit into the nearest high-pressure hydrant and pierce the bulkhead or door of the room encompassing the fire. Once the jet has ceased to back spray (a classic indication that piercing has occurred), the operator can immediately (i.e. in fractions of a second rather than seconds or minutes) stop the abrasive and further risk to personnel within the target room. After drenching the room with mist, other fire fighters can enter the room to dowse down with conventional fire fighting hoses.

The apparatus of the present invention are useful in a wide variety of applications, including abrasive jet cutting, slotting, machining, milling and other processes of material removal or dissection, grit blasting, bead blasting, wet blasting, nuclear decontamination, biological decontamination, surface cleaning or preparation, paint cleaning preparation, and chemical decontamination.

The invention will be further apparent from the following examples with reference to the accompany figures which show by way of example only forms of apparatus for fluid jet cutting of workpiece, systems for fighting a fire, and ships equipped with same. Of the Figures:

Figure 1 shows a schematic layout of apparatus according to the present invention;

Figure 2 is a photograph of apparatus according to the present invention;

Figures 3-11 shows alternative embodiments of the present invention; and Figures 12-14 show views of a backpack fluid jet blasting apparatus according to the present invention.

Referring to the schematic layout of apparatus embodying the invention shown in Figure 1, fluid jet cutting, cleaning or blasting apparatus 10 comprises connector 20 for connection to a connection point (not shown) of a static water main (not shown), high pressure water isolation valve 30, system control manifold 40, safety relief valve 50, pressure meter 60, slurry/additive water feed 70, abrasive control orifice 80, bypass line 85, abrasive control valve Vl, pressurisable vessel assembly 100 comprising pressurisable vessel 90 and vessel cap assembly 95, abrasive/additive outlet line 110, shutdown control valve V2, water line 120, abrasive/additive/water mixing tee 130, and outlet nozzle 140.

Apparatus 10 is provided in the form of a backpack, with nozzle 140 configured to be hand-held for convenient direction and control in use. Alternatively, in-use nozzle 140 can be connected to a manipulation device. In use, connection means 20 is connected to a static water main (not shown) in order to provide the required water supply. Pressurisable vessel 90 is loaded with a volume of abrasive slurry. In a first suspension cutting jet state, valve 30 is open, valve V2 is open and valve Vl is closed. Water enters apparatus 10 through connector 20, passes through valve 30 and enters system control manifold 40 where it is split into first and second feeds. The first feed passes via water line 120 to abrasive/water mixing tee 130. The second feed passes along slurry water feed 70 to abrasive control orifice 80, and is prevented from flowing along bypass line 85 by valve Vl which is closed. Instead, the water flows from abrasive control orifice 80 to pressurisable vessel assembly 100 where the second feed mixes with abrasive to give a mixture of water and abrasive which then flows along abrasive outlet line 110 through valve V2 to slurry/water mixing tee 130.

At slurry/water mixing tee, the first and second feeds are mixed and exit the apparatus 10 at outlet nozzle 140 in the form of a high-pressure suspension jet of abrasive slurry.

The apparatus is configured such that the pressurisable vessel assembly 100 is at an in- use pressure of at least 250 bar, and the suspension jet of abrasive slurry exits the apparatus through nozzle 140 at a pressure of at least 250 bar.

In a second water jet state, valve Vl is open and/or valve V2 is closed. With valve V2 closed, fluid flow through the valve is prevented and so the only route for fluid to exit apparatus 10 is via water line 120 to nozzle 140 where a water jet is produced. With valve Vl open, water passing along slurry water feed 70 enters abrasive control orifice 80 and is able to continue to flow along bypass 85 back to system control manifold 40 which it then exits via water line 120. The pressure that has to be exerted upon pressurisable vessel assembly 100 to effect a fluid flow through abrasive outlet line 110 to slurry/water mixing tee 130 is such that the flow of water is preferentially along bypass 85.

