GB1568654A

GB1568654A - Molten metal pouring equipment

Info

Publication number: GB1568654A
Application number: GB826778A
Authority: GB
Original assignee: Flogates Ltd
Current assignee: Flogates Ltd
Priority date: 1978-03-02
Filing date: 1978-03-02
Publication date: 1980-06-04

Description

(54) MOLTEN METAL POURING EQUIPMENT (71) We, FLOGATES LIMITED, a British Company of Sandiron House, Beauchief, She eld, S7 GRA, do hereby declare the invention, for which we pray that a patent nay be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment: - The present invention relates to molten metal pouring equipment, and more particularly to improved sliding gate valves and components thereof.

According to one aspect of the invention, there is provided a stationary valve plate for use in a sliding gate valve for controlling molten metal flow, the stationary plate in use having its underside in contact with a slidable valve plate operable to control the flow through the valve, the stationary plate being made from flat steel plate and having an orifice inset from its periphery in which an annular refractory insert is retained, the insert being flush with the underside of the stationary plate and at least the underside of the steel plate being in a surface hardened condition.

According to another aspect of the invention, there is provided an assembly comprising a valve-mounting plate and a stationary valve plate, for use in a sliding gate valve which has a slide plate mounted to slide in contact with the underside of the stationary valve plate to control molten metal flow through the valve, wherein the mounting plate and the stationary valve plate are elongated members made from flat steel plate each having an orifice therein inset from its periphery in which a respective annular refractory insert is retained, the insert of the stationary valve plate being flush with the underside thereof and at least the underside of the stationary valve plate being in a surface hardened condition, the assembly further including means for clamping the mounting and stationary valve plates in face-to-face contact with their respective inserts coaxially in register.

The invention also provides a sliding gate valve including a stationary plate or an assembly, as defined in the respective two preceding paragraphs, an orificed slide plate, and means biasing the slide plate into firm face-to-face contact with the underside of the stationary valve plate, the slide plate being movable reciprocally to and fro along a path of a given length to open and close the valve, and the stationary valve plate being dimensioned larger than the path swept by the slide plate whereby, during reciprocation, the slide plate remains fully in supported contact with the overlying stationary valve plate. The valve slide plate may have a plurality of orifices and a plurality of discharge or teeming nozzles, for instance two of each, the orifices and nozzles optionally being of different bore sizes.

The valve can be of the three-plate type, in which case it has three orificed valve plates comprising the said stationary valve plate, a slide plate and a stationary lower valve plate. The slide plate of such a valve is sandwiched between the said stationary valve plate and lower plate. The latter plate is upwardly biased, to cause the three valve plates to be pressed firmly into faceto-face contact with one another.

In the aforementioned assembly, the clamping means can comprise lugs on one plate and cam-locking devices cooperable therewith on the other plate, the lugs and cam-locking devices being arranged to develop progressively increasing clamping forces when the said devices are moved for clamping the plate together. Conveniently, the said devices are pivotally attached to the underside of the mounting plate and the lugs project from the periphery of the stationary valve plate. The positioning means can comprise abutments depending from the mounting plate for engagement by the periphery of the stationary valve plate.

The steel plate forming the stationary valve plate can be hardened in any convenient way such as by work-hardening it.

Preferably, however, the underside of the steel plate is flame hardened, carburized or nitrided to achieve the surface hardened condition. The upper surface of the plate can also be hardened.

Since the refractory insert in the stationary valve plate is exposed to flowing molten metal, it degrades owing to wear and erosion attack. The insert is therefore advantageously replaceably fitted in the plate by means of readily-strippable bonding agents, such as frangible heat-resisting cements or refractory mastic compositions, to allow the insert to be pushed out easily when it needs replacing. Mastic compositions may be preferable since they are well able to accommodate differential thermal expansion between the insert and the steel plate. Desirably, the mounting plate insert is likewise replaceably retained in its setting in the mounting plate orifice.

The underside of the stationary valve plate may in use become worn in the region swept by the orifice area of the slide plate, from any of several causes. The said region could advantageously be furnished with a a wear-resisting contact surface for the slide plate. In a preferred embodiment, therefore, the underside of the stationary valve plate may have one or a pair of recesses which extend away from the plate orifice, and a flat refractory element is secured in the or each recess to form a contact surface for a slide plate. The refractory element(s) can be detachably secured by a suitable cement or mastic bonding agent.

