GB2217815A

GB2217815A - Pressure relief valve

Info

Publication number: GB2217815A
Application number: GB8908769A
Authority: GB
Inventors: George Lambert
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-04-22
Filing date: 1989-04-18
Publication date: 1989-11-01
Anticipated expiration: 2009-04-18
Also published as: GB8809620D0; GB8908769D0; GB2217815B

Abstract

A spring-operated pressure, relief valve for pressure vessels, comprises a valve closure head 4 located in a cavity 19 recessed below the outer rim of the surrounding body 1, by which it is fitted to the pressure vessel. The cavity is preferably provided with a drain channel (23 Fig 2) to allow removal of liquid from around the valve head and seating, so avoiding freezing. The valve body 1 is preferably of integral construction, e.g. made by casting, and can incorporate a bursting disc seating 1b, also preferably integrally formed with the body. The operating spring 6 may be enclosed to protect it from contact with the contents of the vessel, and the valve body is preferably of low profile and attached to the vessel by a series of countersunk bolts. A monitoring channel 15a in the outer part of the valve body communicating with a pressure gauge 15, can be made easier to clean by aligning it with the bursting disc seating aperture. <IMAGE>

Description

Title: Relieving Toxic and Other Gases from Containers.

This invention relates to a method and apparatus for relieving toxic and other gases from containers, and more particularly it relates to improved pressure relief valves and their construction.

It is well known to fit pressure relief valves to vessels and containers containing liquids or gases so that these are retained under normal working conditions but, when the vapour pressure of the substance within the container exceeds a predetermined limit, the valve opens to allow gas and/or liquid to escape through it and so relieve the excess pressure. The control of internal pressure within vessels is also commonly achieved by use of a bursting disc, which is made so that it ruptures at some predetermined pressure and allows contained materials to escape through it. The contained material released by the opening of the relief valve and/or the rupturing of the bursting disc may escape directly to atmosphere or may be directed through a receptor vessel or other containment system when discharge to atmosphere is considered undesirable.

These devices are useful as a means for protecting the vessels or containers from excessive internal pressures which could lead to damage of the vessel (even its destruction) and an uncontrolled escape of the contained material. Control of the escape of the contained material is especially important when it is hazardous, for example toxic or inflammable.

The conventional pressure relief valves are not entirely satisfactory, however, for a number of reasons. For example, an escape of gas or volatile liquid may be on such a massive scale that very high speed flows occur, even above the speed of sound.

Similarly, the amount of a volatile liquid evaporating may produce a rapid chilling effect, and if its latent heat of vapourisation is high enough evaporation may even produce cryogenic temperatures.

These conditions impose severe demands on the materials of construction and the form and operation of the valve so great care has to be taken to ensure that they are able to withstand such conditions satisfactorily. Very high speed flows can erode or damage the valve or other equipment, and subjection to very low temperatures can cause some materials (e.g. carbon steels) to be seriously weakened or embrittled.

Another problem can arise if the valve is exposed to cold conditions when in use. This is the risk of water collecting around the valve seating and freezing, with the result that the correct opening of the valve is impeded and the desired escape of material cannot take place when the predetermined pressure is reached. This results in an excessive build up of pressure within the vessel, beyond the design limit and possibly beyond the safe limit, with consequent risk of rupture of the vessel and all the consequences which can follow an uncontrolled release of hazardous materials.

Other problems can arise from the fitting of the valve unit in relation to the vessel, as conventional forms of valve usually protrude considerably from the body of the vessel to which they are fitted, and so are very susceptible to damage. Furthermore, the conventional mode of fitting, with the bursting disc inside the vessel, can present problems in the routine examination or the replacement of the bursting disc. In particular, the official regulations governing procedures for making a new pressure test, after certain seals have been broken or items disconnected, can be very time-consuming and troublesome.

I have now found that pressure relief valves can be improved so that they no longer suffer from such disadvantages.

Thus according to the present invention I provide an improved spring-operated pressure relief valve which comprises one or more of the features: (a) a low exterior profile, and especially a construction in which the head of the valve itself is recessed below the surrounding valve body; (b) means for draining the external cavity containing the valve head, so as to allow for the removal of water and other liquids and prevent their accumulation, (c) a form of valve body construction which is made integrally (i.e. by non-welding techniques) so as to avoid or minimise the potential weaknesses liable to arise from welding and other conventional joining techniques, Thus, in its simplest form, the invention provides a springoperated pressure relief valve which is constructed so that the head of the valve itself is recessed below the surrounding valve body.