In use, an operator has two options available to stop abrasive flow. The first is to open valve Vl, which will allow the clean water component previously diverted through abrasive control orifice 80 to be immediately re-mixed with the main flow water at system control manifold 40. Valve Vl only ever sees clean water. The second option available is to terminate the abrasive flow slightly more quickly than with the first option, and is to close valve V2 which is located on the abrasive outlet line 110 of pressurisable vessel assembly 100. Valve V2 will therefore see slurry during closure and to ensure full functionality and safe future operation can be replaced every time it is used to stop abrasive flow.

The apparatus (Figure 2) can be used with different slurries and/or other chemical agents for multiple tasks that are useful onboard a ship or elsewhere. Grit blasting and abrasive/additive cleaning are two other such tasks. Paint stripping and chemical decontamination are also possibilities. To have this flexibility and immediately ready- for-use facility, the backpack is stored with the required pressurisable vessel containing abrasive in place.

If the apparatus is to be used in an application that requires a non-abrasive material to be supplied from the pressurisable vessel 90, vessel 90 (or pressurisable vessel assembly 100) containing slurry can be conveniently swapped for another vessel containing the desired materials/chemicals.

Once used, the pressurisable vessel 90 or pressurisable vessel assembly 100 is replaced with a fully charged pressurisable vessel 90 or pressurisable vessel assembly 100 . These pressurisable vessel assemblies 100 can include the required fluid mixing module which will ensure that the correct percentage of added material is mixed with the clean water depending on the task required and the characteristic of the added material.

The manual valves Vl, V2 and 30 mean that the apparatus is immune to power failures or interference and is not prone to breakdown, and is also simple to operate and maintain.

In certain embodiments, the apparatus is not carried by an operator, but instead is mounted upon apparatus such as a wheeled frame. In certain embodiments, such an arrangement is provided with additional pressurisable vessels 90 or pressurisable vessel arrangements 100. in certain embodiments, an additional pump such as a petrol, diesel or electrically powered pump is provided in order to ensure adequate water pressure.

In Figures 3-11, alternative embodiments are shown. Common reference signs are as follows:

Rl - main flow restrictor/orifice

R2 - abrasive control restrictor/orifice

R3 - diffuser flow restrictor/orifice

Gl - pressure gauge/sensor Pl - pressurisable vessel assembly

Vl — as above

V2 - as above

V3 - module/back-pack isolation valve

V4 - emergency depressurisation valve V5 - first flow isolation valve

V6 - non-return valve

Figures 12-14 show various perspective views of a backpack fluid jet blasting apparatus according to the present invention. As will be noted, there are two "bottles" on the backpack, the first being the pressurisable vessel 90, and the second being an oxygen bottle 200 for breathing apparatus (not shown). Thus, a fire fighter wearing the apparatus of Figures 12-14 and wearing the

As the apparatus is an inert piece of high-pressure pipe work with manual valves, it is resistant to EMP, chemical and biological warfare and possesses no EMC/EMF signature.

Advantages:

1. A portable fire fighting backpack unit, preferably weighing less than 25 kg. More preferably less than 15 kg.

2. As for 1 with a pressurisable vessel / pressurisable vessel assembly.

3. As for 1, with a composite pressurisable vessel / pressurisable vessel assembly. 4. As for the above with a hand held gun held by the same operator so as to minimise the hose length.

5. As for 1 with an emergency shut off valve Vl, in the clean water slurry bypass line, to cut off water flow to the slurry module. 6. As for 1 with an emergency shut off valve V2, in slurry located at top of slurry outlet (sacrificial valve) to be replaced with each module change.

7. As for all of the above with a modularised system for fire fighting, cutting, cleaning and decontamination.

8. As for all of the above, the pressurisable vessel / pressurisable vessel assembly will be replaceable and can be filled with various material ranging from cutting abrasive to grit blasting beads to chemical cleaning solvents, foaming agents, retardant chemicals, neutralising materials and decontamination chemicals.

9. As for 8 with the pressurisable vessels being fitted with a vessel cap assembly incorporating a calibrated mixing device designed to mix the correct percentage of each required abrasive/additive into the clean water flow.

10. As for the above but the pressurisable vessels/ pressurisable vessel assemblies are filled with polymerically enhanced water so as to maintain suspension during storage.

11. As for the above when the system is fitted with a pressure gauge which is in sight or hearing of the operator or operators assistant during operation, pressurisable vessel assembly change-over or maintenance .