As an alternative, hardened, flat metal element(s) may be used and removably secured for instance by screws or other fastenings such as rivets. Steel elements are potentially cheaper than refractory elements and may be preferred for this reason.

Advantageously, direct contact is minimised between molten metal and refractory parts of a valve, including the stationary valve plate insert, to reduce the likelihood of deposits from the molten metal accumulating and leading to flow blockage.

To achieve this end of minimising direct contact, an enveloping gas curtain may be developed around the flowing metal. Accordingly, it is a preferred feature of the invention to provide the stationary valve plate with a gas supply channel extending through the steel plate to the insert, for conveying a pressurised gas into the refrac tory insert, which is internally grooved, or is gas permeable, or is furnished with an inner gas-permeable lining in use for creating a gaseous shroud between flowing molten metal and the inner wall of the annular insert. If gas such as argon is fed to the insert at a high enough pressure and flow rate, the gas shroud may be caused to ex tend- through the orifice of the associated slide plate and through a depending teeming nozzle, thereby protecting both the said orifice and the nozzle from blockage.

Finally, the invention embraces a molten metal pouring vessel such as a ladle or tundish when fitted with a sliding gate valve according to the invention.

The present invention will now be described in more detail by way of example only with reference to the accompanying drawings, in which: Figure 1 is a partial cross-sectional view of a ladle fitted with a sliding gate valve to which the present invention can be applied, Figure 2 is a plan view from underneath of a sliding gate stationary valve plate embodying the invention, and shows the associated valve mounting plate to which the head plate is secured, Figure 3 is a part-sectional, part-elevational view of the valve and mounting plates, taken along the line III-III of Figure 2, and Figures 4A and 4B are schematic views showing the relative positions of the stationary valve plate and a twin-nozzle slide plate in a valve-closed and a valve-opened setting, respectively.

In Figure 1 there is shown a ladle 10 having a metal casing 11 containing a refractory lining 12. The ladle 10 has a bottom-pour opening including a well 13 and nozzle 14. A mild steel mounting plate 15 provides a means for locating the nozzle 14 and a stationary orificed valve or head plate 16 of a sliding gate valve such that the nozzle passage and the orifice of plate 16 are concentric.

Flow of metal through the bottom-pour opening is controlled by the sliding gate valve 23. The valve 23 has an orificed, reciprocal slide plate 24, which is slidable to and fro under the stationary orifice plate 16 to open and close the valve to metal flow. Movement of the slide plate 24 is gained by a push/pull rod 25 operated by an actuator, not shown. The slide plate 24 is biased into face-to-face, sealing engagement with the underside of the stationary head plate 16 by a plurality of springs 26. A depending discharge nozzle 28, through which a jet or stream of molten metal issues when the valve is open, is secured to the slide plate 24.

It will be understood that the valve 13 is shown closed in Figure 1, the passage through the slide plate 24 and the nozzle 28 being out of registry with the orifice of the stationary plate 26. The valve is fully open when the said passage is moved into exact registry with the orifice of the stationary plate 16. The slide plate 24 serves to vary the flow of molten steel when it is moved to intermediate positions partially covering the orifice of the stationary plate 16.

The illustrated valve 23 is known. With the exception of their conventional metal encasing members, not referenced, the stationary head plate 16, the slide plate 20 and the nozzle 28, are made wholly from refractory materials. A high-density alumina refractory containing 85-95% Awl203 is suitable for the head plate 16 and the slide plate 24.

In accordance with the invention, we propose that the valve 23 be modified by replacing head plate 16 by the head plate 30 seen in Figures 2 and 3. The head plate 30 is secured to the underside of a stationary valve mounting plate 31 also seen in Figures 2 and 3. The assembly comprising plates 30, 31 includes positioning means 32 for the plate 30 and means 33 for clamping the plates together.

Head plate 30 comprises an orificed, generally rectangular flat steel plate 34 having a refractory insert 35 detachably bonded in its centrally-disposed orifice 36.