It is an especial advantage to make the valve so that the cavity in which the valve head is recessed and also is provided with a drain channel to allow removal of liquid from around the valve head and its seating.

It is preferred that the improved valve, provided according to the present invention, comprises all three features (a), (b) and (c) above, but feature (c) (non-welded construction) is especially important because the use of welding - though conventional and usually regarded as unavoidable - has the marked disadvantage of causing distortion (which can reduce seriously the accuracy of construction) and potential weakness (which can be especially troublesome and hazardous in crucial positions such as the locating of a bursting disc seating).

The invention also provides a spring-operated pressure relief valve which is constructed so that it has a body construction which is made integrally, without welding. This may be done most conveniently by casting techniques, and then finishing the cast body by machining the various surfaces and apertures as required.

For the purposes of this invention, the "body" of the valve is to be regarded as comprising at least those parts of the vlave which provide the seating for the valve head and the means for attachment to the pressure vessel (i.e. the portion which sits upon and is fixed to the so-called "tank pad").

The invention provides the complete valve assemblies as such, but also provides the components therefor, and especially the integrally formed body components.

The materials of construction for the valve body according to this invention may be any of the conventional ones, for example metals (especially alloys) which have the desired properties in use (strength, resistance to corrosion, resistance to wear and fatigue, etc..) as well as the appropriate properties for integrated fabrication, especially by casting.

A preferred form of the invention comprises a spring-operated pressure relief valve which is constructed so that it includes a seating for a bursting disc. This seating is most advantageously positioned so that it is within the vessel when the valve is in use on a vessel. Preferably, in this embodiment, the bursting disc seating is also made integral with the rest of the body, i.e. an integrated construction of the valve body is employed to include the seating for a bursting disc.

The construction of the valve according to the present invention has the advantages of increased robustness and less risk of damage of the vital valve head, through it being positioned in a recessed manner, and also a greater strength and reliability through being being of integrated construction. In addition, the recessed positioning of the valve head results in the great advantage that any contents of the vessel which are vented through the device are deflected away from the vessel instead of laterally, as is the case for most conventional valves.

A further advantage which arises from the incorporation of the bursting disc housing within the vessel is the facility to examine or replace the bursting disc from inside the vessel without having to resort to the conventional procedures of removing the entire valve assembly from the vessel. This allows the work to be done with considerable saving of time and expense which would normally be involved as a result of the need to test and get approval of the assembly when it is re-fitted to the vessel. Also, as some valve assemblies can be very heavy, weighing several hundred kilograms, the need for sturdy lifting equipment every time they have to be removed and replaced is something which users prefer to avoid or, at least, to minimise.

According to the present invention the said valve construction may also be improved by provision of a channel for the connection of a monitoring device, for example a pressure gauge or a sampling device, disposed so that it can be cleared from the inside of the vessel while the valve is fitted in position therein.

This may be achieved by making the said channel (conveniently referred to as "the monitoring channel") so that it lies at an angle to the axis of the valve assembly, inclined inwardly towards the vessel interior, and is substantially aligned with the opening of the bursting disc housing. This is in distinction from the conventional alignment of such a channel, which is substantially transverse to the axis of the valve assembly, so that it is aligned in a direction which does not allow easy access from the inside of the valve body (for example through the opening of the bursting disc housing) and so cannot coincide with the opening of the bursting disc housing and prevents any access from the said opening of the bursting disc housing.As can be appreciated, such a conventional alignment prevents any clearing device being inserted into the channel except from the outside of the valve and the vessel, so that any efficient clearing of the channel can only be achieved by inserting the clearing device from outside or by removing the valve from the vessel so that the clearing device can be inserted from the interior of the valve body.

Insertion of a cleaning device from the interior is far better than insertion from the exterior, for example because the channel commonly narrows from a wide outer opening (suitable for receiving the pressure gauge or the like) to a very narrow channel at the inner end communicating with the interior of the valve body, so that forcing a cleaning device in from outside is liable to force dirt and contamination into the valve body and damage or block the channel.