12. As for the above when the backpack is fitted with a ballistic back protection shield in case of mechanical failure of the pressure module.

13. As for the above combined with and using a high-pressure clean water source. 14. As for the above using a high-pressure lightweight high-pressure clean water hose.

The teaching within this document explains how through use of design and novel material technologies the most efficient water jet cutting technology has become a viable portable system that can perform vital military and civilians tasks. It will be appreciated that it is not intended to limit the invention to the above examples only, other embodiments being readily apparent to one of ordinary skill in the art without departing from the scope of the appended claims.

Claims

1. Apparatus for fluid jet blasting of a workpiece, comprising a module for containing slurry and adapted to be handled manually by an operator.

2. Apparatus according to claim 1, being adapted to be portable.

3. Apparatus according to claim 2, adapted to be carried by an operator.

4. Apparatus according to any of the preceding claims, wherein in-use the fluid is water.

5. Apparatus according to claim 4, additionally comprising connection means for connection with a fluid supply connection point.

6. Apparatus according to any of the preceding claims, the fluid jet blasting being selected from the group consisting of: abrasive jet cutting, grit blasting, bead blasting, wet blasting, abrasive surface cleaning or preparation, and paint cleaning preparation.

7. A system for fluid jet blasting of a workpiece, comprising: (i) a main for water under pressure; (ii) at least one connection point spaced therealong; and (iii) apparatus for fluid jet blasting of a workpiece, said apparatus comprising a module for containing slurry and adapted to be handled manually by an operator, and adapted for connection with said at least one connection point.

8. A system according to claim 7, the fluid jet blasting being selected from the group consisting of: abrasive jet cutting, grit blasting, bead blasting, wet blasting, abrasive surface cleaning or preparation, and paint cleaning preparation.

9. A system according to claim 7 or 8, said fluid jet blasting apparatus being configured to be switchable between:

10. A system according to any of claims 7-9, being a system for fire fighting.

11. A system according to claim 10, said fluid blasting j et being fluid j et cutting.

12. A system according to claim any of claims 7-11, comprising a plurality of connection points.

13. A system according to any of claims 7-12, the apparatus being adapted to be portable.

14. A system according to claim 13, the apparatus being adapted to be carried by an operator.

15. A ship including a system according to any of claims 7-14.

16. A method of fluid j et blasting of a workpiece, comprising with:

(i) apparatus for fluid jet blasting of a workpiece, said apparatus comprising a pressurisable vessel for containing slurry and adapted to be handled manually by an operator, and adapted for connection with an at least one fluid supply connection point; (ii) a main for water under pressure; and (iii) at least one connection point spaced along said main, with said apparatus connected to a connection point of said main, operating said fluid jet blasting apparatus such that a fluid blasting jet is generated with said slurry from said module and water from said main, and blasting said workpiece with said fluid blasting jet.

17. A method according to claim 16, the fluid jet blasting being selected from the group consisting of: abrasive jet cutting, grit blasting, bead blasting, wet blasting, abrasive surface cleaning or preparation, and paint cleaning preparation.

18. A method according to claim 16 or 17, said fluid jet blasting apparatus being configured to be switchable between:

19. A method according to any of claims 16-18, being a method of fire fighting.

20. A method according to claim 19, said fluid blasting jet being fluid jet cutting.

21. A method according to claim 20, said fluid jet blasting apparatus being fluid jet cutting apparatus and being configured to be switchable between:

(a) a first state in which said slurry from said module and said water from said main are mixed to generate a suspension cutting jet; and

(b) a second state in which a water jet is generated from said water from said main, said method comprising the steps of:

(i) with said fluid jet cutting apparatus set to said first state, fluid jet cutting said workpiece with said suspension cutting jet; and

(ii) with said fluid jet cutting apparatus set to said second state, fighting said fire with said water jet.

22. A method according to claim 21, wherein in said second state, said water jet is a spray or mist.

23. A method according to any of claims 16-22, said main comprising a plurality of connection points.

24. A method according to any of claims 16-23, said apparatus being adapted to be portable.

25. A method according to claim 24, said apparatus being adapted to be carried by an operator.