The steel plate 34 has its opposite surfaces ground parallel and smooth, and at least the lower one 38 of the surfaces is in a surface hardened condition. Such a condition can be achieved by any conventional hardening techniques. Flame hardening or hardening by carbonizing or nitriding may be chosen. The orifice 36 is tapered frustoconically from the upper surface of plate 30 towards an inwardly-directed, insert-retaining lip 39. Insert 35 is an annular member having a parallel sided bore 40, through which metal flows during pouring, and an external periphery 41 which corresponds in shape with the wall of the orifice 36. The insert is detachably bonded in the orifice by a frangible heat-resisting cement or a refractory mastic composition. So bonded, the insert can be pushed upwardly out of the orifice (after detaching the head plate 30 from the mounting plate) when wear, erosion or bore blockage make replacement of the insert necessary. The preferred bonding agents are ones which stip clearly from the orifice wall. The bottom end 42 of insert 35 is ground flat and coplanar with the underside 38 of plate 34.

The insert has its top end 43 stepped to mate with a stepped bottom end 44 of a refractory insert 45 in the mounting plate 31.

The plate 30 extends lengthwise either side of orifice 36 for such distances that a slide plate of a valve for which plate 30 is intended remains fully in contact with the underside 38 of plate 30 throughout reciprocation of the slide plate. Hitherto, slide plates and head plates have been of generally the same shapes and sizes. Thus, in prior constructions having a central, singleorificed slide plate, for instance, the plate is only in full supported contact with the companion head plate in a valve-open setting. Displacement of the prior slide plates to close their valves resulted in them projecting sideways beyond the ends of their head plates. In this condition, the slide plates are only partially supported against the head plates. Since spring means are provided to bias the slide plates against the head plates, such partial support causes uneven biasing of the slide plates. In turn, distortion of parts of the valve could occur.

Moreover, since refractory slide plates are generally weak and brittle, they have had to be heavy, thick members to withstand the effects arising from such partial support without distorting or breaking.

In contrast, by making the head plate 30 at least as long as the distance swept by the associated slide plate during reciprocation, and generally longer, complete support of the slide plate can be attained. If the head plate 30 or tfie assembly of plates 30, 31 is made sufficiently rigid, the complete support afforded by plate 30 makes possible some reduction in the thickness of the slide plate. Slide plate refractories are both dense and costly, so valuable savings in weight and expense may result thanks to the advantageous support provided by head plate 30.

For use in a valve which features a single orificed slide plate, head plate 30 may only need to be extended to one side of its orifice 36.

For certain other valves which feature either single or multi-orificed slide plates, head plate 30 will be extended lengthwise in opposite directions either side of orifice 36. The illustrated head plate 30 is so extended, and can be used with a twinorificed, twin-nozzle slide plate 50 as schematically shown in Figures 4A and 4B.

These Figures show the complete support afforded to slide plate 50 in the valve-closed setting (Figure 4A) as well as in either of the valve-opened setting for metal flow through either of nozzles 51, 52.

Experience may show that the underside 38 of head plate 30 wears along a track swept for instance by the orifice region of the slide plate. The effects of such wear can be mitigated by furnishing the underside 38 with wear-resisting means. To this end, the underside 38 of the plate 30 (which is designed for use with a twin-nozzle slide plate) may be recessed in the areas enclosed by the chain dotted lines 55. Flat plates of refractory material e.g. chemically bonded or fired, or very dense preformed zirconia plates may be bonded in the recesses to form wear-resisting contact surfaces for the slide plate. Suitably hard metal plates, e.g.

of steel may be used instead, secured in place by fastening such as screws or rivets.

The wear-resisting plates need not cover the full area swept by the slide plate during reciprocation. In some instances where the slide plate has a single orifice, only one recess and one wear-resisting plate disposed to one side of orifice 36 may be needed.

The thickness of the or each wear-resisting plate need not be great, thus minimising expense when made from costly refractory material, owing to the support afforded by the remaining thickness of the steel plate 34, aided by the mounting plate 31.

The mounting plate 31 comprises a generally rectangular flat steel plate 57 having a central orifice 58 in which the refractory insert 45 is secured. Insert 45 is bonded in orifice 58 and has an external periphery corresponding to the wall of orifice 58. The said periphery and wall are similar to the form of the periphery of insert 35 and the companion wall of orifice 36 in the head plate. The insert 45 is preferably a pushout item, normally retained in the plate 57 by an easily strippable frangible cement or mastic composition.