As a further preference, the spring-operated pressure relief valve also incorporates means for partly or completely enclosing the spring actuating mechanism of the valve. By partly enclosing the spring mechanism, it is at least protected from mechanical damage, for example in storage or installation in the pressure vessle in which it is to be used. Advantageously, however, it may be enclosed within a sealed container, within the vessel, to protect it from contact with the contents of the vessel. Most advantageously, this container for the valve spring actuating mechanism is sealed so that it provides a seal not only against access of the contents of the vessel but also against any such contents which may enter the space between the bursting disc and the valve seating.

Further advantageous features for inclusion in the pressure relief valves of this invention include construction of the valve body so that the chamber between the bursting disc and the valve head is adapted to drain any liquid contents out through the bursting disc seating aperture when the bursting disc is removed.

Still better, the draining arrangement should be adapted to drain any liquid contents sufficiently to clear the entrance to the enclosure containing the operating spring assembly.

This can be achieved very simply by constructing the bursting disc seating aperture so that it is inclined to the valve body so that the axis of the bursting disc aperture is inclined downwardly from the horizontal when the valve is fitted in a vessel.

In order to ensure that access from within the vessel to remove, replace or examine the bursting disc is assured, the securing bolts of the ring or other securing means around the bursting disc seating should be clear of any part of the vessel mounting on which the valve is fixed (the "tank pad").

Also, the mode of fixing of the valve body to the "tank pad" can be greatly improved by making the uppermost part of the valve body as a rim adapted to be secured to the seating on the vessel to which it is fitted (the "tank pad") by countersunk bolts which are recessed into the outer rim of the valve body. The use of countersunk bolts not only provides a secure fixing but also serves to keep the profile of the valve assembly as low as possible.

To improve the arrangement still more, I prefer that the countersunk bolts are not only recessed into the outer rim of the valve body but are also disposed in a single circular arrangement around the said outer rim. This arrangement allows for a good sound form of construction, in which the number of bolts can be sufficient to give the desired strength without weakening the valve body, and also allow more room for a cavity or recess within the top of the valve body which can then be of adequate size to allow any venting of the contents of the vessel (i.e. in the event of the bursting disc being ruptured) to be as unimpeded as possible. Many known designs of valve do not satisfy this requirement, as they can restrict the outflow of vapour.

The optimum construction of the valve of the present invention includes the feature of the valve head being in a cavity recessed below the outer rim of the valve body. This helps to protect the relatively delicate parts of the valve, i.e. the valve head itself, and also helps to keep the profile low.

To avoid the problems of freezing of trapped water in cold weather, the valve body should be constructed so as to include, for the cavity in which the valve head is recessed, a drain channel to allow removal of liquid from around the valve haed and its seating.

Also, it is desirable to shape the interior of the cavity in which the valve head is recessed so that any vessel contents vented by operation of the valve head are guided and ejected in an upward direction away from the valve body and the vessel to which it is fitted, preferably with a venturi action to improve the ease of flow. Much of this "upward and away" flow is inherent in the basic formation of the cavity as discussed above, but the flow characteristics can be improved by designing the shaping of the internal cavity or recess to minimise the resistance to vapour flow.

The integral construction of the valve body has many advantages which are substantial and significant. It not only eliminates a lot of precision machining, welding and the testing of such welds, followed by remachining to ensure correct alignment, but also reduces the number of components which have to be made and assembled. It eliminates the costly purchase of separate bursting disc holders for every type of disc, as it reduces requirements to a detachable flange manufactured to mate with the integral seating and standard discs can be used; the acceptable face tolerances are already established in the integrally machined seating of the valve body according to my invention.

More important, however, is the elimination of the need for a separate top flange and its ring of securing bolts (attaching the flange to the body) with the problems of strength and reliability associated with construction by previous methods. The form of construction used in the present invention also adds considerably to the ease of escape of vapours, partly through the ability to provide an increased efflux area and increased escape diameter virtually throughout the whole flow channel through the valve assembly.

The invention is illustrated but not limited by the accompanying drawings, which are not drawn to scale.

Figure 1 represents a vertically sectioned perspective view of a pressure relief valve according to the invention, incorporating a bursting disc and shown in position on a vessels tank pad.

Figures 2 and 3 represent vertically sectioned perspective views of alternative forms of pressure relief valve according to the invention, incorporating no bursting disc and shown in position on a vessel's tank pad, and secured thereon in Figure 2 by bolts and in Figure 3 by a screwed-in connection.

Figure 4 represents similarly an alternative form of pressure relief valve according to the invention, in which the spring mechanism is protected by being partly enclosed though not totally sealed against contact with the contents of the pressure vessel.

In Figure 1, the relief valve assembly comprises a main hollow body section (1), formed integrally by casting, and machined on its lower end to form a flange (la) and at its side to form a second flange (lb) which serves as a seating or port for attachment of a bursting disc.

At its lower end a hollow tubular section or casing (2) is attached, closed at one end (its lower end) and machined at the other end (its upper end) to form a flange (2a). Flanges (la) and (2a) are formed so as to join together to form a sealed interface, their sealing being assisted by bolting together or screwing together (by bolts or screw threads, not shown), and with a gasket or sealant material (for example mastic) between them (also not shown).

The bursting disc (10) is secured in place on the seating or port (lb) by a surrounding collar or holder (11) held down by bolts (12). Sealing may be assisted by a gasket or sealant material (for example mastic) between them (not shown).

The uppermost part of the body (1) is topped by a broad flange or collar (20) with a central recess (19) surrounded by a wide rim (21) of sufficient size to overlap the aperture in the vessel to which it is to be fitted and to accommodate a series of countersunk bolts (13) spaced evenly around the central recess (19). Within the main body (1) is a central valve stem (3), to which is secured at its upper end (most conveniently by screw-threaded attachment) a valve head (4) which seats within a centrally placed aperture in the central recess (19). The seating of the valve head (4) against the bottom of the central recess (19) is shaped for example by suitable machining of the contacting faces to form a substantially gas-tight seal.

The lower end of the valve stem (3) passes through a seal (17) set in the lower end of the body section (1), the seal comprising a valve stem guide hole and a surrounding packing compressed by a screwed collar (17a). The lower end of the valve stem (3) extends through the seal (17) into the lower tubular body (2) and extends downwardly for most of its length in a guide tube (5) secured to the lower face of the body (1) and is surrounded by a helical spring (6) held in place in a compressed state so that its upper end presses against a rebate in the lower face of the body (1) and its lower end presses against a bottom locating collar (7) held in place by an adjustable locking nut (8). The locking nut (8) is provided with a seal wire (9) which passes through holes in the nut (8) and the lowermost end of the stem (3).

The main collar (20) sits upon the area of the tank shaped to receive it (usually a thick strong ring of metal (14) having a flat surface designed to accept the valve collar (20), welded into the tank aperture, and commonly described as the "tank pad"), and secured in place by the countersunk bolts (13) passing through the collar (20) and into the tank pad (14). A sound gas-tight seal of the interface between collar (20) and tank pad (14) is assisted by a gasket or jointing material (16) compressed by the tightening of the bolts (13).

In the collar (20) is fitted a pressure gauge (15) so that it copltrnunicates with the interior of the main valve body (1) by way of a hole (15a) drilled through the mass of the collar (20) at an angle such that it is substantially in line with the bursting disc port (lb). Optionally, this hole (15a) may communicate with the gauge (15) by way of a restrictor (not shown) which serves to protect the gauge.

For assembly, the valve stem lower section (3) is passed through the seal (17) and the helical spring (6) is fitted around the lower valve stem guide tube (5) and its compression adjusted by the bottom locating collar (7) and secured by locking nut (8) and seal wire (9). The valve head (4) is thus forced by the spring (6) into sealing engagement with the aperture in the central recess (19) and the valve stem guide tube (5) and helical spring (6) are enclosed by casing (2), which is secured by flange (2a) to flange (la) of the main body (1). This protects the spring from access of materials which may be corrosive. The bursting disc (10) is secured in place on seating (lb) by bolts (12) and holder ring (11). The whole assembly is secured in place on the tank pad (14).

In use, the contents of the pressure vessel to which the valve assembly is fitted are retained by the bursting disc (10) and are barred from access to the spring (6) or the valve head (4). When the pressure within the vessel exceeds the set working limit of the bursting disc (10), the disc bursts and releases the vessel's contents into the space within valve body (1), and the resulting increased pressure therein raises the valve head (4) against the action of spring (6) and vents the contents through the recess (19). The shape of the recess causes the contents to be vented in a direction away from the body of the vessel (i.e. upwards in the drawing, indicated by efflux zone (22)).