The positioning means 32 serve to assist the maker or user when assembling the plates 30 and 31 to obtain registry between the bores of the inserts 35 and 45. The positioning means comprise a plurality of depending abutments secured to plate 57 for engagement by the side and end edges of plate 34. Pins or studs conveniently form the abutments. As shown, there are two pins or studs for each side and each end of plate 34.

The clamping means 33 serve to draw the head plate 30 tightly against the underside of the mounting plate, and comprise a plurality of cam-locking devices 60. These devices are pivoted to one of plate 34, 57 and engage suitable lugs 61 on the other of said plates. When pivoted towards a clamping position, the devices 60 exert progressively increasing clamping forces owing to ramped or wedged interfit with the lugs 61.

As shown, the devices 60 are pivoted to plate 57 and the lugs 61 are formed by ears projecting outwardly from the periphery of plate 34, there being four such devices and corresponding lugs. The positioning of the clamping means is selected so as to obtain clamping forces of optimum uniformity on the two plates.

When pouring many metals, and in particular Al-killed steels, it is desirable to minimise contact between the metal and refractory valve parts. One way of minimising such contact is by developing an enveloping curtain or shroud of an inert gas, such as argon, about the flowing metal.

Means to create such a curtain are shown in Pighre 2 A channel 63 is formed in plate 34 to convey pressurized gas from a gassupply connection nipple 64 into the insert 33 channel 63 communicates with an encircling grove 65 in the wall of orifice bore 40. The insert 35 need not have such a groove if it were made of a gas permeable refractory material. Alternatively, the insert could have an impermeable refractory body having an inner lining of a gas-permeable refractory sleeve, with which the channel 63 is in communication.

The refractory parts including the inserts 35, 45, the slide plate and its nozzle(s) can be made from materials conventionally adopted, such as high density 85-90 weight to alumina. The inserts should have sufficient thickness to have a suitably long service life and to withstand thermal shock.

By way of example, an insert 35 may have a bore diameter of 100 mm, and a wall thickness of approximately 70 mm if made from alumina. Its length, between faces 41 and 42 may be approximately 60 mm. The steel plate 34 may be approximately 50 mm thick, 1095 mm long and 265 mm across its narrower part. Across its wider central part, plate 34 may be 320 mm in width.

The lives of the inserts 35, 45 could be extended by lining them with inner zirconia sleeves which are highly wear and erosion resistant.

Thanks to the head plate construction described above, considerable cost savings are possible by minimising the amount of expensive refractory material needed. The steel plate 34 may be re-used many times by replacing its insert periodically. Since the steel of which the head plate is made is substantially tougher than conventional allrefractory head plates, the mounting plate 31 need not be so massive and heavy. This is because of the backing provided therefor by the head plate. Lighter mounting plates are cheaper and easier to handle, therefore.

If desired, the head plate can be fitted with one or more lifting attachments exemplified by the screw eye 70 to aid handling during servicing of the valve.

Whilst the drawings show a two-plate valve in Figure 1, the invention is equally applicable to a valve having three valve plates, namely a stationary head plate, a stationary bottom plate and an intermediate side plate sandwiched therebetween.

The said valve plates are urged into firm facial contact with one another by spring means such as coil springs 26 which press upwardly on the bottom plate.

It has been disclosed hereinbefore that the surface area of the valve head plate may be recessed at 55 and furnished with a refractory material. Such a recess can be filled with wear and erosion-resistant materials by thermal spraying techniques.

The area of the upper surface of the slide plate 50 which is contactable with molten metal during reciprocation of the slide plate may similarly be recessed and provided with a protective layer of thermally-sprayed re fractory material. Plasma-spraying is pre ferried. Suitable materials for spray deposition in the recess include low-friction ma tcrial of refractory nature such as metalgraphite composites and low-friction sintered materials refractories e.g. of high thermal conductivity, dense refractories such as 8Q95610 Awl203 or zirconia, and carbides such as cobalt, nickel, chromium and tungsten carbide.

The sprayed refractory can be selected from fused alumina, which has good resistance to chemical and mechanical erosion and gives excellent thermal protective coat ings, zircon, which are hard and resist wetting by molten metals well, zirconia, which is useful for protection against higher temperatures than alumina and is chemically stable toward molten metals, chromia, which produces dense wear-resistant and low friction coatings, titania, which gives a hard coating resistant to molten metals, and magnesite, which has excellent resist ance to molten metals.