A marked advantage in use is that the line (15a) to gauge (15), being aligned with the bursting disc port (lob), can be cleaned by a wire or the like inserted via that port, and also that the shaping and positioning of the port (lb) allow the bursting disc to be removed for examination or replacement by simple access from the interior of the vessel without having to break the seal at joint (16) as the securing bolts (12) are aligned to clear the lower face of the tank pad (14). Also, by making the port (lob) so that its lower edge is level with the bottom of the cavity in the body (1) and at a slight declining angle, any liquid contents in the cavity within (1) easily drain back into the vessel and so do not accumulate there.

In Figures 2 and 3, the form of relief valve shown has no bursting disc and the helical spring (6) is not enclosed in a casing. The various parts and their functions are essentially the same as for the embodiment shown in Figure 1, except that the contents of the vessel have access by way of openings (lc) in the main body (1) to the lower face of the valve head (4) and the venting of the vessel occurs when the internal pressure reaches a limit which is sufficient to overcome the helical spring (6) and so lift the valve head (4) from its seating.

Drainage channels (23) are provided through the collar (20), usually as drilled holes, to allow any liquid in the recess (19) to run away and not accumulate therein. These drainage channels are shown as extending from the recess (19) to a gap (24) between the collar (20) and the tank pad (14), but if desired may be formed through the whole of the collar (20) to its outer edge.

In Figure 3, the construction shown uses an alternative method for securing the assembly in place on the tank pad, i.e. the body (1) is made to engage the inner rim of the tank pad by a screwthreaded attachment (25) - thus dispensing with the use of securing bolts (13) - and the top of the body (1) is provided with a series of slots (26) to form a castellated top which can be engaged by conventional means for the purpose of screwing the body into and out of the tank pad. In this form of attachment to the tank pad. the screw connection my be made using a tapered or nontapered screw formation, as may be desired according to the wishes or requirements of any particular user.

In the drawings, the direction of flow of contents from the vessel on venting is shown by the arrows.

A spring limiter (18, in Figure 1) to prevent total spring compression to a solid state - whilst not always necessary - may be fitted between the locating collar (7) and lower guide tube (5).

In Figure 4, there is shown an alternative construction in which the various parts and components are given numbers which correspond to the numbers as used in the previous Figures 1 to 3.

In Figure 4, the construction shown uses an alternative construction for securing the bursting disc in place and for providing some protection for the spring. Though it does not protect the spring from physical contact with the materials (e.g.

liquid or gaseous chemicals) within the vessel, nevertheless it does provide useful protection against physical damage from impact (especially lateral impact) which may be encountered during storage and/or fitting of the valve in a vessel.

The valve comprises a tubular extensdion of the body (1) with a thickened zone (2) at its lower end, to which a bursting disc assembly can be attached. This comprises a bursting disc (10) held in position against the bottom rim (2) by a sealing ring (11) secured by bolts (12).

The valve stem (3) carries a valve head (4) at its upper end, and fits within a guide sleeve (5) surrounded by a helical spring (6). The spring (6) abuts against an adjustable lower bearing plate (7), secured in position by lock-nuts (8 and 8a) screwed on to the threaded lower end of the spindle (3), and also abuts against the underside of an upper bearing plate (7a) in which is formed a series of apertures (7b).

The uppermost part of the valve body is essentially the same as in Figure 1, with the main collar (20) sitting on the tank pad (14) and secured thereon by countersunk bolts (13) and sealed by a gasket (16).

In assembly, the lower, subsidiary, part of the valve body (1) may be constructed from tubing of adequate strength and secured to the upper part of the body and to the bottom rim (2) by welding or the like. (It is in the uppermost parts, where the valve body fits in to the aperture in the tank and is secured to the tank-pad, that the strength is mainly needed; the lowermost parts are not under tension, only under compression) The upper bearing plate (7a) with apertures (7b) is a loose fit within the hollow bemneath the collar (21) where it narrows to form the seating for the valve head (4). When the body and lower rim (2) are assembled by welding, the body becomes integral and so traps the plate (7a).This is normally no disadvantage, as the head, spindle, spring can all move freely within the body cavity, and the end of the spindle and the lock-nuts can be accessed through the opening in the bottom, where the bursting disc is fitted.

If desired, however, the lower part of the body (1) may be attached in a detachable manner (e.g. by a screw threaded connection - not shown) provided this is at a position which does not weaken the assembly as a whole.

In operation, the whole assembly is fitted into position on the tank pad, as described above, and the bursting disc is secured in place by ring (11) and bolts (12). The tensioning of spring (6) is adjusted (present) so that it will allow the valve head to lift at a pressure which is less than that at which the bursting disc is set to rupture - usually by a suitable safety margin (preferably at least 10% less than the bursting disc's rupture rating).

Then, when the pressure within the vessel rises to that at which the bursting disc ruptures, the contents of the vessel flow upwardly, in the direction indicated by the arrows, past the spring (6) and on outwards through the apertures (7b) in the seating disc (7a), and then past the periphery of the valve head (4), and finally in an upwardly direction (22) to escape to atrosphere.

The advantages of this form of construction are that the flow of the vessel's contents in a general upwardly direction is substantially unimpeded and does not have to make radical changes of direction (which could tend to restrict the flow), while the whole of the valve assembly (valve head, valve stem and helical spring) are safely contained within the protection afforded by the body (1) and collar (20).

Claims

WHAT I CLAIM IS:

1. An improved spring-operated pressure relief valve which comprises one or more of the features: (a) a low exterior profile, and especially a construction in which the head of the valve itself is recessed below the surrounding valve body; (b) means for draining the external cavity containing the valve head, so as to allow for the removal of water and other liquids and prevent their accumulation; or (c) a form of valve body construction which is made integrally (i.e. by non-welding techniques) so as to avoid or minimise the potential weaknesses arising from welding and other conventional joining techniques.

2. Pressure relief valve as claimed in Claim 1 wherein the valve head is in a cavity recessed below the outer rim of the valve body, and the cavity in which the valve head is recessed is shaped so that any vessel contents vented by operation of the valve head are guided and ejected in an direction (e.g. upwards) away from the valve body and the vessel to which it is fitted, preferably with a venturi action to improve the ease of flow.

3. Pressure relief valve as claimed in Claim 1 or Claim 2 wherein the cavity in which the valve head is recessed is provided with a drain channel to allow removal of liquid from around the valve head and its seating.

4. Pressure relief valve as claimed in Claim 2 or Claim 3 which comprises a valve body which is of substantially integral non welded construction, for example made by a casting technique.

5. Pressure relief valve as claimed in any one of Claims 1 to 4 wherein the valve body comprises a bursting disc seating which is also preferably made integral with the rest of the body,

6. Pressure relief valve as claimed in any one of Claims 1 to 5 wherein the valve body incorporates a monitoring line or channel communicating between the exterior of the valve body when mounted on a vessel and the interior cavity of the valve body, said monitoring line or channel being inclined downwardly so that is substantially aligned with an aperture in the valve body which is inside the vessel when the valve is installed for use, and the said line or channel is thereby accessible for cleaning by way of said aperture without the requirement to remove to valve body from the vessel to gain such access.

7. Pressure relief valve as claimed in any one of Claims 1 to 6 wherein there is incorporated an operating spring assembly which is enclosed within a protective enclosure within the vessel when the valve is installed in a vessel for use.

8. Pressure relief valve as claimed in Claim 7 wherein the protective enclosure for the operating spring assembly, within the vessel, is sealed from the adjoining cavity within the valve body, for example the chamber between the bursting disc and the valve head.

9. Pressure relief valve as claimed in any one of Claims 5 to 8 wherein the bursting disc seating aperture is inclined to the valve body so that the axis of the bursting disc aperture is inclined downwardly from the horizontal when the valve is fitted in a vessel.

10. Pressure relief valve as claimed in any one of Claims 1 to 9 wherein the valve body is adapted to be secured to the seating on the vessel to which it is fitted (the "tank pad") by countersunk bolts which are recessed into the outer rim of the valve body.

11. Pressure relief valve as claimed in Claim 10 wherein the countersunk bolts which are recessed into the outer rim of the valve body and disposed in a single circular arrangement.

12. Pressure relief valve substantially as described with reference to any of the accompanying drawings.

13. Components, for example integrally formed body components, for a pressure relief valve as claimed in any one of Claims 1 to 12.