The sprayed refractory can also be selected from mixed oxides, including inter alia alumina-titania and alumina-chromia.

The sprayed refractory could further comprise a directly-sprayed cermet or a plurality of alternately sprayed layers of metal and refractory material; the deposit could be selected from calcium, strontium, barium and magnesium zirconates, cobaltzirconia and magnesium aluminates.

The sprayed refractory could moreover be selected from refractory silicides, borides, nitrides and carbides.

WHAT WE CLAIM IS: 1. A stationary valve plate for use in a sliding gate valve for controlling molten metal flow, the stationary plate in use having its underside in contact with a slidable valve plate operable to control the flow through the valve, the stationary plate being male from flat steel plate and having an orifice inset from its periphery in which an annular refractory insert is retained, the insert being flush with the underside of the stationary plate and at least the underside of the steel plate being in a surface hardened condition.

2. A valve plate according to Claim 1, wherein the underside of the steel plate is flame hardened, carburized or nitrided to achieve the surface hardened condition.

3. A valve plate according to Claim 1 or Claim 2, wherein the upper surface of the steel plate is also in a surface hardened condition.

4. A valve plate according to Claim 1, 2 or 3, wherein the refractory insert is detachably retained in the plate orifice by frangible heat-resisting cement.

5. A valve plate according to Claim 1, 2 or 3, wherein the refractory insert is detachably retained in the plate orifice by a refractory mastic composition.

6. A valve plate according to any one of the preceding claims, wherein the plate orifice is frusto-conically tapered and the insert has a correspondingly tapered outer peripheral surface.

7. A valve plate according to any one of the preceding claims, wherein the underside of the steel plate has one or a pair of recesses which extend away from the plate orifice, and a flat refractory element is secured in the or each recess to form a contract surface for a slide plate.

8. A valve plate according to any one of the preceding claims, including a gas supply channel extending through the steel plate for conveying a pressurised gas into the refractory insert, which is internally grooved, or is gas permeable, or is furnished with an inner gas-permeable lining, in use for creating a gaseous shroud between flowing molten metal and the inner wall of the annular insert.

9. An assembly comprising a valvemounting plate and a stationary valve plate, for use in a sliding gate valve which has a slide plate mounted to slide in contact with the underside of the stationary valve plate to control molten metal flow through the valve, wherein the mounting plate and the stationary valve plate are elongated members made from flat steel plate each having an orifice therein inset from its periphery in which a respective annular refractory insert is retained, the insert of the station ary valve plate being flush with the underside thereof and at least the underside of the stationary valve plate being in a surface hardened condition, the assembly further including means for clamping the mounting and stationary valve plates in face-to-face contact with their respective inserts coaxially in register.

10. An assembly according to Claim 9, wherein the clamping means comprise lugs on one plate and cam-locking devices cooperable therewith on the other plate, the lugs and cam-locking devices being arranged to develop progressively increasing clamping forces when the said devices are moved for clamping the plates together.

11. An assembly according to Claim 10, wherein the said devices are pivotally attached to the underside of the mounting plate and the lugs project from the periphery of the stationary valve plate.

12; An assembly according to Claim 9, 10 or 11, wherein the positioning means comprises abutments depending from the mounting plate for engagement by the periphery of the stationary valve plate.

13. An assembly according to Claim 9, 10, 11 or 12, wherein the underside of said

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. fractory material. Plasma-spraying is pre ferried. Suitable materials for spray deposition in the recess include low-friction ma tcrial of refractory nature such as metalgraphite composites and low-friction sintered materials refractories e.g. of high thermal conductivity, dense refractories such as 8Q95610 Awl203 or zirconia, and carbides such as cobalt, nickel, chromium and tungsten carbide. The sprayed refractory can be selected from fused alumina, which has good resistance to chemical and mechanical erosion and gives excellent thermal protective coat ings, zircon, which are hard and resist wetting by molten metals well, zirconia, which is useful for protection against higher temperatures than alumina and is chemically stable toward molten metals, chromia, which produces dense wear-resistant and low friction coatings, titania, which gives a hard coating resistant to molten metals, and magnesite, which has excellent resist ance to molten metals. The sprayed refractory can also be selected from mixed oxides, including inter alia alumina-titania and alumina-chromia. The sprayed refractory could further comprise a directly-sprayed cermet or a plurality of alternately sprayed layers of metal and refractory material; the deposit could be selected from calcium, strontium, barium and magnesium zirconates, cobaltzirconia and magnesium aluminates. The sprayed refractory could moreover be selected from refractory silicides, borides, nitrides and carbides. WHAT WE CLAIM IS:

1. A stationary valve plate for use in a sliding gate valve for controlling molten metal flow, the stationary plate in use having its underside in contact with a slidable valve plate operable to control the flow through the valve, the stationary plate being male from flat steel plate and having an orifice inset from its periphery in which an annular refractory insert is retained, the insert being flush with the underside of the stationary plate and at least the underside of the steel plate being in a surface hardened condition.

steel plate is flame hardened, carburized or nitrided to achieve the surface hardened condition.

14. An assembly according to any one of Claims 9 to 13, wherein the upper surface of said steel plate is also in a surface hardened condition.

15. An assembly according to any one of Claims 9 to 14, wherein the refractory insert in either or both of the plates is detachably retained in the plate orifice by frangible heat-resisting cement.

16. An assembly according to any one of Claims 9 to 15, wherein the refractory insert in either or both of the plates is detachably retained in the plate orifice by a refractory mastic composition.

17. An assembly according to any one of Claims 9 to 16, wherein the plate orifice in either or both of the plates is frustoconically tapered and the insert therefor has a correspondingly tapered outer peripheral surface.

18. An assembly according to any one of Claims 9 to 17, wherein the underside of the steel valve plate has one or two recesses which extend away from the plate orifice, and one or two flat refractory elements forming a contact surface for the slide plate are secured in the recess or recesses.

19. An assembly according to any one of Claims 9 to 18, including a gas supply channel extending through the steel valve plate for conveying a pressurised gas into the refractory insert thereof, which is internally grooved, or is gas permeable, or is furnished with an inner gas-permeable lining, in use for creating a gaseous shroud between flowing molten metal and the inner wall of the annular insert.

20. A sliding gate valve including a stationary valve plate as claimed in any one of Claims 1 to 8, or an assembly as claimed in any one of claims 9 to 19, an orificed slide plate, and means biasing the slide plate into firm face-to-face contact with the underside of the stationary valve plate, the slide plate being movable reciprocally to and fro along a path of a given length to open and close the valve, and the stationary valve plate being dimensioned larger than the path swept by the slide plate whereby, during reciprocation, the slide plate remains fully in supported contact with the overlying stationary valve plate.

21. A valve according to Claim 20, wherein the slide plate has a plurality of orifices and a plurality of teeming nozzles.

22. A valve according to Claim 20, wherein the slide plate is sandwiched between the said stationary valve plate and a stationary orificed lower valve plate, the lower valve plate being biased upwardly to urge it, the slide plate and the said stationary valve plate into firm face-to-face contact with one another.

23. A valve according to Claim 20, wherein a recess is provided in a surface of either or both of the stationary valve and slide plates and is filled with a thermallysprayed deposit of a wear and erosion resistant refractory material.

24. A valve according to Claim 23, wherein the sprayed refractory is selected from fused alumina, zircon, zirconia, chromia, titania and magnesite.

25. A valve according to Claim 23, wherein the sprayed refractory is selected from mixed oxides including aluminatitania and alumina-chromia.

26. A valve according to Claim 23, wherein the sprayed refractory comprises a directly-sprayed cermet or a plurality of alternately sprayed layers of metal and refractory material.

27. A valve according to Claim 26, wherein the deposited refractory is selected from the zirconates of calcium, strontium, barium and magnesium, cobalt-zirconia and magnesium aluminates.

28. A valve according to Claim 23, wherein the sprayed refractory is selected from refractory silicides, borides, nitrides and carbides.

29. A stationary valve plate for a sliding plate valve, substantially as herein described with reference to Figures 2 and 3 of the accompanying drawings.

30. An assembly comprising a mounting plate and a stationary valve plate for a sliding gate valve, substantially as herein described with reference to Figures 2 and 3 of the accompanying drawings.

31. Sliding gate valves substantially as herein described with reference to Figure 1 when modified in accordance with Figures 2 and 3 of the accompanying drawings.

32. A molten metal pouring vessel when fitted with a valve as claimed in any of Claims 20 to 28 or Claim 31.